Testing The Charging System

Step 1. First things first, load test the battery. Most places like Auto Zone will do it for free. Even if it measures over 12.5 vdc it can still be bad under a load. Battery is typically rated at 19 amp hours and 270 Cold Cranking Amps (CCA).

Start the engine and measure DC Volts across the battery terminals, the regulator should...

click here to read the entire tip ►

glider

When you locate the bad part after testing, replace them both anyhow because the other part usually fails soon after.

dlingle61

On my 98 Ultra I first replaced the regulator (this is before I found this site) I still wasnt charging then found this site and did your tests. I found that my stator was burnt. So have replaced it, but now testing the new regulator I have 11.5 on both pins so the bad stator must have fried it? Also this new regulator is a 50 amp should I be replacing it with 35amp?

glider

Sounds like the regulator is toast. Replace the regulator with the correct one for the stator size and the bike.

dlingle61

So I just had a expensive learning experience. Thanks for the info and I like the site. Dave

glider

Harleys are always an expensive learning curve, don't feel bad.

diggerdaveaz

First of all Glider.... THANKS for your info, it has helped me eliminate a few suspected problems. Ok...I've done all the testing you posted and everything is checking out fine and within the specified ranges. BUT.....at idle I'm getting less than 12v charging at the batt terminals. As I go thru the gears (I hooked up my meter so I could watch it) I get anywhere between 12.2v up to 14v. Even at 50mph in 5th gear I'm barely getting over 12v, if I kick it down to 4th gear then I get over 13v at the terminals.
I've replaced the regulator and even replaced the 40a breaker thinking maybe it was weak. Is there such a thing as a "weak" stator? I'm at a loss here, I've been wrestling with this for over 2 weeks now, can't afford to take it to a shop.
'02 FLHRI
Thanks in advance.
DiggerD

glider

There's always the possibility of a weak stator where one magnet is shorted out. Don't overlook that. Your best bet at this point would be to open the primary for a visual inspection.

diggerdaveaz

Thanks Glider, I guess I'll have to proceed to that step......dangit

Chopper

diggerdaveaz if I was going to all the work of opening it up I would go ahead and just install a new stator using new mounting bolts. I have seen stators stop working then start working again, a sign there ready to go and have also seen low output from them, you will probably smell the smell when you pop the cover, like Glider said check the magnets in the rotor that none are loose, then when you go back up you know what you have. Just what I would do, good luck.

diggerdaveaz

Thanks Chopper......I hear ya on that. Going to start with the "sniff test" first, and at least take a short ride and reach hwy speeds and see what my meter is reading, exhausting all possibilities before major surgery.