Best use for extra battery pack in rv

[Willowflowage]

I just bought a new 200 amp Lifepo4 to build into a portable self contained box. Including solar charge controller, battery monitor, ect to wheel around while camping this allowing more sun in my usaully shady campsites.
I will continue to boondock with my existing golf cart batteries for some time but would like to use this as an extra source of power for the trailer.
Any ideas of a switch or plug to either run together with, (not sure if this is smart) or to transfer from the golf cart batteries as they get low, to the new battery simply?
Goal being a longer stay on cloudy days. My power needs can be quite low of maybe 40 amps a day but who doesn't want a little spare. Currently using 200 watts of movable panels. So this will be a nice boost as far as storage. More panels in my future I know.

 

[time2roll]

I would use an A-B battery switch and simply cut over to the LFP when the GC2s are dropping low.
Otherwise half the energy will be wasted charging the golf car batteries.

 

[jameshowison]

If not an A-B switch then you'd need some sort of DC to DC charger, like an Orion 12/12 or https://www.renogy.com/blog/what-does-a-dc-to-dc-battery-charger-do/

Can't parallel since need different charging profiles, right?

 

[HRTKD]

I would use an A-B battery switch and simply cut over to the LFP when the GC2s are dropping low.
Otherwise half the energy will be wasted charging the golf car batteries.

From an efficiency perspective, this seems to be the best way to go. Each battery bank would need it's own shunt and monitor so you know what its state of charge is.

 

[acdoctor]

Appropriate size Anderson connectors and the aforesaid A B switch.

 

[Willowflowage]

If not an A-B switch then you'd need some sort of DC to DC charger, like an Orion 12/12 or https://www.renogy.com/blog/what-does-a-dc-to-dc-battery-charger-do/

Can't parallel since need different charging profiles, right?

They will both have independent chargers. Just looking for a simple switch and plug in for the new battery box to the old one on the RV hitch.

 

[Willowflowage]

From an efficiency perspective, this seems to be the best way to go. Each battery bank would need it's own shunt and monitor so you know what its state of charge is.

Sounds good. I'll have to locate a switch and probably some kind of plug for the portable battery.

 

[Defens]

I have a similar question I just posted On the beginners forum. My current plan is to run a lead with Anderson
connectors straight to my 12v panel to hook up the battery box with breaker, etc. I’ll just turn off the master disconnect on the trailer when I want to connect the battery box. That way the lead acid GC2 can still charge via rooftop solar, and my shunt and Trimetric monitor won’t get confused. Although, I could include an A-B switch, which means I would need to turn off the master.

 

[time2roll]

I could include an A-B switch, which means I would need to turn off the master.

A-B-Off could replace the master.