Towing the Electro Metro and Neon EV bench testing

by admin on November 16, 2008

My car moved farther today than it has the entire time I have owned it. How?

By towing it to South Milwaukee and back for for the EV Build Day.

Yesterday, I finished off the towing setup. I cut (mangled) the guppy mouth to fit the tow bar through. Then I did a test-tow around the neighborhood.

I made sure the parking brake on the car was off and the key was at the first click, which unlocks the steering, without turning the car on. The Metro towed well. Of course, I had terrible acceleration with the 4 cylinder, 2.2l Chevy S10, but I love the good fuel economy the rest of the time!

The idea of the tow bar is two-fold. In the short-term, I need to be able to take the car to the emissions test station. In the long-term, I plan to be able to take the car to the MREA energy fair’s alternative car show, and other EVents. I have also hear from other EVers that there will be some point when you screw up and discharge the batteries, mess up the controller, or for some other reason, disable the vehicle.

May as well have a tow bar on there right away. I wasn’t able to get over to the emissions test station (they close at 1 pm on Saturdays.) I will have to take it in this next weekend.

The other reason to have the tow bar was to drag the car an hours’ drive away to the EV build day. I much prefer to be able to work indoors, with good tools, surrounded by people who know much more about cars than me.

I wanted to be able to add brake and turn signals to the car in a “tow mode”. When I tow it, the brake and turn signals from the truck will make the car do the same thing.

We pulled the tail assemblies off. Inside the taillight are several bulbs; turn, tail, brake, backup, and marker lights.

We drilled a hole and added another bulb holder. The one I bought has a dedicated connection for ground, needed because we are mounting the lamp socket in plastic.

We ran trailer wire harness with a standard 4-pin connection from the front of the car, through the firewall, inside the body panels, to the back of the car. Rich was able to pop off body panels and stuff wire in there in about five minutes. By myself, it would have taken all afternoon, and I would have broken something.

Once the wiring was all the way to the back, we wired the harness to the lights, and then jumpered the connection in front to the battery to test the lights.

Photos of the build are here:

After we were done with that, we took a look at the rear battery mount.

Originally, I ran two pieces of bedframe left to right, across the top of the spare tire well. the one closer the the rear was drilled through, and attached into the frame with bolts on either end. The front bracket was left loose, because there wasn’t any great place to weld to, and I added some angle metal over the front-top edge of the batteries, back to the back bottom bracket, with threaded rod.

Unfortunately, the metal was thin and bent funny when it was tightened down. That let the batteries slip, and one of them half-fell into the well.

We took the batteries out and discussed different ways of mounting the batteries, including adding more batteries, cutting the bottom out of the car, and all sorts of wild ideas.

For now, I just need the batteries to not slide around back there!

We tried using some large, self-tapping screws through the front angle, into the frame, to pin that down. I snapped both, and we had to pull them back out with vice grips and try again. It went better the second time.

After that, I ran a section of threaded rod vertically right through the center of the spare tire well – directly into the threaded center where the bolt went in to hold the spare tire in place. The rod goes straight up, between the two center batteries.

I drilled a hold in the center of another piece of angle iron (more scrap bed frame) and laid that over the top of the batteries. The rod goes through the hole and is pinned down by a washer and nut.

Now the batteries can’t go anywhere! By holding the batteries down from the top, and in from the front and back, it leaves room around the sides of the batteries for me to add a battery warmer and rigid foam insulation.

I also got an enclosure box from Tom. It’s roughly one foot square plastic with three holes in the bottom designed for conduit to connect directly to.

The next thing to do on the car is clean up under the hood: install the project box and put fuses, relays and things in there, bolt down the controller and 12v vacuum pump, and install a new throttle.

On Tom’s car, he bench tested the drive train. After bringing a pallet of batteries over on a forklift, he connected the motor to the batteries and the AC drive (controller). Since I saw Tom last, he bolted the motor down to the adapter plate, and the transmission to the face of it. He also cross-braced the right angle with a support on either side, bolted in place for now, to be welded later.
I didn’t have a good camera with, but I got a little video with my point ‘n’ shoot. Sorry for the quality of it. I didn’t have a tripod, and the lighting was by tripod only.
In the first video, the transmission is neutral, and it’s in 3rd or 4th in the second video.

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