battery light = 15 volts ?

MartianBob

Registered User
My battery light has been coming on intermittently lately. When the light is on I'm getting 15 volts across the battery. When it's off I'm getting 14. Happens when the car is hot or cold. Does not seem to be affected by turning on ac, headlights, or stereo. Battery is relatively new.
Is the alternator starting to take a dive or some other cheaper part?

Thanks
Bob
 
15 volts seems a bit on the high side---the normal static voltage of the battery is 13.2 volts fully charged and it takes approximately 1.5 volts to "force" it to take a charge so the maximum you should ever see is about 14.7 and the voltage can be much lower if the battery is run down a ways and things can still be fine----I would think that 15 volts would indicate the regulator in the alternator is defective..................Dan
 
Is the voltage regulator something I can replace inside the alternator?
I'm not an EE but I've done my share of soldering on this car.
What is the expected behavior if the top connector is disconnected while running?

Thanks
Bob
 
A fully charged good batter should read 12.6v. 2.1v per cell. 15v is high and that should be whats causing the light. I would take it down and have it tested. It may be possible that even though you have the volts, you may not have the amps. Not likely, but always possible. A reman from Autozone runs about $132 plus core. The voltage regulator is about $82. If it were me, I would look for a local rebuilder and see what they can do for you.
 
Where were you able to source a voltage regulator for our cars. I can't find a rebuild kit or regulator anywhere?

Bob
 
the regulator is inside the alternator... your better off going to AZ and getting a replacement, not only does it save a bunch of hassle but when the alternator does go bad in the future they'll replace free.


btw... the harness on the alternator controls the built in regulator

one wire is a positive feedback that goes to the volt gauge on the cluster if you have it
one wire is a ground
one wire is a positive from the ignition switch that turns the regulator on when the key is on
 
Thanks for the info, $62 at autozone.
The guy I talked to at Advance said they don't sell the VR and I'd never find one somewhere else. I'll give it a shot.
Thanks for the responses.
Bob
 
Thanks for the info, $62 at autozone.
The guy I talked to at Advance said they don't sell the VR and I'd never find one somewhere else.
Welcome to he**.. your fun is about to begin :rolleyes: There are some suppliers that sell the regulator/diode bridge for the mitsubishi 110A alt. Some owners have chosen to replace theirs with a newer 3G alt from later model fords. They're stronger and hold up better.

Anyways.. write this down if you don't already know it..
NEVER charge a drained battery with the 110A alt. Bench charge it to full capacity. If you do this, your reman alt might just survive more than 2-3 months. :cool:
 
the regulator is inside the alternator... your better off going to AZ and getting a replacement, not only does it save a bunch of hassle but when the alternator does go bad in the future they'll replace free.


btw... the harness on the alternator controls the built in regulator

one wire is a positive feedback that goes to the volt gauge on the cluster if you have it
one wire is a ground
one wire is a positive from the ignition switch that turns the regulator on when the key is on

Actuallly.. the alt case is the ground. 1 wire is a feedback wire (and which is redundant) that goes directly to the battery. If you were to remove it, the alt would still work, but I don't know for sure if it would regulate too high or not.

The other wire turns on the "battery" warning light on the dash. It has nothing to do with the battery... just means that the reglator has determined that the alt voltage is not what it should be.

The alternator is "always on" so to speak with the regulator acting with high impedance. Sometimes that circuit will fail and the regulator will draw current all the time thus draining the battery if it sits. You need a ammeter to check for that.

I wired in a relay due to that very problem that breaks the lead to fix my battery drain problem.
 
if you have a napa auto parts near they can rebuild it,they did mine.plus i got 2 from a junkyard,SC,alt.if cant get it fixed.pm me
 
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