Wires to batteries - way to figure out the cranking batt

[jwanck11]

OK. I have two batteries that are both cranking batteries.

One of the batteries has quite a few cables going to the neg and one to the pos terminals and the other one has one one cable going to each the neg and pos terminals.

Can I assume that the battery with only one cable going to each terminal is being used as the starting battery?

[kko]

yes sir

[zad0030]

My boat sounds like it was wired the same and both would start the engine.

[lee]

All of the grounds on one battery does not make it the starting battery as the grounds all will loop through out the whole boat. The ground from one battery should actually connect to the other battery. Both batteries should be able to start the boat.