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Hi guys, so I really want to build my own EV, but I can't justify the cost of the batteries for a fun side project, the wife would kill me, but, I've had this idea for a while now, using a 240v ac motor or maybe even 2 connected to the gearbox powered by a decent petrol generator. The amount of fuel the generator would use would be minimal and there would be no need for any batteries of any kind... In theory. I'm just spit balling at the minute but has this ever been done? Thanks
 

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I doubt anyone ever has. It wouldn’t be very practical, you would only have a brake and a clutch, no throttle and the AC motor would always be trying to spin at synchronous speed. You could have a clutch like a normal car and change gears to change the vehicle speed but any incline or decline would just cause more problems. Also sizing of components would make this idea pretty useless.
 

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This is a series hybrid, without the battery. It is the same idea as used in a diesel-electric rail locomotive. Since the generator and the motor would each be less efficient than a mechanical transmission, the whole system would be less efficient than just using a transmission.

The amount of fuel the generator would use would be minimal and there would be no need for any batteries of any kind... In theory.
Why would use expect fuel use to be minimal? What theory are you basing this on? All of the energy to drive the vehicle comes from the engine which drives the generator, and more energy will be needed than with a mechanical transmission (due to the inefficiency of the electric generator and motor), so the engine will burn more fuel than it would with a mechanical transmission.
 

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I doubt anyone ever has. It wouldn’t be very practical, you would only have a brake and a clutch, no throttle and the AC motor would always be trying to spin at synchronous speed. You could have a clutch like a normal car and change gears to change the vehicle speed but any incline or decline would just cause more problems.
There would be no reason to have a clutch, and a multi-speed transmission would be unnecessary. The motor would need an inverter (not just an AC synchronous motor connected directly to an AC generator output), so it would have the same control as any EV. If the generator output is AC, then the inverter would be an AC-input unit, commonly called a variable frequency drive (VFD).

It is essentially an EV with the battery replaced by a generator set.
 
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