# Needing Expert Advice with a 4-cell 2P2S build



## spartacus001 (Aug 2, 2011)

Hi guys,

I'm needing some expert opinions here for a build. I'm a newb so I need to pick your brains. 
I plan to build my own 4-cell 2P2S battery pack using aftermarket 18650 so I can charge them individually.

Since my
https://forums.mtbr.com/lights-night-riding/review-ebay-1800-lumen-cree-xml-t6-led-bicycle-headlight-lamp-759177.html last year

This light now quits at around 35mins (high) after an overnight charge. After a year of moderate use the battery capacity is only functioning at 20%.

*Build Specs*

*Charger to be used: SYSMAX-Ind-Intellicharge

Battery option A: Xtar protected 3100mAh 3.7v 
* 









* Option B: Samsung Unprotected 2600mAh*









*Battery Holder type: *









*Configuration Wiring 2P2S:*









*
Questions:*

1.	For the new pack: If I wire in the protection board from the OLD pack can I use *Protected *cells in the holders?

2.	Will this 'double' protection cause undesirable outcomes?

3.	If I use my individual cell charger can I Omit the old protection board and use 
UNprotected (and Protected) cells directly?

Thanks


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## Infinity123 (Dec 11, 2009)

The picture of the configuration wiring might be wrong! The connecting wire in the middle should not be there. Or maybe it has something to do with balanced charging of the battery pack ?


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## Toaster79 (Apr 5, 2010)

Infinity123 said:


> The picture of the configuration wiring might be wrong! The connecting wire in the middle should not be there. Or maybe it has something to do with balanced charging of the battery pack ?


Wrong! Always wire cells in parallel first then in series, so the two parallel cells act as one single


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## HEY HEY ITS HENDO (Feb 23, 2008)

see post #9 in this thread.....LINK

the battery holders will not hold protected batteries .

these are good batteries, i have tested them ... http://www.solarforceflashlight-sales.com


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## Knight511 (Nov 26, 2010)

HEY HEY ITS HENDO said:


> these are good batteries, i have tested them ... http://www.solarforceflashlight-sales.com


Caution for those that may not be running antivirus... that site is laced with a Trojan. :thumbsup:


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## Vancbiker (May 25, 2005)

My experience with holders that use coil springs is that the batteries "bounce" on them over rough terrain. This breaks the connection which can cause the light to flash, change modes, or turn off, depending the driver used. Go with the Digikey/MPD holders. They use a leaf spring on each end of the battery.


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## mattthemuppet (Jul 16, 2004)

I'd go with the Samsungs, Digikey holders and re-use the PCB from the old pack. You'll still get better run time than you did with the original pack when new and you'll save a few $. The PCB is needed to protect against overdischarge or shorts - both things that can happen before you realise it, especially if you're putting cells in and out a lot. If you don't want to re-use the PCB (no reason not to that I can think of, but others might chime in), there are a bunch of 2S PCBs on eBay for ~$10 inc. postage - aim for 2.5A or so overcurrent, 2.75V overdischarge and that's about it.


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## HEY HEY ITS HENDO (Feb 23, 2008)

i bought a couple of 18650 off Buyincoins..
....... they averaged 450mah over 5 discharge tests!! :madmax:


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## spartacus001 (Aug 2, 2011)

Thanks Guys,
I'm still waiting on parts so I put together a temporary pack for now.

*Here is An older but working laptop battery from a Dead HP Pavilion 6000. *









*Voila! Harvested 6 working 18650s 2600mAH*
**Caution* Do NOT* attempt this if you don't know what you're doing. It can lead to a nasty little _boom._, fire and/or serious personal injury 
Read this guideline from CPF before attempting this: 
Tutorial: Laptop Battery Pack 18650 Extraction










*Yay. The Battery pairs are already spot welded in Parallel*









*The Old MS Battery Pack wiring. 
Bottom side:*
From what I can tell this is congruent with the wiring diagram above in my first post.









