Are these symptoms of a bad voltage regulator?

66 Fastback

Famous Member
Is your multi-meter accurate?
However, it sounds about right with your fully charged battery reading of 13.4 volts. Contrary to your comment about that being too high, a new 12 volt battery should have about 13.2 volts at full charge.
I have some cheap meters that read a volt or two different from my better meter. You might see if a someone else or autozone can slap a meter on it and verify the voltage.


Top Poster
Pookster, pull that alternator down and check it with your "handy-dandy multimeter". Resistance for every winding, and check all diodes.

Trust me. ;)


Well-known member
Recently had a similar problem, but the tools to check properly. Turned out I had a bad winding in the starter. This killed the battery which then killed the voltage regulator. Alternator made it thru OK.

I would suggest that you hook up your meter to check voltage drop while starting the car. My fully charged battery would read 12.3 volts, but would drop to 7.5 while cranking. 10 volts may be acceptable but anything less and you have a problem.

The Zone can check about any starter or alternator on their bench. Even Walmart can check your electrical system. Trick is to find someone experienced enough to really be helpful.


Well-known member
Took my car to the local autozone to have my alternator tested and to check the voltage to see if my multimeter was reading right. They say that the alternator is fine, and they also got the reading of 17 volts like I did. So should I still check the windings in the alternator, or what. Also, how long can I keep my new battery going like this until I really start doing some damage, or will keeping the water full, keep the battery from being destroyed?


If the level is droppin in the battery it loosing more than just water so you will be hurting it. How fast I dont know but long term it cant be good.

Lazy JW

Staff member
I had a GMC pickup that always charged over 17 volts. It boiled the battery something fierce; after the second battery went bad I bought an Optima and lived happily ever after.

PS. That works if the ONLY problem is excessive charge voltage.


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Yes there are ways to check them., describe the problems you are having. It will also be better and less confusing for you to start your own new thread instead of posting on this very old one. Good luck