This guide will explain how to add a leisure or house battery with Isolation to your Delica. A VSR or Voltage Sensing Relay is used as a smart charge controller, allowing your leisure battery to charge while the vehicle is running, but prevents you from pulling down or killing your starter batteries while the engine is not running. The VSR detects the higher voltage of the alternator when the vehicle is running, and automatically connects the leisure battery. Otherwise the circuit is broken. This allows you to use all your camping gadgets,without the fear of killing the starter battery. Most VSRs also come with a manual bypass switch. This allows you to use the leisure battery to start the vehicle in the event the starter battery dies.
Here is a basic schematic of the setup. It is recommended that fuses are added as close to the power sources as possible. We run 80A inline fuses. Sizing will depend on the gear your run, but 80A is probably plenty. We have started the car with the leisure battery through the 80A fuse without issue.
We have a 30Ah sealed AGM battery for our leisure battery. The sizing is based off our gear. It tucked up nicely in the rear fender with a custom rack and some minor mods. Below are images of our install.
We also have a semi-custom split fuse box in the engine bay. One side for standard accessories, and one side for the leisure accessories. In-line fuse circled in red, bypass switch circled in blue.
We located the actual VSR itself inside the B-pillar unibody, above the seat belt mechanism. This was a good empty space to fill, with a short and simple wire run.
The wires were run into the B-pillar by following the sliding door lock control wiring, which conveniently enters right into the battery compartment. We just cut some extra holes in the existing grommet.
The connective wiring runs to the back by following the coolant overflow drain hose (there is a nice gap to run through) to get from the battery compartment to the undercarriage. From there we just go straight back with some thoughtful ziptie placement.