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Need help with replacing a lead-acid sealed battery with a Lithium Ion battery

  1. Jun 3, 2010 #1
    What I am trying to do is replace my 12v 5Ah lead-acid battery with a 14.8v 6600mAh lithium ion battery. It powers a small fan belt. And for some reason I cant get the lithium battery to work. Can somebody tell me what I might be doing wrong, or if it will even work?

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  2. jcsd
  3. Jun 3, 2010 #2
    #1: Do NOT charge the Lithium battery with the same charger used for the Lead-Acid battery!! This is a potential fire and/or explosion hazard!

    As for the problem you're having... assuming the Lithium battery is fully charged, it's possible that the motor has a protection circuit that doesn't like the higher voltage. What exactly happens when you connect the new battery? Does it run if you reconnect the lead-acid battery?
  4. Jun 8, 2010 #3
    Yes I have a separate charger just for the Lithium battery.

    The battery is fully charges and when I connect the lithium battery and turn the motor on it sounds like it actual runs, but just for a split second. Then nothing happens after that. When I connect the lead-acid back up the motor runs just fine. Why is that?
  5. Jun 8, 2010 #4


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    Sounds some form of protection circuit either in the battery pack or in the motor (or of course a dead battery).

    Can you please measure the terminal voltage while you test it. If the terminal voltage drops markedly when the motor stops ("after a split second") then there is a problem with the battery. Either a dead battery or some built in current limiting.
  6. Jun 9, 2010 #5
    After I start the motor the terminal voltage drops all the way to 00.0. I have a hard time believing that its a dead battery because its brand new. Would it work if I got a smaller Voltage battery?
  7. Jun 9, 2010 #6


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    Do you have any specifications on the battery pack. Does it have any built in over-current proctection?
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