Addendum to my other "Adding a second battery.........." post

**Rgpracer** · 03-13-2021, 05:54 PM

Sorry, couple extra questions.......do you always wire to use both batteries simultaneous and charge at same time or should I put an isolator (selector switch) in to isolate batteries?

Sorry and thanks
Ray

**huntindog** · 03-13-2021, 06:03 PM

Are you adding a new battery to your existing one? If so, then the selector switch is a good idea. If you are geting 2 new batteries, then I would not install one.Reason is an old battery will drag a new one down. If you start with a matched set, then keep them that way by using them as a set. Batteris age from time, and cycles.
This is for regualar lead acid batteries. Other types of batteries is not considered in this aswer.

**RV Sailor** · 03-13-2021, 06:23 PM

No switch. Batteries should be the same. Best to build the largest bank you can.

I’ve copied a discussion on one of the sailboat forums I am part of , where 1 large house bank is preferred over two small ones

https://forums.sailboatowners.com/th...e-bank.184137/

**Rgpracer** · 03-13-2021, 06:46 PM

Originally Posted by huntindog

Are you adding a new battery to your existing one? If so, then the selector switch is a good idea. If you are geting 2 new batteries, then I would not install one.Reason is an old battery will drag a new one down. If you start with a matched set, then keep them that way by using them as a set. Batteris age from time, and cycles.
This is for regualar lead acid batteries. Other types of batteries is not considered in this aswer.

Adding a second battery if cca's are ok, so good on selector.
Thanks