QuestionQUESTION: hey i have a 1974 Plymouth valiant and the battery wont hold a charge and i had the alternator tested at a shop and it passed so what could be wrong with it?
ANSWER: Hello Travis,
From your description, It sounds like your battery may have a dead cell. Take the battery to any major auto parts store or Sears and have them test the battery. They will do this for free.
Good luck,
Bob
---------- FOLLOW-UP ----------
QUESTION: i had changed the battery and it is still discharging,what else could be wrong?
AnswercHello Travis,
Thanks for the feedback!
To find your problem from this point, you're going to have to do some detective work. Here are a few suggestions as to where to begin:
1) You didn't mention the test results from your alternator test. A shorted diode in the alternator can cause the problem you have. It will still charge but drain the battery when the engine's off. Be especially careful if the current alternator is a cheapie rebuild from an auto parts store. Many of these units still have problems, Best to buy a Chrysler rebuilt or new alternator--quality is much better but so is price. Unfortunately, in the alternator game, you get what you pay for.
2) Check the output from the Voltage Regulator. If output is insufficient or shorted, replace.
This is an electronic part and is not user serviceable
3) Detective hat on? Another common cause for battery drain is an interior light left on, a short in the wiring harness or aftermarket add-ons like stereos wired so they a constantly on. Get the help of a mechanic if you can't find anything and have him/her measure current draw with the engine off. Current draw above factory spec's will help confirm/deny that the problem is
within the rest of the car.
As you can see, the problem gets significantly more complex the deeper you go. But keeping that old valiant on the road is worth it, heh?
Best of luck,
Bob
