to have two Lithium Batteries on board and switch back & forth from one to the other with an electrical switch just like having two fuel tanks?If so HOW & what type switch DPDT?

Get a Blue Seas or Perko switch that says 1 / 2 / 1 and 2 / Off.

Or split up your circuits and use the Blue Seas All on/All Off/Emergency Combine with an ACR.

[quote=Sgrem]Get a Blue Seas or Perko switch that says 1 / 2 / 1 and 2 / Off.

Or split up your circuits and use the Blue Seas All on/All Off/Emergency Combine with an ACR.[/qu Thanks for responding Sgerm but these are larger type switches .I`m looking for something like an in dash type switch ie. left /right for example

No. An in dash will not have the amp carrying capacity and will burn wires, burn boats, and let the smoke out of your equipment. You need to look at amp loads, wire size, lug size, and switch capacity for those amps.

Think light switch vs main breaker in your house.

Although you could mount the big battery switch mentioned above on your dash and run heavy heavy gauge wire to your batteries and buss bars.

What are you trying to accomplish?

Sgrem I apologize for not being clear on what i`m working with. I`m tryna run a 46lb thrust troll mtr w/ spot lock gps on a small 8' Pelican Bass Raider powered with a 12.8v 50ah lithium but I have two & want to use one as a stand by without having to manually change the terminals with a small switch.

Just being LAZY

Just hook the batteries together in parallel with short jumpers and it will work together seamlessly.

But 50ah should be plenty for a day.

I use 30ah on my 21ft aluminum Lund.
I use 60ah on my 26ft giant bay boat with oversize Ttop. Have never run out of juice in a day.

I`ve tried that but troll mtr will not operate. It`s a 12.v not 24.v!

Parallel. Hook positive to positive and negative to negative. Then you will have 12v only and 100 ah.

Do not hook it up in series.

Thanks Sgrem it worked Parrallel was the ticket! Why parrallel instead of Series though ??

Series adds the volts 12V + 12V= 24 volts/ 50AH
Parallel adds the amp hours 50AH + 50AH= 100AH/12V

Wayne P. Explained it.... but yes use Google Fu and educate yourself on series vs parallel.

Guys Thank you BOTH! I knew I was in the right place .

Yes I could do it with 200amp relays and a little understanding of how they work.