Bottom line: With the key removed in the OFF position, with the battery removed I get zero Ω resistance between the black and red cables. I'm no electrical engineer, but I don't think that's right.


How I got to this point...
Day 1: I try to start the bike. Engine turns over but doesn't quite start, nothing really out of the ordinary. I keep trying, engine keeps turning over until it eventually just clicks, like I killed the battery. I take the battery out, and put it on the charger.

Day 2: I take the battery off the charger and put it in the bike. Lights come on like they should when I turn the key. I try to start, it clicks but doesn't turn over. I take the battery back out and put it back on the charger. I notice that the battery is strangely hot to the touch, almost scalding hot.

Day 3: This time with a voltmeter, I verify that the battery is charged when I take it off the charger. I read ~10 volts. I put it back in the bike and try again. I notice sparks when I'm connecting the cables; I think this is strange as I have never noticed this before. This time there's no click when I try to start, all lights just go out. They don't come on and nothing happens no matter what position the key is in. I assume I've blown a fuse, so I open the electrical panel and check the resistances of the four 15A breakers and the 30A breaker-- I'm not aware of any other breakers or fuses. I get low resistance on all. I start to put things back together and check voltage on the battery, and I get zero. I take the battery out (it's warm at this point, but not hot) and get ~4V on the battery, and zero resistance across the cables.

If anyone has any suggestions, I'd appreciate the help.

 

Not sure what year your bike is, but HD's will not start if the battery is below 12v. This protects the system from burning up while cranking on the starter.
It sounds like you need a new battery.

 

What does your battery voltage drop to when your tryin to start it ? It could be your battery charges but doesn't hold the charge making your battery not have enough amperage to start ...

 

In his post he said 10v after charging, and if it is getting that hot I seriously doubt it is any good.

 

That hot and 10 volts means your battery is shot. You may have another problem, but it's going to be hard to troubleshoot until you get a good battery. You should have no continuity between your positive and negative cables with the battery removed. If you have zero resistance, the starter solenoid may be shorted out.

 

For starters (no pun,.........really) when connecting a battery always install the positive terminal before the negative, doing it the other way lets it spark (because its grounded) on contact whereas installing the positive first you get no sparks because there is no path to ground. You may have blown a fuse doing it this way and 10V is too low, get a new battery and check the fuses before starting with a test light.

 

Wow, thanks for the responses.

So, we can all agree that my battery is shot. The main thing we need to figure out now, though, is why there is a zero-ohm short from the red to black connections to the battery, even when the key is in the off position.

I've uploaded a diagram I scanned from my service manual to help talk through my troubleshooting:


I have disconnected the start relay and checked all points with an ohmmeter; it appears to be working properly.

I checked the resistance from the green and red/black wires that connect to points 30 and 87 at the starting relay. I get no resistance between the two points, regardless of the position of the key. Based on my reading of this diagram, that is impossible unless the ignition switch is shorted. That doesn't explain, though, why there is a short between my battery terminals.

I haven't yet gotten at the starter solenoid. The next thing I intend to do is disconnect the starter and check the resistance between its two terminals-- I think that if I find no resistance, that means my starter solenoid is shorted out. Is that right?

Thanks again everyone for the help.

 

You can still get some sparking no matter what order you hook it up if there is any kind of a load on the circuit. If you graze the terminals at all instead of sticking it right in you will get spark.

I agree, before he does a ton of troubleshooting get a new battery connected, since it was cranking before I doubt there is any other trouble other than a bad battery. Unless he screwed up the starter/solenoid by cranking it so much.

 

charge battery and load test it my bet battery is toast.

 

Exactly.

I'm thinking the same thing here too. The zero resistance between his battery cables could be caused by a shorted solenoid, and hooking a battery up with a shorted solenoid would darn sure throw sparks when he hooks up his battery.