Help with dead cell in Ping battery.

Discussion in 'Electric Bicycles' started by motorbikemike45, Oct 9, 2011.

  1. I have a ping 36V, 20aH battery on my older e-bike. I have been riding the new e-bike, working the bugs out, determining range, etc. and sort of neglecting the older bike for a couple weeks. I topped off the battery on the older bike and took it for a ride after I'd depleted the charge on the new bike and was waiting for it to charge. I can go about 35+ miles per charge on the old bike, so imagine my surprise when the battery died at 25 miles. The analyzer showed 15 amp hours used and at 38.1 volts.

    When I got home I put it on the charger. When the charger shut off, only 11 of the 12 LED lights were on, #5 was dark. I ran it just long enough to bring the charger back on and the results were the same, #5 LED still unlit. I'd guess I have a dead cell. I don't want to pay the shipping(over $140.00) to return the battery to Ping in China for a replacement under warranty, but I don't think they have any service providers anywhere near me in NW Pennsylvania.

    Does anyone have any ideas? I e-mailed Ping and explained the situation. Do you think I could replace one cell in a LiFePo4 battery? I haven't taken the case apart because I don't want to void the warranty, so I really don't know how these things are constructed. I appreciate any help.

  2. Ypedal

    Ypedal Member

    They are foil pouches with thin tabs soldered to a PCB board in parallel groups.. it is fixable but a royal pain to work on, also dangerous if you have no clue what you are doing.

    see :


    These lipo packs are NOT the same, but similar, imagine a pack made of dozens of cells like this...
  3. Thanks, Ypedal. Your advise and videos are very helpful. I'm a good shade tree mechanic, but these high tech batteries are new to me. After Ping e-mailed me to try to balance the battery by leaving it on the charger for an extended period and it has been charging for nearly 48 hours, it is fairly conclusive 1 cell is dead. I can soldier wires using a pencil iron and rosin core solder, though I learned to solder on copper pipe. I'm still debating trying to repair this expensive LiFePo4 battery, or shipping it back to Ping in China. They said they would pay to ship it back to me when they are finished repairing it.

    Decisions, decisions.
  4. Ypedal

    Ypedal Member

    depends on how bad it is..

    a weak cell can still work.. a bad cell had to be removed..

    The BMS has resistors that drain power from the fully charged cell groups while the low one's catchup, the problem is that this happens in milliamps ( ie: SLOW.... )

    Using a cell phone charger can speed up ballancing drastically, by charging each cell group directly via the ballance leads or the cell terminals directly you can get the job done way faster.

    WARNING : most cell phone chargers will want to charge to 4.20v, your ping pack has lifepo4 cells that will be fully charged at 3.65v .... so using a regular cell phone charger you need to keep an eye on things and pull the plug at 3.6v.. it's ok if it goes up to 3.9v.. and not a huge deal even if it does hit 4.2 but try to prevent it.
  5. At Ping Battery's suggestion, I left it on the charger. After 96+ hours I was ready to give up when the #6 cell finally began to blink. 2 more hours on the charger and it stayed on. I think it is a weak cell, but I am relieved it has survived. The battery box I built for it on the bike had no way to monitor the LEDs so I was simply waiting for the charger to shut off and unplugging it, Now I am cutting a little window in the battery box so I can monitor the LEDs. I will leave the charger connected after it shuts off till the LEDs are all lit. I'm putting a little glasine(mica) pane in the window to keep the dirt and water out.

    I want to thank you for the help, advice, and support, Ypedal. It is much appreciated.
    Last edited: Oct 14, 2011
  6. dshortt1

    dshortt1 New Member

    Charger for individual Ping battery cells

    Ping has an individual cell charger that I just bought from San Diego Electric Bike for $8.00.

    I had the same problem with 4 cells that weren't charging properly. May still need to replace one cell. San Diego Electric Bike is an authorized repair station for Ping and can replace cells. Check out their website for information. (
    Last edited: Aug 20, 2013