# MagicShine battery dissection / testing



## baker (Jan 6, 2004)

I have 7 MagicShine batteries...yikes! They've generally worked fine for me. No fires, etc. However, on my 24 Hour solo race in September, I had 2 batteries that flaked out on me way before I would have expected. One was a friend's that I borrowed and one was mine. I had charged all of the batteries to the green light stage prior to the race.

Fast forward to this week when I received an RC battery hobby charger (much more complex and feature laden than the standard MS charger). Due to the recent battery issues, I also started reading more about li ion batteries and realized they shouldn't be stored in full state for long periods of time.

So, after testing the new hobby charger for charging, I decided I'd use the "storage" feature and discharge most of my packs to the recommended state. Well, one of the packs kept coming up with "connection broken" when I attached it to the hobby charger.

Plug it into the MS charger, green light. Plug it into the light head, functional. Strange. I figure with 7 batteries (not all purchased from Geoman), I'll sacrifice this one and dissect it to see what's up.

Surprisingly, the plasti-dip just peels off (once you get it started enough to grab onto). I slit open the shrink wrap and the insides look just as I'd expect: 4 2200mah 18650 cells wired 2s2p, with a protection circuit.





The sketchiness reveals itself when I put the voltmeter on the cells. The whole pack tests to 8.14V, which would seem ok. However, testing the individual cells reveals some issues: 4.27V, 4.27V, 3.86V, 3.86V. Completely unbalanced, with two cells significantly overcharged and two significantly undercharged. Yikes!

I actually have 20 RC car balance leads on their way to me in the mail and will install them into this pack (and maybe all the rest that don't get covered under the recall). The balance leads in conjunction with the RC hobby charger should provide a much safer method of charging these batteries. I may need to replace the protection board on this one too. Not sure what's up with the connection broken message...


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## circusubet (Aug 5, 2006)

*Updates*

Bakes,

Would you be kind enough to keep us updated? Link to the charger? Great pics.

Thx,
John


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## linger (Nov 10, 2010)

Baker,
Bravo, you are doing the right thing.
Keep in mind that the RC "Balance" chargers do the balancing by switching in a small relay to bleed current from the higher voltage cell. It works well for small imbalances. However, your cells are VASTLY imbalanced. 
The current bleed is usually small - around 200 mA. If you are charging at 1A, the 200 mA may not be significant enough for such a big imbalance. In order for the charger balancer to work well with such a big imbalance, you will need to charge at a low charge rate. I'd start it at a small .3 - .4 amp charge rate.


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## baker (Jan 6, 2004)

circusubet said:


> Bakes,
> 
> Would you be kind enough to keep us updated? Link to the charger? Great pics.
> 
> ...


Sure. I picked up a Sky Charger B6AC.


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## baker (Jan 6, 2004)

linger said:


> Baker,
> Bravo, you are doing the right thing.
> Keep in mind that the RC "Balance" chargers do the balancing by switching in a small relay to bleed current from the higher voltage cell. It works well for small imbalances. However, your cells are VASTLY imbalanced.
> The current bleed is usually small - around 200 mA. If you are charging at 1A, the 200 mA may not be significant enough for such a big imbalance. In order for the charger balancer to work well with such a big imbalance, you will need to charge at a low charge rate. I'd start it at a small .3 - .4 amp charge rate.


Thanks Linger. That is good info that I did not know.


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## MtbMacgyver (Jan 23, 2007)

Here's a post I put in the Magicshine Light Announcement thread with relevant information.

http://forums.mtbr.com/showpost.php?p=7510498&postcount=30

You can balance charge the pack if you install a balance connector, but it won't stay in balance because of the soft shorts in the cells. You'll have to keep balance charging it to keep it in balance. These kind of soft shorts are typically caused by metal particle contamination during the manufacturing of the cells. They can lead to real shorts in the cells which can cause serious safety issues. This is exactly what cause the fires and recalls of a bunch of laptops a few years back. So balancing will bring back the runtime of the pack, but it won't necessarily eliminate the potential safety issues.

Also, there are two different types of RC balance chargers. Some work as Linger describes by applying a small balance current during the charge process to equalize the cells. The other type charges each cell completely independently. This second type will always balance the pack in a single charge cycle no matter how far the pack is out of balance. This second type of charger does all the charging through the balance connector.


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## baker (Jan 6, 2004)

Once the balance connectors are installed, I plan to always balance charge them. Is there any reason not to? 

Assuming I continue to balance charge the packs, have I (mostly) eliminated the safety issues? Or, are my batteries poked because they've been run unbalanced for a length of time?

My charger works by connecting the power taps and the balance connector...

Thanks for the info.


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## linger (Nov 10, 2010)

baker said:


> Once the balance connectors are installed, I plan to always balance charge them. Is there any reason not to?
> 
> Assuming I continue to balance charge the packs, have I (mostly) eliminated the safety issues? Or, are my batteries poked because they've been run unbalanced for a length of time?
> My charger works by connecting the power taps and the balance connector...
> ...


Baker,
That Macgyver guy is spot on.
There is no reason not to balance charge.
Balance charging eliminates some of the safety risks (overcharge) but not all (internal shorting).
Since the cells were not balanced before, one cell got overcharged multiple times and one cell probably got overdischarged multiple times.

You can check for internal shorting by doing a balance charge and monitoring the voltage over time. Usually this is the last step in a battery manufacturing plant that is accomplished during the formation process. All too often, it's skipped due to the time constraint. If the battery voltage on one cell drifts downward significantly more than the other over time - you have a soft short. Soft shorts lead into big shorts. There is nothing you can do about this and you might as well donate the pack to that annoying kid across the street.

Even if the voltage stays constant - the cells are still at risk.

When a cell is overcharged multiple times, you get lithium metal plating that starts to occur. Every overcharge cycle plates more and more until it pokes through the separator and creates a short. The anode/cathode expands at different rates during the charge/discharge cycle and imperfections will wear through the seperator.

When a cell is overdischarged, the copper anode literally starts dissolving within the electrolyte and then it recrystalized elsewhere and may also result in a short. You will loose a significant amount of capacity in that cell (which makes the problem worse the next cycle since you will hit the overdisscharge voltage even sooner).

Good luck!


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## Francis Cebedo (Aug 1, 1996)

baker said:


> Once the balance connectors are installed, I plan to always balance charge them. Is there any reason not to?
> 
> Assuming I continue to balance charge the packs, have I (mostly) eliminated the safety issues? Or, are my batteries poked because they've been run unbalanced for a length of time?
> 
> ...


If you have a balancing charger, then it's not much trouble to balance them every time. The only downside is it takes longer to charge them each time. In the RC world, balancing is only needed every 10-20 charges.

But with these cells, they're so out of whack it's probably a good idea to balance every time. Also, charging time is not big deal. Your charger is probably way faster than your Magicshine charger anyway.

