I am not sure what is wrong with my car but I can't believe I may have to purchase another battery after only 4 weeks. The previous battery was in the car for only 6 months and the one before that was in the car for 22 months.

The latiest episode started last week. While at the track the car wanted to die a couple times. The dash warning lights started to come on so I would give it al little gas and everything seemed to be fine. On the way home from the track I switched my power FC commander to view the battery volts. I was shocked to see the readings were in the 11.XX range. I got the car home and didn't do anything with it until yesterday. I started it up and the volts were reading in the high 12's to low 13's. I figured it fixed itself

Tonight I was going to head to the track, when I started the car the readings were in the 12's but with a little gas I was able to get it up to 14.1 volts. I started heading to the track and the volt reading on the commander started going down. After 5 minutes the readings would not go above 12.9 volts. By the time I got back to the house the readings were in the 11 volt range. While idleing in front of my house it dropped all the way to 10.1 volts before I turned the car off. After pulling the car into the garage I turned the key so I could get a reading on the commander it was reading 11.1 volts.

Any ideas what is going on? Could it be another bad battery? By the way these are $149 batteries and the alternator was rebuilt 5 months ago.

Thanks in advance

 

Sounds like a charging system issue to me. Have your alternator checked out. Just because it was recently rebuilt, doesn't mean that it's working right. If you go to a sears auto center (or similar) they can check your battery, charging system and starter for $10.

Also, most good batteries have a warrantee. You might want to look into that before you spend another $150.

 

Thanks...the batteries have all been replaced under warranty. Wouldn't the charging system warning light come on if that was the problem?

 

It could be bad diodes or voltage regulator. It sounds like it is generating some power, but just not enough.

Also, this might be obvious, but double check the alternator belt tightness.

 

When all the dash warning lights come on while you're driving, that's usually a sign that your alternator isn't working...(be it the belt or the alternator itself)

 

I usually just disconnect my negative lead to my battery when the car is running to see if the alternator is working. Also us a multimeter to check your voltage from the positive lead from the alternator.

 

I would check all the connections starting at the battery, where ever you have it located. The fact that it seems to work OK cold or when you first start up tends to lead me to think about connections. The circuit may be skewed and after a short time the connection in question heats up and can't flow current. It could be ether side of the circuit (- or+). In any case the alternator in a skewed circuit is likely been beat up a bit and MAY be damaged. Again I would inspect the harness for faults. If its OK remove the alternator and have it tested or drive the car down and have the system as a hole tested. Just remember a poor connection will show a lot more heat at the point of trouble. The FD I have is a 93 and it has a extension on the alternator power feed, it's there to make space for the battery connection. I would surely look at how it's doing. If you see anything plastic melted that's surely not a good connection and will cause this type of problem.

 

Yeah, it sounds like its definately alternator related.

 

dont disconnect the neg terminal when engine is running. you are supposed to disconnect your pos. terminal. if you disconnect your neg. terminal you loose most if not all your grounding (given that you did not do a ground wire upgrade) this will cause your car to idle erratically.

 

You may also wish to check your engine harness main ground. IIRC, it should be attached to one of the brackets which hold the oil cooler lines (assuming stock oil cooler lines). Poor contact of this wire can cause irratic battery behavior.

 

i just bought my fd like a month ago...i havent drivinit since the day i bought it..*insurance, registration* well i finally get to it today..and the batt is dead..well i left the dome light on..lol. *sighs* well i get a jump from a buddy and proceded to go fill up..well it dies at the pump...been runnin for almost an hour..now..i noticed that the neg lead on my batt was loose...would this cause my batt not to charge fully...???

 

My car died at an auto-x last year, it was wierd but the alternator would work when cool but not when hot. Freeway = 12-13 volts, auto-x = 10 volts. I had it rebuilt, works fine all the time now.

FYI, don't track the car with low voltage, the fuel pump is not getting what it needs and you could just pop the motor when it leans out.

 

check you alternator!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!