buddha,
That would probably do it. I usually stuff my probes right into the battery where the cables clamp on. Of course on these rigs, the battery is in a remote location. Using my meter at the battery, I will set it on DC volts, read the battery at rest, then without disturbing anything, start the truck and read again. You should see an appreciable increase in voltage, somewhere in the 14.5 range.
You might get a helper and try it again using the battery posts. The fender might have been a poor ground. Be sure to run the RPM up to get your alternator cooking.
With the truck stopped, putting the negative cable on first, then the positive cable, you might see a very very small arc..if you see a big zap you have something shorting to ground.
If the battery was new yesterday, it sure doesn't seem like it should be that low now. 12.6 volts equals 100% battery charge, and, hard as it is to believe, 12.3 volts is only a little over 50% charge. I knew this was going to come up, so I did some "battery basics". We both get to learn!
Stuart
