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  1. #1
    danaco
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    Help Please from Elec Wizards !

    If you would not mind answering or directing me in a useful direction here......I have a Lupine 7.2V-7.5AH Li-Ion battery that is two years old and cared for properly. It will now not take a charge any longer from the Charger One unit and would not take a "jump" start directly from the wall charger as suggested on the Lupine site. Thinking the battyeries were shot, I opened up the pack to put in replacement batteries. Prior to sourcing cells for the replacement, I tried charging the pack By-passing the PCS with mt HP 12V-1.2 Amp variable regulated power suppy. It charged up the batteries fine telling me the cells are in good shape. I got full power and time when hooking up the light head. It seemed to self regulate at 8.25V @ 1.1- Amps.

    I know I left them charging too long, they got pretty warm. I would like to know if this is OK to charge them like this and if so how long do I leave it hooked up so I don't kill the pack or blow it up. What are the rules here ?

    I now suspect the PCS is bad and wonder if it can be repaired, are any of you up for that task ?

    Hoping someone will help me out !

    Thx, d

  2. #2
    mtbr member
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    Please, do not use any other charger than the one made to charge LiPo/LiIon batteries! If you suspect the PCB is faulty, measure each cell, and see if they all have the same voltage. If there's a cell that has voltage much different than the other cells, or if any of them has voltage lower than 2.5V, than you've found your problem. If all the cells have pretty much the same voltage between 2.5-4.2V than move to the PCB. If you can discharge the pack, but cannot charge it, than you've got faulty PCB or faulty charger.

    Overcharging your pack can result in explosion or fire, over discharging your pack can result in explosion or fire. That's about rules. Your pack is 2S2P so DO use the charger ment to charge 2S packs. Charging with any other charger like NiMH, NiCd,Pb, etc charger will result in fire or explosion due to inproper charge algorithm.

    If you find out your PCB is dead, buy a new one! If you find out your charger is dead, buy a new one!
    Last edited by Toaster79; 03-16-2011 at 04:43 PM.

  3. #3
    mtbr member
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    Quote Originally Posted by danaco
    I tried charging the pack By-passing the PCS with mt HP 12V-1.2 Amp variable regulated power suppy. It charged up the batteries fine telling me the cells are in good shape. I got full power and time when hooking up the light head. It seemed to self regulate at 8.25V @ 1.1- Amps.

    I know I left them charging too long, they got pretty warm. I would like to know if this is OK to charge them like this and if so how long do I leave it hooked up so I don't kill the pack or blow it up.
    You have to be extremely careful charging Li-ion batteries. You can do it with a variable power supply as long as the power supply has both voltage and current regulation. It's absolutely critical that the voltage regulation be set to 4.2v per cell and the current regulation be set to max cell charge current which is typically the same as the cell capacity. Since your power supply only goes to 1.1 amp, which is below the capacity of these cells, you can just set the current limit to 1 amp. If you're bypassing the protection PCB, then you need to charge each cell individually to be safe. Even that isn't really completely safe because really bad things can happen if you have an electronic failure in the regulation circuits of the power supply. It's really best to always have the redundancy of a protection PCB when dealing with li-ion cells since they can burst into flames if handled incorrectly.

    The fact that your pack got hot tells me you didn't have the power supply set correctly. Li-ion cells should never ever get hot while charging. If this happens, you've likely already damaged the cells and this can cause bad things to happen down the road. At this point, I think you should just replace the pack.

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