SUMMARY OF THE THREAD:
A hybrid/EV car DIY system using high power, low weight model airplane electric motors (about 2kg or 5 lbs each), one for each rear wheel. Cost analysis and possible reductions.
Motors driving wheels by using a synchro belt or chain drive for each rear wheel, 8 to 1 approx transmission ratio. Integrated freewheel to avoid excessive rpm to the motors. Motor support attached to suspension arm (motors therefore unsuspended weight) or back side of brake discs-drums. A big pinion on the inside of the tim, mounted on a metal saucer with holes for the wheel bolts. Saucer to be installed between the rim and the hub, displacing the wheel only 2-3mm outwards.
15kw motor......899 EUR.....or about $1,170US times 2......$2,340
controller.........599 EUR.....or about $780 times 2.......$1,560
Let's see....add that up, carry the one........$3,900
A small lithium battery pack of 8kW (good for about 30 miles at about 250 Wh per mile) is about $2,500, weighing about 60kg or about 133lbs.
BMS can be about $500.
You could be using two 7kW motors, for instance. A Peugeot 106 electrique weighs in about 1,100 kg or 2400lbs. It is 21kW peak, BUT
there are 30% losses from motor to wheel (single big engine coupled to a complicated transmission). It means the Peugeot could be using a 14.7kW peak motor if only there weren't such big loses. That is, two 7kW direct to the wheels.
The total cost of the hybrid system we are proposing here can be brought down by $3,400 when using the two 7kW motors (good for a 2,400lbs car). These motors are $99 each, their controllers are $129 each
So $99 + $129 = $228, times 2, total cost is $456
that is, the 14kW system (good for a 2,400lbs car) is 3,444 cheaper than the 30kW system
This brings the cost for the 14kW system somewhere around
In order to get further price reductions, batteries are the next target.
A 14kW system is about $6,500 with lithium batteries for $2,500 and a $500 BMS.
If four 12v lead deep cycle batteries are used, the price for the batteries would be about $600, and no need for BMS. So again the price for the 14kW system can drop by $2,400. That is, the new price would be:
These batteries can be recycled from telecom companies, getting them very cheap. Say $100. That would leave the price for the 14kW system at
Surely range would be affected, down to about 12 miles, and battery weight would double. But still a working system.
Of course, if someone is willing to design and machine the pinions and motor supports by himself, the cost can be further reduced to a few hundred dollars.
Also to the calculations:
Peugeot is moving a 307 cabrio EV with a 17kW fuel cell and a small battery for 300 miles. After the battery is over, it is clear that the only propulsion can come from the 17kW. And it seems it works:
Further on that, a Peugeot 106 electrique is 2,310 lbs and 56mph top speed:
And it is 11kW continuous, 20kW peak:
11 kw Motorleistung Nennleistung (11kW nominal power)
Maximalleistung 20 kW von 1.600 bis 5.500 U/min (maximum power 20kW from 1,600 to 5,500 rpm)
If you are looking for a cheap commuter solution, I suggest the following:
Buy a compact light car for $1,000 with no power steering and possibly no vacuum pump. Rear wheels should have good clearance for the system. Cars without vacuum pump are not easy to find, I think the old Fiat Panda is like that. In the worst case, a small car with no power steering, there are many of those.
Install the cheap 14kW system with 4 telecom batteries. The weight the system with batteries will add is about 150 kg or 330lbs, very acceptable even for a small car. Your costs will be
$1,000 for the car, $3,600 for the system. You get a road capable hybrid for
Total: $4,600 (road capable hybrid with a pure electric range of 12 miles). Say goodbye to 80% of your gas bills while keeping long range. (Sell your present car and you get a negative cost for the change).
If you are still not satisfied with electric performance and range, then you can take all the old irons out of the car: engine, gearbox, differential, transmission, exhaust, gas tank, etc. Then you can install the system for $3,600. If you'd like to get more range, then you can install 8 telecom batteries instead of just 4, remember the engine and gearbox are out now. Then an electric vacuum pump for the brakes for about $200. So the only added costs would be the vacuum pump ($200) and the 4 added used telecom batteries for $100.
That is: $1,000 (car) + $3,600 (14kW system with 4 recycled telecom batteries) + $200 (vacuum pump) + $100 (other 4 recycled telecom batteries).
Total: $4,900 for a road capable pure electric with about 24 miles range (12 miles for each 4 telecom battery pack). Say goodbye to 80% of your gas bills. Keep your present car to recreate the long luxury journeys of car pioneers and as a vintage legacy for future generations...Sentimentalism is not for free and this change will have a positive yet moderate cost You can still sell the old engine and gearbox for some hundred dollars.
Note that two 15kW motors with their controllers are $3,900. And that two 7kW motors with their controllers are $456.
Instead of two 15kW motors (30kW), it makes much more sense mounting FOUR 7kW motors and controllers (28kW) for a total of $912, instead of $3,900.
Four motors will be required in a medium car, so there should be space for them in the rear wheels. In case of a compact small car, it could still be possible mounting one motor for each wheel. The front wheels will be more difficult because of the steering, but possible if the motor supports are attached to the back part of the front discs.
Frankly, I don't think anyone can find a more competitive alternative.
LINKS FOR THE MOTORS
6000W - 1350g
7kW - $150 - 1570g
7.000W - $99.99
6.500W - $102.70
9000W (15 sec) - 799 € - 2100g
15000W (15 sec) - 899 € - 2590g