Among the most common battery isolating devices are battery isolators and battery combiners that allow two or more batteries to be isolated so that, for example, the use of the service battery cannot discharge the starter battery.

Battery isolators allow two or more batteries to be charged simultaneously from a single alternator or from a single charger without connecting the batteries together. Battery combiners are an excellent replacement for battery isolators as there is virtually no voltage loss, so there is no need to increase the output voltage of alternators or battery chargers.