Weekend test driving

Some more test driving was done on a beautiful winter saturday. A couple of visitors also made a short test drive with the Corolla eFX and we learned together that it is extremely silent. It was  sometimes hard to notice its movement because the wheels are the only thing making noticeable noise. On the video most of the noise is made by the train that goes by far away.

Some simple performance tests were also made. We learned that the corolla could climb the slope on our yard on its first and second gear, but on third gear it did not accelerate anymore uphill. On even road it started rather easily with third gear. We still had no voltage or current meters installed on the car so we did not learn about the used motor current or battery power.

I just received a pair of 400A shunt resistors bought through ebay that will soon be installed to measure battery and motor currents. With the shunt resistors and a battery voltage meter installed it will be much easier to evaluate the performance of the car.

The second test drive

A temporary ~72V battery pack was created using four 12V 12Ah lead acid motorcycle starter batteries and two 13,2V 6,9Ah LiFePo4 battery packs in series. The two LiFePo4 packs are the same ones used in my electric lawn mover introduced in my other blog.

The power on/off switch was also a temporary solution. A switch was brought into the cabinet through the driver side window.

After charging the batteries the controller was tested and the motor rotating direction was verified. The last job before driving out from the garage was to change winter tires to the front as our yard has a steep and icy slope that could not be climbed with summer tires.

It was about -10 degrees celcius when the Corolla eFX was reversed out of the garage for the first time. I had never driven an electric car before and it felt great to accelerate from 0 rpm just using the throttle pedal. I took the risk to reverse all the way down of the icy slope in our yard unsure if the corolla would make it back to the garage on its own. On the bottom of the slope I changed to the 1st gear and gave some throttle. The Corolla moved up the slope easily and silently! It was so fun that I drove back to the bottom once more before driving back to the garage.

On this second test drive I did not have any voltage or current meters installed so I do not know what kind of motor and battery currents were used. Once I have installed some meters I'll drive up and down the same slope many times to learn about the current levels used and if the regenerative braking works correctly or not.

Motor controller power connections

I had some 50mm^2 welding cable available and it was used for the motor power connections and for the shorter wirings inside the controller's enclosure. While connecting the power cables on the controller I noticed that the motor output connectors are very close to the round control signal connectors. I had to lower the head of one of the M8 bolts to prevent it from making a short with the signal connector body. The clearance between the connectors are now just 2mm. I will use some additional insulation between them for peace of mind.

Fitting the motor controller

A L-shaped steel rod was bolted between the original engine mounting and the gearbox. The motor controller enclosure was placed on top of the steel rod. In this position the enclosure can be accessed easily and the throttle cable reaches the modified hall throttle pedal.

Motor controller programming

The motor controller was carefully powered up for the first time using a laboratory power supply. Only the power cables and the serial cable was attached to the controller to program it. About 20Vdc was given to the controller and it drew less than 100mA current when turned on.

A RS-232 cable was provided with the controller. Luckily my laptop has a serial port which is getting rare on newer laptops. The laptop used for the programming runs Windows XP so there should be no problems.

I installed the programming software that is available from Kelly Controls web page. Then after powering up the controller and having the serial cable connected between the PC and controller the Kelly Controls software found the motor controller by itself!

The programming software was easy to use and the available options were quite well explained. Most of the default setting were accepted at this time but some were altered. I am preparing for the second test drive where I would use 6 small lead acid batteries is series. For these weak batteries I wanted to set the battery current limit to as low as possible (80A). I also adjusted the throttle voltage range to be 1.2V to 3.8V after testing the throttle pedal output with a multimeter. With 5V power supply the hall throttle signal range was measured very closely from 1V to 4V so I will start with about 0,2V margin on both ends.

Finally I altered the regenerative braking settings a little. I would like to have the "release throttle regenerative braking" feature enabled, but this braking mode was not as well explained as the other two available braking modes. The second test drive will show if I had understood the braking parameters correctly or not.