I will start with a 'warning' we sell battery packs, but we are only doing this because we felt ripped off by the stores that sell AGM, Lead Acid etc. and not able to claim the warranty due to using them under the bonnet as our 2nd bats.
We are currently selling lithium ion battery packs exclusively, 1865 & 2170 ATM
These are 12v and 24v used to power compressors, fridges, LED lights and anything else we can find were you take the bats. to the appliance, not cable to.
Here is an Elec. Eng. who has tested Lead Acid batteries and found them to be below the specs, no surprise, but LI under spec.
https://www.youtube.com/watch?v=iy3hga_P5YY Jump to 7 min for start of results
We are also testing LTO bats ( not mentioned in this vid, ) which have a cycle of 25K, so for some of use the bats will outlast our lifetime of 4x4 trips.
But, solid states are due in 2024 and will outlast EVs and Tesla is designing/hoping will transfer between old and new EVs.
So the take away is stop buying batteries you can hardly carry.