Tuesday, January 15, 2008

Well, it's been a little while since I last updated. And yes, I have cut my hair since the pic was taken! I've gotten quite a bit of work done. I now have the motor installed in my Tercel, and I'm working on battery racks and component layout. So far it's looking like I'll have 3 or 4 batteries up front (plus one for the 12v system) and then 9 or 10 more in the back. Although this is far from optimal as far as weight distribution goes, it'll get me on the road. I'll always be able to modify it later on.

In the spirit of doing things on the cheap, I'm working on a component shelf that will allow me to transfer all of the major components and wiring from my truck to my Tercel by simply unplugging a couple connectors and loosening a few wing nuts. This way, I won't have to buy new contactors and stuff while the Tercel is still in the test stages. It will contain the controller, both contactors, fuse, circuit breaker (maybe), current shunt, and a few other minor items. It will have one connector for 12v power and signal wires (power on, amp meter, volt meter, controller status lights, and a few other things), another connector (one of the big Anderson ones) for the motor, and another Anderson for main battery power.

It will also have a plug for the charger, which is only going to be used on my truck. I've purchased 14 6A 12v smart chargers to use in my Tercel. By using individual chargers, I'll get an automatic equalize charge, not to mention saving a bundle of dough. They will be mounted on-board (they're very small, maybe 8" long), and they will all be tied to one main charge plug. Since they're smart chargers, they'll automatically switch to a trickle charge when the batteries are topped off, taking better care of the batteries than any group charger ever could.

I've been working on my own homemade controller design, but I don't think it will be done in time (hence the reason why I'm working on the removable component board). My controller will be an IGBT controller, driven by a flash-programmed PIC, which will allow me to edit the firmware at any time just by plugging it into a computer serial port. I have a Powerex 600A 1200V IGBT that I purchased surplus off of ebay. This should provide more than enough current-handling capability. If I size the filter caps right, it should be able to handle at least 200V or more. I'm also working on an LCD interface using a 16x2 44780-controlled blue LCD, which is easily interfaced with the PIC.

Initially, it will probably be a pretty bare-bones setup, but later on I hope to add features like built in cruise control, current limiting, RPM limiting, throttle endpoint adjustment, and more. That's the great thing about building these things yourself- once you have the basic power stages and driver complete, you can add all kinds of crazy features for very little cost, often by just adding a few lines of code.

Anyway, I've got some more to report, but I think this post is long enough... I'll try to add some more updates ASAP.