# DIY Lights: How to build your own battery...



## Homebrew (Jan 2, 2004)

I'm still planning on doing a full rewrite of the DIY Bike Lights FAQ, but I'm just wanted to post a few pics and info on building your own homebrew battery.

*Ingredients:*
4/3A NiMH cells
wire
connector
fuse
solder/flux
desoldering braid (for untabbed cells)
shrink wrap (large enough to fit over your selected wire)
electrical tape
water bottle (preferably flip top and not screw top)
Great Stuff spray foam

*Tools:*
Soldering Iron
Vice (helpful)

*Cells:*
The 4/3A NiMH cells are what most of the bike light companies are using because they are relatively small in size and have very high capacity. These are 1.2V each so you will need five cells for a 6V battery, six cells for a 7.2V battery, and eleven cells for a 13.2V battery. The cells are usually available with tabs or without. Tabs are just strips of metal spot welded onto the cells to make it easier to connect them. These can be a bit flimsy so I prefer to solder directly to the cells using desoldering braid. The best prices I've found on these have been at the Battery Station:

https://www.batterystation.com/nicads.htm

*Wire:*
You can use 18 guage or larger speaker wire or some 12 AWG lamp wire or really whatever you have handy.

*Connector:*
I have a Jet light which uses a 5.5mm outer diameter x 2.5mm inner diameter DC power connector. Older NiteRider, VistaLites and many others lights use this connector. The Jet comes with a cord to connect the battery to the light so all I needed was the jack to plug into. This one from Radio Shack (part number 274-1576) works perfectly shoved up into the bite valve of a standard water bottle if you remove the outer nut.









https://www.radioshack.com/product....name=CTLG_011_003_005_000&product_id=274-1576

And you can just as easily use a inline power jack like this one:








https://www.action-electronics.com/acadaptr.htm (#PH-258B)

If your system doesn't have a cord, you can use a connectorized cable like this one from Digikey:

2.5mm x 5.5mm right angle connector with 18 AWG cable part # CP-2200-ND
2.5mm x 5.5mm straight connector with 18 AWG cable part # CP-2186-ND
https://dkc3.digikey.com/PDF/T041/0253.pdf

You may see this type of cable at other places but be sure to check on the guage of the cable. For example the ones at Action Electronics are pretty small wiring at around 22 AWG and the DigiKey cable is much larger at 18 AWG. The straight connectors are good if your light head has a cable connector and the right angle connector is good if you plugging directly into the light head. You may need to trim some of the plastic around the connector to expose more of the metal shaft on the right angle connector.

*Fuse:*
Most of the light companies use resettable PTC fuse device for overcurrent protection. These are also available at DigiKey:









part # SRP350-ND or part # SRP420-ND
https://dkc3.digikey.com/PDF/T041/1130.pdf

Another more robust and slight more expensive option is Klixon fuses which offer thermal protection and over current protection. Might be worth it if you aren't using a smart charger to protect against overcharging.

https://www.ti.com/snc/products/controls/battery-mm.htm

*Other Stuff:*
Silver solder makes a stronger connection but requires higher temps and takes longer to melt. For this reason, I think the standard tin/lead is better. Since heat kills cells, the less heat needed the better. Get the fluxed solder and plus some extra flux. Use rosin flux, some of the others can be quite corrosive. Rosin flux cleans up easily with an brush and rubbing alcohol if you care to. If you're using tabbed cells, you only need a small wattage iron around 25W. If using untabbed cells, you'll need more power closer to 45W to get the job done quickly so as not to overheat the cells. Smaller work like the connectors should be done with the smaller wattage iron. The shrink wrap is to protect the wires from shorting at the connector. Radio Shack should have you covered for all this stuff. The water bottle should be a smaller sized flip top type. I used this one from Performance:

https://www.performancebike.com/shop/profile.cfm?SKU=3339&subcategory_ID=4341

The spray foam is to fill up the extra space in the bottle, hold everything together, and support the bottle so it doesn't collapse. Whatever you do, don't use the DAP brand spray foam. It doesn't dry in the bottle and it _WILL_ corrode your batteries. The Great Stuff brand works well but does have it's own caveats. The 'stuff' is very messy and expands quite a bit so don't overfill. If you get it on your hands and don't remove it immediately with acetone (fingernail polish remover), it will be there for days before it wears off. You might try filling a bit at a time. The other thing is you have to remove the residue from last use between uses. It's better to wait until it drys. I use an old spoke to clear the tube and spray nozzle.

