The 24V (2 x12V) battery equalizer is only suitable for lead acid batteries (VRLA).
The 48V (4 x 2.4 – 12V) and 72V (6 x 2.4 – 12V) battery equalizers are suitable for lead-acid batteries (VRLA), lithium iron phosphate (LFP), nickel cadmium (Ni-Cd) and nickel metal hydride (NiMH) batteries. The equalizer starts working when the voltage is above 2.4 V, which means that this equalizer can be used with a singlecell battery from 2.4 V to 12 V. A maximum of 2, 4 or 6 batteries can be connected to an equalizer at the same time.
With fewer batteries, the extra cable can be left free (positive and negative pole should be avoided) without affecting the balance effect. The equalizer is not affected by the way the batteries are connected, in series or in parallel, both can work.