Having charging problems on a 02 ultra, when i check AC voltage at the stator plug I'm getting 53 volts - everything i've read talks about minimum reading, is my too high?

Sudeep Chatterjee

• 3267 Answers
• Posted on May 26, 2009

SOURCE: battery wont charge more than 12.25 at 2000 rpm

Check the rectifier, its responsible for charging the battery when running, the fuse too, however the rectifier if it can not be repaired, better to buy a new one......................sodeep

SOURCE: Recently having problems with my 2000 Fatty not

First, take your battery somewhere and have it load tested. Fat Boys are tough on batteries as the battery sits in the "horseshoe" oil tank and is subjected to high temperatures due to the hot oil in the tank. Battery life is typically two years although I've seen some go longer and some not last that long. Have the battery tested before you start spending money.

To check the stator, you unplug the regulator at the engine case. Down inside the plug you'll see some electrical connectors. Connect a DVOM (digital volt ohm meter) to these connectors (one lead to eac pin) and put the meter in the 50 volt or higher range AC voltage. This is important that your meter be set to measure AC voltage because at this point, the voltage is indeed an Alternating Current voltage coming out of your alternator. Start the engine and bring it to a high idle. You should be reading over 20 volts AC. The book says that you should read 12-18 volts per 1000 engine RPM. If your engine is turning 2000 rpm, your meter should read 24-36 volts AC.

To test the regulator, first charge your battery to a full charge. Then connect your DVOM across the battery, red to positive, black to negative. Put the meter in the 20 volt DC range. Start the bike and bring it to a high idle. The voltage will start at somewhere around 12.5 volts and climb to about 14.5-15 volts. This would indicate that the regulator MAY be alright.

Now, have you changed any of the lights on your Fat Boy? I've seen people change and add lights to the point where their alternator could no longer put out the current necessary to handle the load. If this is the case, you may need a higher out charging system.

I don't know where you're located but $260 seems quite high for a voltage regulator.

SOURCE: why is my 2006 street bob not charging

If the regulator was replaced and wasn't properly grounded it will not charge.

SOURCE: I have a 2000 fatboy stopped to get gas battery

Hi,
To check if you got a charging fault, get a multimeter and switch to voltage put across the battery. You should be getting at least 13.4 volts.
Turn lights on and this should fluctuate upwards. If your getting anything lower then what I stated you have a charging problem. Rectifiers and regulators can only really be tested of the bike with a specific tester. Hope this helps, let me know how you get on.

Jason

SOURCE: After leaving the last gas

Ok, let's check the charging system. The battery is easy. Take the battery out of the bike and take it to an automotive parts store. Ask them to load test the battery for you. If the battery is over two years old, it could need replacing.

Once you're sure the battery is good and it is FULLY CHARGED, we can test the rest of the system. You'll need a DVOM (digital volt ohm meter) to check the system. With the battery back in the bike, connect the DVOM across the battery. Red meter lead to the positive terminal of the battery, black meter lead to the negative. Put the meter's function selector switch in DC VOLTS, 20 VOLTS or greater. Start the bike and bring it to a high idle. The meter should read 14.5 - 15.0 volts.

Now, to test the stator, follow the wires from your regulator down to where it goes into the engine cases. Disconnect the connector and look into the engine side of it. You'll see two metal contacts down in there. Set you meter's function selector to AC VOLTS, 50 VOLTS or greater. Start the engine and bring it to a high idle. Touch each one of the metal contacts down in the engine side of the connector with a meter probe. It makes not difference since we're measuring AC voltage at this point. The meter should read at least 30 volts.

Now, if the alternator (stator test) does not put out at least thirty volts, the stator is bad and needs to be replaced. If the alternator does check good but not enough voltage at the battery, your regulator may be the culprit. Make sure all connections are clean and tight and that the body of the regulator is grounded good. Recheck the test at the battery. If it still fails, replace the regulator.

Now, I've seen may problems such as your's that are intermittant. In other words, the problem is here on minute and gone the next. I fought that on one bike for over a year until we finally replaced the entire charging system and fixed it. If your bike proves to be doing that, you may wish to consider that option. Fix the thing and be done with it. I wouldn't buy the rotor, just the stator and the regulator.

Good Luck
Steve

Testimonial: "right on with the test procedure. Battery didn't show it was charging. While the stator test showed 30vac, an ohm test showed it was grounded. Thanks "