The big sign that your cells are going bad is if they don't hit 4.2 volts during a charge cycle. Or if they're way imbalanced after a discharge cycle, that's bad too.

fc


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## baker (Jan 6, 2004)

Wow, great info. Thanks linger, Mtbmacgyver, and francois. 

While all of this MS battery stuff is being worked out, I've acquired a Supernova E3 Triple for my bars and a Turnigy 5800mah li poly battery for one of my Magicshines. Those, in conjunction with the RC charger, should allow me to safely ride through the winter (well, thru just about anything really). 

As Francois mentioned, the RC charger can charge really quickly. I'm amazed at the charge rating for some of these RC packs. My battery is "only" rated to 2C charge. Some of the bigger more expensive ones are rated to 10C. That is crazy fast charging.


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## Francis Cebedo (Aug 1, 1996)

baker said:


> Wow, great info. Thanks linger, Mtbmacgyver, and francois.
> 
> While all of this MS battery stuff is being worked out, I've acquired a Supernova E3 Triple for my bars and a Turnigy 5800mah li poly battery for one of my Magicshines. Those, in conjunction with the RC charger, should allow me to safely ride through the winter (well, thru just about anything really).
> 
> As Francois mentioned, the RC charger can charge really quickly. I'm amazed at the charge rating for some of these RC packs. My battery is "only" rated to 2C charge. Some of the bigger more expensive ones are rated to 10C. That is crazy fast charging.


Always charge at 1C or less. For those not familiar, 1C charging is charging a 2200 mah battaery at 2200 mah. 2c is charging it at 4400.

Charging at more than 1C requires a fancy charger and it shortens the life of the battery (even if it is rated for it). It gets it out of balance quicker so balance charging is critical. And finally, charging at 2C doesn't cut your charge time in half. It only cuts it by 30%. And so on..

In RC, fast charging has some merit since you can charge faster and be ready for the next race qualifier, etc.

fc


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## baker (Jan 6, 2004)

francois said:


> Always charge at 1C or less. For those not familiar, 1C charging is charging a 2200 mah battaery at 2200 mah. 2c is charging it at 4400.
> 
> Charging at more than 1C requires a fancy charger and it shortens the life of the battery (even if it is rated for it). It gets it out of balance quicker so balance charging is critical. And finally, charging at 2C doesn't cut your charge time in half. It only cuts it by 30%. And so on..
> 
> ...


More good info. I feel like I'm in battery kindergarten. 1C is sure fast enough for bike use anyway.

Another cool thing I figured out with my new charger: it can be hooked up to my computer and I can capture data on charging, discharging, balance, etc. Pretty neat data.

Can I get a good idea of the relative capacity of a pack by running it through the discharge cycle and paying attention to the capacity graph?


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## circusubet (Aug 5, 2006)

*Charger*

Mac,

Just barely knowing what end gets hot on a soldering iron I hope you and others don't get tired of questions. I try and research before asking. That being said you mentioned,

" This second type of charger does all the charging through the balance connector", what type is this?

Since I plan on this for the long run, looking for a charger that will work for a few different types of batteries I may encounter, what is this charger you mentioned.

Is it possible to re-build the MS packs with new batteries or better to start with holders mentioned elsewhere?

Thanks in advance,
John


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## gticlay (Dec 13, 2007)

Ni-Cad has it's shortfalls but damn they were easy to use. Charge, fully discharge, repeat. They never blew up or burned houses with regular normal care 

I'm sort of afraid of my battery packs now.


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## Francis Cebedo (Aug 1, 1996)

circusubet said:


> Mac,
> 
> Just barely knowing what end gets hot on a soldering iron I hope you and others don't get tired of questions. I try and research before asking. That being said you mentioned,
> 
> ...


I would not recommend this at all!! This may work for Baker since he has 7 packs and is comfortable with soldering and volt meters, etc. Balancing a magicshine pack entails soldering wires to each cell then bringing them all out to an external plug. It is a very intensive and risky process. And at the end, these magicshine cells are still suspect.

The charger is a $60 device here http://www.amazon.com/Charger-Battery-Batteries-Charging-Software/dp/8499000193 but you will still need compatible charger plugs.

At the end of the day, I would say, Get a battery and charger from Jet Lites. They will have several levels of sophistication available and they are a good US company.

fc


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## Francis Cebedo (Aug 1, 1996)

If you are comfortable with chargers and lipos, I bought this last month and it is a staggering value.
http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=14988

Hobbycity is a Hongkong company that cells Lipos at 1/4 of what the US companies sell it at. I used to pay an arm and a leg for shipping but now they have a US distributor for some select products.

The key to Lipos is make sure to get one with a hard case for cycling use. Lithium Polymer (lipo) batteries are soft and can get damaged or shorted on impact.

I'll run this battery with the Magicshine or some equivalent light to get an idea of run time.

fc


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## MtbMacgyver (Jan 23, 2007)

circusubet said:


> Mac,
> 
> Just barely knowing what end gets hot on a soldering iron I hope you and others don't get tired of questions. I try and research before asking. That being said you mentioned,
> 
> ...


Here's an example of the type of charger that charges each cell individually through the balance connector. They actually aren't the most flexible type. They are typically dedicated to Lithium type batteries.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=2055

I'm not a big fan of using cell holders with individually protection Li-ion cells. There's nothing wrong with doing that from a technical point of view, it just requires too much work to keep cells together that are balanced from a capacity perspective. If you end up with mismatched cells, the pack will shutdown early when the protection in the weakest cell turns it off. My bias against cell holders may also be related to having 4 mountain bikers in the family and having to keep up with 12 packs. I'd rather get the packs setup right when I build them and then never mess with them after that.

Yes, it's certainly possible to rebuilt the magicshine pack with high quality cells. As long as the original charger is working ok, I don't see a problem with using it with a new pack.


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## BobRocket (Jul 19, 2004)

I would not recommend charging a battery pack at a higher rate unless you know the rated specification for the actual cells. High rate charges on low rate cells = disaster.

Most occurrences of flaming cells that vent occur during CHARGING, so be very, very careful tinkering with charging.

Not knowing exactly what you are doing and the repercussions of your actions when tinkering with balancers and rate of charge is a recipe for disaster or at least you are putting your health and well being at risk.

The pack that was opened in the OP has cells that are significantly out of balance. Given the cheap price of higher quality and much safer packs, that could replace this pack, the owner of that pack should simply discard the pack (recycle) it and eat the cost. Balancing a pack like that is far more work than what it is worth. Can't you just buy a new pack for the price of a balancer?

My advice is based on working in the lithium ion battery industry for 10 years. I have a very good understanding of what is happening in the case of this unbalanced pack and the efforts that are being proposed to fix the issue are not worth the effort and are somewhat dangerous if the person doesn't know 100% what they are doing.

I am just making recommendations that the give the highest degree of safety for the end user.


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## baker (Jan 6, 2004)

BobRocket said:


> I would not recommend charging a battery pack at a higher rate unless you know the rated specification for the actual cells. High rate charges on low rate cells = disaster.
> 
> Most occurrences of flaming cells that vent occur during CHARGING, so be very, very careful tinkering with charging.
> 
> ...


