Saturday, July 4, 2009

The plans have evolved a bit more now. The automatic transmission is now on it's way to Sydney so that Geoff from GT Tooling can make the adaptor plate and coupler. The plan is to remove the torque converter cut it open and use the internal splines to create a coupler. The secret is to recreate the normal transmission fluid path from the centre of the pump shaft back to the outer shaft where it returns to the transmission. He is also going to make a plate for the rear of the motor to mount the air conditioning compressor and power steering pump

The other problem to overcome is that the transmission clutch for 1st gear will not engage if the transmission pump is not operating ie when the car is stopped at lights etc. I am going to do some tests when I get the transmission back to see how long the pressure remains in the box after the motor stops turning. This should be proportional to how good the seals are. Geoff has suggested that an accumulator connected by a solenoid valve could be used to apply pressure instantaneously to the box when the accelarator is pressed. The logic behind this may be a bit hard to apply and it may be restricted by how fast the clutch can operate compared to the motor.

The other option is to use an electric pump operated from a pressure sensor to keep the pressure up to the clutches. The pump would only operate when the pressure drops below the point at which the clutch would disengage. To make this more efficient, the pump could also be turned off if the brakes are applied, so that when you lift your foot off the brake the pump starts and by the time you apply the throttle the clutch has engaged (if it engages fast enough). Either way there is a bit of testing to do before I proceed any further.

I have settled on a controller for the project. I will be building the controller myself from an open source design see link http://www.paulandsabrinasevstuff.com/evmotorcontrollers.html
It is a 144volt 500Amp controller and it meets my requirements for power. Parts have been ordered andshould be delivered within 8 weeks. Construction should take a few more weeks after that.

For batteries I will be using Lithium Iron Phosphate batteries from Thundersky. I am still tossing up between the 90 Ah and the 160 Ah batteries. I was going to try to fit all of the batteries under the rear seat where the fuel tank was but the available space is just too tight to fit all of the 90's in the one spot. Depending on which battery I can afford at the time I will mount some under the rear seat and some in the engine compartment. I calculate that I can probably get about 90 Km range from the 90 Ah batteries and about 160 Km from the bigger batteries.

I am looking at 2 different battery management systems. The 1st is an open source processor controlled shunt device which has over & under voltage protection. The 2nd option is an active powered system where a small power transformer feeds each cell independently and the amount of current to each cell is controlled by the state of charge of the cell. This gives the best balancing but is limited by the size of 45 transformers and the addition wiring to each cell. The main advantage with this system is the simplicity. I will have to get a few batteries and do some testing to see which way works best and is safest.

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