Sunday, May 31, 2009

Synkromotive Potbox Issues and Temperature Faults

Over the past week, I've been able to give the Synkromotive controller some good real-world experience during my commute. The controller is very smooth and has several parameters to keep the battery pack healthy. I also like that the Synkro controller doesn't tap off the main pack for part of its power supply which has led to pack imbalances in the past. You can see several voltage-current graphs on the Synkromotive website here. Click on SynkView at the bottom. You'll have to install MS Silverlight to see the graphs. Click on Logfiles/Civic and then an .XML file on the right to see various drives.

One major issue I had was that the car tended to lurch when first starting up. This isn't too bad on the freeway, but can be a real pain when in stop-and-go traffic. Last Thursday I was driving home in hot weather in stop-and-go traffic on the freeway in the middle lane. The car seemed to get progressively worse during the drive home with its "lurch-starting."

About 2/3 of the way home, the controller faulted and just stopped the car dead in the middle of the freeway. I attempted to clear the fault and get the car started again by turning the ignition key off and on. I must have been impatient (sometimes it takes a full six seconds for the controller to precharge and be ready), but I wasn't able to clear the fault. Traffic was slow, and two kind men helped me push the car off the left side of the road. This was a somewhat unnerving experience, but I guess it's part of the game when trying out a Beta-test motor controller. After propping open the hood, removing the primary 12V power from the controller and hard-booting it, it seemed to start up again and I drove the rest of the way home.

The beta controller units have been having a few issues with noisy temperature sensors. During initial acceleration, the electrical noise tends to cause a spike in the temperature sensors, causing the controller to shut down. After I got home from this incident, I observed some of the potbox inputs (Ainput in the Smi window) and realized that I have a really crummy PB5 potbox. The resistance goes from zero ohms and jumps up erratically to 400 ohms or so and then goes smoothly up to 5K. With this new information, I was able to set the "zero throttle" point above the 400 ohm point which makes acceleration much smoother and bypasses the glitches in the potbox.

Yesterday, I was driving someone home in the Civic. Again, it was a hot day and we were in stop-and-go traffic. The controller faulted again and shut the car down. Fortunately my friend, who was in a hurry, could walk the remaining eight blocks home while I rebooted the system. Ives at Synkromotive gave me some updated firmware with some extra noise filtering on the temperature sensors. After running the car through the same route with the new firmware and doing some extra stop-and-go testing, I couldn't get the controller to fault again. We'll see what happens the rest of the week.

Despite the faulting condition, I've been extremely happy with the power, smoothness, logging and programmability of the Synkromotive controller. This is going to be a really good product when it hits the shelves in July.

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