*Top side with the PCB:*









*Soldering the replacement Pack by adding Series circuit: *









*Soldering on the PCB on the other side:*









Now I just need to get some large Dia heatshrink to wrap it all up. 
After monitoring the Charge it for about 3 hrs it remainded cool and normal.

@ 3hrs I measured the voltage: *7.88volts*
Interestingly after leaving it unplugged for 9 hrs the voltage read: *8.04 volts!* Voltage balancing<?> 
I'll give it a full charge and test it tomorrow night after I fix my 2 broken spokes


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## MK96 (Nov 5, 2012)

It is better to charge each cell separately. I realized that as I disassembled the original blue ebay pack. Voltage reads after day: the 1S: 3.84, 3.85 and 2S: 2.4, 2.98. After charge/discharge cycle I throw away those 2S bad cells - capacity about 750mAh and 1000 mAh under 1A load. I also have some Thinkpad T400 3.6v 2600 Sanyos sitting at 3.8 and Sonys 3.7v 2200 from Lenovo G530. I do some charge discharge tests, but it is likely to throw them away. I believe they will have small capacity 



spartacus001 said:


> Thanks Guys,
> I'm still waiting on parts so I put together a temporary pack for now.
> 
> *Here is An older but working laptop battery from a Dead HP Pavilion 6000. *
> ...


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## MK96 (Nov 5, 2012)

I also came across the old laptop batteries, disassembled the Thinkpad T400 and Lenovo G530 batteries and I have got 6 x 2600 3.6V red Samsung cells and 6 x 3.7V green Sony cells. I recharged Sonys - heat up during charge (330-360mOhm int. resistance, charger stopped at 27 degrees Celsius) - so I am not plannig to use them. Now I am charging Samsungs (260mOhm int. resistance) to see if there is at least 1600-1800mAh, if not I won't use them too. I don't think used cells from laptop are any good.


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## Vancbiker (May 25, 2005)

MK96 said:


> I don't think used cells from laptop are any good.


In my experience, the usefulness of cells from laptop batteries will be determined by why they were removed from service in the laptop. If the laptop is 3 years old and only runs 30 minutes on a charge, it's probably not worth the effort to tear up the battery.

I have salvaged 6 excellent Sanyo cells from the neighbors fairly new laptop after it was irreparably damaged, and 4 very good Sony cells from my son's laptop when the pack suddenly lost significant runtime despite being just over a year old. One set of the 2P cells in that battery were bad. I suspect one failed which killed its parallel mate.


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## MK96 (Nov 5, 2012)

In my case all of the cells are exhausted, every cell is in nearly the same state :skep:



Vancbiker said:


> In my experience, the usefulness of cells from laptop batteries will be determined by why they were removed from service in the laptop. If the laptop is 3 years old and only runs 30 minutes on a charge, it's probably not worth the effort to tear up the battery.
> 
> I have salvaged 6 excellent Sanyo cells from the neighbors fairly new laptop after it was irreparably damaged, and 4 very good Sony cells from my son's laptop when the pack suddenly lost significant runtime despite being just over a year old. One set of the 2P cells in that battery were bad. I suspect one failed which killed its parallel mate.


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## spartacus001 (Aug 2, 2011)

My battery pack was 4 years old and it was still holding its charge. 
On this build the burn time on a ride was 2hrs on High + another 30 mins on Low before it shut down.
Not bad at all.


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## MK96 (Nov 5, 2012)

Mine are 2 & 3 years old, Sanyo holds 920 mAh and Sony 730 mAh - not worth bothering :skep:


spartacus001 said:


> My battery pack was 4 years old and it was still holding its charge.
> On this build the burn time on a ride was 2hrs on High + another 30 mins on Low before it shut down.
> Not bad at all.


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## rtirado (Dec 31, 2012)

Out of curiosity, couldn't you get one of the MagicShine 4.4AH Li-ion batteries and make it work with that light as well? Looks like it has 4×18650 Li-ion battery (8.4V4.4AH) in it.