Well, I can certainly appreciate the caution...however, with 7 MagicShines packs, 2 other packs from batteryspace.com, and already owning an RC charger, I'll be giving the balance connector a shot. The cost of 20 balance connectors is less than $10, so it'll just be a small cost and effort for me to add balance connectors to my packs. Oh yeah, I'll need to pick up some shrink wrap from Batteryspace.com, too.

The pack in the original post may be a total loss, but I have 8 others that could have a more useful life with the addition of balance charging.


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## savagemann (Jan 14, 2008)

baker said:


> Well, I can certainly appreciate the caution...however, with 7 MagicShines packs, 2 other packs from batteryspace.com, and already owning an RC charger, I'll be giving the balance connector a shot. The cost of 20 balance connectors is less than $10, so it'll just be a small cost and effort for me to add balance connectors to my packs. Oh yeah, I'll need to pick up some shrink wrap from Batteryspace.com, too.
> 
> The pack in the original post may be a total loss, but I have 8 others that could have a more useful life with the addition of balance charging.


Got a link to where I can pickup those balance connectors?
I've been looking around a bit for some, and have come up fruitless thus far.


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## baker (Jan 6, 2004)

savagemann said:


> Got a link to where I can pickup those balance connectors?
> I've been looking around a bit for some, and have come up fruitless thus far.


http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9735

Chop off the one end and wire to your pack.

I have no idea how long it'll take to get these from HobbyKing. My battery only took like 3 days, but that was from their USA warehouse.


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## savagemann (Jan 14, 2008)

Sweet, thanx man. I had looked at those, but wasn't 100% sure if it was the right thing.


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## mczen (Mar 9, 2008)

"At the end of the day, I would say, Get a battery and charger from Jet Lites. They will have several levels of sophistication available and they are a good US company."

Fancois, are you saying we can just run MajicSHines off a Jet Lites battery?


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## Francis Cebedo (Aug 1, 1996)

mczen said:


> "At the end of the day, I would say, Get a battery and charger from Jet Lites. They will have several levels of sophistication available and they are a good US company."
> 
> Fancois, are you saying we can just run MajicSHines off a Jet Lites battery?


I think so! Let me ask David from Jet and let me test it out here at home.

fc


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## mczen (Mar 9, 2008)

Great! please keep us all posted and thanks for the info.


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## cycljunkie (Feb 6, 2004)

*Dinotte*

I read in another thread that the Dinotte 4 cell battery will work fine with the MS light head. $5 cheaper for battery and smart charger.


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## BobRocket (Jul 19, 2004)

cycljunkie said:


> I read in another thread that the Dinotte 4 cell battery will work fine with the MS light head. $5 cheaper for battery and smart charger.


You are correct. You can run an Magicshine off a Dinotte pack with no issues.

The Dinotte pack is well designed and built pack that is tested to be 100% water proof and dust proof. I highly recommend the Dinotte packs.


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## random walk (Jan 12, 2010)

I thought this was a clever web page:

http://scriptasylum.com/rc_speed/_lipo.html

Near the middle it shows how to wire up multiple packs to be balanced/charged using a single balancer unit. E.g.,

http://scriptasylum.com/rc_speed/_picture.html?bal_gen_2s2s_nomain.gif~14

Assuming a quality balancer-charger is used -- is this safe? Are there any drawbacks?


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## circusubet (Aug 5, 2006)

*Thanks linger, Mtbmacgyver, baker, walk, and francois*

Thankls to all you who sit and prolly answer the same damn questions all the time:madman:

Thanks to your patience.

John


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## circusubet (Aug 5, 2006)

*Another Darn Question*

Ok, I have been nosing around a bit and came upon this statement.

"mAh stands for Milliamp Hour, a technical term for how much power a particular battery will hold. Batteries with higher mAh values theoretically last longer without requiring a recharge. "

Soooo am I correct in thinking that a battery pack rated like, 7.4V 2400mAh rechargeable Li-ion 18650 battery pack, will not last as long as one rated at Li-Ion 18650 7.4V 8800 mAh PCB protected Rechargeable Battery?

Price naturally seems to escalate with the life of the battery pack?

Thank you one more time for your wisdom...

Thx,
John


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## BlownCivic (Sep 12, 2006)

A battery rated at 8,800 mAh will theoretically last 3.67 times as long as one rated for 2,400.


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## savagemann (Jan 14, 2008)

I'm no electronic expert, but correct me if I''m wrong here as this is how I've always thought mAh relates to stuff........
If your lights draws 1 amp on high, and you have a 4400 mAh battery, then in theory, you should get 4.4 hours of runtime....aside from whatever % efficiency the driver runs at. If it runs at 90% you can lop about 10% off that.
I am also assuming that PCB protection could lessen runtime even further by a small amount.
Does that should about right?


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## tgoff (Feb 7, 2010)

francois said:


> I think so! Let me ask David from Jet and let me test it out here at home.
> 
> fc


I would like to make a Y cable to run the Magicshine MJ-818 tail light off of the Jet Lites A-51.

Are the 2 pin waterproof connectors on this site the same as Jet Lites? http://www.batteryspace.com/water-proofconnectorscables.aspx I know the Trail Tech connectors are the same as on the Magicshine.

If they are not where could you get the connectors to make a Y cable to run the tail light.

Thanks


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## sandan (Feb 17, 2004)

BobRocket said:


> You are correct. You can run an Magicshine off a Dinotte pack with no issues.
> 
> The Dinotte pack is well designed and built pack that is tested to be 100% water proof and dust proof. I highly recommend the Dinotte packs.


Maybe a dumb question but are the Dinotte connectors the same as the MS connectors? Or is there some soldering to be done? 
[edit] Never mind I got the answer from another thread[/edit]


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## 96m2comp (Oct 12, 2007)

francois said:


> If you are comfortable with chargers and lipos, I bought this last month and it is a staggering value.
> http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=14988
> 
> Hobbycity is a Hongkong company that cells Lipos at 1/4 of what the US companies sell it at. I used to pay an arm and a leg for shipping but now they have a US distributor for some select products.
> ...


Francois: Any updates to using this pack from Hobbycity? Does the battery have any protection from over charging/discharging? What are you using for a charger?

Baker: That is very interesting in what you found voltage wise between each cell! Keep us posted as you "doctor" the pack please.

Chris


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## baker (Jan 6, 2004)

Got in the jst-xh wiring. Took about 5 minutes to wire up the pack. It's on the charger now. We'll see how it goes...


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## Francis Cebedo (Aug 1, 1996)

96m2comp said:


> Francois: Any updates to using this pack from Hobbycity? Does the battery have any protection from over charging/discharging? What are you using for a charger?
> 
> Baker: That is very interesting in what you found voltage wise between each cell! Keep us posted as you "doctor" the pack please.
> 
> Chris


No updates yet. I'll try tonight.

