Hello everyone. I have a 1992 FLHTC. The battery keeps draining. Has anyone else had this issue and what was done to fix it? Where should I start? The charging system is charging fine. When the bike sits for 2 days the battery drains. Any help would be greatly appreciated...

DIESEL

 

Hi Diesel, how old is your battery? These things can last as little as a couple of years or a decade, then turn their toes up. Could be as simple as it is clinging to life.

 

One way to check is to remove one battery cable. If it sparks that indicates a drain. Now a couple of things can cause that, and it would be considered normal. One is an alarm system, and the other is the radio. The radio has very small drain to keep the clock set, and the radio presets. Anything else means there's something possibly not shutting off. If you put a meter between the battery cable that was removed and the battery, read the voltage then pull each fuse until it drops. That will tell you where your drain is coming from.The ignition switch may not be completely removing the voltage when turned off, but that's more rare of an occurrence.,,

 

Hey guys, thanks for the responses. The battery is new. That was the first thing I changed. Next was the charging system and it is good. The one thing I noticed is when you flip the switch all the way to accesories all the lights stay on. Is this normal and if not what is the fix?

 

You might want to pull the battery (or disconnect it from the bike), fully charge it, and then let it set 24 hours. Measure the voltage to ensure it is still fully charged, probably something like 12.6 volts or more. If it didn't lose voltage, then start looking for a drain on the bike. I think there are a number of ways to do this but it was my bike, I would put an ammeter between one of the battery cables and the bike to see if I could measure any current drain. The radio and the alarm (if you have one) may draw a few milliamperes but that should be the only thing drawing current.

If you are showing more than a few milliamps draw, I would probably start pulling fuses one at a time until the drain stopped. When you pull the fuse for the circuit that is drawing current, the meter should show the drop. They you would need to figure out what's going on with that circuit.

Good luck.

 

Well,
I fully charged the battery. Went riding for a few hours and a few stops. Last stop the battery was dead so it must be the charging system...

 

Or the battery is shot. If your charge it, start the bike and rev the motor with a meter on both terminals, you should see the reading go up with motor speed. If it does then it's probably the battery that's not holding a charge. Might be loose connection some where. There are other tests, but look for the most common before you spend lots of $$$ unnecessarily.,,

 

It's not unheard of for new batteries to be bad so don't fly right by that possibility.

You said you rode for 3 hours (if that's what you meant by a "few" hours) plus a couple of stops and starts. If the charging system wasn't putting out at all your battery, even fully charged, wouldn't have lasted that long. Especially with the lights on and whatever else draws power. You already know the battery won't hold a charge so I'm leaning towards the battery being the culprit.

An easy thing to check though is pull the plug out of your stator (the crankcase plug) and see if it's fouled with oil or gunk. (Also, and I'm sure you would, make sure it is fully seating) The crankshaft seal behind the alternator can develop a leak and if you run a wet primary it's not something you'd notice right away. That motor oil seeping out past that seal can gunk up the rotor and stator which will reduce charging efficiency. I seem to recall the MOCO cheaped out and used a single lipped seal there instead of a double lipped one but I'm not sure how many models and years that affected. But even the double lipped ones can go bad.

But back to the battery. If you just check the voltage like most do you might be getting an erroneous reading. The better way to do it is turn on the lights (with the motor off) and let them burn for about two minutes. Then turn the lights off and check the battery voltage. This is sort of a poor man's load test. The battery should still read 12 volts or higher, if not there's probably something wrong with it.

An outright load test is good only if you know someone who can do it correctly. The load applied and the time to discharge (basically how long it takes the battery to fall to a prescribed voltage) is important for a valid test.

My money is on a battery problem. Even if you have a erroneous drain it would probably be something the charging system would overcome while the bike is being ridden.

Keep us updated!

 

I have a 92 ultra classic and i was having the same issues. It was the solenoid on the started it was staying engauged and draining the battery as i was riding it. Had the starter and solenoid rebuilt have not had a problem since.

 

+1 on this.

Also to just test if the battery is holding a charge, you have to "burn off" the top of the charge after removing it from the battery terminal. If you charge a battery, then immediately check it, you might get something like 12.9 VDC. Then after leaving it sit and checking it again, you might see something between 12.6 and 12.8 VDC and assume the battery is loosing its charge. This is not necessarily the case as the topped off charge will dissipate which is normal. To test correctly, charge the battery and then put a small load, like lights or something for about 10 seconds, remove the load and check the voltage. Then leave the battery sit, disconnected from everything, and test it again in a few hours. The voltage should be the same which should be in the 12.6 to 12.8 vicinity for a gel or maintenance free battery.