Total Motorcycle Community Forums

1500 Vulcan 1988, works fine until it heats up. About 15 minutes into a ride. Then I lose my lights, turn signals and then issues effect the engine. It stalls out and won’t start. Battery is dead. When cold the charging system puts out 14 volts. But I believe the charging system stops working as it heats up. Any ideas?

No ideas anyone?

14v at what rpm.... Otherwise. Have you carried a VOM and checked the battery at 10 minutes?

I’m going by what the shop told me. And since they were doing it in the shop I’d assume at idle.

I'm not much more than a back yard tinkerer. This has me intrigued. I don't know why....

14 volts at idle is usually a good alternator and voltage regulator... However a test needs to be done to show a voltage of about 15 to 15.3 at normal cruise speed. look for a Volt meter display for the charger connector. I have one that fits the charger disconnect.. it could be plugged in while you ride. https://www.amazon.com/Battery-Tender-0 ... way&sr=8-7

Then You say the battery is dead? A good battery should provide enough to keep all running longer than 15 minutes. I've driven a car at night for about an hour with no fan belt, no charging....

This seems to point to multiple problems..
First, I'd pull the battery and have a load test dome to prove its health.
Then I'd do alternator testing as above...

This would test the major parts. The reliability of the failure does not point to a ground short in wiring which is normally intermittent in nature.
What else can you add about the characteristics of its breakdown? Do the lights fade out or a quick fail? Does the motor sputter then die? Is there a fuel loss too?

Two brand new batteries gacked out. One lead acid, one maintenance free. Shop contacted me today, said the charging system puts out proper voltage but after 5 minutes of running drops off to nothing. They’re going to test the stator next week. So they’ll test that, then possibly replace it, same with regulator/rectifier. I’ll keep you all updated.

Stator tested good according to shop. New regulator/rectifier on order.

Was it run long enough to get warm... like that 5 minutes under load? I hope they found it for your sake.

I have no idea how long they ran it for, but it’s a small shop and I’ve been dealing with the owner and we’ve communicated that this is a problem that arises as it warms up. (Discovered the voltage drop after running prior to testing the stator so I’m going to say they’d run it long enough to get it warm)

Regulator was replaced and seems to have fixed the issue. Took a 80 km round trip ride from the shop and had no issues (would have had issues on that length of ride previously.) so hopefully that’s it.