electric supra project

MORE BATTERIES!

Sun, 25 Apr 2010 22:02:28 +0100

The other week I visited Paul Compton, who had some Hawker Genesis batteries he wanted to offload. They'd been intended for his hillclimb car, but events have overtaken that project and Paul's decided to part it out.

They're a mix of old and slightly used, but there's 26 of them!

POWER CABLES

Fri, 2 Apr 2010 18:56:41 +0100

Running high power cables under a car body is always fun - you really need to protect them from mechanical damage - things like kerbs, speed humps & dead cats (joke!) all do horrid things to the underneath of vehicles! Last thing you want is to get stuck because your main power cables have burnt out...

These cables are 70 sq mm welding cable, with double-wall rubber insulation. I've added mechanical protection using a combination of 25mm flexi-conduit and 3/4 inch electric utility conduit (another load of bits bought in Canada - I wish we had this stuff here in the UK!)

Alternative heater

Fri, 2 Apr 2010 18:24:34 +0100

Well after all the hassle of building the hot-water heating system, I'm still not happy with it. The decider was when I reinstalled the battery tray so I could move the car (we had some workmen who needed to get their wheelbarrows past the car). I forgot to install the heater assy, and just couldn't face having to lift the batteries out again, then the heavy tray....

So I decided to re-investigate the dashboard, to see if I could find a way to get at the heater core. In the end, I didn't find a way, but I found the next best thing - a way around the problem!

The evaporator core from the aircon system was redundant, so its chamber is just sitting there. All the incoming cabin air passes through it, and it feeds directly into the heater core area. Best of all, it's easy to get at - I just had to remove the glovebox and a few bits of trim.

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!