Request clarification ref Will Prowse's "The Minimalist" 200W, 12v system for truck camper

[SaltyNomad]

I'm new to solar systems, new to this forum and grateful for your feedback.

I've installed a 200W, 12v solar system on a Lance 825 slide-in truck camper, following Will Prowse's The Minimalist design, and using his recommended components (thanks Will for the tutorial). The design is at this link: https://www.mobile-solarpower.com/the-minimalist-great-for-small-vans-and-cars.html. Now that's it's installed it raises two questions:

(1) Regarding the camper's 12v system leads that were connected to the old lead-acid battery, do I simply reconnect them directly to the new lithium battery, or do I instead remove the in-line 40amp breaker and connect the leads to a 40-amp fuse on the new Blue Sea fuse block? In Will's tutorial, he connects the battery, inverter, and MPPT to the fuse block and states that other appliances would also connect to the fuse block. I interpret that as meaning the camper's 12v leads are the total appliance load and would also connect to the fuse block and not directly to the battery?

(2) Regarding the camper's factory-installed Blue Sea ACR, I read (after the install) that an ACR intended to disconnect the truck battery from the house battery when the alternator is not powered should not be used with a LiFEPO4 house battery, as it could damage either the battery or the alternator. The info I could find seems to point to replacing the ACR with a DC-DC charger. It isn't clear to me if the system risk and solution apply to The Minimalist design. Can anyone clarify?

Thank you!
Cheers,
Jeff

 

[fratermus]

I read (after the install) that an ACR intended to disconnect the truck battery from the house battery when the alternator is not powered should not be used with a LiFEPO4 house battery, as it could damage either the battery or the alternator. The info I could find seems to point to replacing the ACR with a DC-DC charger. It isn't clear to me if the system risk and solution apply to The Minimalist design. Can anyone clarify?

The ACR uses voltage setpoints to connect/disconnect the banks. The disconnect setpoint, IIRC, is 12.75V. Cool if you have a lead bank, because the resting voltage will typically drop below that after a short time. LiFePO4 resting voltages are higher and so the disconnection will not trip until quite late in the game.

If you want to keep the ACR you may be able to use the "Control Switch Remote" to deactivate it at will. You may also be able to use IGN signal to activate it; there are multiple models of the ACR with different features. If the feature is not present then one might use IGN to trigger a small external relay to drive the Control Switch function. If ACR is otherwise performing well then DC-DC is unnecessary expense, IMO.

Anecdote: I have a Battery Doctor VSR that disconnects at 13.2v. I have a switch on the ground (accessible from driving position) to disable it when I don't want alternator charging, or when I don't want the connection held after the the engine is turned off. At some point in the evening the bank drops <13.2v and the VSR disconnects. The chassis/starter batt doesn't seem like much of a parasitic pull so I am not paranoid about it.