There is no charging/discharging protection for the Hobbycity lipo battery. This is true for any RC lipo battery.

For discharging, rc lipos depend on a lipo cut-off module usually part of the electronic speed control module. For charging, the rc chargers take care of charging protection.

Do all lithium batteries for lights have low voltage protection circuits?

fc


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## gticlay (Dec 13, 2007)

You won't know anything for those batteries for enough charges to have them unbalance and blow up


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## baker (Jan 6, 2004)

Thanks gticlay! I'm already paranoid enough without the negative reinforcement. ;-)

Hopefully this won't be a case of curiosity killing the cat.

Actually, another thing I forgot to mention with the pictured charger...it has a temperature lead and will cut off charging at a user specified value. Pretty neat.


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## tgoff (Feb 7, 2010)

I really wanted to give Jet Lites A-51 a shot but for my needs it looks like it is not going to work. I cannot find a source for the type of connectors they use so I would not be able to use the Magicshine tail light, MJ-818, with their battery. I do not want to use another dedicated battery for the tail light.

With the information from this thread and here http://forums.mtbr.com/showthread.php?t=576334 it appears that the DiNotte battery and connectors will work with the Magicshine headlight and tail light. So my set up would be MJ-808, MJ-818, Y Cable, and DiNotte 4 cell endurance battery plus charger.

MJ-808......................................$ 44.99
MJ-818 (includes Y cable)...........$ 29.99
DiNotte 4 Cell Battery.................$ 70.00
DiNotte Charger..........................$ 30.00
Geoman Shipping.......................$ 12.95
Dinotte Shipping.........................$ 5.00

Total.........................................$ 192.93

If Jet Lites is listening either make a tail light or make your connectors/cables available to be able to use other brand tail lights,

Magicshine Commuter 900 from Geoman is 119.99 plus shipping. Buying and using the Magicshine charger would lower price by $20.


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## MtbMacgyver (Jan 23, 2007)

francois said:


> Do all lithium batteries for lights have low voltage protection circuits?
> 
> fc


Yes. Well made systems will have 2 levels of low voltage cutoff. One in the driver typically at 3V per cell that would be considered the normal cutoff. A second protection pcb in the battery pack that monitors each cell and shuts the pack down when any cell falls to the safety limit. The safety limit is typically between 2.7 - 2.5 volts. This second level of protection should only trip in what should be considered an error case. If a bike light had a check engine light, it should come on in this case to indicate there is a condition that should be checked out by a mechanic.

This is something that would be good to test and list in the data for your light shootout. PM me if you want info on how to test these cutoff voltages.


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## Cat-man-do (May 16, 2004)

BobRocket said:


> *I would not recommend charging a battery pack at a higher rate unless you know the rated specification for the actual cells. High rate charges on low rate cells = disaster.*
> 
> Most occurrences of flaming cells that vent occur during CHARGING, so be very, very careful tinkering with charging.
> 
> ...


I have to say I agree wholeheartedly with Mr. Rocket, especially on the second highlighted item. I'm not saying that cell balancing can't work. It can work great *_as long as you have cells that are well matched initinally by SoC ( state of charge ), age at the same rate and have few ( if any ) soft shorts._ To me it seems like a lot of work to install balance leads unless you really enjoy tinkering with batteries. However you don't see many Li-ion batteries sold that use external balance leads. Not that it can't be done but I would think it easier to just switch over to Li-Po which does use the balance leads.

I have to disagree with MacG on using cell holders. Yes, it is a pain to have to take cells out of a holder but not so bad if it is your main light and you are responsible for your own stuff. I use a four cell holder for one of my lights. When necessary I take the cells out and recharge each cell "separately" to it's max SoC ( hopefully 4.2volts ). Most of my cells only vary by 0.01v. One cell is 0.03v less. For the time being I can live with that. When that difference reaches 0.05v, it's time for some new cells. In my book this is the simplest way to balance charge your battery and requires little technical know-how. All you need is a cell holder, some protective cells, a cheap Li-ion charger with circuits on each of the separate cell bays and you will always have a balanced cell pack. Almost forgot, a digital multi-meter to monitor the cell voltages once they're done, very important. At least with a set-up like this it is real easy ( and cheap ) to replace the cells when needed.

Now as to the first item I highlighted from Mr. Rocket. Check out this link ( see link ) and you'll *see why me and BR take the same stand. ( *or maybe not )


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## baker (Jan 6, 2004)

Cat-man-do said:


> I have to say I agree wholeheartedly with Mr. Rocket, especially on the second highlighted item. I'm not saying that cell balancing can't work. It can work great *_as long as you have cells that are well matched initinally by SoC ( state of charge ), age at the same rate and have few ( if any ) soft shorts._ To me it seems like a lot of work to install balance leads unless you really enjoy tinkering with batteries. However you don't see many Li-ion batteries sold that use external balance leads. Not that it can't be done but I would think it easier to just switch over to Li-Po which does use the balance leads.


I like to tinker / learn, so in addition to buying a li-po pack and charger, I've dissected the one screwy pack of my 9 MS compatible packs. Adding a balance lead took about 5 minutes and the cost was about $1. Certainly not a lot of work or money and I've learned a lot about batteries and chargers through the whole process.

I'm not sure that the absence of external balance leads on Li-ion batteries is a good thing. In retrospect, it seems like an omission to save money on the packs and chargers.

Switching to Li-po's is pretty much my plan moving forward. Although, the 6 remaining MS packs I have could potentially be converted to be much safer with some simple surgery. Given that I now have a Supernova E3 triple (dyno driven) for my bars, 2 battery packs I built myself (and have slightly higher faith in), plus a 5800mah Li-po pack, I'm not sure I'll be bothered with that surgery...


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## MtbMacgyver (Jan 23, 2007)

baker said:


> Well, I can certainly appreciate the caution...however, with 7 MagicShines packs, 2 other packs from batteryspace.com, and already owning an RC charger, I'll be giving the balance connector a shot. The cost of 20 balance connectors is less than $10, so it'll just be a small cost and effort for me to add balance connectors to my packs. Oh yeah, I'll need to pick up some shrink wrap from Batteryspace.com, too.
> 
> The pack in the original post may be a total loss, but I have 8 others that could have a more useful life with the addition of balance charging.


Just keep in mind the fact that the magicshine packs are out of balance is a symptom of the problem as opposed to the root cause of the problem. The root cause is cells with soft shorts. That results in the pack going out of balance quickly. You're not fixing the actual problem by putting a balance connector on the pack and always balance charging the pack. That's basically a bandaid that'll let you keep using questionable cells.

Doing this may increase the chance of something bad happening since this will let you keep using cells that have a problem. Charging those cells can cause them to develop a more serious short and hence a more serious problem.


----------



## MightyDingus (Jul 31, 2010)

Try giving Jet Lites a call. It's 50/50 that the owner answers the phone. Let him know what you are trying to do and he may sell you a bare battery lead so you can make your own connector/converter. The owner has been incredibly easy to work with for me. 

