Something's draining the battery, I did the test light to the negative post and clamp trick and pulled fuses and still can't find the cause. I have replaced the battery twice within about 2 weeks, last one wouldn't take or hold a charge. Any suggestions? Thanks in advance.

 

Have you pulled the alternator and had it load tested? PITA I know, but the best way to tell if it is doing the job.

A quick and free way to do a quick test is to crank the car, turn all of your electric items on (radio, leave doors/trunk open, AC full on, headlights, etc.) and disconnect the ground while running. If it DIES, that is a sure sign your alternator cannot handle the load. Even if it DOES NOT DIE, it is no guarantee that your alternator is not close to failing.

It is NOT foolproof, but do not do it for long. It creates an open loop in the system and IT IS possible to fry your electrical components if a big voltage spike occurs during the test.

The PCM contains the voltage regulator and they RARELY go bad.

If the Alternator tests OK, then you have to begin checking wires, grounds, connectors, etc.

 

Alternator is showing 14+ volts at idle.

 

First check and clean all connections, and use an actual multimeter and check the draw. Some draw is normal especially with aftermarket cd players or car alarms. Also idle the car, turn on all loads (lights, heater, defrost, and so on), then check voltage.

 

There's no aftermarket cd's or alarms, car is bone stock(I'm 2nd owner). I cleaned cables, starter connection. Car starts very easy. Must be something I'm missing, put 2nd new battery in yesterday 2PM, 12.53 volts,(just to check) by 5 pm it was down to about 7.5 volts on multimeter. Test light on negative post and clamp did not light at the 12.53 volts, still don't light??

 

Okay I need to know charging voltage with loads, and how much of a draw is on the battery using a multimeter to go any further.

 

With radio, heater fan on high, headlights on bright, rear window defroster, doors open and dome light on, engine idling it's charging at 14.35 volts. Sorry for the slow responses but it's like 15 degrees outside and 4 inches of snow. I didn't check voltage today when I started it, its been on a 2 amp charger overnight.

 

Has the car had any recent repairs to the starting charging system besides the battery? Symptoms you describe usually point towards a heavy short or key off drain. I assume if you leave the battery unhooked when the car is off it wont go dead. Grab a hefty multimeter with a fuse then test for draw. Give this a read and check the key off drain the same way you did with the test light. http://www.popularmechanics.com/cars...battery-drains

Check back with the readings if you dont find the issue.

 

No recent repairs except the battery. Multimeter reads -.62 millivolts between the negative battery clamp and the negative post.I pulled fuses and circuit breakers 1 at a time, the reading didn't change. Wouldn't pulling the fuse for a bad circuit cause the reading to change?

 

You should be able to find the draw doing that. Last time I did this it was a trunk light staying on. What setting did you use I thought it read in amps for some reason. I will need to get my MM from work and test my draw on my car and see where we are at.