Battery drain upon turning key to "Start"

'86 El Camino, V8, starter, alternator, and two batteries all load tested OK. Instantly upon turning key to Start, fully charged battery drained to less than 4 volts - either of two batteries. Instantly!

With everything off and all fuses and circuit breakers removed, get +9.5 volts between negative pole of battery and ground at alternator mounting frame. Same with either small wire disconnected from battery post on solenoid. No volts with both removed.

Have replaced all three electrical switches on steering column - same problems.

You have a problem with the ground connection. It either between the battery and the car frame, or between the car frame and the engine block.

How are you going to feel when it turns out to be a ground cable missing,loose or dirty? Why did you not check the grounds before replacing “all three switches on steering column”? Where do you suspect all that stored energy in those batterys went?

I agree with tardis. Try connecting a jumper cable (the kind you use to jumpstart a car) from the battery terminal to the engine block and see what happens.

Make that the NEGATIVE battery terminal

Since this is a GM product with a side terminal battery, take a close look at the cable ends under the protective boot. Corrosion often builds up there, unseen.

Thanks for the reply, Tardis. I can see how the poor ground might keep the solenoid/starter from working. But that same high resistance would keep the battery from flowing - NOT drain the battery, as it has twice today and dozens of times previously.

Repeated normal attempt and drained battery - the re-charger tells me so! Tightened all ground connections and cleaned battery posts on 2nd battery and on battery terninals - with files. Repeat attempt drained the 2nd battery.

I, of course, do not believe that the batteries are being drained. A typical battery is about 50 Amp-hours capacity. That’s 600 Watt-hours. Let’s say that it this case instant means one second. That means that 2.16 million Watts for one second of energy had to go somewhere. That would end up as a lot of heat. Since you didn’t report that the battery or any part of the car was glowing red hot, I don’t think that it happened. I think that you are fooling yourself with some of your measurements and methods.

Clean battery and ground connections is step 1
if that does not work,
Try it this way. Disconnect positive lead to starter motor.
Ignition off, voltage at pos and neg on battery (should be at least 12 volts or battery is suspect.)
Check voltage using ground at alternator, if less voltage then you have a bad ground connection.
Have someone turn key to start position, check voltage at battery, and see if there is a drop, voltage drop should be minimal, if not there is a direct short somewhere in the ignition circuit, which I doubt because it would blow a fuse, unlss you have an external relay for the starter system. If you get the kill I would suspect relay.
If not same thing except check voltage at cable for starter motor. if all is ok it is your starter motor that is fried.

You mention the starter as being load tested if I read this right. Since I assume the engine was never cranked over by the starter motor, what was the current draw being pulled by the starter on the initial surge?

Or was this starter being bench tested? (Not always the best route to go)

And not trying to sound too stupid here but the engine is not seized up is it?

There’s a positive short to ground somewhere. There shouldn’t be 9.5 volts with a ground-to-ground measure with everything off.


Tardis: Thanks fer tha gitback! I respect what you believe, but a second pair of eyes saw the the volt meter across the battery instantly drop to less than 4 volts. After I released the key to “Run” - having seen the drain on my dash voltmeter below 8, the bottom of the scale- the battery slowly recovered to 9 volts - NOT 12. It was a +battery to -battery thru a short somewhere in the “Start” circuit. The negative post of the battery accepted all the amps. Nothing burned out. I’ve repeated such tests over a dozen times - same results. Please think outside the box on this one - beliefs aside, some half dozen automotive electrical “experts” have said, “WOW!” I may be missing something, but I’m not fooling myself! WHY would there EVER be a +9.5 volts at the alternator GROUND, relative to the NEGATIVE POST of a fully charged battery???

I think that you are fooling yourself with some of your measurements and methods.

Ah! The age old trap of letting our errant assumptions lead us astray. We are all susceptible, especially with those damn electrical problems.

OK4550: good thoughts - THANKS! Starter (new 12/08) tests fine out of the car on the floor and at Autozone. For awhile last Friday, it completely started the engine fine about a half dozen times. We haven’t a clue as to why it worked OK or why it stopped working OK. So, the engine is NOT seized!

TESTER: YES! MOST definitely!!! Where would you guess???

If you’re reading anything higher than 0.10 volts across the negative cable at ANY time the cable is bad.

The cable should have, in theory, zero volts dropped across it. You say you’re seeing a 9.5 volt drop across it. Either the cable is bad or the connections are bad.

Measure from the battery NEGATIVE post directly to the other end of the negative cable. Voltage should read ZERO. Then measure from the same post to the engine block. You should still read ZERO volts. Then measure from the same post to the frame. It should still read ZERO volts. Anything other than zero, or about 0.10 volts WHILE CRANKING THE ENGINE is too high and indicates a bad cable or connection.

Your voltmeter is broke.

Try disconnecting the bulkhead connector at the firewall for the fuse block, and then see if you still have a voltage reading ground-to-ground.


TESTER: After spending the morning removing, reorienting and reinstalling the steering column [not easy solo], read your post of 4/9/11:16 - GREAT suggestion! But, couldn’t even see much of the bulkhead connector with the wiper motor in place, mounted with three bolts. Third one is below the motor - can’t see it or reach it with any combination of long&short sockets, extensions, or socket wrenches - including one with a swivel head. Cannot grip - let alone pull - the hood side of the bulkhead with the wiper motor in the way. Is that one big connector??? Can only see one plastic retainer clip - are there others???

On the passenger side, there are two accessible bolts on the fuse panel. Would it be OK to remove it??? Inspection might indicate signs of excessive amps.

No, the voltmeter works fine - I’m the one that’s broke.