For a complete charge of a 24V LiFePO4 battery, a charger with a voltage ranging from 28.4V to 29.2V 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.

Yes, you can. But 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.

Leaving a lithium-ion battery on the charger overnight can be generally safe if you are using a charger like LiTime lithium battery chargers which is designed to stop charging once the battery reaches full capacity. Most modern lithium-ion chargers are designed with this feature to prevent overcharging.