This is definitely an interesting experiment I'll call it. Maybe questionable how much real world utility there is in such an upgrade as I'm not seeing it expand any use cases, and may even compromise some. Weight is a good advantage. Some real integration hurdles to work through. Application can be a bigger dictator of battery type than it may seem. Funny thing is that even most EVs in the last decade, has used standard FLAs for accessory support.
The low internal resistance of lithium's is one to watch. The RV forums has seen reliability issues with alternators when charging lithium batt's. Charge time is one way to look at it but brush and regulator life can be compromised even with shorter durations of heavy current. I'm not sure how much capacity margin is in the alternator charging system in extreme uses like cold weather where electrical loads can be high with all the heating and electrical accessories that the LX has.
Already some great consideration items
@sdnative has pointed out. Few other things
- Safety of such a high current source underhood. Lead acids are somewhat self limiting in shorts because of their higher internal resistance. Lithiums may be a greater liability and risk to fire as you know it's unfused, at least to the starter
- Capacity: While lead acids have recommended discharge levels to maximize service life, the reality is they have built in useful emergency reserves which can be almost the full rated capacity.
- Jumping: May be difficult to jump if it goes dead, as the drained battery itself becomes a large load. If using a BMS, will want to understand the workflow necessary to get the car jumped and battery/BMS re-engaged
Not to discourage you and I'm all for pushing the envelope. Just some integration things to watch.
