Namely - if I sit at idle with the a/c on high and the lights on for more than a few min, the lights start getting real dim and I measure only 9-10V at the battery. Holding the throttle at ~1200 rpm or higher, all is well. All is fine if I don’t have the lights or heater/ac on as well.
After a long drive on the highway, it starts easily as long as it doesn’t sit more than a day - then it starts turning over really slow. If I leave the lights on more than 5 minutes with the engine off, it won’t crank at all, just clicks, and I get 7-8V at the battery. If I leave the dome light on more than 20-30 min it won’t turn over either.
AutoZone said the alternator tested fine and the battery was testing as needing a charge - after a charge it put out ~400 amps for a couple of seconds and dropped quickly. Sometimes at idle when the lights start dimming, they suddenly get bright again for a few seconds (usually when the cooling fan turns off), then slowly dim again.
Voltage regulator? Or battery? The battery is a 4 year old Sears Diehard Weatherhandler that’s been run nearly dead (3-4 volts) 3 times in the past month because of this. The alternator is original - 1991 model sold new in 10/90, 150k miles.
Forgot to mention - the battery was tested outside of the car after being bench charged, and I’ve cleaned the posts and clamps. Didn’t see any major corrosion.
I’ve read that a lot of batteries are rederened useless if they’re acting up and have been dropped to bare minimums at least 5 times. My guess is your battery is on it’s way to the graveyard.
Try another battery from another car like a friends, or mom/dads, or whoever you know that would help you out and see if that seems to do anything differently.
Thanks Gray. Unfortunately, both of my parents vehicles have side post batteries, and both of them would require an anti-theft code on the stereos (both of them have lost the codes) to get them working again. Plus, their batteries are a lot bigger.
Most of my friends have domestics that have bigger batteries anyway. I’m sure the battery is pretty much shot after being run down so many times too. It’s only been run close to /totally/ dead twice - headlights barely coming on, hazards wouldn’t work, and I couldn’t even get a click when I turn the key. The other times it usually turns over once then won’t turn again, or I still at least hear the click of the starter solenoid trying to engage. The battery isn’t swelling or gassing or anything (yet) though.
I guess I’ll grab a $35 battery from WalMart Friday, or if my paycheck’s big enough I’ll grab an Optima gel cel from autozone. I know the Optima will take a lot of abuse as well… if it keeps acting up I’ll swap in another alternator
Never heard of an Optima “Gel Cell” but I do have an Optima myself. I have a pretty large stereo system in my car and the Optima definitely is a reliable battery.
I never have any worries as I used to with a an Autozone battery I used to have. I have the Red Top version, I’ve heard that the Yellow Top is more for my car audio but oh well… this works perfect for me.
Also one tip, if/when you replace your battery… go ahead and fabricate an extra ground for it. I used some 4 gauge Monster Cable wire, approximately 2 feet long, and ran it right under the battery. I’m pretty sure that’s where the batterys ground is… I can take pictures if you need me to.
