Just got my new (to me) 1997 FXDWG home yesterday. Took it for a short ride and it didn't have any battery power when I tried to restart it. I looked under the seat and saw that the positive terminal on the battery had melted! I took the battery out and put a new one in.

It started hard, ran good, and then started running awful....missing and going from one to two cylinders. I rode the one block home only to find the positive terminal of the *new* battery had melted right off. I noticed the amp gauge (the bike has one of those trick fuel/amp sensors built into the left side tank cap) was up at 16 volts riding home......

I'm thinking the voltage regulator is the most likely culprit, but am wondering why it would run terrible if it was only the regulator. Could the positive terminal being disconnected cause rough running?

Any thoughts appreciated.

 

Not sure about the running rough part but as far as the melted terminal goes, you might want to make sure the battery is secured. If the battery isn't secured it could be bouncing around while riding and arching against the frame.

 

Thanks. The battery was well secured and insulated from the frame.......

Would a bad ground cause the arcing?

 

Only seen a terminal melt off once. A truck starter solenoid stuck and the starter was running constantly. By the time the driver stopped and figured it out, the terminal melted off the battery. If your battery is being drained hard enough to melt the + terminal off, I'd guess there's got to be a hard short somewhere in the + battery line before the fuse.

 

Look at the wire harness going through the frame where the front tank bolt goes through it. Sometimes, the wire harness gets chaffed and causes a dead short. If the voltage regulator goes south, then that could cause over amperage, but I believe you'd still need a huge draw from the battery...

Look at the inside of the battery cover, to see if it is arching against it? Even if the battery is secured, misalignment can cause a direct short there...

If you have a questionable grounding, clean it well. If I remember right, there is a bolt on the frame under the battery tray, on the right side where the negative cable connects. That can indeed get pretty crusty over time...

 

Thanks, good info. Definitely a short somewhere. But....there's another thing: the hard starting. I cranked it for a while without the engine firing. As soon as I took my finger off the button the engine caught. Happened a few times after the initial battery problem. Then it started running rough, skipping and running on one cylinder. All could be a short, but who knows where. Electrical is my weakest area........

 

The melted terminal was caused by a loose connection. I'm thinking the bad regulator may have generated enough heat to soften/loosen the wire connection at the + terminal. Once the connection is loose the bike will run rough/poorly and it can start to arc, which just compounds the problem, generating even more heat which eventually melts the terminal.

You're lucky that battery hasn't gassed up and exploded or caught fire on you.

I'd say replace and test the new regulator, go over all your connections and clean/tighten them down (especially your grounds).

 

Once the terminal saw the kind of heat that melted the terminal, you should have also replaced the cable. the crimp on the end is more than likely the original culprit. A bad battery can also destroy the voltage regulator and charging windings.

 

Replaced the voltage regulator.....runs like a champ!