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  1. #1
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    I want to make a NiMH battery

    I thought I would post this in the larger thread about homemade lights, but those cats are talking way, way over my head. Better that I ask my simple question here.

    I have a 12 volt, 10 watt light running on an enormous SLA battery. I would love a smaller NiMH battery. Manufacturer only has 6v NiMH batteries.

    So...

    Why can't I run a 6v battery on my 12 v light?


    and....

    if I can't, how should I go about making my own battery?

  2. #2
    Gone riding
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    You can't run your 6 volt battery with your 12 volt light because the lower voltage would result in a dim, yellow light, and shorter runtime. If your confident that you can make you own battery, there are a few ways you can go about things. You can buy cells in two different types, tabbed ot un-tabbed. It is possible to build packs using both types, although a tabbed pack would be easier to start with.

    Check out these links first:

    "Homemade Nightrider Battery Pack"
    Homemade Niterider batteries

    "TigerLight Custom Batterypack construction details" - although this is for a flashlight, the same technique is used to build any un-tabbed pack.
    http://www.candlepowerforums.com/ubb...&o=365&fpart=1

    Cheers, Dave.

  3. #3
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    You can run a 6v battery on your 12v light, but it'll be far too dull...

    You can get 12V by wiring two 6V batteries in series. Eg, ---- - 6V + ----- - 6V + -----

    http://www.otherpower.com/otherpower...ry_wiring.html

    The easiest option might be to get a battery shop (places that sell/make batteries for laptops, phones, etc) to make one out of multiple cells that are wired together - just like regular laptop and similar batteries. Tell them the light specs and how much time you want from the batter pack, and they should be able to come up with something. I had one made that sits inside a sacrifical water bottle, in the carrier.

  4. #4
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    Get these guys to make you up a pack;

    www.cheapbatterypacks.com/

  5. #5
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    Ten "sub-c" cells (1.2 volts each) will give you your 12 volt battery pack. You could use NiMh, NiCad or LiOn cells and you'd decide which to use based on expense and the type of charger you already have or are willing to buy.

    Personally, I didn't want to buy a new charger, so I replaced the worn out NiCad batteries for my NightSun with NiMh cells. Total cost, less than $30 for a cell pack superior to the replacement that NightSun sells for 5 times that much...

  6. #6
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    Homebrew has recently written this great thread which is well worth a read:

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

    Cheers, Dave

  7. #7
    Doesntplaywellwithmorons!
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    Quote Originally Posted by Low_Rider
    You can't run your 6 volt battery with your 12 volt light because the lower voltage would result in a dim, yellow light, and shorter runtime..
    Longer runtime, not shorter.

    Voltage curves for light brightness, power consumption, and bulb life of halogen bulbs is exponential, and the cutting the voltage to 0.5 of nominal will cut the brightness to 9% of normal and the power consumption to 25% of normal.
    I don't post to generate business for myself or make like I'm better than sliced bread

  8. #8
    Doesntplaywellwithmorons!
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    Quote Originally Posted by EBasil
    Ten "sub-c" cells (1.2 volts each) will give you your 12 volt battery pack. You could use NiMh, NiCad or LiOn cells and you'd decide which to use based on expense and the type of charger you already have or are willing to buy.

    Personally, I didn't want to buy a new charger, so I replaced the worn out NiCad batteries for my NightSun with NiMh cells. Total cost, less than $30 for a cell pack superior to the replacement that NightSun sells for 5 times that much...
    LiIon cells are 3.6V each, not 1.2V, so 10 of them would be a 36V pack.
    I don't post to generate business for myself or make like I'm better than sliced bread

  9. #9
    Gone riding
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    bzzztttt!! 36 volts, and not real cheap either........
    I didn't pick up on that. Thanks DeeEight.

    I might mention here too that most electronic component manufacturers have a "free samples" section on their site for students/buisnesses/intersted parties to order a few samples to test. (hint, hint - free resettable fuses........)

    Cheers, Dave.

  10. #10
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    Quote Originally Posted by GrantB
    I thought I would post this in the larger thread about homemade lights, but those cats are talking way, way over my head. Better that I ask my simple question here.

    I have a 12 volt, 10 watt light running on an enormous SLA battery. I would love a smaller NiMH battery. Manufacturer only has 6v NiMH batteries.

    So...

    Why can't I run a 6v battery on my 12 v light?


    and....

    if I can't, how should I go about making my own battery?
    Connect two 6v batts in series and you have 12v.

    I've used all kinds of batteries on my bike. Different types of batts are always a trade off of one another. For me, my two big issues are weight and reliable. By far lead-acid have been the most reliable. The problem with NiMH batts is that they aren't durable. They really die quickly when abused on a bike ride or if it is cold out. My guess is that there is nothing wrong with NiMH batts other than they are made as cheap as possible to still be affordable. If NiMH batts were made with the same type of casings as lead-acid, I'd use NiMH. They are much lighter and their discharge curve is much more consistant.

