This is crazy IMO.set to 14.6 volts is a good setting
…
Lifepo4 will take every amp your solar panel can produce, up till the BMS shuts it off.
The BMS is there to act as a fail-safe in case your normal regulation / protective systems fail.
At both the high and low ends, by the time BMS isolates, if happening regularly you are throwing away for sure hundreds of lifetime cycles, potentially thousands.
Nothing wrong with "fast charging" but increase amps while keeping volts well under 13.9V.
> I have a .5 voltage drop in the system
You should fix that.
> Once the resting voltage goes below 12.9 volts you battery is almost dead.
Not true. 11.9V is still above 10%, especially if it hits that under a high load, let it rest it will recover.
Of course better to start recharging, and for longevity best to stay at higher SoC but no need to stress if you touch 12V sometimes.
> I lost about 4x 12 volt fans and many 12 volt lights from these surges, but havent since I added the relay.
Need a little cheap lead batt in line to buffer the load dump, same as alt charging.