Individual cells/holders vs welded batteries- Mtbr.com
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  1. #1
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    Individual cells/holders vs welded batteries

    So tonight I was messing around with some of my gear. I previously tested the yinding and the amperage was a bit lower than I thought so it prompted me to try swapping around some things and re evaluating my testing methods. My results were surprising. For my tests I used the latest version of the yinding and several battery packs- a nitefighter 5200mah BAK, a Gemini 5200 mah with Samsung cells, a mudder case which came with an Amazon version of a kd2 loaded with ncr18650 b cells, and a Fenix 2 cell case with a 20awg magicshine cable about 5 inches long loaded with cheapo eachine 3000mah protected cells that I bought on Amazon. In all cases the holders consistently maintain 200-300mah better than equivalent welded packs. I know that many people thought that the opposite would hold true. Going to test more but so far here's where I'm at
    Nitefighter pack-


    Fenix



    Mudder



    Gemini

  2. #2
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    wow, totally opposite of what I had expected. Makes me want to buy that case off of kd instead of getting kits now.

    edit: just got to thinking, though. Maybe those notorious spring connectors are causing voltage sag, inducing the driver to draw more current to compensate....who knows? certainly not me.

  3. #3
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    I know why its a problem, every opened up a welded pack??? The leads from the cells to the protection circuits are a joke. And the boards and traces are so small, there is a ton of resistance causing losses.

    Where as cases like the mudder, fenix, etc have large boards (though technically fenix cant compare as no protection circuit, only reverse current) with traces that are larger and less resistance than the leads going to ends of pack to protection boards.

    I just didnt think it was THAT much of a difference,lol.

    Manbeer, I forget what was your "error margin" on your test leads hat you found in the other tests? Sad that premade welded packs are castrated by the poor design on the protection circuit, they really need to get that right.

    Thanks for this manbeer. Shows stock packs (with good cells) work, BUT not as good as once though versus cases that have the much more efficient protection boards. Im going to have to run the same test and include my mj880 clone case and solarstorm cases, If you dont have either of those, and Ill post up my findings.

  4. #4
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    manbeer, if you want to measure/compare something, use either constant load, or check both voltage & current of particular light setup and calculate the power.

    Also, IMHO, textual form of measurement results is pretty adequate: no need to publish dozen of multimeter pictures...

  5. #5
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    which battery pack/case/holder?

    wasn't sure if I should start a new thread...it seems relevant enough, so here goes.

    I just salvaged a bunch of 18650 cells from an old laptop. I wanted to use them in a drop-in pack. I was looking at the solarstorm v2:
    http://forums.mtbr.com/lights-night-...yc-943638.html
    and the "mudder" case that's sold on kd:
    http://forums.mtbr.com/lights-night-...kd-965526.html

    I know that "mudder" case isn't quite as convenient (no screw-top) as the ss case, but it seems more straight-forward. I'm not going to be using the usb output on that ss case. I won't likely be modding anything. the cells will be removed after every ride and periodically charged as needed in a separate 4-bay cell charger. Any idea which would better suit my needs? TIA.

  6. #6
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    My understanding is, that "mudder" case is not designed for such use, and will be quickly destroyed by frequent opening.

  7. #7
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    What is this showing? Is this the current draw on high?
    The Mudder battery pack takes 2.2A while the Gemini takes 1.7A to power the light?

  8. #8
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    Ok so I'm a bit confused by the results now. Doing a bit more messing around and it seems that the ones with the highest current are the ones with the most voltage sag. Makes sense as usually when voltage goes down, amperage goes up. So now I can't figure which would be better but I am assuming that higher volts would. Going to have to add in a voltmeter to the chain now and get readings for both. Also worth noting that my mudder packs trip protection at around 3.2 amps or so after a few seconds. My XS was pulling 3.45 amps for a brief period presumably due to the voltage sag

  9. #9
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    I wouldn't worry so much about voltage. Driver adjusts adjusts voltage.

    http://www.cree.com/led-components-a...nal/xlamp-xml2

    Voltage sag is going to be based on the cells. More current you pull the more their going to sag.

    Look at it this way, all wire, fuses, circuit breaks, have a "voltage range". You can run 110v household current through those cables (they are dc adapter supply connectors ) but you pull more than 3-4 amps you'll likely melt something.

    Current is the problem, not voltage. But one is a function of the other.

  10. #10
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    Quote Originally Posted by manbeer View Post
    .....Doing a bit more messing around and it seems that the ones with the highest current are the ones with the most voltage sag. Makes sense as usually when voltage goes down, amperage goes up.
    I'm with Archie....

    Convert your Amp and Volt readings to Watts and see if the Wattage consumed is closer to equal among the power sources.
    Last edited by Vancbiker; 05-12-2015 at 09:45 AM. Reason: fix typo
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

  11. #11
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    where are you reading this sag? Before or after the driver?
    Quote Originally Posted by manbeer View Post
    Ok so I'm a bit confused by the results now. Doing a bit more messing around and it seems that the ones with the highest current are the ones with the most voltage sag. Makes sense as usually when voltage goes down, amperage goes up. So now I can't figure which would be better but I am assuming that higher volts would. Going to have to add in a voltmeter to the chain now and get readings for both. Also worth noting that my mudder packs trip protection at around 3.2 amps or so after a few seconds. My XS was pulling 3.45 amps for a brief period presumably due to the voltage sag

  12. #12
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    He's measuring inline with the packs not between driver and emitters. I think most of us do because its just way easier.

  13. #13
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    Yes, measuring voltage in line from pack to lightheads. I will figure out the wattage one of these days when I rig up a more convenient setup. I suspect that the driver is just pulling extra current to compensate for the reduced voltage. When I see specs listed the voltage usually says "7.4 volts" so in theory the reason most of the lamps I've seen MAY actually list true current but on a test bench at 7.4 volts. Most of the lights I tested on regular packs didn't come close the rated spec so this seems like it could be the factor

    Fwiw the specs Jim lists on action led seem to be in line with what I've tested on actual fully charged battery packs so there may be a slightly larger discrepancy between the Chinese clones and the Gemini/gloworm/magicshine etc even if the listing shows a close current draw

  14. #14
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    Its not always a simple relationship between battery voltage and current draw either. My Yinding and both my KD10 lights have a very sharp peak at around 7.2V where the current draw will shoot up by around 20% (from 1.8A to 2.2A).

    Heres my numbers (driven off a bench power supply) for the KD10.

    In mA:
    Step 7V 8V
    1 50 70
    2 135 180
    3 235 310
    4 355 450
    5 500 605
    6 660 775
    7 850 960
    8 1070 1160
    9 1320 1385
    10 1700 1710

    Off : 18mA


    http://forums.mtbr.com/lights-night-...l#post11653182

  15. #15
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    Thanks for that info, I remember seeing something about it in the yinding test but didn't know it was that way on the kd2 as well. Sounds like it may be common. Going to read through that thread, looks like there is some good info. I'll be working on a better test setup tonight if I don't go riding as what I have now works well but is inconvenient. Fwiw your numbers on the kd2 are right about where mine are

  16. #16
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    Quote Originally Posted by znomit View Post
    Its not always a simple relationship between battery voltage and current draw either. My Yinding and both my KD10 lights have a very sharp peak at around 7.2V where the current draw will shoot up by around 20% (from 1.8A to 2.2A).
    The driver type and the very steep voltage to current curve that LEDs have will be responsible for that. Cheap drivers often use a simple PWM method to limit current. Changes in input voltage result in changes to the amount of energy flowing during the on time period of a PWM cycle.
    GoPro adapters for bike lights http://www.pacifier.com/~kevinb/index.html

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