Magicshine circuit protection/battery questions- Mtbr.com
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  1. #1
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    Magicshine circuit protection/battery questions

    Bit of a noob so bear with me here... I bought a Magicshine MJ-808 recently and decided I didn't like the wacky plastic case that the battery was in so I took it all apart, found a suitably smaller case and went to work putting it all back together. That version of the MJ808 has a battery gauge board and a circuit protection board mounted to the battery. After I pulled the whole thing out of its old case and dropped it into my new case, the battery wouldn't take a charge. I left it charging for about 10 minutes but the battery voltage never increased. The charger is putting out 8.5 volts and when I remove the circuit board and the battery gauge, he battery will take a charge. So...

    -- did I toast the circuit board or does it have to reset?
    -- anyway to test the board?
    -- suitable replacement for the board if this one is toast?
    -- do I really need the board if I charge the pack while I'm present (as opposed to leaving overnight)

    thanks.

  2. #2
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    Sounds like the board got damaged somehow. You can get replacement 2S Lithium protection circuits from batteryspace.com or all-battery.com.

    The protection circuit that comes with the MS battery is bad anyway. They cut off at too low a voltage. You'll be doing yourself a favor by getting a new one which cuts off at the correct voltage.

    Here's their cheapest one: http://www.batteryspace.com/PCB-for-....0A-Limit.aspx

    This one has a balancing function, which can prevent premature pack failure:
    http://www.batteryspace.com/pcmwithe...02s20-265.aspx

  3. #3
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    desolder
    OMG. The last one is 15,95 without shipping. They are made of gold, I suppose xD

  4. #4
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    Thanks.

    Would this board work?:http://www.batteryspace.com/pcbfor74...agesocket.aspx

    It looks easier to solder (larger) and would fit atop the pack nicely.

  5. #5
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    These look promising....

    http://www.batteryjunction.com/pcb.html
    Draft College Republicans

  6. #6
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    -- do I really need the board if I charge the pack while I'm present
    this is my prefered option
    no you dont need it !!
    ...Scun.thorpe, UK

  7. #7
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    Would this board work?:http://www.batteryspace.com/pcbfor74...agesocket.aspx

    Yes, that one will work fine, too.

    I recommend against charging a 2S pack without a protection PCB or balance charger. The MS charger itself is NOT a balancing charger, so it has no ability to sense individual cell voltages. You are completely reliant on the PCB to prevent an overcharge/overdischarge and possible explosion (which the original MS PCB is failing to do - hence the recall). I would err on the side of caution and always use a protection PCB for multi cell packs. A balancing charger (e.g. using either a PCB with balancing, or charging with a RC hobby charger) will add another layer of safety that IMO is sorely lacking in the current MS battery/charger.

  8. #8
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    Quote Originally Posted by HEY HEY ITS HENDO
    this is my prefered option
    no you dont need it !!
    Depends on your definition of "need". Technically your right, you can make it work, but it's really risky. Monitoring cell voltage during charging is one important function, but the protection pcb also provides equally important monitoring during dicharge. Given the history of the magicshine cells going out of balance, you're really playing with fire by running without a protection pcb unless you going to manually watch the voltage of each cell bank during both charge and discharge. If the pack gets out of balance, it only takes one discharge cycle or one charge cycle to have a serious problem without a protection pcb.

  9. #9
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    (which the original MS PCB is failing to do - hence the recall)
    Do we know that as a fact? Did they already explained the reasons for the recall?

  10. #10
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    Quote Originally Posted by bravellir
    Do we know that as a fact? Did they already explained the reasons for the recall?
    The official CPSC report has not been released yet, but check out this thread over at the DX product forums:
    http://www.dealextreme.com/forums/Fo...hreadid.752701

    The protection IC is the Seiko S-8232AVFT-T2, which has a discharge cutoff off at 2.0V. IMO, this is too low for safety. User singlespeed recommends replacing the IC with S-8232NYFT-T2, which cuts off at 4.2V and 3.0V.

    The premature pack failure is probably due to the cells becoming unbalanced over time, as MtbMcGuyver has discussed. I have confirmed this myself with one MS battery which had become badly unbalanced and inoperable. I tested the cells and one pair fully charged, but the other pair was at 2.2V!

    The discharge protection of the "AVFT" will reset when the discharged cell gets back up to 3.0V, but this will NEVER happen because the other cell-pair is fully charged and at 4.3V, so the protection IC is preventing BOTH charge AND discharge. I was able to resolve the situation by adding a balance cable and using my balancing hobby RC charger.

  11. #11
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    Let's just wait for the report.
    I have 3 packs, all are more than a year old. One of them its so badly unbalanced thatís almost useful. The other two are just fine.
    I wonít call the balancing problem a safety issue. The pack wonít charge or you will not get full runtime from it.
    I think that something else is going on. That report of a pack getting into flames while not charging and not connected to the led makes me think that maybe, maybe, short circuit caused by poor build quality and poor design could be the problem or at least big part of it.
    Buts that is also speculation. Let's just wait a while for that report.

  12. #12
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    When it comes to Li-Ion battery packs, I am very much a beginner.

    What causes the individual cells in a battery pack to go out of balance? If the PCB is supposed to regulate both charge and discharge, how does this happen? Does it depend on the quality of the PCB?

    In theory, if a PCB functions well, it sounds like a simple Magshine charger should be adequate.

    Can anyone shed some light on this?

    Thanks

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