Dead battery

ford
f100

#1

In my 54 ford pickup with 350 chevy engine the battery goes dead over night i follow some suggestion like taking the fuses out one by one. no change i connect a text light from the ground cable to the battery ground post and light comes on . help please and thanks.Ray.


#2

If you have a generator, try disconnecting the voltage regulator and see if the light goes out. If so, one of the relays is probably stuck.

If you have an alternator, try disconnecting your alternator and see if the light goes off. If so, your problem is there, probably a shorted rectifier.

Original thread:
http://community.cartalk.com/posts/list/2160221.page


#3

I am assuming you have generator along with a seperate voltage regulator that may have a stuck relay causing the trouble. Try removing the wiring to the regulator and see if the test light goes out then and proving that is the trouble area. If that doesn’t work then remove wire branches that extend from the positive side of the battery to see which one has the trouble on it. Keep following the troubled wire leg until you isolate the trouble.

If your vehicle uses an alternator then I suspect Tardis is correct and you will most likely find the alternator is causing the trouble.


#4

i disconnect red wire from alternator and try to connect the test light from the battery to negative post and the test light does not come on, so could it be a bad alternator?


#5

You have a bad diode in the alternator. A good diode only allows DC current to flow in one direction and that one way flow charges the battery only. When a diode goes bad or “shorts” it allows the battery to discharge through the alternator and kills the battery.

Put a new alternator in and all should be fine.

You should first make sure the battery is fully charged before installing a new alt
as a “dead” battery could kill an alternator as they were not meant to recharge a “dead” battery.

People do it everyday by getting a jump after leaving lights on etc but why take the chance to toast a new alt.


#6

Yep.