For a complete charge of a 12V LiFePO4 battery, a charger with a voltage ranging of 14.4V±0.2V is necessary. If a charger with a lower voltage is used, it can still charge the battery, but it won't reach full 100% capacity.

Trickle charging is not acceptable for lithium batteries. Charging a LiFePO4 battery with a trickle charger not designed for this type of battery could lead to overcharging or damage due to the different charging requirements of lithium batteries compared to traditional lead-acid batteries.

Charging a battery to less than 100% and avoiding complete discharge always increases cell longevity. Similarly, maintaining operation within the 20%-80% state of charge (SoC) range will prolong the life of lithium batteries.

In the case of LiTime deep cycle lithium batteries, they can withstand over 4000 deep cycles at 100% Depth of Discharge (DOD), over 6000 cycles at 80% DOD, and more than 15,000 cycles at 60% DOD.

If the correct voltage limit is set for the LiFePO4 lithium ion battery you are charging, there should be no issue leaving a lithium ion battery on the charger overnight. LiTime Battery uses a LiFePO4 cell giving a nominal voltage of 12.8v and a fully charged voltage of 14.6V. A charger with 14.4-14.6V CC/CV output will do the job with consideration not to exceed roughly 1C maximum current output of the charger. As long as the CC/CV profile is used, the maximum voltage is at the correct level and the current is not excessive, you will achieve a safe and full charge on your battery.

It depends on the voltages of your LiFePO4 lithium batteries. LiTime 14.6 volts charger is recommended for 12V LiFePO4 lithium batteries. And LiTime 29.2 volts charger is recommended for 24V LiFePO4 lithium batteries.