My '04 C4S seems to have developed a battery charging issues that is the worst on hot days. It started fine this AM - 1.5 hours of fwy driving today - 1.5 hour stop - 20 mins of local driving - 2 hour stop - and the car wouldn't start. Nothing was left on. It was hot - 105 and the car was parked in the sun.

I was able to jump it - though it had to be hooked up for 10 mins or so before it would work and then for the entire 1.5 hour drive home - the Volt meter was low - showing between 11.5 -12.5 depending on RPM.

The battery was just tested and charged while it was in the shop two weeks ago to have a power steering house replaced. I had run it down a few times leaving the radar detector plugged when the car was sitting for 5-10 days.

I have the car on the trickle charge now.

Any suggestions on what to look at?

 

Replace the battery. After you run the battery down with radar or lights, it will never be up to 100%. Combine that with the heat and you have a dead/weak battery. Dead/dying batteries sometimes will not take the charge properly. Also, test your alternator to make sure it is charging properly.

 

My concern is the low voltage reading on the drive home - after jumping. That seems to indicate a charging problem - rather then the battery?

Also - the battery was just tested - at my local Indy - and rated 90+% performance.

What is the best way to test the alternator?"

 

A dead battery may not take the charge properly. So after you jumped it, it would still not take the charge. In the heat batteries can die suddenly and without warning. In AZ, most batteries are expected to live only two years due to heat. I replaced the battery on my Acura two months ago after 600 mile drive. Stopped the car, came back next morning and it was 100% dead.

Most auto parts chains will test the alternator for you for free.

 

If the battery is a couple years old, that is the first place to check. Alternator or regulator next. When my alternator went, the voltage meter would drop down steadily even as I was driving, well below 10.

 

If you are sure your battery is good, you can try to test the alternator and cables as described here

http://www.renntech.org/forums/topic...tage/?p=240055

 

take a V reading with the car running at the jump point in the engine bay. If its 13+ good. Now take one at the battery if its 13+ change the battery. If its not, you need to clean up the + wire feed and possibly replace it from the battery to the jump point as well as the cable from the jump point to the starter to the alternator. Points of interest to clean:

On a 99 anyway:
Battery posts
Thru front bulk head post
Under the car attached above the clutch bell is a connection Bastard to get too also feeds power to relays on back shelf.
Ground strap from engine to chassis on right side of engine near wheel well.
+ jump post in engine bay
Connection at Alt and starter (can be gotten to by removing TB and first cross pipe between plenums.

Good luck.

 

when my alternator went, and it was pretty fast, a lot of warnings came up on the computer read out...lots of charging system info.
sounds like you have a dead battery.

 

Thanks guys - I appreciate the help. The alternator is showing 13+ on the multimeter and now that I charged the battery on the trickle - the car shows 13-14 when running. I am going to change out the battery to be on the safe side.

 

Still replace batteries every two years and if you don't drive everyday keep on a
Battery maintainer

 

Quick update here - it was the alternator - all fixed now.

 

Glad you get it sorted out.