I have told this story before but incase you haven’t heard it I had a Curtis controller blow full on about a year after the conversion. I didn’t have proper cooling and I was enamored with the low end tongue. Luckily I had an RPM limiter so the motor would rev to 5K then shut down right a way. I was heading out for another fun drive and was about a mile from home when I heard a noise like a marble being dropped into a tin box. I turned around and got it home. I didn’t have an auto opening garage door at the time so when I got back in the car to pull in the garage she blew. The car was in neutral when I turned it on and the controller was behind the seat at that time so when it went it was a large sounding explosion and lots of smoke in the cab. I hit the silk so to speak. I mean I never moved so fast before. As soon as I was out of the car I realized what had happened and the motor only cycled through a couple on and off rev’s before I managed to get back to shut it off. I have had other cooling issues Curtis controller for a while until I finally cut the ends out of the controller and put a blower on one end and blow air directly through the controller. The controller is high and dry in the trunk with a sock filter. I have had the controller apart a couple of time over the years and everything looked clean and in good shape. I monitor the temp in the summer and with this setup it has never gotten half as hot as it did with a finned heat sink.
Miswiring and crashing into the wall is a good reason to have the car on stands with the drive wheels off the ground when working. I have never had that mishap with my EV during all the years of tinkering but I did just about run over my self when working on my 4X4. I had been working on it most of the day and had it all tuned it up and just before I closed up my work shop for the night decided to reach in and fire it up one more time. It did fire right up but the dam thing was in reverse. Luckily if you if you can call it that the shop doors were closed and stopped my cruiser enough to kill the engine. Otherwise it probably would have gone out and down the hill into the creek. Next day I put a switch on the clutch so the peddle has to be pressed down to start the vehicle. As for the controller blowing I am sure the fact that I did not have adequate cooling and I had my foot all the way down every time I drove the car. One of my reasons for opening up the ends on the Curtis besides cooling was I figured the explosion was so loud and did so much damage was because the blow out happened in a sealed container. Did you ever put a firecracker in a tin can? Any kid will tell you that you get more bang for the buck in tin can. When the cap blew the explosion was amplified by the extra pressure. It shredded the control board which I am sure is what caused the full on mode. Only one cap was blown and the end plug on the housing came out like a small missile. That blow out happened in 2000 and ever since I say to my self when I start up is this the day this POS is going to blow up again? That is why I put it in neutral before I push the start button. I am pretty sure if it ever blows the energy will pass through the open ends and do less damage. Something I hope I will never find out.
Oh yeah! It was a lowly 400 amp Curtis 1221B controller but when that failure happens it isn't just full on -- it is all your batteries can dish out until you shut if off or something else yields. I dropped 120 volts worth of Optima into a Prestolite MTC motor and the torque was so huge that the brakes couldn't stop the tires from spinning. I had the front locked and the backs burning rubber while I was accelerating away (without steering as I had the front tires locked.) The ride stopped when I turned the ignition switch off. That took several seconds as I was hurling backwards when it happened and it is very hard to take your eyes off the direction you heading into without control!
I remember you telling about that. Backwards at full on! You could probably sell tickets for a ride that exciting.
