Hi all, my car has been sitting in the driveway for about 4 months now(cant drive till March) I start the car every once in a while but of course its always dead from just sitting there. I jump it...it starts and I leave it on for 30-45 mins then I shut it off. 1-2 hours later I try to start it again but its dead......im thinking battery not alternator. Thoughts?

 

If you have a DVM(a meter), then once started the voltage at the battery should be just about 14.2 volts. If you read that, then it's not the alternator. Make sure your battery terminal post are clean as this can keep the alternator from charging the battery. It seems as if you battery might be toast unless your terminals are so dirty it's not allowing the alternator to re-charge it once it's running.
If you have a meter, then without starting the car, the battery voltage should certainly read more than 12 volts.

Oh.......letting it sit that long inbetween starts is good for it either. But.......look through your pass through into the trunk and make sure your trunk light isn't on.......that will drain the battery. Make sure your trunk is shut.

You might want to consider getting a trickle charger or unhooking the battery if you are gonna let it sit that long.

I also wouldn't just let it sit there and idle for that long when you do start it....that's not good for it either......try to go for a drive of at least 15 miles to allow the alternator to re-charge the battery.

 

um if you have a DMM you can test voltage output of the alternator to test it....also after running for awhile test the battery and see what voltage is then after it sits for a few hours test the battery static voltage and see if it dropped....

an old school method to test the alternator is get the car running and take a pretty long (6 inches at least) screw driver and put it close to the pulley on the alternator if there is magnetism the alternator is still working properly but you can't tell if it's putting out the correct amount of volt with0ut a meter....the screwdrive thing is only to make sure it is making a magnetic field in the field coild of the rotor of the alternator!

 

The real old school way is to disconnect the battery after you start the car, and if it still runs.............then it's not the alternator.

 

gotta get a meter and check it out....and disconnecting the battery after starting the car will probably fry everything..no thanks lol

 

No it won't.....once you start the car, the battery does nothing but accept a charge from the alternator....the car runs off the alternator. But that's okay.....it's best to get a meter!

 

the suggestion given are all somewhat good in its own ways.

you can also start the car, and pull the positive terminal. if your alternator doesn't full field, the car should die soon after. this is the short-cut way without any meters used.

but of course, running the car and seeing above 13.8v with a meter will put all doubts about the alternator. and if the battery can't even give 12.6v just sitting there being charged, then you know the culprit.

buy a $20 battery tender!

 

^haha yeah that is truly old school.....but i think on all of our electrical systems and computers in our cars it does not work like that on new cars! haha

NOTE: MAZSURFER AND I ARE NOT RESPONSIBLE FOR ANY DAMAGE TO Y0U OR YOURSELF IF YOU TRY OUR "OLDSCHOOL" EXAMPLES!!!

 

or i got a better solution for you if you love your car.

move to cali

 

^batteries still go bad in cali...just not as fast haha....unless california is exempt from battery failure haha!!!!j/k

 

After re-reading the first post............. I don't think it's not being driven because of cold weather..................is it OP?

 

maybe i shud move to cali considering the only reason my car has been sitting for so long is cuz DUI laws in Jersey are the strictest in the US.

 

Ha.........I was right! See below!

 

What's OP?

 

Original Poster.....in this case, that would be you.
I learned that from being on this site too damn much.

 

learn something new everyday. lol

 

well i got the battery checked out today and it was totally drained when out and got an Exide NASCAR select

 

haha u and me both mazurfer (i think ur on more than me compared to post counts) but i know what u mean haha