Car Question

[long-a-coming]

Car keeps losing all battery power. Starts right up with a jump, its a new battery, but will go dead as soon as turned off even if it runs for 30 min. Does this sound like an alternator?? Nissan Sentra 2002.

Any do it yourself car folks out there?

 

[Teegate]

Yes. The best way to tell is to start the car and while it is running disconnect the battery. If the engine dies or seems to be about to die the alternator is not putting out. Your car does not need a batter to run, the battery is basically there to start the car.

I forgot to mention to turn your headlights and maybe the heater fan on before disconnecting the battery. If the alternator is weak it will not be able to keep the engine running with those on. You can also try it with them off and if the car continues to run then turn them on and see if it stalls. Just be careful removing the terminals so they do not touch anything.


Guy

 

[long-a-coming]

hey thanks Guy. I'll let you know how it goes.

 

[mudboy dave]

Guys got it right another thing to do is measure voltage at the battery, it should be about 14 volts if much lower then the alternator is no good. Now the other thing (uncommon but does happen), the voltage is regulated by the computer on some vehicles, it is possible however when voltage is not regulated it usually causes voltage to surge causing your headlights to brighten and possibly even blow bulbs. let us know what happens when you disconnect the terminal. Worse comes the worse I can take a run to Berlin one of these evenongs and check it out for you if it goes any further.

 

[ecampbell]

I think it is best to use a DC volt meter. Expect 14.something volts. Anything like 12 of 15 volts is wrong. The alternator could be damaged running it unloaded. Even a dead battery provides a load for it.

 

[46er]

I think it is best to use a DC volt meter. Expect 14.something volts. Anything like 12 of 15 volts is wrong. The alternator could be damaged running it unloaded. Even a dead battery provides a load for it.

Disconnecting the battery with the car running could also blow the ECU. This was something to try when cars had generators. Can easily cause a lot of electrical problems.

If you can get it to one, I'd take it to Autozone, they'll test the battery and alternator for free.

 

[MarkBNJ]

Do you have a charge/discharge gauge on the dash? If you do it will be in minus territory if you're discharging the battery while running, instead of charging. Also, most cars have circuits to detect when the alternator fails, and will at least display an idiot light. Are the terminals and clamps nice and clean? Corrosion can interfere with charging too, but I imagine with a new battery you have clean connections.

My dad had a similar problem not long ago with his Volvo wagon, and it turned out to be a corroded connection down near the starter motor.

 

[mudboy dave]

see i heard the same thing and I have never had anything happen and have done it numerous times. Voltmeter won't lie to ya though. I would not and i repeat not go to autozone for an alternator to be tested. I had 2 of them tell me my alternator was good then i went to advance. Mark is onto something as well with corroded connections. It can make a battery appear dead. If the cables are shot or the terminals themselves it could be making a good connection everytime you hook the cables up.

 

[long-a-coming]

Guys,
I appreciate all the great tips. I felt in over my head and dropped it off at my wife's family's long time mechanic. If future problems persist I will consult with my pine barrens brothers again. If it was just the no-start thing I would of tried but it had to go in for other problems as well, the most annoying problem being the automatic shifter was stuck in park, requiring me to jam a paper clip into the hole to get it in gear. I've been doing that for 2 months now and I'm sick of it. It also needs a new motor for one of the power windows and it just needs an overall checkup.

 

[Broke Jeep Joe]

Be Careful.

Careful with the shifter deal. The interlock is usually activated by the brake light switch. If the brake light switch is bad, meaning no brake light operation, it does not let the car come out of park when the pedal is depressed for safety reasons. The release is there to get it out of park for repairs or what have you. Just an FYI

 

[long-a-coming]

Careful with the shifter deal. The interlock is usually activated by the brake light switch. If the brake light switch is bad, meaning no brake light operation, it does not let the car come out of park when the pedal is depressed for safety reasons. The release is there to get it out of park for repairs or what have you. Just an FYI

As of yesterday the brake lights were working. I will ask the mechanic about this thanks

 

[Chrisr]

It could also be the electric window motor causing the drain. I had a car, that had electric seats and the motor (for the seats) went bad and put a constant drain on the battery.