ok my friends car he said theres not enough juice to start it but if he jumps it than it will run fine (with lights, music, etc). but its everytime he goes to start it that it will not start. he thinks its the alternator. i told him i think its the battery cause once the cars running it doesnt use the battery to stay running right? it uses the altenator? he said he just baught a new battery over the summer so its only about 3-4months old....whatd you think??

 

Still sounds like battery to me. If it's the alternator and he jumps it, it will eventually die running on just the battery. Maybe he needs to clean his connections.

 

it is the battery. alt runs the car and batt starts it pretty much. if you ever want to test your alternator, take off a battery terminal while the car is running. if the car shuts off your alt is not providing enough electricity to keep it going. just an FYI.

 

uh no, that test bad for your car. the battery is used as kinda a surge buffer for your electrical system.

heres my suggestion, jump start the car and drive around for like 1/2 hour turning everything electric in the car on. if your car doesn't stall on the road, then it's not the alternator.

My sister's camry recently ad the same symtoms. We changed the battery and it's normal now.

 

or you could take it to auto zone and check to see if you have enough juice left in that battery...

 

uhh wrong. it is bad to drive like that for long periods of time. but for the 5 seconds it takes to see if it is bad or not, that does no harm to the car. not to mention your idea would leave him.her in desperate need of a tow truck if it is the alternatior since the alt would be dead and the battery would now be dead.

 

Have a free battery check in autozone first

 

Get the battery checked. If it's new and it is the problem, it should be covered by some warranty. I beleive it's also covered in cse of alternator failure depending on where you bought it.

 

i think we found the problem. tested the battery and alternator and both tested fine. but his + bat terminal is wierd. hes got 3 wires going to it, all of which look stock (95 jetta). one of the wires is realllyyy corroded and actually burnt a little bit(guessing due to high resistance which would cause it to heat up). so hes going to cut/splice it and crimp a new ring terminal on and see if that helps. it was wierd, cause the wire would get WICKED hot after letting the car run for a bit. and the car wouldnt start until that wire cooled down again.

 

nope youre wrong. i read on another car forum site that doing this can actualy cause voltage spikes of something like 150amps which can potentially fry you alternator and/or starter and other electrical components because the battery acts as a surge protector to the electrical system.

 

I would like some further explanation of this. I don't see how an alternator normally rated at 110 - 125 amps can generate 150 amps at idle. If you're getting voltage spikes your alternator/voltage regulator needs to be replaced. A battery doesn't not act as surge protector (kinda strange you call someone wrong say something crazy like that). You can even have voltage spikes even with the battery connected believe it or not!

 

The fact is it won't. and the fact is our alts produce 100-125 (i think its 115) at max output so Baxtel is absolutely correct. and the battery does not act as a surge protector. its does act as somewhat of a buffer that helps to keep the voltage steady, but any surge will fry your car, battery or not (not that those alts can reach 150 amps without super spinning anyhow). so another point for Baxtel. perhaps working with cars is a bit better than reading on another forum. they can be very helpful but also very misleading. and if a battery is a surge protector...............why do we have fuses?