E Bike Batteries Worn Out After Few Months?

Discussion in 'Electrical' started by Jacob1993, Jul 19, 2016.

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  1. Jacob1993

    Jacob1993 Guest

    I bought these brand new batteries for my E bike just a few months ago. They're 48v and worked like a charm for the first month or so. I admit I goofed up early on and left them charging overnight several times, but have been diligent lately in unplugging it after its charge is full.
    But lately, the batteries can't seem to hold a charge at all. I drive on even ground for maybe 15 mins and they start to die. It's gotten so bad I can't even drive to the grocery store and back (a ten minute round trip) without the batteries running down on me.
    I have two battery chargers and have used them both, but to no avail. Again, I've only had these batteries for several months, but they're already so worn down its like I've had them for years!

    Is there anything I can do to fix them? I really don't want to have to replace them, money is a real issue. Any helpful answers would be greatly appreciated.

  2. FurryOnTheInside

    FurryOnTheInside Well-Known Member

    This is actually the wrong forum. This is for discussing the electrical systems of ICE bikes (ignition etc). You want the "electric bicycles" forum really. I'm sure you'll still get some answers from the regulars who check the new posts.

    A 70% charge is best for long term storage of Lithium batteries AFAIK. I never heard of a way to fix batteries.
  3. crassius

    crassius Well-Known Member

    years ago with laptop batteries, one could sometimes refresh them by draining them completely several times by hooking a small light bulb to the power pin - leave it hooked up till batt is dead, unhook, wait a while and hook again - after a few times, recharge batt, then drain again

    when batt is too far gone for this to work, one can buy the individual cells fairly cheaply and rewire the new ones into the old case, but there is a danger when soldering them in (I had one cell catch fire while soldering once)
  4. Steve Best

    Steve Best Well-Known Member

    That was for NiCad Crassius, Li batteries won't work that way.

  5. crassius

    crassius Well-Known Member

    not sure about which suffers from that charging lock condition, but I've been building laptop battery packs with Li cells for maybe 10 years now

    get the ones with tabs on them so you can heat-sink them between body and where you're soldering
  6. KCvale

    KCvale Motorized Bicycle Vendor

    Your battery pack must not have a BMS built in it.
    That's what controls you battery charging and balancing.

    You may be able to dissemble you pack and replace any faulty cells but that's not easy.