Hello everyone! Im exhited to make my first post here. With all the information in the internet and now with IA I was supposed to have the proper answer for this matter, but I haven't so I need some expert to clarify this for me.
I'm a new owner of a 47 ft CC Commander. With two 5.3 detroit diesel engines. The thing is, next to the steps down to go to the engines room there is a little button named Engine alternator by-pass. Can anyone explain me how that works? It that related to the two battery banks (engines and services), in that case I suppose if the engines bank dies or has no enough charge to start the engines, with this button I can swith to services bank to do it, no?
With an electrician, I noted that the alternator voltage increase from 36 +- to 42+-, when I turn on that switch. Its like key a booster for the engines bank. But also it seems to be related to the services bank.
Due to I changed the batteries recently from lead acid to lithium, i need to be sure of what this button can do, just to avoid any risk.

Im looking for anyone's response, please!