Need help with DC electrical issues on my motorcycle

[Carlos C]

The main fuse keeps overheating to the point it's melting. It seems like the circuit is overloading. This fuse is a 30-amp automotive size blade type, and is the correct amp rating, according to the owner's manual. All electrical systems are still functional, and could not find any visible damage to the parts of the electrical harness that are exposed on the bike.

The wiring for the main fuse has never been tampered with, besides replacing a broken ring connector to the battery. This fuse provides the power to the bike directly from the battery. The rest of the systems' fuses are the 15-amp, mini-blade type. They all are in perfect condition. I had just replaced the voltage regulator, and suspected that the new one may not be regulating properly, but that's not the case. The static battery voltage is 13.1 VDC, and 13.75 - 14.0 VDC while the engine is running, even while revving it up. I made sure that all non-essential accessories were not running during this test.

I placed the system to ignition on/engine off for about five minutes, and no rise in temp was detected. As soon as I started the engine, I could feel the new fuse getting warmer. After about five minutes, the fuse was too hot to hold, but the wiring around it remained cool to the touch.

Before I take the whole bike apart, to inspect the complete harness, I'm willing to take suggestions, and answer questions. Responses will be greatly appreciated. Thanks in advance.

Carlos

[Doutie]

Say Carlos, I think you may have a bad battery. When you run the engine the alternator is working it's butt off trying to charge the battery and that high charge current is overheating your fuse. Was the regulator also a victim of the same root problem.

[Carlos C]

Doutie:

I checked the static voltage again this morning, and it was 12.7V. Then, I did a load test, and it read about 10.4V, and the needle was on the borderline between "Good" and "Weak" on the tester, but it read 11.0V on the volt meter at the same time. I replaced the battery last October, along with the voltage regulator that went bad last month. Since the battery is still under warranty, I'll see if the dealer will replace it. I also borrowed an Amp meter, so I'll see if I can read the amperage coming out of the regulator. I'm pretty sure that the problem is somewhere in the charging system (battery, regulator, or stator) or the wiring in between these items.

Thanks for your input, and let me know if you can think of something else. I'll post the results of my test later.

Carlos

[Carlos C]

I took the battery to the Harley dealer, which kept it for about an hour running tests, and turned out to be a good battery. Unfortunately, I don't have time today to test the amperage coming out of the regulator, but I need to download an electrical schematic that shows the regulator on it, for further troubleshooting. All the ones I have from the Harley manual, have it omitted. The Harley techs kept mentioning loose grounds, but I have already checked them. As of now, they're just as clueless about what's causing the main fuse to melt, as I am.

Carlos

[Doutie]

Carlos, the amp meter is a good next step. If you install it between the 30 amp fuse and the battery, it will tell you how much current is passing thru the circuit and also the direction. If the polarity of the amp meter is correct, then a draw from the battery (such as lights) will read as a negative current flow and the charging system should show a positive current flow. Nice to know which way the train coming down the track. Another stupid simple problem I've seen for this problem is a loose or dirty fuse holder. Either will be a point of resistance that will generate heat as current passes thru it.
Good luck and remember that some mere mortal human
being built the silly thing, so you can fix it if you have
enough information.
Doutie