Battery wont charge, alternator checked out fine.....Help

[lightningfish]

driving 20+ minutes does not charge my battery. Took out the alternator had it checked along with battery and both are fine. Changed out ground cable still nothing. The car seems to drive fine but each time I turn off the car and start again struggles more to start until needs a jump. Not sure what to check next. Help

[lightningfish]

1991 240sx

[glitched]

how old is the battery?

If the battery was low or dead, driving for 20min will not fully charge a battery. Alternator's arent really designed to fully charge a dead battery.

you should use a battery charger if the battery was recently discharged.If the battery is old and has been discharged a number of times, it is most likely dead and you need a new one.

[del82]

Replace the battery =/ even if it's new, sounds very much like a battery with a bad cell. Course, if it's new, you'll probably be able to get it exchanged for free, or really cheap.

[lightningfish]

I took the battery in and they said it was ok, would they be able to tell when it's out of the car???

Drive Fast, Take Chances

[Vegascorbin]

Check all fuses.What is the voltage at the Battery when the car is running? Should be greater than 12.5 and closer to 14.

You may have a situation where the Altinator is trying to but out hte voltage but the wiring is bad preventing it from charging.

Be sure to check the Positive cables and Alt. connections in addtion to the grounds.

If alt. tests good and Battery tests good then it must either be a faulty test or fuse/wiring.

Charge the battery with a charger before you test voltages. much easier.

[Justin35ll]

how old is the battery?

If the battery was low or dead, driving for 20min will not fully charge a battery. Alternator's arent really designed to fully charge a dead battery.

you should use a battery charger if the battery was recently discharged.If the battery is old and has been discharged a number of times, it is most likely dead and you need a new one.

Couldn't have said it better myself

[del82]

I took the battery in and they said it was ok, would they be able to tell when it's out of the car???

Drive Fast, Take Chances

Well, that'd be a problem for the warranty...that said, there are times when batteries with bad cells will still pass a load test. There's a smaller meter that doesn't actually load the battery when it tests, those kind seem to be more accurate. Apparently they're also around a thousand bucks per unit

glitched also has a point, if you drained it dry you'll need to add water if its not a maintenance free, and put it on a trickle charge to get the power back. I assumed you'd driven it more than once and still got no charge into it.

[S13_love]

Replace the battery!

And, if that doesn't work...well, at least you got a new one.

I had this problem with my car when i got it. I put the battery charger on it for a good 4 + hours and when i went to start it......nothing.

Then I replaced the battery and everything worked fine since.

[1KleenS13]

Did you check the wire that goes from the alt to the batt? Put a DVOM on the batt when it is running, and see if its charging (should be over 13.5 volts).

[jeezy240]

check the alternator fuse under the passengers side fuse box. those like to blow and act like a bad alternator.

that should fix the problem. its a 75 amp fuse.

[lightningfish]

fuses are fine, getting 14 at the battery when the car is running. Even though its pretty new I'm thinking it might end up being the battery having a bad cell letting it charge now and checking back in a while.

Drive Fast, Take chances

[lightningfish]

since I'm getting 14 v at the battery wouldn't that narrow it down to the battery????

[Terrorinc17]

Yes it's the battery.

[lightningfish]

Turns out it was the starter, it was just slowly going out.

[Vegascorbin]

So our problem really was that the car would not start not that you had a battery/altinator problem.

Glad you found the problem but boy did you have us going down the wrong path.

Again glad you got it fixed and VERY glad you reported back what the final fix was.

[lightningfish]

Thanks for all the help, if nothing else i learned a lot about my car the last few days.

[sg101]

Turns out it was the starter, it was just slowly going out.

Hi, I'm having the same problem as you. Could you please elaborate "Turns out it was the starter, it was just slowly going out." since I'm a auto beginner but I'd like to follow your suggestions/directions to fix the problem myself.Thanks

[MYFREE95,240SX]

k heres one for u all battery is brand new, alternator is brand new, still wont charge checked fuses all good.all connections are good. car will only run off battery and now there is no charge coming from alternator just replaced it like 3 weeks ago was having the same prob as now and worked fine for 3 weeks now happening again. someone had mentioned my stereo being wired wrong and all that was wrong was the acc wire and power wires were switched so i had no memory and could only opperate radio when car was on could that have fried the new alternator?dosent make sense to me cuz radio was like that for like 6 months before any problem arrose. power regulator? car will start fine when charged somewhat let me know what you all suggest.