Disconnect and charge the battery. LEAVE IT DISCONNECTED after it is charged and measure voltage. Should be better then 12.6 V. Let it sit for an hour UNCONNECTED and measure voltage. If below 12.6V then the battery is BAD

 

???
Ohms isn't a reading that should have worked with a connected battery. Amps is the scale to use. If your meter was on Ohms, it would have blown a fuse.
Now, if your meter was on Amps, a reading of " -.87 " would make a LOT of sense. The " - " part because the leads were backwards, and the " .87 " as Amps would be a perfectly acceptable reading for a vehicle which just got connected. It would drop in steps down to probably .15 amps or so after about 30-40 minutes.

 

What CeeJay said. You can sometimes get an ohms reading that way but it's not live. Check between the battery cables with the battery unhooked from one. I don't think it's worth doing before chasing the battery itself. Charge as said above with it disconnected and let it sit a while.

 

It looks as if the old battery was the culprit. I appreciate all the help and suggestions. A new Interstate battery has seemed to have done the trick. Everything is back to normal. Lessons learned:
Lock the car
Suspect the battery first
Multimeters are our friends
Step through the diagnostic suggestions above. It was all good advice.

Thanks!

 

And don't forget to buy a CTEK MUS4.3 from Amazon, even though it's your daily driver and some Forum members will tell you that a daily driver doesn't need a battery maintainer. It'll keep your battery fully charged, extend its life, and minimize electrical gremlins and aggravation. I look a CTEK as a cheap insurance policy, with nothing to lose.

 

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