Hi guys. This problem is baffling me because it is so blasted intermittent that it makes it troubling which side to tackle. It all revolves around the electrical system. I'm going to list everything that the bike has been doing so this may take a while.

In July 2010 I was having trouble starting the bike. I would charge the battery and the battery would not hold a charge. I could charge the battery and start the bike but the voltmeter on the console would drop almost immediately to the 8-9 range. If I ever shut the bike off it would not restart. I replaced the battery.

I rode the bike during the winter a good bit. I also upgraded the headlights and driving lights to some brighter halogen lights back in October. Even during my winter driving I never had problems.

In April 2011 I started riding a good bit and that is when the problems returned. The voltmeter would read about 11 when I would try to start the bike but the starter wouldn't engage. If I rocked the bike back and forth I could get the starter to engage. So, I was thinking the starter was bad. When I would ride the voltage on the console with the lights on would be right above 12 and would hold at that level.

Then the battery began to act just like it did back in July when the battery was replaced. I would hook up a trickle charger to the battery and charge overnight. The battery charger would show 14.8 when fully charged but the bike would not start and the voltage on the console would read around 11.

The funny thing is that when I use my batter charger to jump start my bike it turns right over. No problems at all. However, once I get on the road the voltage drops to the 8-9 range almost immediately with the lights on. My turn signals will not even work because the voltage is so low.

Sometimes I can see the voltage increase as the engine throttle increases. At other times there is no increase in the voltage at all.

So, I am baffled as to where to start. I have ruled out the starter because the engine starts fine when there is enough voltage. Am I looking at a regulator problem, an alternator problem or can you think of something else that I am not even considering?

 

First off, what's the voltage at the battery when the bike is running at, say, about 2K RPM?

Next, it sounds a lot like you have either a bad connection between the battery and the rest of the bike (there's only like a dozen connections) or a short somewhere. You just need to start tracing it out. Put your volt meter at each point along the way (follow the schematic in the factory shop manual) and see what you have with a load, like the headlight, turned on. I would guess either dirty/corroded connection(s) at the breakers or maybe a bad starter relay or a bad ignition switch.

 

As a spotty-faced budding engineer I was taught that when a warning light comes on the only thing of which we can be certain is that the bulb works!

Your dash voltmeter is telling you things are not right. Do you have a multi-meter, so you can accurately measure what is actually going on?

Also do you have a factory service manual? There are a number of simple checks you can make to test if your stator is faulty, providing the correct charge, if your regulator is working right etc. My money is on a faulty stator earthing out and discharging your battery.

 

Hmmm, Batteries and Harleys eh? What make is your battery? in my experience if it isn't an H-D or a Motobatt then anything over 6 months is a bonus. A screwed battery will give the impression of charging probs....only way to solve it is to test the alternator as per factory manual.

If the battery is stuffed it can eat the charging voltage as it overcomes internal resistance. Had a similar problem with my old Sporty, battery cured it but always do your tests before buying anything.

 

Thanks for the replies. I'll get my voltmeter out, start those checks and let you know what I find. BTW, took a ride yesterday and everything is in what I would call a "normal" phase again. The voltage fluctuates as I ride and increases as the alternator produces more current. The bike starts fine, runs fine and appears to have no problem. Now, I could just as easily get on the bike this afternoon and have the same charging issue as before. This problem seems to go in cycles (no pun intended). One minute it's fine. The next minute no starting and no charging. Weird.

 

Doubt this is it but tossin' it against the wall to see if it sticks.... Buddy had a sporty that would do alot of what you are talking about, long story short, it was the positive cable that goes from the battery to the starter post, one inch from the post it was so corroded that it had seperated, good vibration it worked, bad vibration, lights got dim, signals didn't work, electronic speedo acted up.

 

Hi guys. Got the trusty voltage meters out this weekend and, through process of elimination, decided it was the voltage regulator. I replaced it and the bike is running great! Voltage under full load stays around 13 volts. Thanks for all the help and all the ideas.

 

Glad you found it! Both times my 91 FLHS acted up it turned out to be the voltage regulator. Once I thought it was an old battery and another time thought it was the turn signal modulator as the turn sigs malflunctioned when the voltage dropped.

Installed an LED volt meter on my handle bars now and can see the lights dancing at a glance in the "green" zone.