isolating deep cycle batteries from other deep cycle AND the cranking battery

[BreakingBad]

Hi all


I'm toying with the idea of changing from AGM to lithium for crank and deep cycle in my Defender.


I have a PTO winch so don't require batteries for winching purposes.


I plan to do this incrementally as funds permit but ideally would like


lithium for crank
lithium for general usage while camping eg: lights, water pump, charging tech devices and occasional inverter usage
lithium dedicated for fridge/freezer


I figure I can fit the crank and a 100amp hr lithium under the front passenger seat and a 200amp hr slimline behind the rear passenger seats. I intend to have the fridge/freezer occupy the space where the 2/3 rear bench seat sits.


I'd like to understand what is required to ensure each battery is isolated from each other.
ie: crank isolated from deep cycle, AND deep cycle isolated from the other deep cycle.

I'd also like to understand what I require in order to charge all batteries from alternator, solar and mains.

[PhilipA]

Assuming that it is an old Defender, not a new one , all you need are 2 solenoids or big relays triggered by the ignition "on".

I have this setup but with a lead acid starting battery, an AGM and a Lithium and DC/DC charger in my van.
i guess I have an additional wrinkle in that I have a switch fed by my accessory feed to the rear cigarette plug controlling the second relay that enables me to connect the DC/Dc charger to the AGM with IGN off. I haven't used it yet! but maybe one day.
Potential use is solar charging AGM and AGM charging Lithium via DC/DC charger with IGN on ACC and all accessories off.
Works well and has for a couple of years.
Regards PhilipA

[Blknight.aus]

ID set it up with a big clunk relay from the starter to the first accessory battery picking up an aux feed to trigger it from the ignition.

from the first accessory battery Id then connect all the other batteries with VSR's in order of priority.

ID then connect a solar reg to the first accessory battery, for mains charging ID wire in an aux jack to plug in any charger you want OR permanently wire in a mains isolating charger (they have a relay that drops the 12v side off if the mains power it turned off)