engine battery: two red positive cables ??

[rgbach]

I have a Class C 2002 Itasca (Triton F-450.) Under the hood, the engine battery has two red positive cables. One is the obvious usual main positive. The other red cable is skinnier. I thought I read somewhere that the smaller cable is for emergency starting from the Auxiliary battery in case the engine battery is dead. Is this correct? ((( the reason I'm asking is, I just realized the eyelet has worn and the small red cable isn't actually connected to engine battery. Thanks
--=Ray=--

[theSane]

I would guess that is correct, but another will have to confirm. Our 2018 F-53 is set up with a switch on the dash to allow the house batteries to provide a "boost" to the engine battery if it dies.

[GaryKowal1]

Simple test to prove you are right. Put a 12 volt test light or multi meter on the broken lead, negative on battery negative. Then press the button that links the batteries for emergency start. Power process you are right.

[Goodspike]

I would guess that one goes to the starter and the other is for the rest of the electrical system. Just another guess, but starting from the auxiliary battery would also probably run straight from the battery to the starter, with a relay in-between. Having a small gauge cable for starting purposes would be pointless or even dangerous.