Automatically allows multiple batteries to be charged and protects primary battery and auxiliary batteries from being drained by one another. Rated for use with alternators that range from 10 Amps to 130 Amps output, and will operate on 6-, 12-, 24- and 32-Volt negative ground systems. These Solid State devices allow electrical current to flow from your alternator to the batteries in one direction only. This allows one or two alternators depending on isolator model to charge multiple battery banks without the banks being connected.