electric supra project

toasty warm...

Tue, 10 Nov 2009 09:53:32 +0000

I finally got the heater system working!

It needed a reservoir to stop the pump sucking air and cavitating, and it was quite a fight to fit it all in, but it works with 3kW of heating power available (tested using the 240Vac mains with both heaters in series). When it’s running from batteries, it’ll have the two heaters in parallel with 132V dc supply.

I discovered the built-in thermostats don’t seem to trigger until after the system boils (my system is vented, so will boil at 100 degrees, unlike a ICE cooling system which is pressurised)

80 to 90 degrees should provide plenty of heat, so I’ll mount a pair of thermostatic switches, one on each heater. These will control the contactors that switch the high voltage DC.

I ran a test with an adjustable capiliary-type thermostat last night - with it set to switch off when the water reached 85 degrees, it took just 5 minutes to warm up from ambient 15 degrees
(this is without the blower running, so no real load).
With the blower on low setting, it runs at around 20% duty.
With blower on max, it runs around 80% duty, so there’s still some heating capacity left for those really cold days

front battery frames

Sat, 31 Oct 2009 19:27:06 +0000

I started off thinking of a single “tray” above the motor, holding 12 batteries. This bolts onto the frame rails in the engine bay, and eventually there will be two “wings” that bolt onto the two damper mountings as well, to make it really strong.

After a lot of trying the fit of things, I’ve now decided to fit 9 batteries into this tray, with one “lane” left empty to house the Zilla’s power box and the cabling. I want to use the protection of the battery frame to safegaurd the Zilla - it’s the most expensive part of the car!

rear battery box, part 2

Sat, 31 Oct 2009 18:42:11 +0000

It looks a lot better with the liner in place!

A welded steel frame will surround the batteries, making sure they can’t move sideways. Long bolts will go down through the two holes in the tops of the batteries, to hold them firmly down onto the steel frame. These batteries won’t be going anywhere!

Eventually I’ll fit a nice lid and the boot carpet will go over the top

rear battery box

Sat, 31 Oct 2009 18:17:23 +0000

Holding the batteries into the rear box is a bit tricky...

...the frame rails aren’t parallel here, so a simple rectangular box would be pretty small and far away from the rails, making it weak.

So I’ve built this shape instead, it will fit up to 9 batteries, but I’ll probably use just 8 to keep the weight down.

This frame is welded into the structure of the car, all the way around. It took several days to do but needs to be really strong.

the beast’s brains

Sat, 24 Oct 2009 17:36:07 +0100

What’s the point in being a geek and building an electric car, if it’s as dumb as a rock?

This Beast isn’t gonna be as dumb as a dinosaur...

Above you can see the real brain, the Zilla Z2K controller from Cafe Electric Llc. This monster can dish out up to 2,000 Amps at over 300 Volts, that’s over 500 kW of power!!
The orange cables are the motor wires, they’re 1 inch in diameter
( 120 sq mm or 4/0 awg if you really want to know)

The Zilla is water-cooled and microprocessor controlled - the smaller green box is affectionately known as the “hairball”, this deals with the low-power circuits. The main Zilla power box and the hairball constantly cross-check each other, so it’s a well-proven, safe and reliable system

As well as this, I have other computer/geeky things lined up to go into this project, including;