  11. #11
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    Source for batteries

    Check out www.all-battery.com for cells as well. They seem to have some good prices.

    Ted

  12. #12
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    Quote Originally Posted by EBasil
    Ten "sub-c" cells (1.2 volts each) will give you your 12 volt battery pack. You could use NiMh, NiCad or LiOn cells and you'd decide which to use based on expense and the type of charger you already have or are willing to buy.

    Personally, I didn't want to buy a new charger, so I replaced the worn out NiCad batteries for my NightSun with NiMh cells. Total cost, less than $30 for a cell pack superior to the replacement that NightSun sells for 5 times that much...


    Can you give some information on how a newb such as I can do this?

    I need a rebuilt battery for my nightsun XC!

    Thank you,

    r.

  13. #13
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    Wow, seriously old thread.

  14. #14
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    Quote Originally Posted by whyrichard
    Can you give some information on how a newb such as I can do this?

    I need a rebuilt battery for my nightsun XC!

    Thank you,

    r.
    The guides posted still look live, and may help a good bit. But yea, very old thread.

  15. #15
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    Here's the nutshell version:

    --cut apart your old Nightsun battery, and note/photo the wiring.
    --buy Nimh Sub-c cells from eBay
    --solder the old wiring onto your new NiMh cells in the same pattern as OEM
    --drop them into ziplock, seal it up, and slide into a new water bottle
    --shoot wall insulation foam into the waterbottle
    --charge it on your old OEM charger

    done

  16. #16
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    Quote Originally Posted by EBasil
    Here's the nutshell version:

    --cut apart your old Nightsun battery, and note/photo the wiring.
    --buy Nimh Sub-c cells from eBay
    --solder the old wiring onto your new NiMh cells in the same pattern as OEM
    --drop them into ziplock, seal it up, and slide into a new water bottle
    --shoot wall insulation foam into the waterbottle
    --charge it on your old OEM charger

    done
    Ehh, wall insulation foam? That would create a ton of heat, potentially damaging the battery every time you charged it, especially if you ever over-charge the battery, or use a quick charger. Maybe it's not that big of a deal, but from what everything I've seen and heard, ventilation is what a battery needs.

  17. #17
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    After you cut your Nightsun battery open you'll find the same thing in there, already. Insulation doesn't create heat, anyway. If you'd like to leave your batteries rattling around, go for that.

    My NiMh battery pack for the Nightsun Max is several years old and has only burst into flames like a dozen or so times.

  18. #18
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    Quote Originally Posted by EBasil
    After you cut your Nightsun battery open you'll find the same thing in there, already. Insulation doesn't create heat, anyway. If you'd like to leave your batteries rattling around, go for that.

    My NiMh battery pack for the Nightsun Max is several years old and has only burst into flames like a dozen or so times.
    Insulation doesn't create heat, it traps heat. Anyhow, perhaps it doesn't get hot enough during the charging or use process to create an extreme amount of heat. It just seems a bit counter-intuitive to insulate heat waste on a semi-heat sensitive item, but if it's been working so far, then great. It's just not something I'd try.

    Also, you shouldn't continue to use batteries which have been burning before. First off, the life of the battery is greatly reduced. Second, the flames likely destroy the insulation on the wires, potentially causing a short-circuit, which will cause the battery to burst into flames a second time due to no ventilation.

  19. #19
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    If you pee on them while they're burning, it doubles their capacity and lifespan. Mine lights now run for several weeks on a charge, and I use only pure asbestos insulation.

    Rebuilt Nightsun batteries will get hot if you fast-charge them, but the old trickle chargers are fine for an overnight charge, based on my experience. We just burned out a high beam on one of the Maxes this last week... battery's fine but it's unlikely I'll sport for a new bulb. Either way, a good $40 investment to utilize the old lights.

  20. #20
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    I went online to batteryspace.com and found a water bottle battery/smart charger setup that I used to replace the old NiCad battery setup for my Nightsun XC lights.

    http://www.batteryspace.com/waterbot...bikelight.aspx

    The smart charger is a wise idea if you move to NiMh batteries. All I had to do was change the connector, and I did also put the temp sensor in through the top of the water bottle lid and seal it with RTV silicone. I did move up to a 13.2v setup too. Serious burn time and it's a huge improvement over the OEM power supply.

    ps, the dickbag at Nightsun wires up the lamps with the colors reversed; red is ground/black is power. Nice customer service touch, huh? At least that's well-documented so most have not had problems.

  21. #21
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    My buddy here on LI has a battery store. I rebuilt a Nightsun Pack for a friend exactly how you guys described. Worked out mint and the cells cost just under 30 bucks.
    I like turtles

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