Rewind a burnt transformer coil for 12v 10 amp battery charger?

Discussion in 'General Electronics Chat' started by sdowney717, Jul 2, 2016.

  1. sdowney717

    Thread Starter Well-Known Member

    Jul 18, 2012
    The input side of the coil failed. It burnt the winding and blew its internal thermal fuse.
    When I bypass the fuse, it blows the breaker. Looking at the winding they got hot, they are loose and varnish turned black.

    Transformer steel laminations are an E and welded on I.
    I can cut it apart. I do not have any winding wire. There is a rewind shop or used to be close by me.
    Wonder what they would want to rewind just the coil?

    Does the steel E have to be arc welded back with the I? Or can it be bolted or maybe run a screw band around it?
    What are the prices for that smallish winding wire?
  2. #12


    Nov 30, 2010
    The only way to resurrect this without buying a new one is to autopsy the remains and build a new transformer matching the original design.
    My opinion is: Let them work their trade or buy a new one. A partial hack rarely works.
  3. sdowney717

    Thread Starter Well-Known Member

    Jul 18, 2012
    This transformer has 2 separate coils upper and lower. The secondary coil is fine only the primary burnt. So would be a single rewind of a primary coil. If the cost is too much then of course not going to fix it. I looked at winding wire on Ebay and got the sense it costs a lot of money.

    It was working good. I had it on the driveway charging a battery. I left the house. Then we had a massive pounding rain, which must have gotten it soaking wet. This charger is about 30 years old. It has survived many rains before.
  4. Lestraveled

    Well-Known Member

    May 19, 2014
    That is only a 150 watt transformer. You should be able to find a reasonable replacement on EBay.
  5. gerty

    AAC Fanatic!

    Aug 30, 2007
    I agree with the above answers....But if you really...
    I had a possible option but it involved a MOT and I don't feel comfortable posting it.... For safety sake.
    GopherT likes this.
  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
  7. DickCappels


    Aug 21, 2008
    Also please consider that rewinding the primary brings with it a risk of causing dangerous leakage currents to the core. If you don't know how to test for that leakage current it is better you not try to repair the transformer yourself.

    In other words, please don't do it.