Battery/Electrical Question

[will4104]

Hello everyone!

Hope everyone's enjoying the day, I am by doing a little PM

While charging batteries and checking connections, I got a spark while tightening the negative side when the wrench came in contact with the bus frame. Pulled out the meter and found 3+ volts between the negative terminal and frame. Checked other battery had no voltage between neg. term. and frame. Weird thing is both positives go to the same block and grounds are at two different points. Not sure what's going on, I would think with a short my, battery/s would go lower than the 76% within the two week intervals I charge them. These are 8D by the way. Not quite sure how the PO figured the powering... Have two 8D's (starting) and one 12v deep cycle marine ( generator ) Have only a couple lights that will work without the inverter on. They are powered off the generator battery. At least that's what I've determined so far...

Thanks again for everyone here!

Will

[Cary and Don]

The first thing I would do is take all four cable ends loose.  Clean the terminals and the posts.  It isn't uncommon for the ground terminal to look good and then find corrosion under it. If the ground terminal has a plate on the wall,  clean under that also.  Then recheck.

Don and Cary

[gus]

What Don said.

That one batt has a poor ground or the two different grounds are not tied together at any point. Engine and chassis grounds should be common.

For max batt life it is probably best to ground both batts to the same good point, they were like that originally, both pos and neg. Mine are still like that.