Put a new battery in my 87 a few weeks ago, The old Interstate battery was 11yrs old. Long service life!




Drove a couple times a week since then, and took a 200mi road trip. Last time I drove the car was Wednesday. no problems.

Went to start the car this morning, no power. Just checked voltage, .72v Yup under 1v..... Slapped the charger on it thinking I may have left a light on. After a few minutes the needle on the charger started jumping around. I took off the charger cables and the ground clamp on the charger cable was very warm. Disconnected both battery cables and the battery is still measuring .72v.

What do ya think, battery shorted out?

 

Toast. Take it back to the place you bought it.

 

Update, pulled the battery out and put the charger on it. Been 2hrs and the charge is at 25%. If it is the battery this Sears Diehard died easily.

 

That's why you have a warranty. Take it back.

 

I think you just got a bad battery, i've had it happen to me (from walloworld)

take it back like everyone says.

 

Another update, With the battery out I used a meter to measure the ohms across the red and black battery cables. It measured 3 ohms. 12 @ 3 ohms would be a 4amp drain. I did change the window switches last year so I toggled the window switches and remeasured the ohms and they were back over 20k.

I charged the battery for a few hours and let it set over night, this morning it measured over 12v so I put it back in the car. I put the amp meter in series with the battery and the drain was .6ma. I connected a battery cutout switch on the battery side terminal. The car started right up and the dash voltmeter measured around 14v. Looks like I need to look at the FSM window switch circuits, I didnt think the windows circuit would be active with the car off.

 

The 4amp drain is back.......

 

Are you measuring 4A or calculating it? Just curious.

P.

 

Measuring, 3.92A. I'll start pulling fuses one at a time to see which circuit.

 

≈4A draw and something would be getting toasty. Those switches?? Wonder if you have a wire that is being pinched as result of disturbing the harness when you installed the switches. Course it could be just about anything else, but that's where my curiousity would be focused first.

Good luck! I've got same routine to do on a friend's car this w/e, as a matter of fact...Love running down leaks, don't you?

P.

 

ok I feely silly now, when I hookup the ampmeter the courtesy light comes on for about 30 secounds and goes off. 3.9a with the light on and milliamps when the light goes off.

 

Took the car for a drive yesterday, I kept my eye on the volts reading on the dash. It stays up over 13.2v most of the time going all the way up to 13.9v and would dip to 12.9v while idling. Is the voltage suspose to fluctuate so much while driving? Car still starts this afternoon.

 

No, either a bad battery or the voltage regulator in the alternator is acting up. As others have suggested, you should take the battery back for replacement (or at the very least tested).

 

And buy a smart charger. They give you a code if the battery is bad. They also shut off automatically so you don't bake your battery when you forget it's on the charger.

 

I have a B&D "Smart" charger, for that reason too. However, I keep a "dumb" charger around too, as the "smart" charger will refuse to charge a battery that has been allowed to completely drain. An hour or so on the "dumb" charger will wake up a battery to the point the "smart" charger may be able to salvage it - has been my experience.

P.

 

Quick update, Have not had the battery die again. I have noticed that the voltage on the display will dip down to just over 12v at idle and it will go back up over 13v when I'm cruising at over 900 rpm. So I just order a new GM-Delco from an auto parts place on the web. I'll swap it out when I install my air pump delete pully.

 

Your voltages are normal. The alternator is barely functional at idle.

I have heard of problems with the antenna or power seats causing high current draw when the ignition is off.

 

I've had the same thing happen. Alternator wouldn't charge at lower rpm and eventually (over time) caused no starts that was initially suspected to be the battery but really needed a new alternator.

Me thinks the battery was not the original culprit and there is a secondary problem. Something drained it to .72v? Sounds like something Cliff mentioned like a motor or a bulb staying on. Most electronics will fail to even turn on below 8-9 volts, so something drained the OP's battery to the bone. I also think the needle may have been jumping around due to a possible poor contact or corroded terminals on the first charger.

Regards

 

I've noticed too my charger bounces like the OP mentioned whenever I'm attempting to revive a severely discharged battery. I'm guessing it has to do with the current limiting in the charger when a severely discharged battery is connected - looks like a near dead short to the charger - the reason my "smart charger" will dismiss a battery in that condition as being shorted and will not even attempt to charge it. (The charger isn't so smart after all, I guess!)

To the OP: Sometimes, depending on several factors, the max charging voltage will not be present at idle. However, the voltage of a standard lead-acid car battery at rest (not loaded) is approx 12.8 volts ± .1. So, at idle anything above that and the battery is being charged and I wouldn't worry about it. But, if it is below 12.8 at idle, then we may have a load or charging issues!

As voltage (supplied by the charging system) increases, the charging current increases exponetially! So, to control charging current, the charging voltage max is limited to about 14.7 volts when cold, and will drop back to about 13.8 when hot, depending on alternator capacity, rpm, and current demand.

Dunno if this sheds any light on the question, but I hope so.

P.

 

The CS130 alternator puts out 25 maybe 30 amps at idle hot - all of your devices easily exceed that so Battery at idle is normal. GM issued a Bulletin years ago pretty much stating that any Dealer that replaced an alternator for this condition wouldn't be reimbursed (and that was for every car they made).

Whatever drained it seems to be gone but underhood lights and a stuck Bose Relay are also common as would any device with a hot feed, ignition off.