Should not the voltage regulator regulate a charge to the battery at all times?? On idle with headlight on voltage gauge reads below 10 volts, it's fine when cruising if I don't have any load on it such as sterio. Whenever I use extra power such as the sterio the voltage drops dramatically even at highway speeds. Do you think I need a new voltage regulator?? Any help would be appreciated.

 

Could be a bad/weak alternator. Seeing how the VR is cheaper and easier to replace you might try that first and hope for the best but the regulator can't help if the source (alternator) isn't working right. Take my advice with a grain of salt because I'm no mechanic.

I had a 1990 touring Harley. Good bike.

 

The voltage regulator just sheds of any excess voltage from the alternator so the battery doesn't get overvoltage.

If you are experiencing low battery voltage while the bike is running I would suspect the alternator first.

 

Jeez.

there are specific charging system test instructions on the electrical forum.

basically the alternator puts out 16 to 20 volts AC per 1000 rpms.
This AC voltage is converted to DC at the regulator, which as mentioned above sheds excess voltage regulating to below about 14.8 volts DC)

at idle your alternator is not putting out alot of voltage.

2.) the meter is the dash likely reads low, use a real voltmeter

3.) electrical tests must be made with a good charged battery, or many of the numbers will come up wrong.

4.) don't just start swapping parts with out a diagnosis of a fault ( which you probably do not have)

mike

 

You may want to ask this in the EVO area.

mikebaby

 

My volt meter reads a full volt and a half low. Take your measurement at the battery like mentioned. Also before you go buying parts you don't need, check EVERY ground wire and strap. There is a big strap from the engine to the frame underneath that gets pretty nasty. Remove it, clean it and the bolts and washers. Then take some emory cloth or some other gritty paper and clean the area of the frame and motor where it bolts to and reinstall.

 

Thanx Dale; I'm kinda leaning towards the alternator now. I checked system for ground faults and load tested the battery, everything is fine there. I then checked the alternator for resistance and the ohm meter didn't move, it stayed on infinite.

 

Thanx Scuba; I didn't know that, I thought the reg. regulates the voltage to the battery depending on the alternator output, but what your saying makes more sense.

 

Thanx Mike; I load tested the battery and it's fine, no ground faults, everything is grounding properly. Checked the alternator for resistance to see if it was shorting but the ohm meter needle didn't move, it stayed on infinite. The manual contradicts itself here, it says that if the resistance reading is infinite there is nothing wrong with the stator but the diagram says the alternator needs replacing if on infinite. Strange, I gotta check this out further.

 

Thanx Guslingertom