Bad Battery Or Bad Connection?

A couple weeks ago my wife had to run errands downtown and I convinced her to let me drive her in our old '53 CJ3B. I went out to start it, turned the key, and nothing happened. Everything was dead. Nothing worked, not even the headlights. I used a multimeter to check the battery and it read 12.6 volts. The ground clamp looked suspect, but when I measured the voltage between the the positive terminal and the body of the alternator, it still read 12.6 volts. Since the headlights are powered from a terminal on the ignition switch, I removed the ignition switch from the dash so I could measure the voltage on the various terminals. The voltage read normal until I turned on the lights. This sounds like a grounding problem. The multimeter is very high resistance and doesn't put a load on the battery. I needed something that would draw current. I found a 12v pump used to fill rafts. When the pump was jumpered directly to the battery, it ran fine, but when it was jumpered to the battery's positive terminal and to the alternator body, the pump wouldn't run. Bingo, the ground cable from the battery must be faulty.



I removed the ground cable from the rusty battery terminal connection and clamped it directly to the negative battery terminal. The engine started right up and all the lights worked.



I found a new battery clamp in my junk box, reconnected the ground wires, and the jeep was back to normal. I took my wife on her errands and the jeep got us there and back.



Mrs. Tomasinator getting chauffeured in the CJ3B:

 

Need pictures of the Jeep

 

I see a couple "Jeep grins"

 

Excellent old school diagnostics!

 

You have a very patient wife!

 

X3! I don't like those clamp type battery terminals for the very reason you experienced. I use a bolt type battery cable terminal with a crimp cable lug. Following the crimp, I add solder to the top of the lug and then heat shrink over all of it except where the actual bolt contact is. Never have had a failure with those. That said, an AGM sealed battery also does wonders.

 

its almost always bad grounds in my experience.

 

I took my 15 year old nephew out to a church parking lot this afternoon to teach him how to drive a stick shift. We were in the '53 cj3b that started this thread. For some reason, my jeep has VW steering wheel. All of my kids learned to drive in a manual transmission '86 Isuzu Trooper and that car was passed down from one kid to the other. They all loved it.

 

...and with a "wrist-breaker," no less.

 

That's the "Wolfsburg Crest" ... Wolfsburg - Wikipedia