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## spartacus001 (Aug 2, 2011)

Yep. It would definitely work but I'm don't have much faith in non name batteries. 
If I do a build use quality cells then I know the light is going to be reliable over the long term.


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## adrenalnjunky (Jul 28, 2007)

rtirado said:


> Out of curiosity, couldn't you get one of the MagicShine 4.4AH Li-ion batteries and make it work with that light as well? Looks like it has 4×18650 Li-ion battery (8.4V4.4AH) in it.


It would work just fine, but it seems that the OP is wanting to upgrade his pack to something with as much burn time he can, while keeping a 4 cell configuration. 4.4AH means 2200mah cells, and they're of questionable origin. (Not hating, I have bought one of these same packs recently.)


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## rtirado (Dec 31, 2012)

spartacus001 said:


> Yep. It would definitely work but I'm don't have much faith in non name batteries.
> If I do a build use quality cells then I know the light is going to be reliable over the long term.


I definitely understand where you are coming from, if I had the electrical expertise I would build my own as well. I just purchased one of the 1200 lumen versions of the light you reviewed and the main negative feedback on it was the battery.
So I guess I was asking for myself on what I should plan to buy in the future as a replacement.


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## MK96 (Nov 5, 2012)

I think you need just a little electrical knowledge and a lot has been written here and in other threads regarding ebay 1800 lumen headlight, Skyray S6 and 'other' 3 XML clone. Basic knowledge is to disassemble the bad pack and replace the cells in manner they were there before. In this thread you can see a wiring of the pack and also photos of the replacement pack. Just take care of the cell poles - the plus and minus :thumbsup:



rtirado said:


> I definitely understand where you are coming from, if I had the electrical expertise I would build my own as well. I just purchased one of the 1200 lumen versions of the light you reviewed and the main negative feedback on it was the battery.
> So I guess I was asking for myself on what I should plan to buy in the future as a replacement.


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## rtirado (Dec 31, 2012)

MK96 said:


> I think you need just a little electrical knowledge and a lot has been written here and in other threads regarding ebay 1800 lumen headlight, Skyray S6 and 'other' 3 XML clone. Basic knowledge is to disassemble the bad pack and replace the cells in manner they were there before. In this thread you can see a wiring of the pack and also photos of the replacement pack. Just take care of the cell poles - the plus and minus :thumbsup:


Yea I guess I could at least try it out, haha. 
For now I will see how long this cheap pack lasts me and start planning on rebuilding it for optimum performance.


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## MK96 (Nov 5, 2012)

I think about 2-3 hour. I went for Lipo battery and this is my setup with the old protection from the pack and I added also a low voltage indicator with a buzzer  Runs far far better now.



rtirado said:


> Yea I guess I could at least try it out, haha.
> For now I will see how long this cheap pack lasts me and start planning on rebuilding it for optimum performance.


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## spartacus001 (Aug 2, 2011)

Wow. That's huge capacity.
I'm not familiar w LiPos 
Are they used by RCer?


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## MK96 (Nov 5, 2012)

Yes they are used by RCer. They are made for high current draws so you can get a little higher capacity than stated on the Lipo. I gave up rescuing cells from laptops because most of the time they were too exhausted and new cells (e.g. panasonic/xtar/keeppower) are unacceptably expensive - 6Ah 2S1P Lipo costs about 27 USD which is a price of 2 18650's and 10Ah 2S1P Lipo at price of about 56 USD which is about 4 18650's. I bought mine at Hobbyking store, but so far I am very pleased with the performance. The old PCB cuts off at 3V (critical threshold for Lipo cells), so it works as it should.



spartacus001 said:


> Wow. That's huge capacity.
> I'm not familiar w LiPos
> Are they used by RCer?


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## adleysh (Jun 4, 2012)

Just finished up my 4S2P battery pack. Instead of taking a risk with soldering on tabs i used two 18650 4S holders glued them together and wired together pairs of batteries (one from each 4S sequence). I then took a balance wire of each of the battery pairs in sequence. leaving me with a 4S2P battery pack. It took a bit of thinking to get the wiring worked out as the sequence of the reverse pack is the mirror of the front pack.

