When you connect up and the car engine is running, the relay operates and removes ALL power from caravan 12V circuits so that incoming power from the car feeds only the fridge 12V and provides current to charge the caravan battery.

What does a relay do in a caravan?

Relays that control current from the towing vehicle to a towed caravans auxiliary (fridge/battery) circuits. They are designed to stop the battery of a vehicle connected to a caravan from being discharged when the vehicles alternator is not charging.

What is the purpose of a battery relay?

When it comes to battery management, battery isolators and automatic charging relays (also called ACRs or voltage sensitive relays) are both used to safeguard reserve battery power to prevent breakdowns and protect other vital vehicle or boat functions.

How does a caravan battery charger work?

To stop anything being powered up in the caravan when the engine is running on the tow vehicle, there is a “habitation relay” which when it detects the engine running, it switches over and disconnects the caravan from the leisure battery and connects the car charging circuit to the leisure battery.

How do I know if my battery isolator is bad?

Check the voltage at your batteries. If you are not seeing close to the same voltage at the battery as at the isolator (minus some small voltage drop over the wire), you have another problem. If the voltage is 12.7 volts or below, you are probably only seeing the battery voltage and no charging at all is occurring.

How does a car battery isolator switch work?

By using diodes to allow current to flow only in one direction, a battery isolator prevents a fully charges main battery from passing current to a partially charged auxiliary battery. Current can flow from the alternator to both batteries but cannot flow from the vehicle battery to loads in the vehicle.

How do you drive a caravan fridge while driving?

All caravan and gas appliance manufacturers advise you to turn the gas off while travelling for safety. This is more due to having a naked flame running on your van, and associated dangers with entering a service station, than any issues with the fridge itself.

Can a battery isolator go bad?

Isolators can also fail by connecting the engine and the house battery. This allows your engine battery to be depleted by the use of your RV appliances.

Are battery isolators necessary?

A battery isolator helps to ensure that the starting battery has sufficient power to start the engine and recharge the batteries if, for example, loads on the auxiliary battery (e.g., refrigerator or navigation lights) cause it to be drained, or if an auxiliary battery fails.

How do I know if my battery isolator is working?

0:252:35How To Test A Battery Isolator - e Marine Systems - YouTubeYouTube

Why put a battery isolator switch on the negative terminal?

The negative cable connects to the body ground already—so theres no additional danger if it rubs. Its the same principle as why you should always disconnect the batterys negative side first before performing electrical service.