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  1. #1
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    OT- li-ion question

    For Christmas I bought the squaw a bettery powered pair of gloves. She has something called Reynauds which causes blood in the extremities to be diverted to the core to preserve body temp when even a slight temp change happenes. This leaves the fingers and toes at a pretty high risk of long term damage. She can reach into the fridge to get a beer when it's 40 C outside and her fingers turn white.

    Anyway, I got a nice set of li-ion powered gloves to help this winter. The warmth lasts about 1hr at the most on high. This is less than half of the claim. I want to get her some spare batteries but the ones from the MFR are $60 EACH. I see similar batteries (7.4 V, 2400 mAh) for as little $17 from battery outlets on the net. This size and power rating is common for Canon Camera batteries.

    Questions:
    1) can I go up in mAh safely (4800 mAh?) to provide a longer lasting battery without damage?
    2) The OEM battery has a 3 stage controller on it, will I get the maximum from the battery if it's not got the controller?

    Thanks for entertaining my cheap guy question.

    Crockpot

  2. #2
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    Not a Li battery expert. FWIW It took about 6 discharge-recharges before my pack reached it's expected runtime. The first runs were a bit less than half. The controller on mine shuts the pack down if any cell pair drops too low in voltage compared to the others,as well as if any of them hit recharge level voltage. I suspect that others will need to know more about the 3 stage controller on the original pack to know if a regular PCM will do.

    Severe Renaud's is no fun. My brother has a mild case.

  3. #3
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    Other types of batteries such as nicad and nimh batteries improve in runtime after a few cycles. That's not true for Li-ion cells. They have their highest capacity on the very first cycle and then it gradually decreases after that.

    In general you can't connect a battery directly to the heating element in gloves. The heating element will burn up because it's not designed to handle the full voltage of the battery. It's pretty similar to connecting a higher voltage battery to an LED. There is a regulator board that controls the power flow to the gloves based on a temperature sensor. It sounds like that controller is part of your battery pack. So you typically can't substitute another battery without including an appropriate controller. You either have to remove the one from the original battery pack or build or buy one for the new battery pack.

  4. #4
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    Ug! Sounds like I am now a ***** to the glove manufacturer. Thanks for your responses!


    Quote Originally Posted by MtbMacgyver
    Other types of batteries such as nicad and nimh batteries improve in runtime after a few cycles. That's not true for Li-ion cells. They have their highest capacity on the very first cycle and then it gradually decreases after that.

    In general you can't connect a battery directly to the heating element in gloves. The heating element will burn up because it's not designed to handle the full voltage of the battery. It's pretty similar to connecting a higher voltage battery to an LED. There is a regulator board that controls the power flow to the gloves based on a temperature sensor. It sounds like that controller is part of your battery pack. So you typically can't substitute another battery without including an appropriate controller. You either have to remove the one from the original battery pack or build or buy one for the new battery pack.

  5. #5
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    Point of clarification. I am not talking of increased capacity with early charge cycles. The cells were checked, tested, and matched as siggested by MtbMacgyver (Thanks again BTW). The recharge voltage started fairly high after these short runs, indicating 50% or more capacity when the pack was in shut down, so I assumed the PCM was shutting down power if a pair of cells fell out of tolerance. Other things could have done that too, but under normal usage after 6 charges, I have no further short runtimes. Well they are going that way but slowly as per norrmal.

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