Here is a pic of it all wired up without the heat shrink cover. The zip ties are just to keep everything together until the heat shrink is on.


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## spartacus001 (Aug 2, 2011)

adleysh said:


> Just finished up my 4S2P battery pack. Instead of taking a risk with soldering on tabs i used two 18650 4S holders glued them together and wired together pairs of batteries (one from each 4S sequence). I then took a balance wire of each of the battery pairs in sequence. leaving me with a 4S2P battery pack. It took a bit of thinking to get the wiring worked out as the sequence of the reverse pack is the mirror of the front pack.
> 
> Here is a pic of it all wired up without the heat shrink cover. The zip ties are just to keep everything together until the heat shrink is on.


Nice work. Will the holders fit the longer protected cells? 
What will be your estimated output voltage and Capacity?


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## MK96 (Nov 5, 2012)

Do you think the ebay light driver can handle 16.8V in 4S? :eekster: The former was 8.4V in 2S. Or do you use it with another light?



adleysh said:


> Just finished up my 4S2P battery pack. Instead of taking a risk with soldering on tabs i used two 18650 4S holders glued them together and wired together pairs of batteries (one from each 4S sequence). I then took a balance wire of each of the battery pairs in sequence. leaving me with a 4S2P battery pack. It took a bit of thinking to get the wiring worked out as the sequence of the reverse pack is the mirror of the front pack.
> 
> Here is a pic of it all wired up without the heat shrink cover. The zip ties are just to keep everything together until the heat shrink is on.


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## MK96 (Nov 5, 2012)

There can be a problem with these holders in terrain due to the soft spring and can break the connections powering the light off or changing modes. Be aware of that.



adleysh said:


> Just finished up my 4S2P battery pack. Instead of taking a risk with soldering on tabs i used two 18650 4S holders glued them together and wired together pairs of batteries (one from each 4S sequence). I then took a balance wire of each of the battery pairs in sequence. leaving me with a 4S2P battery pack. It took a bit of thinking to get the wiring worked out as the sequence of the reverse pack is the mirror of the front pack.
> 
> Here is a pic of it all wired up without the heat shrink cover. The zip ties are just to keep everything together until the heat shrink is on.


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## adleysh (Jun 4, 2012)

MK96 said:


> Do you think the ebay light driver can handle 16.8V in 4S? :eekster: The former was 8.4V in 2S. Or do you use it with another light?


I highly doubt it will work off 4S but I posted it to give you the idea so u could adapt this design for a 2S2P set up with similar wiring and a 3 wire balance lead.

Yes this will fit protected cells as that was the reason I built it this way. The sprung holder does present the risk of batterys "bouncing" but mounted horizontally with heat shrink to keep everything in should reduce the risk, coupled with these springs being quite strong helps but only time will tell.


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## MK96 (Nov 5, 2012)

So let us know how it performs in terrain :thumbsup:



adleysh said:


> I highly doubt it will work off 4S but I posted it to give you the idea so u could adapt this design for a 2S2P set up with similar wiring and a 3 wire balance lead.
> 
> Yes this will fit protected cells as that was the reason I built it this way. The sprung holder does present the risk of batterys "bouncing" but mounted horizontally with heat shrink to keep everything in should reduce the risk, coupled with these springs being quite strong helps but only time will tell.


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## adleysh (Jun 4, 2012)

spartacus001 said:


> Nice work. Will the holders fit the longer protected cells?
> What will be your estimated output voltage and Capacity?


voltage will be 14.8v and on paper the batteries I have will give me 6000mah however I rekon it will be more like 4000-5000mah


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## MK96 (Nov 5, 2012)

You mean the whole pack or single 18650? Single 18650 is max. 3400mAh - that is for panasonic. But fleabay sells 4-5-6000mAh 18650 far from reality 



adleysh said:


> voltage will be 14.8v and on paper the batteries I have will give me 6000mah however I rekon it will be more like 4000-5000mah


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## adleysh (Jun 4, 2012)

MK96 said:


> You mean the whole pack or single 18650? Single 18650 is max. 3400mAh - that is for panasonic. But fleabay sells 4-5-6000mAh 18650 far from reality


Full pack, 2P. Each battery is 3000 mah on paper but probably more like 2000-2500 mah. With two in parallel will give an output of 6000 mah on paper.


