I bought a new battery a few months ago and this afternoon my car wouldn't start.

I put the key in and there was nothing, not even the open door chime. Then I turned the key and still nothing. I took the key out and put it back in a few times, then the radio came on, but no ac fan motor. Then I took the key out again and tried again and nothing.

I got a jump start and every thing worked fine with the key at acc. And it started and I drove it back to my office. I got the recept for my battery warranty. I started to drive to the store and get the battery replaced.

When I got out into traffic I noticed the car shuddering and my air bag light came on.

I pulled back into my parking lot and I noticed when I turned on the AC or rolled up or down a window the battery light would come on and the idle would slow and almost die. This to me sounds like the alternator is just bearly putting out enough power to keep the car running.

The shop we towed it too sad it's the battery, and the computer is not working properly with a bad battery. So he wants to replace the battery and see what happens. In my opinion a car should run fine with or without a battery once it is started.

But my specific battery experience is with an 82 Camaro with a very simple computer, not a newer import with a complex computer.

Is this right? Does the computer need the extra voltage to run properly.

 

Your alternator is bad....

 

That's what I think too, but the shop called and said they replaced the battery and it's running. We'll see what happens when I get there to pick it up.

 

bad alternator that isnt charging the battery so it runs down. of course it started with a new battery...its fully charged. after you drive for a bit, it will go dead too.

 

you're thinking of a long time ago. When cars started carrying computers they could no longer just run off an alternator. Without computers they could hardly do it (I've had some good experience with this fact). 9 times out of 10 both the alternator and battery fail together. Mainly due to the fact that once the battery dies you've put so much strain on the original alternator that it dies.

You certainly could have a bad battery. Sounds like one or more cells is not holding a charge. That's something I would have trusted to Autozone or Advance Auto as they check that stuff for free (don't bother with their alternator test because most of the time the staff has no clue how to do it properly in the car).

I'll agree with Sooner that if it fails again it will most likely be your alternator. If you have a voltmeter a fast way to check is to see if you're putting out 14.1 - 14.6 while your car is running.

Another way to check for a bad battery is to test before you go to bed, check the voltage. And then when you wake up see what the voltage is. I had to do this with several "Never Start" (Wal*Mart's EverStart) batteries.

Given the cost of our alternators I would certainly want to be sure that its that before I go and replace it.

Did the garage warranty the battery for you? I certainly hope so.

Jay

 

I'm sure they metered the running engine, but I'll be sure when I get the car in the next 20 minutes and report back.

 

The main problem with those diagnostic tips is that they are home mechanic diagnostics. If you want it done properly (accurately is a better word) then you should take it to Advance or Autozone. If you think its the alternator and you're going to do the job yourself. ALWAYS get your old alternator tested first. And make sure they test the new alternator before you take it home. Trust me, its better to take 20 minutes there rather than get it in and find out its junk.

Jay

 

alternator