Harley-Davidson® Charging System
Bob LaRosa & Mark DiPietroTech review of the Harley Davidson charging system. Here’s an easy way to make sure your battery is charging. Everyone is at your house and ready to ride. You saddle up and CLICK, your Harley-Davidson does not start. Bob and Mark review an easy way to check your battery and make sure it’s staying charged.
and for Dyna riders:
Dyna Battery Removal and Replacement
Next Service:
Drain Fluids Softail
Drain Fluids Dyna
More on Electrical Troubleshooting
To start this basic service. You wanna remove the seat, to access the battery, to do a thorough charging system check. With the seat removed, you wanna put your volt meter leads red to positive black to negative. When you turn this ignition switch, on you're gonna have to hit that handlebar, What's known as the rocker switch. Wait for the engine indicator light to go off in the speedometer, before you start the motorcycle to check the battery charging system.
The Harley Davidson charging system is not an excited field charging system as seen in the automobile industry. It is a permanent magnet, spun off the end of the crank shaft dictated by engine RPM. When spinning it makes direct AC voltage, which is then converted, regulated, and rectified through your regulator rectifier. Output should be no more than 14.8 volts DC, to the battery. Without a battery being a hundred percent charged, there is no reason to check the charging system because the battery could be the failure point.
Indicator lights off start the motorcycle. As you can see return voltage on this particular motorcycle was 14.2 volts, DC. This is correct. If this voltage were to be 14.8, you would have an overcharging condition. If it did not quite reach 14 volts, you would have an undercharging condition.
Both of these conditions require charging system either repair or maintenance that goes beyond basic service. Once you're done with this procedure, we like to make a habit of putting an external battery charger on the battery, it not only replenishes what you did during the charging system test, but it gives you good peace of mind that the battery is fully charged, after the service is complete. After the charging system check, remove the negative cable from the frame. We do this, so you don't disturb the led threads on your battery. Once those threads are disturbed, the batteries rendered useless.
Pull back the cable, wrap it in a clean cloth, electrical tape we prefer. Make sure it touches ground nowhere. This disengages, the entire charge the entire electrical system from the motorcycle, for your safety.
I have a 2026 Harley Davidson Softail Slim S, the battery went bad 2 weeks after I got it, I replaced the battery and everything seemed fine, then I noticed that If I did not ride or turn on my bike the battery would lose its charge. I did not ride for one day and the bike did not turn on, tested the battery and it was at 20% I put it on a charger, got it up to 50 % and got the bike to start. Kept the charger on and saw that the battery charged right up to a 100% I am wondering what could be causing this? A bad voltage regulator maybe?
I have an 08 Electra Glide Ultra Classic and the voltage dropped down while riding and the headlights dimmed. I revved the bike a few times and it came back up and brightened the headlights. No issues starting the bike, tho. What could cause this?
I have a 02 Harley Buell Blast 500 and I hooked up battery backwards and my wires smoked up white. I quickly switched battery around and connected correctly and again all my wires went up in again in white smoke so I unhooked battery and put on trickle charge. Is my electrical system going to be okay.