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## adrenalnjunky (Jul 28, 2007)

beginning to wonder if things might be better using 32650 cells - 6000mah each. 2 d-size Li-ion cells in series for 7.4v just like a 18650.


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## MK96 (Nov 5, 2012)

I think they are not 6000, but ~4-5 



adrenalnjunky said:


> beginning to wonder if things might be better using 32650 cells - 6000mah each. 2 d-size Li-ion cells in series for 7.4v just like a 18650.


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## adrenalnjunky (Jul 28, 2007)

MK96 said:


> I think they are not 6000, but ~4-5


The Fei Long brand 6000ma cells have been tested and shown to be accurate capacity - but at $25 each, they're about what 2 3100ma Panasonic 18650's cost, so might just be a wash.


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## MK96 (Nov 5, 2012)

So the RC Lipo is still cheaper :thumbsup: 25$ each is way too much :skep:



adrenalnjunky said:


> The Fei Long brand 6000ma cells have been tested and shown to be accurate capacity - but at $25 each, they're about what 2 3100ma Panasonic 18650's cost, so might just be a wash.


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## adrenalnjunky (Jul 28, 2007)

MK96 said:


> So the RC Lipo is still cheaper :thumbsup: 25$ each is way too much :skep:


Not really - most of us are willing to pay $10-12 a cell for Li-Ion 18650 cells in the 3000-3400mah capacity range. You'd need 2 of them to get to 6000mah capacity in parallel, so it is about the same as Li-Ion cells.

That and I'll personally never use a LiPo pack that I intend on carrying on my person- I've had R/C LiPos swell up on me while just sitting on the shelf with about a 80% charge on them.


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## spartacus001 (Aug 2, 2011)

I had my first experience w LiPo pacts this week.
A friend's Macbook battery swelled to the point it wouldn't fit in the slot so out of curiosity I decided to take it apart.A few minutes w a heat Gun had everything part.









All of the 6 cells had trapped gas in the jackets. So I carefully pricked the packs to drain the gasses. Everything went fine except two wires came undone. Unfortunately the leads were too small for me to see where they attached. The PB had white goop all over so I can see where to attach.


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## spartacus001 (Aug 2, 2011)

Well It's done. Here is my 2S2P build that can use removable cells. 
As you can see the holder does in fact fit Protected Cells. There is almost no wiggle room so this should reduce the risk of battery-bounce.










I epoxied the holders back to back. The wiring was pretty straight forward. The +ve and -ve Diagonal wires configures the Parallel battery pairs and the Series configuration is already built into the holders.

The cells will be charged individually in an intellicharger. I only had a short ride last night so I wasn't able to test the full capacity. I'm guessing it'll be over 3hrs on a single MS.









Using a Lowe Pro digital camera pouch I added some velcro straps and a fast-tec buckle to it. 









I'm thinking about doing a 2nd one and adding a PCB so I can use Non-Protected cells.

*Question:*_ Unrelated to this build. 
On my MS clone, I noticed that when the PCB cuts off the current it can only be reset by plugging in the charger. Is this normal??
_


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## adleysh (Jun 4, 2012)

Good job, if u get a turnigy charger you could charge them all without taking batteries out and then heat shrink the pack to make it all neater.


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## mattthemuppet (Jul 16, 2004)

reading stuff like what you posted about the macbook battery gives me the heebiejeebies. Please don't do that again - those cells swelled because of some kind of serious internal problem (short/ massive over discharge etc) and should be chucked immediately. The very last thing you should be doing is poking a hole in the covers - sometimes lithium batteries can give off hypochloric acid when they swell/ explode, which is a completely terrifying chemical, so much so that we got the health&safety peeps to remove a bottle of it from our lab. It causes long term irreversible lung damage, amongst many other things. If a battery dies like that, it's for a reason, recycle it and get another.

