On the way to work today my FatBoy just died. I managed to get it off the side of the road. When I tried to start it, there were no lights and it didn’t even try to turn over. This happened a few weeks ago. That time it died in the garage. I put a trickle charger on overnight and it seemed to fix the problem. The bike only has 12,000 miles and this is the third battery. Anyone have an idea what could be causing problems?

 

Sounds like the bike isn't charging your battery while it's running. Could possibly be a draw in the electrical system some place as well but I would first look at hte charging system to verify that it is in fact charging.

 

Get a volt meter and stark checkin'.

 

Average life of new battery is 5yrs if maintained.

U're on Ur 3rd on a 2 yr old bike..

Yeah I'd be checking the charging system instead of putting a new battery in every time she goes dead..



.

 

Go to Radio Shack and buy a $15.00 volt meter.........analog/digital (more money) and start with the charging system. Check the battery voltage (red terminal s/b positive and black is ground-negative) with the bike not running........should be showing 13+ volts. Make a mental note, now start the bike and look at what the charging system is doing. As you rev the engine the reading across the pos/neg terminals should be greater than the previous number.......almost 14 volts. Also check the resistance between the negative battery terminal and the bike chassis. Near the aft end of the fuel tank is the chassis ground terminal. Also check the resistance between the pos battery terminal and the chassis......should be an open circuit.

You may have a bad stator and it's not charging the battery properly.......do you ride every day or do you ride occasionally........do you use a battery tender if you ride occasionally?

BTW Hal you're not killing the battery.........your bike is!

 

Can I have those 2 worn out old batteries?

 

do you use a trickle charger all the time..i never use them and also never have had a battery die..my brothers sporty is a 2003 and it still has the original battery..i purchased my new bike in 2009 still on original battery .they have never been on a trickle charger ever and same goes for my boat and rv no trickle chargers i just run everything once a month through the winter..ive done this for the last 30plus years without issue ..charging a bettery that isnt low is just wrong ask a battery tech not to mention most trickle chargers dont shut off they just keep charging which is death to a battery..

 

A good charging system should output around 14.2V at any rpm. Your battery with the bike off should be around the upper 12v's or so.

If your getting in the neighborhood of 13-13.5v while running your having an issue with either the stator not outputting enough current to run the bike or the rectifier/regulator is going bad.

There are ways to do resistance checks on the stator to see if one phase is grounded out or if 2 phases are shorted together.

I'm not extremely familiar with Harley's charging system but on my Daytona 675, well most new triumphs, they used a shunt type R/R that had a tendency to fail and overheat. The symptoms are what you describe and a good fix was to replace it with a MOSFET style R/R commonly found on many Jap bikes. They run much cooler and don't overheat and die.

I will have to look but there is a procedure to check both of them well written up on another forum that I'll post a link to when I get to my laptop.

Definitely check your standing battery voltage and your running voltage and report back

 

Thanks for the info. I wasn't sure what the voltage levels should be. As far as riding to work, it's mostly weather dependent. I average 3-4 times a week, plus a couple hundred mile trip on the weekend.

 

Sorry, no longer have them.

Normally, no. As a general rule I don't use a trickle charger at all. I bought one just for this issue. I was deployed last year. Just before I returned, the wife took the bike in, had all the fluids changed, put on new tires and a new battery. That was early April.