I received my A51 in the mail today, and am hoping to give it a test in the next day or two.


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## baker (Jan 6, 2004)

MtbMacgyver said:


> Just keep in mind the fact that the magicshine packs are out of balance is a symptom of the problem as opposed to the root cause of the problem. The root cause is cells with soft shorts. That results in the pack going out of balance quickly. You're not fixing the actual problem by putting a balance connector on the pack and always balance charging the pack. That's basically a bandaid that'll let you keep using questionable cells.
> 
> Doing this may increase the chance of something bad happening since this will let you keep using cells that have a problem. Charging those cells can cause them to develop a more serious short and hence a more serious problem.


Good points. I don't plan to continue using the wacky pack, it has become an experiment for me.

I've been trying to balance charge the pack (last night and this morning). At a charge rate of 300ma, I can see the charger attempting to balance the cells. It is neat to see the voltage rise in both cells, then go down in the healthy half and up in the unhealthy half of the pack. I think the discrepancy in voltage got down to about .12 volts at some point.

However, what I'm seeing as charging progresses: the good half of the pack is continuing to rise (4.04ish) and the bad half appears to be stalling at 3.86ish volts. I'd like to keep charging til I get to 4.20 on the good half and see what's up. I think what I'm seeing is evidence of the "soft shorts" that you have mentioned.


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## Francis Cebedo (Aug 1, 1996)

MightyDingus said:


> Try giving Jet Lites a call. It's 50/50 that the owner answers the phone. Let him know what you are trying to do and he may sell you a bare battery lead so you can make your own connector/converter. The owner has been incredibly easy to work with for me.
> 
> I received my A51 in the mail today, and am hoping to give it a test in the next day or two.


I talked to the owner of Dinotte and Jet Lites today and they cannot recommend that their batteries be used with any other charger or light head unit (specially magicshine). The issue is there's charge/discharge protection mechanisms on the battery, charger and head unit and they're all meant to work together and back each other up. So it may possibly work, but it's not safe.

fc


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## baker (Jan 6, 2004)

Well, the balance charging is continuing along, and doing better than I suspected it would:



I'm interested to see what happens during a discharge. I wonder if things will go unbalanced again...


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## linger (Nov 10, 2010)

baker said:


> Well, the balance charging is continuing along, and doing better than I suspected it would:
> 
> I'm interested to see what happens during a discharge. I wonder if things will go unbalanced again...


Great job Baker,
You seem to be learning a lot quickly. Whenever you are ready to do DIY battery packs, you know have the equipment to do a high quality balance charge to just about any battery on the market. It's a little disconcerning to me that most all the bike light batteries on the market do not balance individual cells. Higher quality cells greatly reduce the probability of imbalance but they do not guarantee that the cells don't get imbalanced over time.

From what I learned from my time working with the fuel gauge chip designers at TI and Renesas, I would not be too concerned about diffences in battery voltages during discharge as long as the overdischarge (2.5-2.8V) and overcharge (4.2V) limits are not exceeded. If the voltages during discharge start deviating - that's OK. As long as they reach full charge (4.2V) at the same time.

I would be interested to see what these batteries actually discharge to.


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## BlownCivic (Sep 12, 2006)

Should we not be seeing 4 voltages here if you are truly trying the balance the pack properly? This is a Magishine pack right? 7.4v? That means there are 4 cells, each intended to be at 4.2v with a full charge, right? It appears to me that in this configuration, you are only balancing 2 cells. Am I wrong?


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## MtbMacgyver (Jan 23, 2007)

BlownCivic said:


> Should we not be seeing 4 voltages here if you are truly trying the balance the pack properly? This is a Magishine pack right? 7.4v? That means there are 4 cells, each intended to be at 4.2v with a full charge, right? It appears to me that in this configuration, you are only balancing 2 cells. Am I wrong?


No, it's a 2s2p pack. So you only see the voltages of the two banks. Each bank is made up of 2 cells hard wired in parallel. By definition the cells hard wired in parallel have to be at the exact same voltage.


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## linger (Nov 10, 2010)

BlownCivic said:


> Should we not be seeing 4 voltages here if you are truly trying the balance the pack properly? This is a Magishine pack right? 7.4v? That means there are 4 cells, each intended to be at 4.2v with a full charge, right? It appears to me that in this configuration, you are only balancing 2 cells. Am I wrong?


It's 2S2P, where the 2P parallel connections are done first. When 2 cells are wired in parallel, they have the same voltage and balance each other. You don't want to do the series connection first - or you would have 4 cells to balance.


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## baker (Jan 6, 2004)

BlownCivic said:


> Should we not be seeing 4 voltages here if you are truly trying the balance the pack properly? This is a Magishine pack right? 7.4v? That means there are 4 cells, each intended to be at 4.2v with a full charge, right? It appears to me that in this configuration, you are only balancing 2 cells. Am I wrong?


2s2p.

My understanding is that the cells in parallel balance themselves.

http://www.rcgroups.com/forums/showthread.php?t=969314


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## BlownCivic (Sep 12, 2006)

Crap! I just built a 2S2P pack that's all nicely Plasti-dipped, and I built it 2S 1st, and then 2P. I'm using 2 - 7.4V protection boards (http://www.all-battery.com/pcbfor74vli-ion186501850072vbatterypacks35alimit-pcb74v32004.aspx). I wondered why the performance of that pack "seemed" a little weak. It's made up with Samsung 30A 3,000 mah cells. I guess I'm taking it apart. The charger must be seeing a full charge on one side of the bank and shutting down before the other side is fully charged.

The individual cells were all fully charged before the packs were assembled.


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## C.E.P. (Dec 4, 2010)

Sorry, deleted


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## baker (Jan 6, 2004)

Well, I finished balance charging the wacky pack at 300ma and the voltages were 4.20v and 4.19v (flip flopping between 4.20 and 4.19 actually).

Discharged the pack to 7.40v at 700ma rate. Cells were within 0.05v of each other.

Balance charged the pack again, but specified 4000ma rate this time. Really only ever hit 2700ma. Cells ended up at 4.20v and 4.19v again (with same flip flopping towards the end).

I never noticed any significant change in pack temperature during any of this testing.

I'd say the balance leads and balance charger are a definite improvement over the basic MS charger and battery.


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## linger (Nov 10, 2010)

Baker,
So what was the discharge capacity of the pack?


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## Sebastian78 (Aug 25, 2010)

What's the point with Magicshine if you have to purchase an "expensive" battery pack as a replacement for the original battery and a RC charger with balanced charging just to use the light?

I'm no battery geek, I have no intention of becoming one. I just want to charge my battery and use my light. Now you tell me I can't anymore?


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## ron m. (Aug 1, 2009)

Sebastian78 said:


> What's the point with Magicshine if you have to purchase an "expensive" battery pack as a replacement for the original battery and a RC charger with balanced charging just to use the light?
> 
> I'm no battery geek, I have no intention of becoming one. I just want to charge my battery and use my light. Now you tell me I can't anymore?


