What does an isolation relay / separator do?

In many vehicles and vessels, such as RVs and hybrid boats, there is often a separate starter battery and accessory battery.
With an isolation relay, priority can be given to one or the other battery in terms of charging current.
After all, charging current often comes from one source.
As long as the voltage of the starter battery is too low, an isolating relay will ensure that all available charge current is used to recharge the starter battery.
If the starter battery is charged, the isolating relay will also supply charging current to the accessory battery.
Should the voltage of the starter battery fall below a certain level again for a certain period of time, the isolating relay will again direct all available charge current to the starter battery.
This way, your starter battery always remains charged.
Cellpower’ s battery separators also have a unique feature.
They are bipolar.
This means that the current through a separator can flow in two directions.
This comes in handy when charging your accessory battery with a battery charger.
While charging the accessory battery, the separator will also conduct charge current to the starter battery.
Once the battery charger is disconnected from the accessory battery, the separator will also cut off the current from the accessory battery to the starter battery.
Thus, your starter battery will always remain maximally charged without draining the accessory battery.