Returning from a 3200 mile trip I noticed that my volt meter was just at or slightly below 12 volts. Started turning things off, acc switch, cruise and spots lamps. When I turned off the spots the voltage went back to normal (14 volts). Stopped for a smoke and when I pushed in the lighter the voltage dropped again to at or just below 12 volts. Please tell me where to start looking to diagnose this issue.

 

Go to the DIY Electrical section, where there are stickys on testing the charging system. There is another by Dr Hess in the Evo section, as an alternative.

 

Off the cuff it sounds like the charging system is fine, I would have a load test done on the battery unless you are able to do it yourself. Maybe lost a cell which will show the symptoms you refer to.

 

On my headlight circuit ( which I gather is on the same leg as the volt meter,) with my headlights on ( double lamped R/G,) my voltage rides just over 12 on the volt meter but checks out at 13.8 at the battery with a multimeter. When I pull the fuse for the headlights, the volt meter jumps to just under 14. The volt meter used to run in the mid 13's with the headlights too but in the last year it doesn't seem to want to anymore.

With heated gloves and the brights on it's always the same except at idle when it drops just under 12 volts. So I'd check it with a meter. You may not have a problem other than a volt meter itself.

 

Of course when you add or take a load off the system the volt meter will respond. Until you have dimming lights or start up issues there's not a problem.


When I brake, with headlights on and a turn signal activated the volt meter can bounce up and down from 12 1/2 volts down to 9 volts. If I run my accessory spot lights with the headlights it stays at about 9 volts. This indicates a load so large it draws off the battery. Too many hours of this will overheat the charging system and can damage the battery.

I rewired my system to be able to turn the headlights off, which are wired to stay on under all conditions. I'm able to ride and recharge at a rate of 14 1/2 volts. I often will not use the accessory spot lights unless absolutely needed. And when the lights are not coming on with the ignition you have a lot higher voltage / current available to crank the starter.

You could replace the charging system with a higher output rate. There's even a super system that charges using a triple phase high output.

 

I agree with this, first check should be the battery...when the bike is running the battery acts as a resevoir for 'extra' electricity and if it is
going bad it won't 'stay full' as well as it should and you well see drops in voltage
when you normally wouldn't.

 

I should have included this in my post too. I run the 3 Phase CompuFire charging system ( 40 amp,) and still have the above readings.

I've been running it for 3 1/2 years and 75,000 miles. I'm very confident in it's performance and reliability.

 

If I have another harley one go bad, I will have a compufire in mine for sure.

 

Thanks for the suggestions. I'll start with the battery and move forward from there.

 

After reading a bit in the electrical section I found the trouble code P0562, low battery voltage. The battery is only 4 months old and the bike is kept on a tender so it looks like there may be a cell issue. Thanks again.