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  1. #1
    i should be working
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    Battey pack for 2x cree XM-L

    I built a 2X XM-L light a few years ago. I was using a battery pack from a light similar to https://www.amazon.com/Nestling-Sola...ght+solarstorm that I shorted out the driver board playing around with it. Also still have the charger (https://www.amazon.com/Gugou-Adapter...8FPFNNR4PTWZA3)


    I opened up the battery pack and the wires look a bit worn but I was wondering what the board was for? I'm not really up to speed on battery DIY, and I wasn't really sure that NiMH batteries needed circuit protection... Anyway I'm sure the battery pack is garbage and I'm looking for something pretty much off the shelf to replace it with. I'll probably try and cleanup the worn wire but I'd like to have a spare anyways. I've been toying around with the idea of using a M18 cordless too battery, but I'm not sure what all the contacts are for and if pack monitoring is needed during operation.

    I'm not sure the capacity of the original battery I was using. It is pictured below. The current Amazon link has a 6400mAh and the light would routinely last 2 hours running both emitters. Is my math wrong that this battery should run 6 hours with 1000mA driver?

    The light is a home brew 2X Cree XM-L with a 1000mA buckpuck driver (https://www.ledsupply.com/led-driver...c-led-drivers)
    I'm not even sure I ever had the right battery for the emitters and driver.
    Battey pack for 2x cree XM-L-img_0162_1_.jpg

    For those interested in the light construction. It is constructed completely of 3mm aluminum sheet metal. The copper wires are twisted inside the cavity of the light and hold the lenses/emitters to the backplate for heat sinking. The whole thing is held with 4X M3 bolts. One emitter is soft white 20 degree (or 30, I forget) spot and the other is elliptical (up/down orientation) cool white and I have a switch to run the soft or both. The optics are Carlo I believe. I designed it in SolidWorks and laser cut all the pieces.

  2. #2
    RAKC Industries
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    Those ARE NOT NiMH cells, those are lithium ion.

    Standard 8.4v battery pack.

    Sent from my SM-G950U using Tapatalk
    Life on a bike doesn't begin till the sun goes down.


  3. #3
    i should be working
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    Like I said. not up to speed on batteries... Even less so that I thought. How can it test the cells/pack? maybe I'll just grab another 8.4V pack off of amazon for 25$.

  4. #4
    RAKC Industries
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    You can use a DMM to check the cell voltages. Anything below 2.5V and their junk (can catch fire if charged).

    We NEVER recommend cheap battery packs, long record of starting fires if your not extremely cautious using them. Charging inside metal container away from anything flammable and never let charge unattended.

    Sent from my SM-G950U using Tapatalk
    Life on a bike doesn't begin till the sun goes down.


  5. #5
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    The cell voltages were 3.9V but I destroyed the pack to check it. I agree about the cheap battery and I have no qualms about getting rid of it. The reason I though it was a NiMH pack is because the charger was a wall wart transformer...

    so what off the shelf battery/ charger would be a good fit for my light setup? I do have a La Crosse NiMH charger for my AAA and AA fleet of batteries. (https://www.amazon.com/Crosse-Techno...s=nimh+charger)

    I suppose I could get some more 2000mAh loose AA cells and find a holder.

  6. #6
    RAKC Industries
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    Problem with using those kinds of batteries is performance will be horrible. There is a reason why lithium batteries are used. Only way to keep solid output for more than a few minutes.

    Your pack in the pack if the protection circuit isnt dead can simply be wrapped in electrical tape (a good amount of it) and still used as long as it doesnt get wet.

    Sent from my SM-G950U using Tapatalk
    Life on a bike doesn't begin till the sun goes down.


  7. #7
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    The Amazon battery packs have a poor reputation on the lights and night riding forum. There are some long threads about batteries there.

    Kaidomain.com and hunk_lee on ebay have a reputation for good packs.

    http://www.kaidomain.com/p/S024442.K...n-Battery-Pack

    Panasonic NCR18650B 7.4V 6800mAh Protected Li-ion battery for Bike Light 2S2P US | eBay

    The hunk_lee battery packs ship from the US. Battery packs from China sometimes get big delays due to restrictions on air freight of Li-Ion batteries.
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

  8. #8
    i should be working
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    So the Kaidomain pack labelled NCR is quality cells, where as this one
    http://www.kaidomain.com/p/S024040.8...0-Battery-Pack
    is not quality cells? It seems to be similar to the Amazon packs.

    Why are all the NCR18650B packs 7.4V and the non NCR are 8.4v?

    Can I still use my 8.4V wall wort charger on the NCR cells? Some of the NCR pack pages have nominal voltage higher than charge voltage. Seems like an error no?

  9. #9
    RAKC Industries
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    The NCR18650B is the specific cell designation. Panasonic to be specific. 3400mah version

    Those cheap packs are made with crap cells mostly, sometimes with weird batteries stuffed in that arent even 18650 cells.

    Why they say 7.4 is beyond me, 8.4v is the full max charge voltage for these packs. 7.4v is how they designate LiPo packs. So yes 8.4v charger fine.

    Hell the 2 cell ncr18650ga pack probably has higher capacity/better run time than the cheap pack you have that died.

    Sent from my SM-G950U using Tapatalk
    Life on a bike doesn't begin till the sun goes down.


  10. #10
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    Quote Originally Posted by rpl3000 View Post
    .....Why are all the NCR18650B packs 7.4V and the non NCR are 8.4v?
    A Li-Ion cell is 4.2V right after charging. In use they quickly drop to 3.7V and hold close to that for the bulk of the run-time before beginning a quick drop to ~3V where the discharge should stop to avoid damaging the cell. Some folks like to reference the fresh off the charger voltage of a 2S pack at 8.4V rather than the nominal "in use" voltage of 7.4V. Bigger numbers sell better?
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

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