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High voltage

Discussion in 'The Garage' started by Robert Dell Aquila, Oct 14, 2018.

  1. Hows it going everyone. Been using this forum to get my bike up and running and everyone has been so helpful. I have a 1978 xs650 with a rephased motor. I finally got the bike to charge after 4 months of trial and error. Just ordered and installed an Electro sports 350 Reg/Rec 70-79. The bike is now charging. However, at idle around 1200 rpm, battery voltage is around 12.7V and when revved the voltage jumps to around 15.6V. Im pretty sure voltage is suppose to jump to around 14-15V. I dont want to fry any of my electronics. Could this be the new reg/rec I installed? Any insight would help. Thanks.
     
  2. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    I'd definitely suspect you new reg/rec... First thing I'd do is verify that your gauge or voltmeter (whichever you're using) is accurate. If it is, check to see the voltage on the red brown line going into the reg/rec is the same as battery voltage. If you're getting a voltage drop across the ignition switch or possibly the fuse... or anywhere for that matter, it would signal the reg/rec to boost the output cause it thinks it low.
     
    Last edited: Oct 14, 2018
    mrtwowheel likes this.
  3. Just checked my mulitmeter on my car and a different bike. Seems fine. Just tested voltage at idle on my bike and it was at 13.5V then checked again after a ride and idle was 14.6V. Are there any checks I can do on the reg/rec itself? Also checked the red wire going into reg/rec and it was same as battery voltage. Not sure how to do the ignition checks for voltage drops
     
  4. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Did you rev it and check after your ride?
    None that I'm aware of. Requires specialized equipment.
    That's what you did when you checked the red wire. Only other thing I can think of is to clean the reg/rec connector real good. You could get a voltage drop there. Since you can't measure inside the reg/rec, there's no way to know. A good corrosion/dirt cleanup wouldn't hurt....
     
  5. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Oops.... just re-read what I wrote. The red wire from the reg/rec is the output voltage. You want to be looking for a voltage drop on the brown input wire. That's where it's looking at battery voltage. Old man brain fart......my bad.....
     
    Last edited: Oct 14, 2018
    robinc and mrtwowheel like this.
  6. I went for a ride and checked my voltage at idle and it was at 14.6V then when I revved it it goes up to 15.9V. I checked the battery with the keyswitch on and it was 11.83V when the bike is not running then when I checked the brown wire coming from the reg/rec with the key switch on it was at 11.46V. So pretty close numbers.
     
  7. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    3/8 of a volt drop. I've read that a half a volt is enough to cause your problem, though I've never personally seen it. Dunno... it's down to either that is the problem, or you got a bad reg/rec. Trying to get rid of that voltage drop would involve taking your ignition switch apart and cleaning the contacts. Fuse holder is still on the table. you have original fuse box? Try swapping the fuse itself and see if that gets rid of some of that drop....
     
  8. No fuse box everything is just ghetto rigged from the previous owner. I did look into the ignition connector block however and saw some corrosion in the probes. I'll trying cleaning those and see if that helps.
     
  9. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    :yikes:
     
    Superjet and robinc like this.

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