*How To Build:*
On each cell, there is one side that has the metal fully exposed and one side that has a paper ring around the outside exposing only the center. The fully exposed section (right side of the picture) is negative and the smaller exposed section is positive (left side of picture). You'll also notice there is a ridge around the outside on the positive side. And as a triple check, you can hook up a voltmeter. If you have the leads connected correctly the voltage will read positive and if they are switched it will read negative.










You'll want to wire the cells in series, positive to negative. For a flat pack, you want to glue the cells together making sure the positive and negatives are properly oriented and then solder them together adding your connector cable to the ends. With tabbed cells, you can bend the tabs toward each other and solder together or without tabs you'll want to add your desolder braid (2 strips might be a good idea if your braid is small). With untabbed cells, the key is to rough up the surface of the cells for good solder adhesion, make sure your cable leads are tinned and don't be shy with the flux. The fuse should go between one pair of cells as shown above. Here's an example of a 6V flat pack battery:










Flat packs are typically just shrink wrapped and that's it. You can probably get shrink wrap from the same place you get the cells from and they can help you with the size. Or you can do what jeffj did, and stretch an old tube over the pack.

For a water bottle battery, attach the cells together in pairs with electrical tape. Solder one end of the pair together with desolder braid and about 8" of wire on the other end. See picture below. This makes it easy to slide them down the mouth of the water bottle and are easily arranged so they all fit on the bottom in a single row.










I just recently build a water bottle battery so I have some actual pics...

The cells:









The connector jack with shrink wrap:









*NOTE:* The center pin of the connector should be attached to the positive lead of the battery.

*NOTE*: Remove the outer connector nut and slide the shrink wrap on the cord *BEFORE* you solder it to the connector. Be sure to slide the shrink wrap as far away from the connector as possible to keep it from shrinking while soldering.

Cut the bite valve core from the lid and remove the bite valve:









Now you just shove the connector jack up into the bite valve and wrap a zip tie around the bottom to secure it:









Now you just slide the cells into the bottle one set at a time, carefully arranging them in a single row at the bottom of the bottle. Then pump it full of Great Stuff and you're done!

Some other links for you to peruse:
https://forums.mtbr.com/showthread.php?t=8670
https://forums.mtbr.com/showthread.php?t=50442
https://forums.mtbr.com/showthread.php?t=49927
https://forums.mtbr.com/showthread.php?t=49290
https://forums.mtbr.com/showthread.php?t=852
https://forums.mtbr.com/showthread.php?t=4155
https://www.candlepowerforums.com/u...8261&page=1&view=collapsed&sb=5&o=365&fpart=1


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## jparker164 (Mar 2, 2004)

*Nice*

Nice work, thanks for the info


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## 24601 (Aug 25, 2004)

Why desoldering brade instead of battery bars or copper strips? Desoldering braid can be a pain. I made batts for years in the RC world.


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## Homebrew (Jan 2, 2004)

24601 said:


> Why desoldering brade instead of battery bars or copper strips? Desoldering braid can be a pain. I made batts for years in the RC world.


From what I've seen, the RC type copper bars are size specific for sub C cells and wouldn't work well with the 4/3A cells which are much smaller in diameter. The braid is flat and works fine.


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## Low_Rider (Jan 15, 2004)

Hey mods, I think this one deserves to become a STICKY somewhere!!

If you look hard enough you can find proper braid, or "pre-tinned" braid, that doesn't require tinning before hand. I've found that with De-Soldeing braid it can be a bit of a pain due to it's solder wicking characteristics. No real biggy though, but it's good if you can find it.

A note to all building their first packs/lights, whatever you do, DON'T use audio plugs as DC connectors. They're not designed for the current that some lights can draw. The last thing you want is hot connectors. Also as mentioned, pay attention to wire gauge too.

Great thread. Some of those links needed grouping somewhere like this too. Thanks Homebrew!

Cheers, Dave.


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## 24601 (Aug 25, 2004)

There are smaller bars available than just the sub-c. I have also used strips from home depot cut down--this is actually probably the cheapest method.

