12 volt battery installed

When I bought my batteries I ordered 5 additional as spares. Rumor has it that the failure rate is about 1 in 30.
I have used one of the spares as the 12 volt battery for the accessories. To fasten it I bought some 6mm threaded rod (600mm zinc plated for $2 from Hardware and General) .
I cut it to length and bent about 30mm on one end 90 degrees. The bent end goes through a 6mm hole drilled in the base where the original battery went.
The battery is sitting on a rubber mat. The threaded rod and the hold down clamp are covered in heat shrink to prevent any possible abrasion.

A few notes

1. My batteries are on a ship on their way from China. Should arrive mid October.
2. Spent Saturday installing the dashboard and stereo. Gotta have good sounds!
3. I have located all the important wires in the loom and designed the necessary opto isolating interface. (Reverse, Tacho and Speedo)
4. I have permanently wired the brake vacuum pump to the ignition
5. Sent plans for battery box to Geoff for fabrication.
   

12 Volt Power Requirements

The maximum 12V power requirement for the vehicle is just under 50A. After replacing the bulbs with LEDs this will be reduced significantly.

Power Requirements:
Accessory	Current Draw		Include in Max total
	Incadessent	LED
Brake	3.2		x
Fan 1	2.7
Fan 2	4.2
Fan 3	6.9
Fan 4	12		x
Idicator L	4.5
Indicator R	4.2
Hazzard	8.9		x
Park	3		x
Headligh L	12.1
Headligh H	13.4		x
Wiper L	3.3
Wiper H	5.5		x
Demister	0.2		x	Faulty
Dome Light	0			Needs Bulb
Total Draw Amps			46.2

12 volt charger mods.

I am using 2 x 'off the shelf' 230v to 12 volt 25A switch mode power supplies for my 12 volt system. One is powered from 0 to +300v and the other from 0v to -300v respectively.

As a consequence 2 modifications were required.

1. The feedback circuit needed changing to increase the adjustable output to 13.8V. This was done by tracing the voltage divider circuit and adding the required resistor in parallel with an existing resistor.

2. The 20 ohm bleed resistor needed removing in order for it not to discharge the battery while the vehicle is not being driven.

The image below shows the modifications. (zoom in for detail)

The completed power supplies have been installed into the Variable Speed Drive where some of the AC filter components have been removed. The device between the power supplies is a 50A circuit breaker that will be used for the 12V protection. The Power supplies will be wired in parallel.

The maximum 12V power requirement for the vehicle is just under 50A. After replacing the bulbs with LEDs this will be reduced significantly.