As JoeHam mentioned, custom battery type is what you'll have to use. Just typing as I think here, I come up with a few things to be cognizant of:
- Lead Acid can be recharged in a less-regulated manner than LiFePO4 because there is a more pronounced voltage rise as state of charge in the pack rises that can be more easily used to determine where in the charging cycle the batteries are at. This doesn't work with Lithium because their voltage curve is so much flatter throughout their state of charge. FLA/SLA will also tend to soak up recharge at a rate they're comfortable with regardless of available current where as LiFePO4 will easy over-current if the current is available, although current in the first stage should still be limited with FLA/SLA to about a third of their Ah rating. Individual cells within a string of lead-acid cells tend to naturally equalize during recharge because of the relationship between the voltage and current with the state of charge curve, unlike Lithium chemistry where such voltage fluctuations between cells would run away uncontrollably without a BMS. Lithium can be recharged at the same rate as the Ah capacity, or as limited by the BMS whichever is less. It is preferable to use State of Charge to regulate LiFePO4 usage, and in Schneider's lineup only the XW Pro combined with a Conext Battery Monitor (or other supported third-party BMS in closed-loop mode) is supported to do that. So, up until the XW Pro, all Schneider/Xantrex/Trace recharging schemes have been and continue to be a combination of voltage and time-based. You can use the 3-stage charging but the float (stage 3) setpoint is going to be a little higher than what you're used to seeing, but in practice LiFePO4 don't need to be floated.
- The rate of discharge from LiFePO4 has to be limited to rated spec, for a EG4 that's going to be 100A continuous and up to 150A for up to 3 seconds, or the BMS will trip into overload.
- The rate of recharge has to be limited to the rated spec, for an EG4 that's 100A continuous and up to 120A for less than 2 seconds, or the BMS will trip. Check if you've got a setting for this so you can limit the SW's 45A to stay under the 100A limit when you take your DC-coupled Solar into account.
- Temperature de-rating for LiFePO4 is different from Lead Acid and needs to be configured manually in the battery menus of the inverter. See what's available there. I can send you screen shots of what an XW Pro gives you options for.
- FLA/SLA recharge stages are Bulk/Absorb/Float holding at 100% SoC at the end. LiFePO4 is going to have different voltage triggers for each stage that all need to be configured manually when using a custom battery type.
- Schneider/Xantrex/Trace inverters are legendarily regarded for their load-surge capacity. Yours has a rating of 7000W for 5 seconds 4000W for 30 minutes, and a continuous capacity of 3800W. It can pull 150A from the battery at the extreme - right at the limit of the BMS in an EG4. It's an avoidable scenario with load management because you don't ever want to have to deal with the headache of a Schneider inverter losing DC bus.
- Any settings for equalization charge or schedule has to be disabled for use with LiFePO4.
- The preferred State-of-Charge operating range of Lead Acid (Flooded or Sealed) is from 50% to 100%. For Lithium Iron Phosphate it's 5% to 95%. Just as staying within that range is critical to longevity of FLA/SLA, it is just as important with LiFePO4 with the latter being much less forgiving.
For your setup easiest solution to prevent any overcurrent scenario concerns would be to use two EG4's in parallel, and then all those battery limits effectively double. As for initial start-up, use your own resistor circuit wired in parallel to the main DC inverter breaker, with its own breaker or shutoff switch, and pre-charge it yourself. Internal capacitors in anything that say "Schneider" on it can be assume to be huge.
State of Charge, as expressed in percentage, is the metric you've got to monitor and control with Lithium.
