Mobility scooter - probably something simple

Discussion in 'General Electronics Chat' started by tomwalshco, Oct 14, 2015.

  1. tomwalshco

    Thread Starter New Member

    Oct 14, 2015
    3
    0
    Electronics neophite, but understand electricity fairly well.

    Late 90's vintage, 24v.

    1st sign of problems when I'd hit a sharp bump, it would cut out completely. But cycling key would get it going.
    Now it won't run at all. Batteries charged. Can hear the relays kick in. Got stuck in a field, may have fried something, but circuit breaker is closed.

    Has 2 pots - one a throttle pot, the other a speed limiter pot.

    Very basic controls - no lights, etc. Couple of analog volt meters (main voltage and charger voltage).
    Need some guidance. Thanks......Pics... (unused spade connectors for some add-ons -- lights maybe, not used)
    [​IMG]

    [​IMG]
     
  2. recklessrog

    Member

    May 23, 2013
    338
    102
    First thing I would do in view of your description is look for dry joints especially on the relays and any other heavy components. Re-solder any suspect looking joints. It could also be intermittent relays, they do wear out or get contacts stuck once the plating of the contacts is worn. this is due to micro arc welding due to sparking. A good thwack with the handle of a screwdriver may temporarily free them, but replacement is the best solution.
    The accumulators also can go open circuit, which will only show up if you try and connect a load such as a bulb across them while measuring the voltage. With no load applied, the meter may well show voltage if its one of the intercell bridges that has come loose but is covered in the electrolyte. the voltage will collapse under load. This fault is common with off road motorcycle batteries due to the constant vibration and mechanical shock.
     
  3. tomwalshco

    Thread Starter New Member

    Oct 14, 2015
    3
    0
    Thanks reckless --
    Guess I'll ohm the pots 1st. One looks like a 25k, the other a 5k, I'm guessing.

    There are 4 ice-cube relays total -- 3 soldered to board, 1 wired with connectors. I'm making an assumption that 1 is for reverse (always slow speed) and 3 for forward.

    I can find the relays and pots on the internet. But just needed a bit of direction before I break out the soldering iron....
     
  4. recklessrog

    Member

    May 23, 2013
    338
    102
    You may need to use a magnifying glass to spot any bad contacts or joints, also look at the multipin plugs and sockets, especially if there is any sign of heating due to poor joints. It does sound like an intermittent connection somewhere.
     
  5. #12

    Expert

    Nov 30, 2010
    16,321
    6,818
    The only one I fixed had corrosion in a connector from the front controls to the brain board.
     
  6. dl324

    Distinguished Member

    Mar 30, 2015
    3,250
    626
    I'd suggest reflowing the solder on any connection you think is carrying high current. I lost headlights twice in an old BMW and both times it was solder joints in the Lamp Control Module that had fractured from temperature cycling.

    The only mobility scooter repair I've done was for frayed wires going into the steering post resulting is loss of power.
     
  7. MrSoftware

    Active Member

    Oct 29, 2013
    504
    124
    You mentioned cycling the key would sometimes resolve the issue. It's worth checking out the key switch, especially if it's got more than 2 wires.
     
  8. tomwalshco

    Thread Starter New Member

    Oct 14, 2015
    3
    0
    Thanks for the suggestions, all.
    Haven't had time to mess with it much -- luckily, I have a backup.
    All the hi-amp solder points look good. I'll get on it this weekend....
    [​IMG]
     
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