hi hope someone can help me with this problem. Here goes i own a 2003 honda accord 2003 v6 automatic .The problem is my battery keeps going dead. i brought it to the garage they told me it was the alternator so i changed it and 2 weeks later the battery was dead again so i brought it back and they did acheck on the alternator and it showed 14.5 volts charging so it was good. they turn all my accessories on and it showed 14.1. now they said it was my battery not holding charge so i changed it and was working fine for 2 weeks car died again. now they tell me it might be a short somwhere so i went and bought a volt meter that u install in your cigarette lighter and as i started the car it showed 14.5 volts. as i put it in drive and started to drive within 10 seconds it went down to 12.0 volts and stays there untill i stop the car and put it in nutral then it goes back to 14.5 volts then i start to drive again and same thing happens 14.5 volts as im doing 40 kph i put it in nutral back to 14.5 volts put it back to drive and drops back to 12.0 then i would speed up to 100 kph volts come back up to 14.1 for afew seconds then drops back to 12.0 so if someone can help me i would really apreciated ty.

 

First make sure battery cables are in good shape, clean, and securely connected to battery. This is most frequent cause of problems by far.

However, given history (alternator and battery), suggest having the crankshaft pulley (harmonic balancer) inspected closely. There is a rubber bushing between the inner drive and outer pulleys that can become loosened, allowing the outer pulley to turn slower (slipping) than inner crankshaft drive. This results in puzzling battery performance, but eventually the battery will die since the time when most load is present is at night w/ lights.

It is not an uncommon problem.

good luck

 

There's also a possibility of a control wire (in the alternator wiring plug) going to ground. That would command the alternator to shut off, as if the ECU wanted it to shut off. In that case you don't get the battery-idiot-light in the cluster.

 

thank you for the input but both af those were checked and cables and posts were changed also and still problem exists.

 

Is the battery light turning on inside the car while driving? Does the check engine light turn on while driving?

I would clean all ends of both battery cables just to rule out a flaky connection. Carefully inspect the wiring to the alternator.

 

I think TX left this piece out. Another way to check the "crankshaft pulley (harmonic balancer)", visual migt not tell the whole story, would be to make a mark across the two sections...after driving for a bit that mark should still be "in-line".

 

the battery and engine lights do not come on.

 

I'm not sure why but the crankshaft pulley failure does not illuminate the battery light. It seems it should but I had this problem on a 97 Acura TL. It would drive until the battery was too weak to push a spark out of the coil, w/ never a battery light illuminated.

good luck

 

hi i checked the crankshaft pulley and it is ok thanks for the input but still cant find the problem

 

In your original post, you say the battery monitor shows ~12 volts, and not alternator light. This can happen, but if the voltage never increases, then discharge is likely. Usually voltage will be 13.5-14.5 volts w/ minimum load.

Does the Alt light come on when keyswitch is turned from Off to On? It should stay on until engine starts and alternator begins charging.

What happens to voltage if you turn on full load; blower max, headlights, and rear window defroster. If voltage stays over 12V, it's probably charging OK. If it drops to 10-11 volts, then alternator is not charging enough.

Also check for current draw w/ the keyswitch OFF. Perhaps something is running w/ engine off to run the battery down.

Tough problems require patience or lots of money. I tend to have the former and not the later.

good luck