16 June 2008

Fabricate - mounting brackets

I finally decided how to arrange the parts to put back in. I had to bend a 1"x3/16" steel bar into what I call the bridge. It goes from one frame rail to the other across the motor bay. It is bolted only to the two frame rails. On the bridge I'll mount one end of the controller, relay box, and contactor box (below the controller). It's finally starting to look almost done! Just one more bracket to hold the controller, one to hold the contactor box, and figure out where to put the DC-DC. Then the high voltage wiring and I'm ready for batteries :).

The relay box is a little circuit I designed to control the contactor mostly. I was never very happy with the contactor clunking on and off every time I touched the go pedal. This design incorporates the charge interlock switch, key switch, brakes, and go-pedal. When the charge door is closed and the key is pushed to start, a relay latches on, enabling the contactor system and the pre-charger (it is deactivated by moving the key away from run). When the go pedal is pressed, the contactor and controller are activated. It stays active until the brake pedal is pressed, then it deactivates. Basically I built a relay flip-flop! With the design I have, it also detects when you press the go pedal and the brake at the same time. I don't do anything with this signal, but it could shut down the main enable latch or something.
Another feature (yet to be added) is when the car is put in reverse, it will limit the maximum speed of the controller (the Curtis manual shows how to do this trick).
It would be possible to use this trick to automatically reduce speed if an over-rev, over-temp, or over-current condition arises, without complicating (making less reliable) the current simple pot-box. I may add this "feature" later.

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