My issue with desoldering braid is as was said. It wicks the solder through and sometimes becomes difficult to get back on the cell. For example, I have one end soldered down. I move to the next cell, solder wicks up and melts the other end releasing my first solder. Not a big issue, but it happens. I also like the stability a bar gives to my pack. Less wiggling around.

I think you would also find shrink wrapping the cells instead of electrical tape as a easier and more stable solution, and I never use flux. Found it an unneccesarily messy step if you have a good iron.

Also, check ebay under the RC heading for cells. Many of the wholesale battery companies market through there and offer some great bulk sales.

BTW--great write up and i hope people get some use out of it. Not trying to belittle it at all. Very well done. Just offering some alternative advice.


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## Circusjunk (Aug 20, 2004)

24601 said:


> Why desoldering brade instead of battery bars or copper strips? Desoldering braid can be a pain. I made batts for years in the RC world.


I have to add my 2 cents in here, I'm not a big fan of the braid either , it just soaks up too much solder. I usually take a Piece of 12 Gauge House wiring , strip it and cut it to length then solder it on.


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## sdkwan (Aug 30, 2004)

I have been wanting to build a DIY light set as well but have been holding off because I really don't need one. I haven't ridden at night. But lately I have been considering it. I have always held back on building one also because of the housing of the light. How in the hell am I going to mount it on my bike or my helmet without looking too "ghetto"?? 

That was one of my major concerns. I didn't want to resort to the old faithful duct tape. 

But last night while walking my dog I had an enlighting moment (no pun intended). See, when I walk my dog at night i use a 18V rechargeable Ryobi Flashlight that I bought in a set of cordless power tools from Home Depot a few years ago. This bad boy is bright as hell and it uses a xenon bulb. Plus the battery life seems pretty good on it. I've used it on a couple occassions, under the sink plumbing, for about 1-2 hrs straight and it was fine. 

You can pick on up on eBay cheap or you can go to Home Depot and buy the cordless tools set and just use the flashlight. This way you get a rapid charger, great cordless tools, and 2 batteries. 

I was thinking of getting another Ryobi flashlight, take off the handle and construct a mounting mechanism for my helmet, which shouldn't be too difficult. And the other piece would be to devise a way to carry the battery pack. The battery pack could be wired all the way to the light and a switch could be added. I was thinking of seeing of the Lightbrain regulator could possibly be incorporated to extend the battery life further. 

But in any case, this way you have an 18v, xenon light for the fraction of the cost of a new light set and the housing is already partially constructed. you just need to devise a mounting mechanism. 

Let me know if anyone has perfected this yet or not.


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## EBasil (Jan 30, 2004)

I've been "rebuilding" Nightsun cell packs for years, as the need arises for others or myself, and chose to use tabbed cells. I used to race RC, too, and like battery bars, but wanted an easy way to connect cells and don't need a high rate of discharge like an RC motor can draw, so the tabs make life easy. I cut them down a little, then simply tin and join the tabs to one another, before folding them to fit between the cells.

For Nightsun, or other 12 volt systems, you can still use Sub-C cells, which are 1.2 volts, so ten give you the 12 volt system. I've recently used NiMh Sub-C's that are cheap and plentiful on el eBay.


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## WolverineGator (Feb 26, 2004)

*Speaking of Batteries...*

I need to rebuild my cygolite's dead batteries. Where can I get batteries or a battery pack? I need a 12 Volt NiMH or Li-Ion to power 10/20/30 watt bulbs.


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## EBasil (Jan 30, 2004)

WolverineGator said:


> I need to rebuild my cygolite's dead batteries. Where can I get batteries or a battery pack? I need a 12 Volt NiMH or Li-Ion to power 10/20/30 watt bulbs.


If you're willing to solder your own, and want to use a "water bottle" pack, then go to Ebay, search for "sub-c" and you'll find plenty of NiMh cells. I can post some step-by-step photos of assembly if you want, later.


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## paddlefoot64 (Jun 5, 2004)

Realistically, how much do you have to spend on supplies to make a 13.2 V NiMH battery to fit a Jet Phantom? I've re-built a computer battery before and had a hard time fitting everything back into the battery case.


