32 - Lithium Battery Installation

I replaced the two group 24 lead-acid coach batteries (see Post #17) weighing 90 lbs. with one 28 lb. lithium battery. I almost bought a 130 lb. 200 amp-hour AGM battery before deciding that lithium made more sense for the same price. I doubt I was getting more than 60 amp-hours from the former before the voltage dropped below 12. The LiFePo4 battery is rated at 80% of 100 amp-hours and is supposed to maintain less voltage drop over a longer discharge cycle.

My battery requirements are pretty constant; support the coach systems I use for one night between sunset and dawn without draining the battery excessively which would shorten the life. These include ...

- maintain refrigerator operation even though it is on propane

- using lights as desired

- operating water pump as needed

- operating furnace as needed

- capacity to start generator

- intermittent or occasional use of other 12V items (e.g., bed operation, using or charging electronic devices)

Installation and modifications: The single battery fit easily and left room for storing an auxiliary charger and small compressor. The battery has built-in management system and low-temperature protection. It is a generic Chinese-made battery from Amazon (brand name "Lisuateli") that has good reviews. The Victron solar charge controller (Post #19) has a lithium charge profile option which I set via the phone app. I have not changed the coach charger/convertor unit, nor the Transit's battery charge system from the standard lead-acid setup for now. From what I have read, regular chargers may not fully charge a lithium battery or take too long. But in limited use so far, the combination of the solar and regular systems is getting the full 14.6V recommended into it according to the Victron app, and I assume the battery's control system protects the unit from overcharge. Time will tell.

Lithium batteries must not be charged at below-freezing temperatures. I am not inclined to trust the battery's supposed low temp protection, so I installed a primary cut-off switch at the entry step (red key-switch in picture). This totally disconnects the battery from getting any charge (from either alternator, house convertor, or solar controller). The coach battery disconnect switch on the wall by the entry only disconnects current to house circuits (lights, fridge, etc.) but still permits charging. So I will switch off the battery totally during below-freezing temps.

I have only had one night of dry camping experience so far. The voltage before retiring was 13.2, and it was 13.1 the next morning. The old batteries went from 12.6V to 12 or less overnight. (Digital voltage reading at a coach power outlet--usually reads 0.2V less than at battery terminals. I don't have the equipment to measure actual SoC or capacity.) My solar system has proved to be adequate in fully recharging the batteries after a night of dry camping. It is keeping the lithium battery at full charge now during coach storage. I believe this one 100 amp-hour rated lithium battery will outperform the two deep-cycle batteries it replaced.