Now, why must you go all pragmatic, practical and logical on us?

Really legitimate point, Sebastian. I think some of us just want to know, and in Baker's case, he just wants to find out what the failure mode was and how to rectify it.

Baker, you did say you used the mismatched cells (overcharged and undercharged), right?


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## MtbMacgyver (Jan 23, 2007)

baker said:


> Well, I finished balance charging the wacky pack at 300ma and the voltages were 4.20v and 4.19v (flip flopping between 4.20 and 4.19 actually).
> 
> Discharged the pack to 7.40v at 700ma rate. Cells were within 0.05v of each other.
> 
> ...


You won't see any heating until a cell actually shorts out.



baker said:


> I'd say the balance leads and balance charger are a definite improvement over the basic MS charger and battery.


Again, yes this will make the battery pack function better, but it doesn't eliminate the danger caused by the soft shorts in the cells. The soft shorts discharge the cells over time. Going though charge / discharge cycles doesn't really make any difference. Let the pack sit for a couple of months and then measure the balance. If it's off then you know the cells are self discharging at different rates, which indicates a problem with the cells.


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## baker (Jan 6, 2004)

linger said:


> Baker,
> So what was the discharge capacity of the pack?


I didn't discharge the pack fully, but looking at the discharge graphs, it looks like about 1700ma at 7.44v. What termination voltage is standard for determining pack capacity? I could run another test to that voltage and record the actual ma value.


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## baker (Jan 6, 2004)

MtbMacgyver said:


> You won't see any heating until a cell actually shorts out.
> 
> Again, yes this will make the battery pack function better, but it doesn't eliminate the danger caused by the soft shorts in the cells. The soft shorts discharge the cells over time. Going though charge / discharge cycles doesn't really make any difference. Let the pack sit for a couple of months and then measure the balance. If it's off then you know the cells are self discharging at different rates, which indicates a problem with the cells.


Thanks again for the input mtbmacgyver. I'd like to do as you suggest and let the pack sit for a while and remeasure the balance. Can this be accurately and safely done while storing the pack outside in fluctuating temps (certainly below freezing on a regular basis)? Geoman is recommending outside storage for safety due to the reported safety problems...


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## MtbMacgyver (Jan 23, 2007)

baker said:


> Thanks again for the input mtbmacgyver. I'd like to do as you suggest and let the pack sit for a while and remeasure the balance. Can this be accurately and safely done while storing the pack outside in fluctuating temps (certainly below freezing on a regular basis)? Geoman is recommending outside storage for safety due to the reported safety problems...


hmm, I don't really know what effect really cold temps will have on cells with soft shorts. I don't know if it'll slow down the self discharge rate or not. I'm doing this same test on a couple of packs. I'm storing them inside in a fireproof bag in an area without other flammable materials.


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## baker (Jan 6, 2004)

MtbMacgyver said:


> hmm, I don't really know what effect really cold temps will have on cells with soft shorts. I don't know if it'll slow down the self discharge rate or not. I'm doing this same test on a couple of packs. I'm storing them inside in a fireproof bag in an area without other flammable materials.


I was storing mine inside my work room (concrete floor) in a metal toolbox or lipo firesafe bag, but got paranoid and started storing them outside in an extra ammo box I had laying around.

I'll probably keep them outside for the time being just for peace of mind (my work room is directly under my kid's bedroom and I'd never forgive myself if the worst case scenario happened).


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## MtbMacgyver (Jan 23, 2007)

I'm curious if you measured the voltage of each bank of the pack with a multimeter after you finished the balance charge? I ask because I've seen a lot of cases where RC hobby chargers were very inconsistent in the balancing because the charger didn't measure voltage accurately for the various cells. 

Even if your multimeter isn't terribly accurate, it's consistent because you're checking each cell with the same meter. I'm just looking for feedback on how consistent other chargers are at measuring the cell voltage.


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## baker (Jan 6, 2004)

MtbMacgyver said:


> I'm curious if you measured the voltage of each bank of the pack with a multimeter after you finished the balance charge? I ask because I've seen a lot of cases where RC hobby chargers were very inconsistent in the balancing because the charger didn't measure voltage accurately for the various cells.
> 
> Even if your multimeter isn't terribly accurate, it's consistent because you're checking each cell with the same meter. I'm just looking for feedback on how consistent other chargers are at measuring the cell voltage.


I did not, but will after today's full discharge. I'll report back with both the RC charger and multimeter values. Actually, I'll try to remember to measure with this, too: Digital Multi-cell Lithium Battery Voltage LED Display for R/C Models (from Dealextreme).


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## baker (Jan 6, 2004)

linger said:


> Baker,
> So what was the discharge capacity of the pack?


Full discharge from 8.4v to 6.0v (actually ended at 5.97v) was 3616ma. The cell voltages seemed to stay close to each other til the very end, then they drastically diverged, ending at a supposed 3.38v and 2.65v.

Here is screenshot from the discharge:



mtbmacgyver, forgot to grab the DMM readings, will do after charging and compare...


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## Sebastian78 (Aug 25, 2010)

There's a new magicshine battery, that is UL and CE approved. It's also got a silicone skin. Anyone got any information about this?


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## @dam (Jan 28, 2004)

Baker: I have a similar charger (identical I think, but different brand). I also usually get quite a few "connection break" messages. If I play with the connector enough I can usually get it to work though. I think the lead on our connector is a few mm shorter than the OEM MagicShine charger's connector. Any ideas how an out of balance pack might give the connection break warning?

I have a two 3p 6600 mAh packs of Tynergy batteries. I discharged them to 3V last night and am recharging them right now. If they have about the same capacity and voltage once recharged, I was going to wire them in series. I figured I'll find a little tupperwear bin to put them in for a houseing, but still need to find a way to attach them to the bike.

Do you know of any problems wiring these two 3 parallel packs in series?


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## baker (Jan 6, 2004)

MtbMacgyver said:


> I'm curious if you measured the voltage of each bank of the pack with a multimeter after you finished the balance charge? I ask because I've seen a lot of cases where RC hobby chargers were very inconsistent in the balancing because the charger didn't measure voltage accurately for the various cells.
> 
> Even if your multimeter isn't terribly accurate, it's consistent because you're checking each cell with the same meter. I'm just looking for feedback on how consistent other chargers are at measuring the cell voltage.


OK, just charged the pack to full...at termination:

charger: 4.20v and 4.12v.
DX lipo voltage checker: 4.18 and 4.13
Multimeter: 4.17 and 4.11

Plugged the charger back in, restarted charge and it read 4.18v and 4.12v. I was wondering if the voltage sagged immediately after disconnection and it appears it does.


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## MtbMacgyver (Jan 23, 2007)

baker said:


> OK, just charged the pack to full...at termination:
> 
> charger: 4.20v and 4.12v.
> DX lipo voltage checker: 4.18 and 4.13
> ...


