Discussion in 'Electric Bicycles' started by dougsr.874, May 31, 2016.

  1. dougsr.874

    dougsr.874 Active Member

    The last 36volt 800 watt kit I bought came without a charger...I bought one off Ebay....soon as I plugged it into the batteries it burnt up....this has happened twice with two different chargers..of the same brand and same vendor....I double checked with tester to be sure of positive & neg. and all was correct.....have no idea where to go from here.....think they were just bad from the vendor.....answers please...

  2. What batteries do you have? And what is the charger
  3. dougsr.874

    dougsr.874 Active Member

    I use 3-12volt , 22 amp batteries in series....lead acid.......charger is no brand Chinese...120v. input.....1.5 amp output........a similar charger came with the first kits I bought and they worked...
  4. HeadSmess

    HeadSmess Well-Known Member

    dodgy ebay charger ;)

    dont rely on chinese electronics!

    for 3 SLA batteries, you want about 42-43.2 v to charge, any higher will cook them.
  5. dougsr.874

    dougsr.874 Active Member

    Thats about what the charger was outputting....problem was that without plugging in charger to 120volts...just plugging in charger to the batteries destroyed the charger...who sells a good charger for my needs>>>????
  6. HeadSmess

    HeadSmess Well-Known Member

    that could be the issue. that you didnt apply power to the charger before attaching the batteries! a decent electrical engineer would make it failsafe for such cases, but chinese just worry about making lots and lots of things, safety/quality can be sorted out later, if at all!

    i just use plain old hard wired transformer based circuits.

    transformer, rectifier, fuse on either side(ie, a mains fuse and an output fuse), and a lightbulb to limit charging current. work perfectly fine on lead acid batteries. a reason i dont like lithium much...they tend to be hard to charge without fancy circuitry, and prone to exploding...
  7. dougsr.874

    dougsr.874 Active Member

    The original charger I used said to ALWAYS PLUG IN BATTERIES BEFORE CONNECTING 120 that wrong>>????Should I always plug into 120v first before pluging in the batteries
  8. danlandberg

    danlandberg Member

    Sounds like power feeding back to charger maybe a charger circuit problem. You can try diods to stop the back feed.