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## Hardtail in Georgia (Dec 19, 2003)

paddlefoot64 said:


> Realistically, how much do you have to spend on supplies to make a 13.2 V NiMH battery to fit a Jet Phantom? I've re-built a computer battery before and had a hard time fitting everything back into the battery case.


 I'm getting ready to build a battery for the same light system as you in the near future and from the links Homebrew posted I came up with about $90.00 for a battery that will give 2.97 Hours at 20 watts. and weigh in at a little less than 2.5 pounds. It's a pretty good deal and will be a better battery than the orginal battery. BTW, there is nothing wrong with the original battery(I just got the lights a month ago) I just wanted a second battery. For reference the original battery weighs about 1 pound 8 ounces and gives 2 hours 10 minutes at 20 watts and costs about $150.

Tucker


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## Homebrew (Jan 2, 2004)

paddlefoot64 said:


> Realistically, how much do you have to spend on supplies to make a 13.2 V NiMH battery to fit a Jet Phantom? I've re-built a computer battery before and had a hard time fitting everything back into the battery case.


I would highly recommend going with these cells from the battery station:

HR-4/3AU SALE w/tabs Sanyo Ni-MH 4000 55 $ 4.00

These are the best bang for the buck. You can spend $6 to get the slightly higher capacity cells or be halfway to another pack. These are still slightly higher capacity than the stock Jet battery which is 3800mAh. You need eleven of these cells for $44 plus about $6 shipping. Add a few bucks for the connectors, shrink wrap and fuse and you're all set. If you do it yourself, you should be able to get a 13.2V battery going for about $60 each and less if you go in on it with a few buddies.

If you mean to reuse the Phantom battery case, it's not a problem. You can reuse just about everything, connector, fuse, etc. Everything but the cells and the shrink wrap. The case isn't really glued or anything. There is just a cap on it, you just pull it off. You will just need to position your cells in a similar pattern.


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## Homebrew (Jan 2, 2004)

Hardtail in Georgia said:


> I came up with about $90.00 for a battery that will give 2.97 Hours at 20 watts. and weigh in at a little less than 2.5 pounds.


Why so heavy? Are you using C cells or something else? The high cap "4/3 Fat A" shouldn't but a few grams heavier than the regular 4/3 A.


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## Hardtail in Georgia (Dec 19, 2003)

Homebrew said:


> Why so heavy? Are you using C cells or something else? The high cap "4/3 Fat A" shouldn't but a few grams heavier than the regular 4/3 A.


 I was using the 4/3 Sanyo 4500mah. HR-4/3 FAUX, They have them listed at 66g each, though they may not actually be that heavy. That weight is also figured for the entire battery set up(everything but the light head and mount). They are $5 ea. I could use a lesser cell to build the battery but I wanted the longest run time I could get, the weight isn't really that important to me unless it's really heavy b/c it's going in my pack anyways. When I get ready to actually buy the materials I may be able to find them cheaper on Ebay or find some other people to split the cost with or something.

Tucker


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## paddlefoot64 (Jun 5, 2004)

My light is on order so I can't look at the connectors. Supposedly Jet has changed something about the wiring or connectors. Does anyone know if they are still using the connectors pictured at the top of the thread?


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## Hardtail in Georgia (Dec 19, 2003)

paddlefoot64 said:


> My light is on order so I can't look at the connectors. Supposedly Jet has changed something about the wiring or connectors. Does anyone know if they are still using the connectors pictured at the top of the thread?


 The new Jet lights are using the right angle connector 2.5mm x 5.5mm. It is a 48 cord from the battery that plugs in to the light head(on the phantom anyways, don't know about the starfire). I am going to get the CP-2200-ND from Digikey.com in the link in the original post. It's $1.35 and has a 6' cable.

Tucker


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## Low_Rider (Jan 15, 2004)

Now this brings up another point. For my new system I'm building a couple of brand new packs up, and I wanted to use the 4500 Sanyo cells too. However, browsing through some other forums (both RC and MTB) I saw this post:



> Anyhow I have a few words about the batteries. While the Sanyo HR4/3FAU looks attractive in terms of size, weight, capacity and price, there is one thing that people have overlooked and that is internal resistance. The HR4/3FAU-4500 are not designed for high current drain application. Their high internal resistance reduce their true capacity by a large margin and also run a reduced cell voltage under load.


