New battery = Dead car?

ColonelCash · Post by **ColonelCash** » 06 Jun 2011, 13:51

Here is a good one for you...

Saturday Night: Car was sluggish on start, so I kinda realized something was up. Eventually, car totally died after I got out of the grocery store. Jumped it off, drove it home without problems. Battery is 5+ years old, and I knew it needed replacing, no big deal.

Sunday Afternoon: Got a new battery installed, car fired up without a problem. They did "test" the battery and it came back as needing to be replaced. Ok, I'm fine with that.

Sunday Night: Driving around town and the battery light comes on the dash. Check the book, it says Generator not working. Battery light goes off in about 10 minutes. I figure the alternator is going bad, although I make it home without much problem.

Monday Morning: Drive to work, no problems with car.

Monday Afternoon: Driving some errands for lunch, I get to a stop light and the car just won't acclerate. It's moving about 1/2 mph and I can barely make it out of the street. When the car was limping around, I noticed the ABS and TRACS light were on. Car died and wouldn't restart immedietly. Waited a couple minutes, car started back up...still in limp mode.

Now, my question is....are these two things related? If so, what are the chances? Car has a rebuilt ABS module (1 year back) and it has the original alternator. My guess is the alternator is totally shot...but am I missing something? Can't run a voltmeter since I'm not with the car right now.

Thanks in advance.

Post by **jblackburn** » 06 Jun 2011, 13:54

It sounds like you've got a bad battery cable that's overheating to the point where current can't flow through it. This is a relatively common problem with these cars over age.

You need to perform a voltage drop test on the cable and running current test to see if the alternator is charging as it should be. There should be info around this site on that. The one I remember that was a good test was in the 240 section.

ColonelCash · Post by **ColonelCash** » 06 Jun 2011, 14:05

Thanks, jblackburn. I thought I had a new cable on the battery, but possibly not. I'll have the shop look at the cables. They rebuilt the engine about a year ago. $3K for a complete overhaul and I could be wrong, but think the cable was replaced. The cables did look OK (visually), but no idea what it looks like out of sight.

Post by **misha** » 06 Jun 2011, 16:53

They always look ok visually,but when you perform voltage drop test they fail.

Here is how to perform voltage drop test:

alternator and regulator.pdf: (130.92 KiB) Downloaded 222 times

Almost forgot....You need 13.5-14.4V(with headlights and blower on) at battery terminals measured with digital multimeter.Everything below 13.5V is bad & not enough to keep the battery charged.

ColonelCash · Post by **ColonelCash** » 08 Jun 2011, 08:12

Update on this: Alternator was shot, and has since been replaced by my local mechanic. Thanks for the suggestions on the root cause.