MPPT can be used to charge any kind of battery. MPPT, Maximum Power Point Tracking, refers to how the solar controller extracts the most amount of power from a solar panel. Solar panels have a voltage-current-curve that varies with sunlight, where the maximum power is available at less current than the short-circuit current, and less voltage than the open-circuit voltage. This optimum voltage-current point is called the maximum power point. The charging circuit is a different part of the controller, and is configured differently for lead acid than for LiFePO4. In the case of the Genasun MPPT controller, there are different versions for 13.5 V Pb, and 3 different versions for LiFePO4 12.5V, 14.2V, and 16.7V batteries.