Now because of my location, (these cells are rare as rocking-hores poo in Australia) I will have to buy these cells from the 'states, and so I can't really do any testing to see if this guy nows what he's on about or not before hand. Has anyone had experience with these cells?? Because I'll be running my lights through a buck regulator I will probably only be drawing 600-800ma anyway, but I might not always be using these packs with this light.

Later on in that thread there were a fair few suggestions for 4/3A 3600 and 3800 cells, it seems they lived up to these guys requirements, but I'm after the highest capacity I can, and really need to hold a decent voltage for as long as possible.

Cheers, Dave.


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## Homebrew (Jan 2, 2004)

The highest capacity cells I have are the 4000mAh so I can't say for sure but I will say this. With a 20W bulb like my Jet, the current drain of 1.5 Amps with a 3 hour drain time on these cells isn't very high. In the RC world, they are looking at 5+Amp so that would certainly be an issue. I'm not sure if the 4500mAh cells are worth the extra cost but I don't think it would be a waste if you were looking for the highest capacity possible.


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## 24601 (Aug 25, 2004)

In the RC world we pull 20-30 amps in stock (depending on set-up) and mods pull 40+. Resistance is a huge issue there but would be nearly negligable in this application.


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## Low_Rider (Jan 15, 2004)

Thanks Homebrew and 24601!!

After thaving a bit more of a look into the world of RC electronics (there are some great forums out there) I soon realised that pulling 1 amp is nothing..... 

I often wondered how on earth people were claiming that they were pulling so much current that their battery tabs got so hot that they melted through the shrink-wrap........... Now I realise why. 

The 4500's look good. The Sanyo website has some decent datasheets for anyone that's interested. Now I just have to track down some cheap cells in the states and take the plunge into my first cross-continent transaction.......  

Cheers, Dave


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## rharries (Jan 5, 2005)

Dear Homebrew (& others)

In your thread you say:
"Most of the light companies use resettable PTC fuse device for overcurrent protection. These are also available at DigiKey"

I am using 5-7000 mAh capacity Ni-MH D cells to replace the d-cells in my original 6-volt Ni-Cad original battery pack (unknown capacity). Will this change in capacity effect re-use of the original fuse? Is this fuse necessary? I am also using a newer third party "smart charger", which automatically senses when the battery pack is fully charged. will this PTC fuse effect the ability of the charger to sense a full charge?

they batteries i bought are TNR-DS Mi-MH 7000 as seen on:
http://www.batterystation.com/nicads.htm


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## airman (Jan 13, 2004)

rharries said:


> Dear Homebrew (& others)
> 
> In your thread you say:
> "Most of the light companies use resettable PTC fuse device for overcurrent protection. These are also available at DigiKey"
> ...


To attempt to answer your questions:

"Will this change in capacity effect re-use of the original fuse?" Really don't have enough info to tell... If you want to be certain, get rid of the old one and install one that you know will work...

"will this PTC fuse effect the ability of the charger to sense a full charge?" The PTC installed and rated properly will be fine. I'd be more concerned about third party chargers and battery temperature. You MUST be sure the battery won't overheat during charging and discharging. That's why I only use Klixon circuit protectors. TNR sells them and last time I bought a bunch they were about $1.50 each.

That's a huge battery! Be careful with that baby...

Good Luck


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## Homebrew (Jan 2, 2004)

rharries said:


> Will this change in capacity effect re-use of the original fuse? Is this fuse necessary? will this PTC fuse effect the ability of the charger to sense a full charge?


The Polyswitch PTC fuses have current ratings at which they will trip (the 350 listed above is 3.5A hold current and the 420 is 4.2A). BTW, the part numbers are still good at digikey but they have a new catalog page, http://dkc3.digikey.com/PDF/T053/1251.pdf . If you haven't changed the bulb wattage or the battery voltage, then the current won't change. So the same one should be fine.

I think the fuse is absolutely necessary to provide short circuit protection. A short would be very bad especially with the cable around your head and along your back on a helmet light. They cost less than a buck and well worth it. Get some.

You shouldn't have any troubles with a properly functioning charger.


