Battery in Boot
Page created by T Dec 17th 2007:Back to Electrical Index
Battery in Boot:
Legalities:Relocating a Car's Battery into the Boot of a Car can require permissions from the relevant state authorities. It's best to check with their requirements before committing to positioning the Battery in the Boot.
Safety:A Battery can be a potential source of danger if not fitted to the Car correctly. Be aware that in the event of an accident a Starter Lead may lose its insulation and become shorted against bare metal. The result can be fire and/or explosion. It's vital that Battery leads be run away from sharp edges and have strong insulation run around them.Batteries produce hydrogen gas which is inflammable and can explode if ignited. The location of the Battery needs ventilation to allow that gas to escape.Follow the recommendations of your State's Transport Authority with regard to securing the Battery to the Car, running cables to it and any other requirement they may have.
The primary job of the Battery is to start the Car. This means very heavy currents running between the Battery and the Starter Motor.It's vital to run a heavy lead from the Battery +ve to the Starter.It's vital to run a heavy lead from the Battery -ve to the Engine Block.It's also vital to run a ground lead from the Battery -ve to the Car's Chassis. This lead must be able to carry the Car's entire Electrical Load (lights Wipers Fans etc). This lead does not carry the Starter current. It's a good idea to make it at least as large as the Alternator'srating.Starter current will be around 200 amps. This is a heavy current and more than enough to weld with. The current involved in startinga car needs to find the easiest path from the Battery to the Starter and back which is why the Starter Leads are so thick.If the Battery -ve Lead is not run to the Engine Block the current that returns from the Battery under starting will be forced to followa complex and damaging path through the Drivetrain where all the Gearbox, Tailshaft and Rear Axle Gears and Bearings will become pitted.There will also need to be a smaller lead between the Battery -ve and the Car's chassis (made at the Battery) so that the Lights, Wiper and Fan Motors can find an easy path back to the Battery. Make only one of these connections otherwise complex *"raised earths" can appear in the car.* raised earths : A "raised earth" is where current returning from one device causes the earth point for another to be higher than the Battery -ve giving the second device less voltage.
Battery in the Front of the Car:
Note that when the Battery is in the front of an Old Holden there is a seperate wire connected between the Engine block and the Battery negative.Note that when the Battery is in the front of an Old Holden there is a seperate wire connected between the Engine block and the Battery positive.Note that when the Battery is in the front of an Old Holden there is a seperate wire connected between the Chassis and the Battery negative.When relocating the Battery to the boot, each of these wires must be replicated in order to avoid serious problems.
Wiring the Boot Mounted Battery:
- Note* Connect the Alternator B+ wire to the large tap on the Starter. the same one that has the Battery +ve connected to it. *Note* Connect the Alternator S (Sense) wire to the Battery +ve.