12.9V for float and 12.8V for reconnect is too low.
For example: say you use relatively little power overnight, the sun comes up in the morning and solar gets the battery through bulk and absorb by 10am. The solar controller then switches over to float but isn't providing any power as the float voltage is lower than the resting battery voltage. You then start using a bunch of power, the solar won't help out until the battery voltage is below 12.9V, which is almost flat for a LiFePO4 battery. Furthermore, it won't kick back into bulk charge until you get down to 12.8V, which means the battery is flat. As a result you missed out on a whole day of solar charging, used an unnecessary cycle on your batteries and go into the night with a flat battery.
If you set the float for 13.3V, the solar charger will carry for as long as there is enough solar power available.