Pack looks good, though I'd use thicker wire and personally I avoid those screw on cover plugs if I can avoid it. It's very easy to twist the internal part when you're screwing on the cover to the point where it shorts. Something like a Magicshine extension cable cut in two is a much better bet, pretty robust and waterproof too.


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## MK96 (Nov 5, 2012)

Nice job with the holders, I wish you a long ride with lights on :thumbsup: But you are doing hazardous things with damaged Lipo :nono: There has been written a lot about proper care of Lipo cells in this forum and also over internet.



mattthemuppet said:


> reading stuff like what you posted about the macbook battery gives me the heebiejeebies. Please don't do that again - those cells swelled because of some kind of serious internal problem (short/ massive over discharge etc) and should be chucked immediately. The very last thing you should be doing is poking a hole in the covers - sometimes lithium batteries can give off hypochloric acid when they swell/ explode, which is a completely terrifying chemical, so much so that we got the health&safety peeps to remove a bottle of it from our lab. It causes long term irreversible lung damage, amongst many other things. If a battery dies like that, it's for a reason, recycle it and get another.
> 
> Pack looks good, though I'd use thicker wire and personally I avoid those screw on cover plugs if I can avoid it. It's very easy to twist the internal part when you're screwing on the cover to the point where it shorts. Something like a Magicshine extension cable cut in two is a much better bet, pretty robust and waterproof too.


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## spartacus001 (Aug 2, 2011)

I guess that would explain the open flesh wounds and my constant nose bleeds 

Thanks for the concerns. This was all done outside the house. 
One can never take the tinkering out of an tinkerer


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## adrenalnjunky (Jul 28, 2007)

mattthemuppet said:


> reading stuff like what you posted about the macbook battery gives me the heebiejeebies. Please don't do that again - those cells swelled because of some kind of serious internal problem (short/ massive over discharge etc) and should be chucked immediately. The very last thing you should be doing is poking a hole in the covers - sometimes lithium batteries can give off hypochloric acid when they swell/ explode, which is a completely terrifying chemical, so much so that we got the health&safety peeps to remove a bottle of it from our lab. It causes long term irreversible lung damage, amongst many other things. If a battery dies like that, it's for a reason, recycle it and get another.
> 
> Pack looks good, though I'd use thicker wire and personally I avoid those screw on cover plugs if I can avoid it. It's very easy to twist the internal part when you're screwing on the cover to the point where it shorts. Something like a Magicshine extension cable cut in two is a much better bet, pretty robust and waterproof too.


That reminds me of the guy behind Brew frames - he unintentionally created a whiff phosgene gas while welding, and it has permanently crippled him.

Brake Cleaner = Phosgene Article


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## spartacus001 (Aug 2, 2011)

*UPDATE:*
I had some time to make a second pack to use with unprotected cells.
With the wires soldered internally it offers more protection and a cleaner look.
A flat surface makes for easier mounting of the salvaged PCB

I extended the four +ve terminals with rivets to allow for better reach/contact for flat-top cells. 
Here it is:


























BTW, I'm sure it has been posted here b4 but this is a great reference from a R/C site for building your own battery packs: 
*R/C Calculations*
Just plug in your pack configuration and it gives you the wiring schematic. I plan to do a 2S3P build in the future.

It will generate a wiring schematic something like this.


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## Action LED Lights (Nov 11, 2011)

spartacus001 said:


> Yep. It would definitely work but I'm don't have much faith in non name batteries.
> If I do a build use quality cells then I know the light is going to be reliable over the long term.


I feel I should make a couple of comments here.