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## rharries (Jan 5, 2005)

Thank you very much! I tested it last night and had 2.5 hours on high (15 watt) beam. It has been a learning experience and I feel I could build 5 batteries of this increased capacity for the cost of a single Niterider battery. I will replace the PTC fuse to avoid injury, now that i understand it's purpose. Thanks agian!


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## menachite (Jan 12, 2004)

Homebrew and Others....

Is a fuse required for a 6v system? If so can you all point me at the right Klixon fuse to buy for a 6v pack.

Which one would I need for a 13.2v pack? If I'm gonna build them I might as well make them safe.

I used to make packs for the RC cars (who hasn't)...but I never had fuses on them so this is new to me.

Would you rather have two mid-rate 4/3A packs in your bag or one monster made from 9000mah D cells? It's time to buy some cells and this decision is driving me nuts.


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## Homebrew (Jan 2, 2004)

menachite said:


> Homebrew and Others....
> 
> Is a fuse required for a 6v system? If so can you all point me at the right Klixon fuse to buy for a 6v pack.
> 
> ...


I haven't used the Klixons but I've been using the two PTCs listed above, SRP350 and SRP420. It really depends on the current you're going to run (current in Amps = the power in Watts divided by voltage in volts) but either one will probably work fine.

And personally, I would rather have two 4/3A packs than one big monster D pack. Two smaller packs gives you more options. With one big one, you're stuck with it whether you need it or not.


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## menachite (Jan 12, 2004)

Homebrew said:


> I haven't used the Klixons but I've been using the two PTCs listed above, SRP350 and SRP420. It really depends on the current you're going to run (current in Amps = the power in Watts divided by voltage in volts) but either one will probably work fine.
> 
> And personally, I would rather have two 4/3A packs than one big monster D pack. Two smaller packs gives you more options. With one big one, you're stuck with it whether you need it or not.


So the math goes: 10w/6v=1.666 so with that value I would want to use the SRP350 3.5A?


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## carbnjunkie (Aug 21, 2003)

*wow...*

nice write up. total cost?


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## Homebrew (Jan 2, 2004)

menachite said:


> So the math goes: 10w/6v=1.666 so with that value I would want to use the SRP350 3.5A?


Sounds good. I have a 15W light with a 6V battery (i.e. higher current) using the srp350 and haven't had any troubles with use or charging.


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## Homebrew (Jan 2, 2004)

carbnjunkie said:


> nice write up. total cost?


Depends on which cells and how many you use but you can get build up the pack like mine for around $50 and it will just as good as the comerical batteries.


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## airman (Jan 13, 2004)

Homebrew said:


> I haven't used the Klixons but I've been using the two PTCs listed above, SRP350 and SRP420. It really depends on the current you're going to run (current in Amps = the power in Watts divided by voltage in volts) but either one will probably work fine.
> 
> And personally, I would rather have two 4/3A packs than one big monster D pack. Two smaller packs gives you more options. With one big one, you're stuck with it whether you need it or not.


Sorry, I must have missed something but what do you use for overtemperature protection?

Thanks


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## Frozenspokes (May 26, 2004)

*Where do you get your light?*

I have searched all around, and the only light bulbs that I have found that come anywhere near those found in mountain bike systems are some 12V landscape floods. These don't really work all that well as the light is more yellow than the ones used by the big guys. That, and I am using Sub C's left over from my RC days. The 12V light requires 10 cells and draws enough amps to drop run time to less than an hour with my 2000MAH cells. I would really like to find something that would run on 6V and maybe draw a few less amps.


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## airman (Jan 13, 2004)

Frozenspokes said:


> I have searched all around, and the only light bulbs that I have found that come anywhere near those found in mountain bike systems are some 12V landscape floods. These don't really work all that well as the light is more yellow than the ones used by the big guys. That, and I am using Sub C's left over from my RC days. The 12V light requires 10 cells and draws enough amps to drop run time to less than an hour with my 2000MAH cells. I would really like to find something that would run on 6V and maybe draw a few less amps.


You may want to try Batteryspace for some inexpensive bulbs.

The lamps are more yellow because of the voltage. Use 11 cells instead of 10 and the color output will improve.