Seems like the charger's voltage readings are fairly accurate. The DX checker looks a little suspect.

Is this the same pack that earlier you had balanced to 4.20 and 4.16? If so, it seems like it's moved out of balance a fair amount in a pretty short period of time.


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## baker (Jan 6, 2004)

MtbMacgyver said:


> Is this the same pack that earlier you had balanced to 4.20 and 4.16? If so, it seems like it's moved out of balance a fair amount in a pretty short period of time.


Same pack, and for this charge, the cells actually started out at 4.20 and 4.19. During the last discharge, the voltages drastically diverged as the pack approached empty (3.38v and 2.65v). Upon reconnection for charging, the cells were not actually that low (recovered a bit while sitting for a day or so?), but the difference in voltages was still huge. I'm assuming that is a bad sign.


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## MtbMacgyver (Jan 23, 2007)

baker said:


> Same pack, and for this charge, the cells actually started out at 4.20 and 4.19. During the last discharge, the voltages drastically diverged as the pack approached empty (3.38v and 2.65v). Upon reconnection for charging, the cells were not actually that low (recovered a bit while sitting for a day or so?), but the difference in voltages was still huge. I'm assuming that is a bad sign.


It's not surprising the cells diverged at the end of the discharge. That just means they have different capacities, due to the problems with one of the banks. It's not good that they didn't charge back up closer in balance.


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## baker (Jan 6, 2004)

MtbMacgyver said:


> It's not surprising the cells diverged at the end of the discharge. That just means they have different capacities, due to the problems with one of the banks. It's not good that they didn't charge back up closer in balance.


I did charge them quickly (4.0a setting, which it doesn't really do, tapers down fairly quickly in amperage). Maybe that had something to do with the end result? Given linger's earlier recommendation to charge at a lower rate when the voltage discrepancy is large, I was curious to see if the higher rate inhibited close ending voltages...


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## linger (Nov 10, 2010)

Baker,
Thanks for sharing your data. A 50mV difference after 1-2 days is a lot and very significant. A couple of things can be happening. Either one bank of cells has a very high self discharge rate or one of the banks was overdischarged. When a lithium ion cells gets overdischarged, the copper plate on the anode starts dissolving within the electrolyte. What we see is an immediate capacity loss that is unrecoverable. If done repeatedly, the copper can replate/crystalize elsewhere, which may lead to more internal shorts within the cell.

Also a battery with high internal resistance can not handle a high charge rate very well. The internal resistance increases over time which directly affects charge time. The typical li-Ion charge is a Constant Current (CC) phase whent the voltage is under 4.2V per cell, and then it switches to Constant Voltage (CV) when the voltage hits 4.2V per cell. A battery with low internal resistance spends most of it's time in the CC phase and less of the time in the CV phase - resulting is a fairly short charge cycle. As the internal resistance increases, the battery spends a lot less time in the CC phase a lot more time in the CV phase - and the overal charge time is greatly increased. Since you mentioned that the charge cycle didn't stay at 4 amps very long, it looks like it switched over to the CV phase rather quickly - which means the the internal resistance is high and your battery has seen better days. Back when I did cycle life testing, I was amazed at the effect charge rate had on cycle life. I was able to kill a battery in under 80 cycles at a 2C charge rate, when this exact battery was usually good for over 2000 cycles at a 1C charge rate. These were custom manufactured super low internal resistance high discharge batteries than can absorb much more current than a typical cylindrical li-ion. The moral of the story is to take it easy on the charge rate.

Hey MTBMacgyver - I sent you an interesting PM! Insider info!


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## Cat-man-do (May 16, 2004)

A question: Does anyone know or has anyone identified "What Company" manufacturers the cells for the MagicShine battery? I know it comes out of China but the company must have a name. With all this talk about the MS battery, it would be nice to know.


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## znomit (Dec 27, 2007)

Cat-man-do said:


> A question: Does anyone know or has anyone identified "What Company" manufacturers the cells for the MagicShine battery? I know it comes out of China but the company must have a name. With all this talk about the MS battery, it would be nice to know.


Whoever is selling them cheapest on the day... 

From Geoman _"Our engineering consultants have determined that these two Magicshine battery packs raise potential safety and reliability concerns (e.g., the inclusion of different lithium-ion cell models within the same battery pack)"_


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## Cat-man-do (May 16, 2004)

znomit said:


> Whoever is selling them cheapest on the day...
> 
> From Geoman _"Our engineering consultants have determined that these two Magicshine battery packs raise potential safety and reliability concerns (e.g., the inclusion of different lithium-ion cell models within the same battery pack)"_


hummm.....not good. Still, someone built these packs. I wonder what company that was. I assumed the cell manufacturer assembled the packs. I see now that might not be the case. Maybe this stuff was throw together by the people who made the Magicshine light. If so, that could explain the poor cell match up.

Still, I would like to know the company or company's that provided cells for the MS.


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## betweenrides (Oct 19, 2010)

linger said:


> Baker,
> ... I was able to kill a battery in under 80 cycles at a 2C charge rate, when this exact battery was usually good for over 2000 cycles at a 1C charge rate. These were custom manufactured super low internal resistance high discharge batteries than can absorb much more current than a typical cylindrical li-ion. The moral of the story is to take it easy on the charge rate....


I am enjoying this discourse on batteries, even though I understand almost none of it!

This statement caught my eye, my apologies if this is considered thread hijacking as it is somewhat off topic. My current bar light ( Baja Designs Strykr) advertises 2.5 hours charge time (it's never taken even that long), while my old NiteRider Sol takes 8+ hours to charge. Is that a bad thing or does it depend on the battery and charger, age of the battery, etc? Granted these are two completely different lights with vastly different outputs.


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## Cat-man-do (May 16, 2004)

betweenrides said:


> I am enjoying this discourse on batteries, even though I understand almost none of it!
> 
> This statement caught my eye, my apologies if this is considered thread hijacking as it is somewhat off topic. My current bar light ( Baja Designs Strykr) advertises 2.5 hours charge time (it's never taken even that long), while my old NiteRider Sol takes 8+ hours to charge. Is that a bad thing or does it depend on the battery and charger, age of the battery, etc? Granted these are two completely different lights with vastly different outputs.


I think some manufacturers provide a fast(er) charger for their product than others. This requires more advanced circuitry if it is to be done right. This doesn't necessarily mean that faster is better. The consensus from the experts is that slower is better for the cells. However technology is changing all the time. Some newer cells ( Li-ion ) are designed for faster charging but that is the exception rather than the rule.

As far as normal Li-ion cells go, how long it takes to charge your battery depends not only on design and capacity but just how far you discharged your battery with the last ride. I think fast charging is more to advantage if you are more into the 24hr race scene. Racers tend to run batteries into deep discharge. For the average casual rider it shouldn't really be an issue. Slower charging is just better if you want your Li-ion battery to last longer. For 24hr racers, the issue is getting ready for their next turn on the course ASAP. If you own a faster charger and use it only for racing, I can't see that as being a big problem.


