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Thread: thoughts on Batteryspace PCM's? (protection circuit modules)

  1. #1

    Default thoughts on Batteryspace PCM's? (protection circuit modules)

    Hi all,

    I was poking around on battery space and came across their external protection boards. Does anyone use these and have any feedback?

    I'd like to run 3s 18650's and charge them through an external plug instead of removing them from the light. I realize this won't exactly balance the cells, but it seems that the purpose of the boards is for protecting packs assembled from non protected cells. Also, what would happen if one cell dies? If you can't tell I'm not an electricianeer.

    Am I causing any serious problems by doing this? These are the exact cells I'm using.

  2. #2

    Default Re: thoughts on Batteryspace PCM's? (protection circuit modules)

    I too am interested in other people opinions

    I need some PCMs for a LiCo 18650 2S and 4S packs, I was planning on using the batteryspace boards also. the 2.5v/cell cutoff seems awfully low, but I intended on seeing if I could swap resistors and come up with something that would be more along the lines of 3.0v for the low end cutoff

    IMO not balancing is asking for problems though. Might be able to get away with not doing it every time, but you should balance the cells sometimes, and preferably check the voltages on the cells before you charge to make sure its reasonably balanced.

  3. #3

    Default Re: thoughts on Batteryspace PCM's? (protection circuit modules)

    So I've been using the batteryspace 3s,2s and single PCM (li-ion) for several weeks now without any disasters I can't really say how "well" they work but so far no flames during normal use. Of course this is to be expected.

    I'm planning on using 3s 18650's in a "permanent" installation and charging through the PCM with an external lead. That is to say, I won't be taking the cells out to charge them individually or balance them.

    I did an initial charge/balance and the cells seem to be very close after several partial charge/discharge cycles. I know the PCM won't balance but all I'm asking of it is to prevent a fire. I'll be doing some long term testing to asses the voltage consistency with repeated charging.

    My main question is...am I asking for trouble or should I reasonably expect the PCM to (nearly) eliminate the risk of fire given this particular situation?

    I'm also curious if the boards could be modded to bring the voltage cutoff up to something like 3.2 volts. Anyone? Would some close up pics do anything for anyone?

  4. #4
    *Flashaholic*
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    Default Re: thoughts on Batteryspace PCM's? (protection circuit modules)

    the pcm does what it does , and it will make it much safe.
    then you add in the thermal fuse , like any good battery pack would have, and that covers some other aspects.

    the "balance" will look all pretty and nice for a while, then it will continually get off more and more. this does not effect the safety, BECAUSE YOU HAVE PROTECTION, it more effects total capacity and longevity. it is only after time where the balance will keep falling off more and more. and if the pack is to be used when it is not doing so well also, like say when cells are at 80% capability, it will rapidly fail to hold descent capacity.
    Example, if one cell item is 5% below the others, cycle , cycle cycle , cycle, that one cell item will effect the balance of the pack way more than that 5%, because the protection will STILL stop the whole charge ,as ANY cell in it reaches full.
    and then eventually, it is not even working the charge alogrythm correct, because it is adressing cell items at different voltages. it cant SEE the cells, only the series set.

    one solution is to provide at least a Maintance balance capability, even if you dont balance it regularly, that way you can See inside, and rebalance at least a few times.

    an Inticement to balance is that All of the cells will be FULLY charged :-) you want that dont you?

    most things you gotta worry about with the protection curcuits, is your Own insulations, and that they will do the actual amps you desired.
    Last edited by VidPro; 09-09-2010 at 06:23 PM.

  5. #5

    Default Re: thoughts on Batteryspace PCM's? (protection circuit modules)

    Anyone have thoughts on modding a PCM to cut off at say 3.5V instead of 2.5V?

  6. #6

    Default Re: thoughts on Batteryspace PCM's? (protection circuit modules)

    Quote Originally Posted by archer6817j View Post
    Anyone have thoughts on modding a PCM to cut off at say 3.5V instead of 2.5V?
    Not happening, they give you the full part numbers of the ICs on the information included with the PCB. Its a seiko, (IIRC) chip with fixed voltage settings. 2.5 isnt that bad if youre using it with a medium/heavy load where it will recover after the load is disconnected.

  7. #7
    Flashaholic
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    Default Re: thoughts on Batteryspace PCM's? (protection circuit modules)

    i know this is an old thread, but i have been using these battery holders. i use them with my hobby charger icharger 206b. i use it mostly for charging unprotected 18650's i am using for a battery backup. it charges them perfectly, but the problem i have is charging AW 18650 protected 2600Mah batteries, the charger will say low voltage. but every once in a while it will charge them. its possible that i just need a firmware update on my charger, or that it gets confused with the second protection circuit. but i give them a thumbs up for what i use them for.

  8. #8
    Unenlightened
    Join Date
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    Post Re: thoughts on Batteryspace PCM's? (protection circuit modules)

    The pcm will keep it safe.
    the "balance" will look all pretty and nice for a while, then it will continually get off more and more. this does not effect the safety, BECAUSE YOU HAVE PROTECTION, it more effects total capacity and longevity. it is only after time where the balance will keep falling off more and more. and if the pack is to be used when it is not doing so well also, like say when cells are at 80% capability, it will rapidly fail to hold descent capacity.
    Example, if one cell item is 5% below the others, cycle , cycle cycle , cycle, that one cell item will effect the balance of the pack way more than that 5%, because the protection will STILL stop the whole charge ,as ANY cell in it reaches full.
    and then eventually, it is not even working the charge alogrythm correct, because it is adressing cell items at different voltages. it cant SEE the cells, only the series set.

    one solution is to provide at least a Maintance balance capability, even if you don't balance it regularly, that way you can See inside, and rebalance at least a few times.

    an Inticement to balance is that All of the cells will be FULLY charged :-) you want that don't you?

    most things you gotta worry about with the protection curcuits, and that they will do the actual amps you desired.

    you can visit www.bestechpower.com for more information.

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