Help Please

[lainy]

We have an 89 Grand Marquis... we just bought a brand new battery for it in October of this year.. The thing is for some reason the batter is dying... What can make the battery die? when its new...

Elaina

[6502dude]

Auto batteries will become useless if they are frequently deep discharged.

If your charging system is okay and car has needed to be boosted after battery replacement, look for sticking relays.

Some of the late 80's GMs would have fuel pump relay, or EEC relay stick on after car was off. This will discharge battery in a few hours to a point car will not start.

This repeated cycle of battery discharge and recharge will kill it in less than 1 year. You may not have need to have car boosted if battery is new enough and shut down / restart in less than 12 hours.

Hope this helps.

[lainy]

Lol.. Is there anyway u can say it in dummy terms? I have nooo idea what ur talkin bout.. lol im sorry... Thanx

Elaina

[Bronco2]

What Dude is talking about is a battery drain after the car is shut off. This could be stuck relays,etc. or as simple as a lite in the trunk that stays on.This test involves a current draw test to see if the draw is within limits.(app. 250Ma). On the other hand,a new battery doesn't mean a good battery. They can fail at anytime,and I have some that were bad right off the shelf. Have the system checked by a Pro.

[lainy]

ok.. So have the battery tested?

Elaina

[33Chev]

It might be worth buying a voltage meter that plugs into the cigarette lighter..really handy..look for voltage output around 14volts +- when first started while charging..it will drop to about 13.8v after the battery peaks up. (Autozone has them..really handy for monitoring charging systems, just let the customer monitor volatage for a period of time, but be sure to unplug it at night!)

It the charging system is throwing out the 14v..you know it is working. Let the car set and check for battery drop over a period of hours..or let Autozone check it for free!

Another area that gets a lot of folks is the mercury switch light under the hood, glove compartment or trunk. The little light may be on...draining your battery over night.. because it is out of adjustment and on all night!

[6502dude]

Originally Posted by lainy

ok.. So have the battery tested?

Elaina

Since you appear to lack fundamental knowledge of charging system ( and likely do not have tools to diagnose fault):

Go to reputable service center and ask them to do the following:

a) Test alternator output and charging capability
b) Test battery & output capacity
c) Measure current drain from battery in KO (key off) condition for parasitic current drain

My guess is that you have a problem with (c).

Many shops will do (a) and (b) free of charge on expectation of selling parts.


If your battery is bad - it may still be under warrranty (subject to pro-ration).

If sticking relay is your problem, as in case (c) - part is about $10. But expect to pay for an hour labour for testing. Your battery is likely is no good as well and needs replacement. If you went to shop earlier and they missed the root cause, you should ask them to replace battery free of charge (no pro-rating).

[lainy]

Yes I do lack car knowledge.. But i guess the battery that was in the car when we bought it was too small for it.. cuz we bought the same size battery that was in there previously... I guess the car needed a bigger battery....