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## betweenrides (Oct 19, 2010)

Thanks, Cat-man-do. I don't race but can see where fast charging would be an asset if I did. Based on the design and execution of the Strykr, I suspect they have more advanced circuitry built in. I'll find out in a year or 2 eh?


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## Todd_F (Feb 7, 2004)

One thing I haven't seen anyone mention is using a Li-Ion PCM with built-in balancing. This is very common for laptop batteries to prevent them from becoming unbalanced and catching fire. This obviates the need for complicated balance charge leads, etc. 

Last season, I picked up a close-out IBM Thinkpad 9-cell pack for ~$30. This contained good quality cells and the all-important PCM with balancing.


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## pimpbot (Dec 31, 2003)

*So lemmie see if I have this straight...*



baker said:


> I have 7 MagicShine batteries...yikes! They've generally worked fine for me. No fires, etc. However, on my 24 Hour solo race in September, I had 2 batteries that flaked out on me way before I would have expected. One was a friend's that I borrowed and one was mine. I had charged all of the batteries to the green light stage prior to the race.
> 
> Fast forward to this week when I received an RC battery hobby charger (much more complex and feature laden than the standard MS charger). Due to the recent battery issues, I also started reading more about li ion batteries and realized they shouldn't be stored in full state for long periods of time.
> 
> ...


These are unprotected cells wired 2s2p with a protection board on the end between the charger/load and the cells, and no center tap?

Is this any different that using 4 protected cells wired 2s2p?


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## desolder (Apr 8, 2008)

pimpbot said:


> These are unprotected cells wired 2s2p with a protection board on the end between the charger/load and the cells, and no center tap?
> Is this any different that using 4 protected cells wired 2s2p?


The MS protection board has a center tap that connects to the battery. It's a little blurry in the photos, but it's labeled "BC" on the board, between the B+ and B- pads.

Four individual single-cell protection circuits will work, but from a production viewpoint, it's more expensive to do it that way since you now need four protection IC's, and four MOSFET pairs.


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## rschultz101 (Oct 5, 2009)

LED driver -> large pictures

can anybody get me large images/pictures of the drivers ?

like to take a look at the different components and their ratings, voltage, watts, etc.
use my contact form, attach picture
thanks , Rob
http://mtbl.robs-x.com


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## pimpbot (Dec 31, 2003)

*So, the cells...*



desolder said:


> The MS protection board has a center tap that connects to the battery. It's a little blurry in the photos, but it's labeled "BC" on the board, between the B+ and B- pads.
> 
> Four individual single-cell protection circuits will work, but from a production viewpoint, it's more expensive to do it that way since you now need four protection IC's, and four MOSFET pairs.


These are not protected cells? As in, you can buy protected cells with the PC board wrapped into the skin of each cell, or you can get cells without the board. The prices on DX are minimally different.

Heh, it has a center tap for charging/balancing, but from what I've seen it doesn't seem to be doing any good. 

I'm tempted to take my dead MS battery apart and reuse the protection circuit since Geoman's recall/replacement is moving along at a glacial pace.


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## desolder (Apr 8, 2008)

No, the MS battery does not use individually "protected cells". Generally, multi-cell packs use unprotected cells, and only a single protection board for the entire pack.

The center tap is only used for over/under voltage shutdown. It doesn't perform any balancing. I recommend against re-using the MS protection board. It uses the Seiko S-8232-AVFT, which has a discharge cutoff off at 2.0V. This is too low of a cutoff voltage IMO.

What are the cell voltages of your MS battery? I have had to balance charge two of my MS batteries with my RC hobby charger because they become unbalanced over time and eventually quit working.


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## circusubet (Aug 5, 2006)

*Ongoing MS Battery*

This has been one hell of a learning experience and it is still ongoing...

How ever since I do not learn as quick as Bakes and several others here I stated trying to source a battery pack compatible with a MS light head ,that had a year guarantee, I could actually to talk to a person and have it shipped from in the US. I found five from this board. Two on fleabay (no one to talk to), one in Canada, (no one to talk to) one overseas, (no one to talk to, horror stories abut returns and return turn around time). Probably many more out there.

Found Cylops. Did a search on the net about them, no problems...Called an US phone number called, spent about ten minutes talking, making sure that I felt good about the year guarantee and who I was dealing with. Then I asked Darryl, who I had on the phone, to purchase two batteries and chargers, he told me he was not set up to sell just batteries or chargers! S**t. After a bit of silence Darryl told me he would sell the individual units AND match the competitors pricing! Bought on Friday, received on Wednesday, charged, ready to go, Darryl calls on Friday to make sure all was good-unreal follow up.

I am still trying to build my own, but for now I do not have to wait on my own poor service.:madman:

Thanks again Darryl.

Thx,
John


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## nmb (Jan 8, 2008)

after reading a lot about these battery packs, and having one for over a year, it started failing on duration of charge.

I already ordered a RC balance charger and charger cables. still waiting for it.

I was thinking of a balance charge using the 4S cable. but then I read that some has used a middle cable on the 2S2P original pack and uses a 2S balance cable. but if the two cells that are in parallel are with different charges, the unbalance remains right?

Since the pack is soldered, to use a 4S balance cable I must take the 2S2P pack apart. I was thinking of getting two 2X18650 holders glued back to back to recreate the 2S2P pack and being able to remove the batteries for a balance charge every time.

I also have a normal 2X18650 charger for my single cell torch light. I could also used it instead of the original MS charger.

What do you guys think of all this?


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## BobRocket (Jul 19, 2004)

nmb said:


> after reading a lot about these battery packs, and having one for over a year, it started failing on duration of charge.
> 
> I already ordered a RC balance charger and charger cables. still waiting for it.
> 
> ...


The tabs are resistance welded and not soldered to the cells (if it is the pack I am thinking of).

You do not have to take the pack apart to balance the cells. Just make connections with leads at the ends of the cells and you are good to go.

It's likely cheaper, easier and safer to just buy a brand new *higher capacity pack*.


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## nmb (Jan 8, 2008)

thanks for the help. I'm just trying to check them since they performed flawlessly for over a year and only started to act now.


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## TwoHeadsBrewing (Aug 28, 2009)

You can buy a 4000mah 2S1P (aka 2S) 7.4v LiPo pack for under $20. It's quite a bit easier and only requires you have an RC balance charger and solder a couple connections. I put my battery inside a water bottle for protection from water, dirt, and makes is easy to mount on the bike.

More info here: http://forums.mtbr.com/lights-night...battery-my-magicshine-627988.html#post8573437

Charger - $12: Emax EC-0856 Balance Charger
4000mah Battery - $15: Sky Lipo 4000mAh 7.4V 20C
Connectors: Can be found at your local hobby store for a couple bucks.


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## nmb (Jan 8, 2008)

great ideia and I'll look into making an even better protection since the water bottle looks a bit overkill in size  btw I don't have holes on my spitfire frame for water bottle support


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