LiFePO4 Battery (Lithium Iron Phosphate)
A rechargeable battery chemistry whose cathode material is lithium iron phosphate, giving a nominal voltage of 3,2 V per cell. In an RV, four cells are connected in series for 12 V and the nominal voltage becomes 12,8 V. Compared with lead-acid it is lighter, has a longer cycle life and suits deeper use.
The distinguishing feature of LiFePO4 is that the voltage stays very flat throughout the discharge. While lead-acid voltage falls step by step, a lithium pack stays around 13 V for a long time and then drops quickly towards the end. This means the loads see a more stable voltage; on motorised loads torque and speed vary less.
For the same usable energy a LiFePO4 pack typically brings a weight markedly below that of lead-acid. Since in an RV weight comes straight out of the load capacity, this difference shows up not on paper but on the registration document.
Against that there are three constraints: the pack cannot be used without a BMS, charging it at low temperature is generally prohibited, and the charge profile differs from lead-acid. If your existing mains charger or solar regulator does not support the lithium profile, you have to replace those as well. On loads with high instantaneous current such as levelling, however, the low internal resistance is an advantage because it reduces voltage sag.
The context in which this term is used: RV automatic levelling guide