172: Monday 30th November 2010

It's been nearly a month since my last blog. I have been researching a makeover for the Probatron. I am going for a bright metallic red with gold flip accent effect and a nice set of Ace C036 turbofan wheels (with 215-35-18 tyres) as painted alloys. I wanted the chrome ones, but I have been put off because chrome alloys have a tendency to peel and then pit if the car is not kept in a garage and only brought out in nice weather, but painted alloys are much more resilient to the weather. I am not sure what is going to happen about the trims for the front, rear and side quarter windows as I am being told that new ones only come with the glass. It needs new trims, but may also need new glass throughout and this would add considerable cost to the makeover. If this is what is needed then it shall be done. I don't want to have new paint with scruffy window trims as this will spoil the overall effect.

I have clocked over 4000 electric miles now. Since I last fixed the throttle, I have had no further issues apart from reduced range affecting the batteries in this the cold weather.

It was heavy snow last night and I went to work in it today. I had to be really careful, because unlike a petrol car, I have uncontrolled torque and lots of it at low revs and that means wheel spin and lots of it. I kept having to back off the throttle to stop the wheel spin, but I was not developing much forward speed to get me on my way. Using great skill I made it to work and then the journey home was even worse as the ice had been polished by a whole days traffic. My journey to work is normally exactly 7 miles, but today it was 7.4 that means I had wheel spun for 0.4 miles in that short journey. Fortunately I can work from home and I shall if it is the same tomorrow. One good point though, there were no issues with the car itself.

171: Friday 5th November 2010

I had ordered a conductive plastic precision potentiometer and it came yesterday. I got a 5k pot this time as I could not find a 10k precision conductive plastic one. The Manual for my controller states that the pot needs to be between 500R and 10k, so this one is fine. I changed it over on the pot box even though the cheap carbon track pot with the thin plastic shaft was still working o.k. The difference is that there is almost no friction on the conductive plastic track, the linearity of the track is much better than a carbon track, the metal shaft supports the spring and throttle arm with no issues. Another thing I noticed was how easily the shaft of the pot turned. The wire wound types that I had were very stiff. This new pot was extremely smooth and easy, but feels really solid. It cost me £17 by the time it was posted to me and taxed etc. This is double what I paid for the last wire wound pots that I bought. These are now consigned to the reserves bench even though they have never been used. Hopefully my throttle problem is permanently solved, or at least for a very long time (years???).

170: Tuesday 3rd November 2010

Nightmare, it happened again! Another potentiometer bites the dust again. It is a good job I have a bag full of cheap pots in my garage, so I transplanted another of these small 10k pots onto the control box with my special brass shaft adapter. I have a feeling that the spring is causing these pots to break down as it is bending the shaft a bit when the throttle is planted. Also the microswitch for the throttle decide to come apart and the bits fell on the floor. I managed to find them all and re-assemble it. When I broke down I put into effect my contingency plan to insert a resistor into the connector for the pot, but in the process I accidentally pulled out some control wires. It took me a little while to notice this and in the process of doubting the correctness of my resistor connection, I pulled one of the pot wires out of the connector. I only had about 1 mile to go, so I fixed the wires in place as best as I could, then got the motor running after a fashion. Unfortunately I could not get enough power to get moving, so I set the creep speed up to maximum and used a back route down a side street that was very quiet and crept along the road. I went over a bump and suddenly I had some on/off acceleration just as I was about to rejoin the main road, cool. I jerked it home (it wasn't too bad in 3rd gear) and parked up. After fitting the cheap pot all is back to normal and the throttle response is smooth again. I know I have 2 heavy duty wire wound pots waiting to be picked up from the post office tomorrow, and I have now ordered a conductive plastic 1w pot as one of my colleagues suggested this might be a better choice. Wire wound pots seem to be useless. I am still looking out for a hall effect sensor that is suitable as well. Hopefully the conductive plastic pot will work out. If it starts getting rough then I will go for a hall effect rotary sensor.