The battery status is shown in three stages:
Green = full
Yellow = under 12 V
Red = less than 11 V
Once the Red "lamp" lights up on the guards of the unit and thus protecting the battery from deep discharge.
Even when on again he continues to protect the battery and switches off again ... of course not when the battery has been recharged!
Functionality:
All thing you need if you want to relay switching higher currents.
The relays are only responsible for a function of the Guardian, that switching off the consumer if the battery is discharged depths, but two connections are provided. Display also works without, these are the other two terminals.
The battery monitor does not tolerate high currents ... so you have to block a switching relay. The battery monitor depends only on the control circuit of the relay and the relay switches the load circuit. Thus, the switch is protected.
Best 12V relay and then depending on what amperage you want to switch.
In the manual, everything is described very helpful and good.
I have it (built themselves) in use for a portable jukebox to the battery status display and protect my battery.
Buy recommendation !!!