Step Thirteen - The Control Box

Now that the racks are installed, it's time to create and install a box that will house the main bits for the EV.

There aren't many "main bits" in an EV compared to a gas car. The main components in my control box are:

- Main Contactor

- Circuit Breaker

- KSI Relay

- Heater Relay

- Main Fuse

- Shunt

From what I've learnt, in a basic DC conversion these are the essentials for any control box or nerve centre. I found an old box which will house all these gadgets nicely with plenty of room for clearances and vital airflow.

I picked up a sheet of Formica board and some metal supports from the local hardware store, and set about creating my control shelf. After rearranging the main bits inside the box like a giant game of Tetris I managed to make everything fit in with room to move.

As you can see with the picture on the left I have the box sitting on the Formica board ready to have the wires connected.

My fuses arrived today from another converter in Auckland (Thanks Nick!) and they're compact enough to fit in the box along with all the other stuff. I'm going to have one fuse for all the front batteries and one installed for the rear batteries.

As you saw in the Heater Install video, I have the Voltmeter and Ammeter installed into a display panel in front of the gear lever. The other ends of the meters come up to the control box where they'll be connected.

Now that my fuses are here and my chunky 70mm² main power cable has arrived, there's no other components to buy (except the batteries) and the rest is comparatively straightforward. It's basically connecting stuff and installing cabling - all things I can do myself.

Once everything was the way I wanted it I drilled holes to allow the cables to feed up from underneath. To make the whole thing look good, I wanted as little cable visible as possible. By having everything enclosed in a box and all the cables running underneath it should look quite tidy.

Some more good news arrived soon after I picked up my welding cable. Rob popped over with my Curtis 1231C Controller. He was up in Auckland over the weekend and collected my controller from my parents house. I was worried it would overhang the control shelf but it fits in perfectly.

Once I had everything the way I wanted it, I bolted in my final motor mount. You can see a close up in photo 4 at the bottom of the page. It's simply a 10mm (0.4 inches) thick slab of steel with holes drilled on each end, and bolted straight to the front chassis. It seems to do the trick nicely.

After a few hours of connecting wires and securing the control board strongly, I'm essentially finished pre-wiring the control box. It's 95% complete but I'm going to be held up while I wait for a replacement solid state relay for the 144V Kill Switch (built into the controller) and a couple of components. It seems one of the brand new relays from Allied Electronics is a paperweight. It's a real bugger because it cost $50 in freight getting it here. Poo. So now I'm sitting about waiting to hear back from Allied Electronics about a replacement relay.

I need to track down a coil suppression diode which will connect to the contactor. Luckily the instructions for the install of the diode are in the construction manual supplied from EV America.

After cleaning up and repainting (rather badly) the lower front grille and front bumper and installed them both, then tracked down a 300mm x 220mm x 20mm thick aluminium plate to act as the heat-sink base for the controller to sit on. I'll try to elevate this plate off the control board so that air can flow underneath it and remove the heat from the controller.

I've been told that aluminium is a good metal to remove and dissipate heat. I've also ordered a choke cable from an old Mini to act as my emergency disconnect cable which will be connected to the circuit breaker.

My next time-killing project while I wait for parts to arrive was to set up the tachometer (rev counter) to display, well, anything when the motor's moving. I figured out a really simple way to do it too! As you can see in photo 8 (bottom of the page) I bypassed the fancy pulse circuit on the tachometer and connected a cable straight to the little needle's "motor".

I found out that by putting 1.5 volts into the needle it registers just over 4000 RPM. And by attaching a little 3 volt motor to the tail shaft of the big motor, and spinning it with a 12 volt battery, the little 3V motor turns into a generator and I get the needle reading about 1500 RPM. I also bought a little adjustable potentiometer which will allow me to adjust the accuracy of the RPM gauge later.

Now obviously this doesn't give me very accurate RPM readings - I'm very well aware of that! What I'd like it to do however, it at least get slightly accurate near the motor's redline of 5600 RPM by turning the potentiometer knob. It will be interesting to see how it works out!

Despite it's inaccuracy, it still looks good to see the RPM needle moving in time with the main motor, and all for $5 in components!

After a successful test spin, I'm now waiting to get the car driving on the actual road so I can fine-tune the potentiometer behind the dashboard to get the gauge more accurate.

During all of the above I got a phone call from the bank to tell me that yes, they've approved the $2500 loan for the batteries! Excellent news! First thing the following morning I jumped on the phone to my battery supplier in Auckland and ordered 12 MDC24/85 batteries at a great price of $215 each ($167 USD). Now, while this might seem a bit of a rip-off for anyone in the USA, as far as NZ prices go, this is the bargain of the century. The local auto store sells the same spec battery for $279 each ($217 USD) believe it or not!

While waiting for the batteries to arrive I got busy and finished a whole raft of tasks. I finally screwed everything down and pre-wired control panel at long last, installing the controller at the same time onto a thick plate of aluminium to keep it cool.

I also installed a "Kill Switch" by using a shiny new choke cable from a Mini attached to the circuit breaker. It looks nice and tidy in the dash and the switch flicks effortlessly! Nicely done if I do say so myself! :)

It turned out to be a very busy Saturday but an incredibly productive one! Now I have a couple of days to relax before my batteries arrive!