I've got a '94 Heritage that has started losing its charge. I thought that it could've been the battery since I'm pretty sure it was original...but no. Got the new battery in and after a few days riding the battery getstoo weak toturn over the motor. For the time being I bought a charger. Thats not a fix though. I can push start it and get home, but once there, it still won't start. No charge after 20 miles. Any ideas on what problem will let it run, but won't let the battery charge? I don't want to keep throwing $100 bills at it until something finally gets it right. I posted in the electrical forum too.

 

Take a look and test your voltage regulator. Neighbor had the same problem on his bike and it ended up being a shorted diode in the voltage regulator that would allow enough juice through to run the engine but was a high current drain on the battery when it was sitting.

The service manual should have a diagram and instructions on how to test it with a simple volt meter.

 

Follow owners manual.

Hope its not the stator. Have to take alot apart to get to it.

The wires from the rectifiar to the stator is a common problem.

David

 

Well, now I am dissapointed, my service manual does not describe any testing methods for the voltage regulator. Thats pretty crappy, byt from what I can see there are three large gauge black wires that come from the stator to the voltage regulator. The main components inside the regulator are three large diodes that regulate the voltage to the battery so that you dont overcharge it. If you measure each of these three wires to ground with a multimeter that has a diode check function on it. Measuring each of the three black wires from the voltage regulator to ground with the black lead on ground and the red lead on the wires will give you one reading, they should all be about the same. Now reverse the wires and put the red lead on ground and the black lead to the wires from the voltage regulator and they should again be all about the same. If anyone of them in either configuration are different then you have a bad regulator.

Basically each of the three wires from the stator are run through the regulator and the regulator either allows the current from the stator to flow to the battery or it switches some of the current to ground in order to maintain the battery at a constant voltage. More than likely one or more of the three "switches" inside the regulator are shorted to always allow current to drain from the battery. You can also verify this by taking a current measurement from the battery with the bike and ignition off. This is NOT a voltage measurement. You don't measure across the terminals but instead disconnect the positive and connect one lead to the battery and the other to the wire you just connected. You need to set your meter to measure current and connect the wires on the meter to the proper jacks. With everything off you should see littel to no current flowing at all.

My neighbors was drawing a steady 4 amps with his bad regulator.

Hope this all helps....

 

Thanks a lot. I'll check the regulator ASAP. I wasn't sure if it could be that. I had a Suzuki back in "85 that had a regulator go south and as soon as the battery died...so did it. That was right outside of Portland while riding from near Seattle to San Diego. Got lucky and a guy gave my bike jump starts and a place tostay untila shop opened up the next morning.

My last HD was magneto fed '65 CH Sporty chopper...it didn't have all these new fangled battery worries. I miss those days.