battery or alternator???

noreaga0221 · Jan 3, 2003

i accidently left the map lights on the other day and the car wouldn't start. got a jump and it ran fine. it sat until today and needed another jump to get started. after school it seemed like it would need another jump but it finally turned over. i get home and not even 10 mins in the door i go to start my car and she wouldnt start. had to get it jumped before i could go to work. after work same thing, then about 10 mins at a light i stalled and again had to get it jumped. when i got home i let it sit for a min then shut it off but it started rightback up.

i'm gonna see if it starts in the morning.

to sum it up, i needed a battery jump everytime i started my car. whats wrong?

loreak · Jan 3, 2003

if it was alternator then even once running it would die cuz the battery wouldnt be getting charged, if it was running fine until you turned it off then battery

hook up a voltometer to your battery and you should get 12 volts off and when the car is turned on 13.5-14.5 volts, that tells you the alternator is working, otherwise it would be probably 11's

300dollarGSX · Jan 3, 2003

Time old alternator test

I'm pretty sure your alternator is okay if the engine stays running and the battery is dead. You can test the alternator by starting the car and disconnecting the negative battery terminal. If the car dies, the alternator is bad. It is also possible to have a poor connection to the alternator (corroded, broken, or fried wires). Take the car to Autozone or the like and they can test load test your battery.

Blackboost · Jan 3, 2003

I believe it's a faulty battery indeed.

Moved to Electronics Tech...

stevep · Jan 3, 2003

Re: Time old alternator test

300dollarGSX said:
You can test the alternator by starting the car and disconnecting the negative battery terminal.

I'm suprised Blackboost let this slide by. Please don't do this to test your alternator. It might have worked fine back in the days of mechanical voltage regulators and non-computer controlled engines, but it's just asking for a blown alternator and ECU. The battery is an integral part of the electrical system, it filters the DC ripple from the alternator. Pulling the battery out of the circuit on a running vehicle can cause the alternator field to collapse and generate inductive spikes of several hundred volts on the output. Those can wipe out the regulator, diodes, and every other modern electronic device in the car. Is it worth the risk? The correct procedure in listed in the manual or let a battery shop check it out.

Steve

Blackboost · Jan 3, 2003

Re: Re: Time old alternator test

stevep said:
I'm suprised Blackboost let this slide by. Please don't do this to test your alternator. It might have worked fine back in the days of mechanical voltage regulators and non-computer controlled engines, but it's just asking for a blown alternator and ECU. The battery is an integral part of the electrical system, it filters the DC ripple from the alternator. Pulling the battery out of the circuit on a running vehicle can cause the alternator field to collapse and generate inductive spikes of several hundred volts on the output. Those can wipe out the regulator, diodes, and every other modern electronic device in the car. Is it worth the risk? The correct procedure in listed in the manual or let a battery shop check it out.

Steve

Believe it or not, I use this little test to know if the alternator is faulty or not. It's just for one or two seconds at most and I have yet to see anything get blown up or damaged. But to each its own.

Please, don't take me wrong since I don't want to enter in an argument about if the ghetto procedure should be done or not. So if you have the chance of a battery shop testing it out for you, go ahead and let the professionals do it.

noreaga0221 · Jan 3, 2003

yea i think its the battery, maybe it cant hold a charge. i got it running with a jump and took of the negative cable and it stayed running.

i got a voltmeter and put it on the battery, it read 14.2 or something close to that. that shows the alternator is working right?
i shut it off to get a reading with the engine not running. i got a reading of 12.6. then i tried to start it and it wouldnt start. took another reading and got 11.6.

gotta buy a new battery.

hybridGS · Jan 3, 2003

Most auto parts stores do free battery and alternator checks with specificly designed machines. You could always just run up to one of them if you want a quick answer without the hassle.

noreaga0221 · Jan 4, 2003

bought a new battery and problem solved

hopefully.....zzzz

battery or alternator???

noreaga0221

loreak

300dollarGSX

Blackboost

stevep

Blackboost

noreaga0221

hybridGS

noreaga0221

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