Saturday, January 24, 2009

Over-Rev Protection, MTF and Labelling

Today involved a bunch of miscellaneous items.

Bryan at Belktronix sent me a little circuit that plugs into the back of the tachometer that triggers the LVP protection and shuts down the controller when the shift light goes on. I basically routed a two-conductor cable through the grommet next to the throttle cable (where the cruise control cable would go) and connected the system.

This picture is crummy because it's difficult to see active LEDs when the flash goes off. I had to wedge the camera between the headrest and the seat to hold it steady enough for a flash-free photo. In short, you can see the bright red LED on the tachometer on, which is also activating the LVP circuit and turning on the battery idiot light on the dashboard (just above the "H" on the steering wheel).

After driving around a bit, I realized that I never really got over 4000 RPM, so I set the shift point at 4000 RPM, put the car in neutral and slowly pressed the accelerator. Surprise, surprise, the shift indicator came on at 4000 RPM, the LVP circuit went active and the controller shut down, preventing an over-rev condition. I pushed the circuit a bit more by pressing down a bit harder on the accelerator from zero RPM and it jumped up to about 4800 RPM before shutting down.

If you choose to implement this circuit in your own vehicle, make sure you set the brightness on the tach for the LED for its brightest setting. You'll have to set this brightness with the headlights on AND off since the tachometer saves two different brightness settings. If you choose a lower brightness, the LEDs gets pulsed and the controller won't fully shut off.

Thanks to Bryan for providing this circuit. I guess I have to fork over some $$$ to him now :)

As part of tying up loose ends, I also drove about 15 1/2 miles round trip to the Honda dealer to pick up two quarts of special manual transmission fluid (MTF). Honda recommends 10W-30 motor oil (which is in there now) or this MTF, which is much thinner. Since I have an electric vehicle, I'd like to remove as much friction as possible in the transmission.

This is the first drive that I took with the Link-10 E-meter hooked up. I appreciated the amp readings and the percentage of battery left over. It took me down to 45% depth-of-discharge to go 15 1/2 miles, so I'm guessing the full range of the car is really 30 miles or so. This will be fine for my 17 mile commute to work, one-way.

Since I'll probaby be showing off this car at a few electric vehicle shows, I wanted to label all the major components to help people understand what the parts are. I still have to mount all the BatMon boards inside plastic boxes, but I have to figure out a heatsink strategy first.

I feel much better now that the tach, over-rev, and link-10 E-meter are installed. This will give me more confidence is knowing how far I can go and how hard I can push the motor before shifting.


1 comment:

Theo said...

Hello Tim,

I wouldn't worry too much about the 30 miles range since the outside temperature is around freezing. You can safely assume you will have enough to commute both ways once it gets warmer (up to 30% more range once it's back to the mid 20s°/70F).

Excellent work by the way !