Battery to Boot

Summary

The battery to boot conversion is probably the single most popular modification done to all rover turbos. Although capacious by comparison to more modern cars, the engine bay is pretty much full of engine. This causes problems when trying to fit aftermarket induction systems such as a cold air box and cone filter. The solution is simply to remove the battery and relocate it in the boot by running a cable from the back of the car to the front.

Requirements

To do this job you will need:

  • Around 5m of between 2 and 0 gauge cable for Live (larger the gauge smaller the cable, 4 and 8 guage is not suitable)
  • Around 1m of between 2 and 0 gauge cable for Earth
  • A suitable circuit breaker or fuse (150amp-200amp)
  • Ring terminals
  • Battery terminals
  • Battery tray or fabrication of secure battery holder
  • Grommets mounting bolts, solder etc

Procedure

Before starting this modification let me stress that this is a serious modification, failure to take the appropriate action in securing the battery or running the wiring can result in fatality in an accident or your pride and joy going up in flames.

Firstly mount the battery securely in the boot, as this is the hardest part of the modification it should be tackled first to ensure that the work can be completed before rendering the car completely immobile. For inspiration you may want to check out the sub box/battery box in the modifications section.

You can reuse the battery tray, but ensure that it is securely bolted to the chassis and not to the trim, a battery is heavy and in the event of a crash or emergency stop will have considerable momentum. Also ensure that any of the fastenings do not penetrate the fuel tank or any other vital components.

With the battery secured, the wiring can now be attempted.

Firstly run a good earth from a solid part of the chassis (remove paint to make a connection) with a ring terminal and bolt. Terminate the other end with the negative terminal so that it can fit without strain to the battery.

Run a short length from the battery positive terminal to the fuse or circuit breaker. The idea is to keep the length as short as possible while keeping it convenient and easy to remove the battery.

Note: While it is not essential to fit a circuit breaker or a fuse it is far better to be safe rather than calling the fire brigade. The fuse will protect the cable from the battery to the engine in the event of a short. The alternator is already fused at the engine end so does not need an additional fuse. Personally I fit a circuit breaker as this allows me to isolate the battery easily if required.




The starter motor trick.


In battery to boot conversions it is quite common to use a distribution block to connect the battery to boot cable to the electrics at the front of the car.

Connection blocks tend to be audio distribution blocks and although rated for the current the engine vibration means wires can work loose and arc.

A far superior solution requires no distribution block and makes the wiring much simpler and more robust. This is the trick that I invented for my battery to boot conversion which has proven popular so far.

The starter wire (right in the picture) currently goes from a terminal on the back of the starter motor to the original battery positive terminal.

In addition two brown wires (left in the picture) which feed the alternator are also attached to the original battery positive terminal.

Remove the original battery wire to starter motor and note the terminal it was connected to.

Remove the brown wires from the battery positive terminal and pull back the cable - the cable can now be rerouted around the ABS unit and should stretch to reach the starter motor.

Using suitable ring connections terminate the brown wires and attach them to the back of the starter motor where the original battery feed was connected.

Solder a large ring terminal on the battery to boot cable and attach it to the starter motor positive terminal.

From the circuit diagram it can be seen that electrically the connection is the same in the original configuration (top) as to the modified configureation (bottom). The absence of extraneous connections or wiring means it is physically neater and more reliable.




The battery to boot cable can now be routed through the bulkhead using a suitable grommet.

Care must be taken to ensure that the cable is not likely to chaff at any point along its length.

The cable can now be routed through the inside of the car to the boot.

An easy method is to remove the door sill trims and peel back the carpet tucking the cable down behind the plastic cable carriers and seatbelt mountings and running the cable up behind the rear seat bolster to the boot

Once the cable has been routed to the boot it can be connected to the fuse or circuit breaker and the job is complete.