Good Luck


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## Homebrew (Jan 2, 2004)

airman said:


> Sorry, I must have missed something but what do you use for overtemperature protection?
> 
> Thanks


I have a thermal probe on my Maha charger but that's it.


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## tedsti (Oct 22, 2004)

bulbs.com is a good source for bulbs. Most bike light systems use MR-11 bulbs. bulbs.com has a 5W 6V bulb that would get you about 2 hours of run time with 2000mah cells. 
You could also order up 10 5000mah tabbed NiMH C cells for $30 and build two packs that would run a 10W bulb for 2+ hours each.



Frozenspokes said:


> I have searched all around, and the only light bulbs that I have found that come anywhere near those found in mountain bike systems are some 12V landscape floods. These don't really work all that well as the light is more yellow than the ones used by the big guys. That, and I am using Sub C's left over from my RC days. The 12V light requires 10 cells and draws enough amps to drop run time to less than an hour with my 2000MAH cells. I would really like to find something that would run on 6V and maybe draw a few less amps.


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## DaFireMedic (Jan 13, 2004)

Has anyone bought some C cells and used a 6 battery holder to create a pack? Are these holders adequate for the job?


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## Richrider (Feb 17, 2004)

*battery heated up*



Homebrew said:


> I have a thermal probe on my Maha charger but that's it.


Homebrew - I followed your recipe and used a Maha charger. I have now cycled the battery pack 3 times on the charger (discharge/charge). The last time the battery got hot enough that I could not hold it, how hot do your batteries get when you charge them?


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## txjohng (Oct 12, 2006)

I actually use a 10 AA cell one to make 12V.

Normal cells are 1.5 volts, rechargables are 1.25 or 1.2 ( forget )

Now, I personally think Cs are a waste of money. The important think to look at is mAh. That is what tells you how long the thing will last.

Normally Cs have 2000mAh - 6mAh
and AA have 1000mAh to 2850 mAh.

Obvioulsy Cs can potentially last longer, but it might we worth having several AA packs as AA are usually a lot cheaper.


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## UrbanPounder (Feb 19, 2007)

12, 24, or 36 AA NiMh 2500mah Energizer and 5 (4)-bay 15 minute chargers is how I run a 20w 8deg 5000hr avg life MR16 halogen. It puts out 16.5+/- volts that lasts 3+ hours and you can see for 2 blocks. Too bright for the streets, but get on a dark trail and it kicks booty. You will be setting little spot fires as you bike on through. Your friends will know your comming before you leave home, this thing is so bright. I do alot of night riding on the asphalt interurbans just for the zen. I have 1 3/4 seasons on the bulb and batteries. Pretty much charging everyday and less in summer. I'd say about 350 charges so far. Some batteries are now failing and I replace them one at a time as such.

Used (6)1/2"dia pvc conduits cut to the lenght of 6 AA's plus spring lenght, pvc cemented them together (like a sixpack of canned beers). Made a bottom cap w/spring bottoms wired to to each other so you have 3 sets of 2 tubes. Idea being, put 12 AA's in series by putting 6 AA's positive side down in one tube and 6 AA's positive side up in the connecting tube. At the top you should see one positive and one negitive ends. Verify the springs and whatever material used for tube connection works. Touch the top two w/ voltage meter for 16.5 volts. Do that to the other tubes keeping the positive on one side at the top and negitive on the other.at the top. make top a cap that ties all three positives together and all three negitives together and wire to light. Used a fuse and switch inline.

Note: Don't screw up and put a battery in backwards. Forever be carefull and slow, making sure each battery goes in the correct direction. These NiMh batteries want to release their energy in a hurry and when short circuted, will heat up quick and destroy itself. FIRE! That makes them great for high drain halogens. My volt meter reads 14+amp delivery at full short, on a single AA. Thats not 1.4amp, its FOURTEEN! By far, these batteries are the best there has ever been. They may be heavy for a AA but they hold alot of energy.


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## UrbanPounder (Feb 19, 2007)

Thought I'd back that up with some pics. The pack has 24 AA's in it and can take 12 more or remove 12. You can add dummy AA's to run less power. The beam shot....11 feet across my living room. Used a cell phone camera...so take it as you may, but it throws plenty of area light and has a tight beam for seeing way out there. I'd put it up against anything, except weight class. Bats are heavy


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