First, Magicshine uses BAK batteries. You may not know their name because they are wholesale only and don't sell under their own name. They are however the largest producer of 18650 batteries in the world. They are a NASDAQ traded company that has been around for a long time. The battery in the Chevy Volt is made up of BAK 18650 cells.

Second, I have seen the plants were Li-ion packs are built. They test every cell they make in racks of testers (hundreds at a time) and grade them. Then only closely matched cells are put in parallel. PCB's only keep series batteries in balance. Parallel sets will slowly get out of balance if not matched. When you buy loose cells there is no guaranty they will be matched. Building 1P,2S packs with a PCB is safe but I would not recommend putting any in parallel.

Third, the connector strips between cells in packs are spot welded to the cells. This process takes about .1 second and current only flows from one spot to the other (you will see 2 beside each other) This produces almost no heat except right at the spot. You should NEVER solder directly to the battery. The heat from the soldering iron can easily damage the battery, setting you up for trouble down the road. Always buy cells with solder tabs installed and solder these tabs together.


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## adrenalnjunky (Jul 28, 2007)

Action LED Lights said:


> You should NEVER solder directly to the battery. The heat from the soldering iron can easily damage the battery, setting you up for trouble down the road. Always buy cells with solder tabs installed and solder these tabs together.


I've always heard this, even years ago when looking at building RC car batteries out of Sanyo Sub-C cells. The local Batteries Plus chain has welded together 18650's for me, for free, every time I walk in there. They have even supplied the nickel tabs. Takes them like 5 minutes if I have the cells glued together in the config I want. I offer to pay for it every time, and they wave me off.


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## adleysh (Jun 4, 2012)

Hey guys just an update on the 4s2p pack I made and commented on previously in this thread. Good news and bad news, the good is that iv found the springs produce no bounce effect keeping a constant current through all terrain. The bad s that I have fallen victim to the ultrafire battery temptation which I knew would jot he 3000mah but did not realise how bad they would be. Out of 10cells bought 3 wer dead and the other 7 ranged from between 123mah to 1690 mah, causing huge problems with matching cells and reducing run times hugely with V sag. Do not waste your time with these cells and save money. I have now decided to go for a Lipo battery with protective plastic case to run my light. With 5000mah it should be a whole lot better.


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## HEY HEY ITS HENDO (Feb 23, 2008)

adleysh said:


> The bad s that I have fallen victim to the ultrafire battery temptation which I knew would jot he 3000mah but did not realise how bad they would be. Out of 10cells bought 3 wer dead and the other 7 ranged from between 123mah to 1690 mah, causing huge problems with matching cells and reducing run times hugely with V sag. Do not waste your time with these cells and save money


Email the seller, tell him you need a refund, and open a paypal dispute
dont let them get away with robbing people!!


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## NEstinkyrider (Sep 10, 2007)

I have a 2s1p pack with removeable cells (similar to luminous diy)that i'd like to use for an xml build i'm planning with linnear driver. 

my plan was to simply turn around one of the cells to make it a 1s2p pack. Is that a bad idea? I've been reading some threads on parallel packs and seeing a lot about 'balance wires' and 'matching cells' etc.... I certainly don't want to be carrying a small explosive in my pack.


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## adrenalnjunky (Jul 28, 2007)

Flipping one cell isn't going to work - you'd end up with both of one end of your batteries at one end of the pack, not connected to the battery connector, while the other end will be bot wired to the connector. There'd be no path to get the "stranded" pole of the battery back to the light. 

Let me create a terribly ugly MS paint image.


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## adrenalnjunky (Jul 28, 2007)

On the Left is what you have, in the middle is what you're talking about doing, and on the right is what you'd need to make a 1S2P setup.


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## NEstinkyrider (Sep 10, 2007)

adrenalnjunky said:


> View attachment 770888
> 
> 
> On the Left is what you have, in the middle is what you're talking about doing, and on the right is what you'd need to make a 1S2P setup.


Yeah, that makes perfect sense. In the back of my head I was thinking it can't be as simple as just turning the cell around. Thanks for clarifying and for taking the time to create that diagram!


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