Bushpower Caravan & Trailer Dual Battery Kit

Complete Vehicle & Caravan/Trailer Wiring Kit with Isolator

This kit includes everything you will need to connect your tow vehicle to your caravan/trailer battery system.

Featuring the 140A Bushpower designed voltage sensitive smart isolator which detects when your main vehicle battery is fully charged and automatically switches over to charge caravan/trailer batteries.

The charge is sent via 7m x 8 B&S vehicle extension cable to a 50A Anderson Plug at the rear of the vehicle (dust cover included).

From this Anderson connection the charge will then be sent directly to the batteries located in the caravan/trailer via 7m x 8 B&S twin core trailer extention cable.

The system is extremely easy to install and comes with an easy to understand installation manual.
Read our installation guide below.

All components are included:

• 1x Bushpower 140A Voltage sensitive isolator, Cut in 13.3V - Cut out 12.8V
• 2m x 6 B&S Positive Cable (to locate your voltage sensitive relay)
• 7m x 8 B&S Vehicle extension cable.
• 7m x 8 B&S Twin Core Trailer extension cable
• 2 x 50A Anderson Connectors with Dust Covers
• Copper Lugs & Heat Shrink
• Installation Manual

All lugs, plugs, terminals, heatshrink and zip ties you will need are also included.

These kits are exclusively manufactured by Bushpower using 100% Australian Cable and comes with a 2 year warranty!

Bushpower Caravan and Trailer Dual Battery Kit Fitting Instructions

Fitting the Kit is relatively simple and requires tools readily available in most home workshops.

Tools required are:

a) Cutting pliers, side cutters or Stanley knife to cut and strip the cable
b) Crimping tool or electricians pliers for terminal crimping
c) Spanner set, socket set or shifting spanner
d) Philips screwdriver
e) Hairdryer or lighter for heat shrink
f) Drill and 3.5mm (9/64) drill bit
g) Multimeter or voltmeter (optional)

1. Lay out the contents of your Dual Battery Kit and check that all the components are in the kit. You should have:

1 x Voltage sensitive relay with mounting screws
1 x 7 meter length of 6B&S red cable with Anderson plug at one end
1 x 1 meter length of 6B&S black cable with Anderson at one end (as above)
2 x Positive Marine type battery terminals
1 x Negative Marine type battery terminal
6 x Copper crimp lugs
6 x Red heat shrink
2 x Black heat shrink
1 x Insulated ring terminal
12 x 200mm cable ties
2 x Red Anderson Dust Covers
1 x 2 meter length 10mm² red cable
1 x 8 meter length 8mm² twin core cable with Anderson at one end.


2. Disconnect the start battery by removing the negative terminal. Ensure ALL accessories, lights and any other powered equipment is off and “temporary” power is fed into the vehicle via a “memory minder” or alternate battery.

3. Select a location for the Voltage Sensitive Relay that is easily accessible and will not have the cables running near exhausts or turbochargers and is preferably close to the start battery.

4. Place the VSR at the required position to use as a template and mark the position of the four (4) holes to be drilled. Drill the holes using a 3.5mm (9/64) drill bit.

5. Secure the top right and lower left holes of the base with the short 4mm screws.

6. Take the 2 meter length of red cable, which has been lugged at one end, and starting from the centre of the mounting plate run the cable to the positive terminal of the start battery being careful to keep the wiring away from any moving parts and preferably running the cable along the inner guard and firewall. Cut the cable to length and attach lug for connection to battery terminal.

7. Attach the insulated ring terminal to the black wire on the VSR. This is an earth wire and it is important that it has a secure and clean (Bare Metal) contact. If possible select a nearby bolt or screw that is earthed to the body.

8. The cable from the start battery goes to the stud on the VSR with the painted RED DOT and marked “Positive + Sense Batt”.

9. Mount the Anderson plug with the 7 meter length of red and 1 meter length black cable at the rear of the vehicle; ensure the Anderson plug is accessible. Cut the black cable to desired length, attach lug and firmly connect to vehicle. Run the red cable to the VSR using the cable ties to attach to the vehicle, be careful not to place near moving objects or exhaust pipes. Cut the red cable to length, attach lug and connect to VSR.

10. Reconnect negative terminal to battery.

11. Locate the auxiliary battery in the trailer/caravan.

12. Locate and attach the 8B&S twin sheath cable to the draw of the trailer/caravan. Leave enough cable to connect to the vehicle. Run the cable from the draw through to the auxiliary battery attaching with cable ties as needed.

13. Cut the cable to desired length to reach the battery comfortably. Attach supplied lugs and connect to battery terminals.

14. The hard work has been done and it’s now time to do some tests.

15. Start the vehicles engine.

16. When the starting battery’s voltage is above 13.3V the relay will close automatically and allow the auxiliary battery to be charged. This is indicated by the red light on the left hand side of the VSR front panel being illuminated.

17. Ensure that the auxiliary battery is charging by checking that the voltage is above 12.8V.

18. Turn off the engine.

19. Check that the VSR disengages when the start battery’s voltage falls below 12.8V. This can take some time so to speed up the process turn on the headlights or leave the door open and interior lights on.

If the VSR works as per the above tests congratulations you have successfully installed the Caravan
and Trailer Dual Battery Kit.