Battery Light

[ddddde]

Hi I have a 98' ford taraus 3.0 v6 and I was driving yesterday and the battery light came on, 5min later my radio shut off then I lost power to my my gauges then the car started to putter. I parked it tried to restart it and nothing battery was compleatly dead. The serp belt is still on, can a alternator take a crap that fast or does anybody else have any ideas of what might be wrong?

[MyTaurus8AChevy]

It may have been going bad before the light came one, so you really don't know how long its been like this...

[Dave_s]

Not sure what is going on, but when the altenator dies the car will continue to run off the battery untill the battery goes dead. It could be the battery light goes on when the charge on the batttery falls below a certain point. This would explain why the car dies quickly after the light goes on. So you would want to start by getting your battery charged and your altenator checked.

[Selectron]

Originally Posted by MyTaurus8AChevy

It may have been going bad before the light came one, so you really don't know how long its been like this...

I was thinking that too.

If you want to check what's going on, you'll need a multimeter. First thing I'd do is recharge the battery. If you would normally remove it from the vehicle to do that, then that's fine. If you normally charge it while it's still in the vehicle, then remove the connector from the battery negative terminal first so that the alternator is taken out-of-circuit, because you may have a heavy leakage current flowing back from the battery into the alternator if it has gone faulty, and it could overload the charger.

If your battery is still good, it will have a terminal voltage of around 13V after it has been charged and left to stand for a while. When you connect it back into the vehicle, that will start to drop to around 12.6V and then settle at that level. If the voltage does indeed stay around that level then you can try starting the engine and then measure the battery voltage - with the engine idling it should be thirteen-point-something volts, maybe as high as 14V - that's if your alternator is still good, and giving an output current.

If on the other hand, you start the engine and the battery voltage heads in the opposite direction and falls slowly downwards below 12.6V and continues to fall then that tells you that your alternator is not supplying a charge current, or at least, if it is then it's not reaching the battery, so suspect a wiring fault between alternator and battery, or a fault in the alternator.

The third scenario which you may find is that as soon as you reconnect the battery, the voltage immediately nose-dives, falling rapidly downwards from 12.6V - that would indicate a heavy current flow, probably in the direction of the alternator, and would suggest either a wiring fault or a failed alternator (if the current was flowing in any other direction, it would be tripping breakers or blowing fuses).

You won't be able to diagnose much without a meter, but if you have access to one then you should get a good idea of what's happening by observing the battery voltage after you recharge it and re-install it. Good luck.

[MyTaurus8AChevy]

Keep in mind that since your battery is completely dead, that you will not be able to fully recharge it again, so once you fix your problem the battery will still show symptoms of a bad charging system. However it will not be your charging system that will be causing this, it will be your battery. To test the system under these conditions you'll need to replace the old battery with either a new battery (which eventually you'll have to do anyway) or with a battery from a second car that has not ever been fully discharged. The battery should always be the last thing that you replace, so fix the problem that caused all of your problems, and then replace the battery before testing the system.