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Discussion Starter #1
do most ev designs use a differential of some kind?? How about axles?? or not..
 

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Yes, every street-driven vehicle which drives two wheels needs some way to allow the wheels to turn as different speeds, so the vehicle can turn corners. That's normally accomplished by having a differential between them, although in an EV it is possible to use a separate motor for each wheel.

What do you mean by "how about axles"?
 

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In front wheel drive vehicles, the transmission and differential gearing are combined in what people call a "trans-axle". In rear wheel drive vehicles, the transmission and differential are separate with a drive shaft between them.

EV conversions either bolt a motor to a transmission or transaxle or they drive a differential directly via a modified driveshaft. But unless your motor is capable of very high speeds or very high torques, you'll likely benefit from having more than one fixed gear ratio available in an EV conversion. Large DC motors can go direct drive provided they have enough voltage to permit them to deliver decent power at high motor RPMs.
 

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Discussion Starter #4
i meant if you have a motor or stator/ring on each front wheel you dont need an axle
just a wire to power them. I like the idea of a motor that doesnt need a redrive/transmission.
What do people use for an electronic differential???I mean a control that slows one motor down and speeds the other one up for cornering etc.?
 

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i meant if you have a motor or stator/ring on each front wheel you dont need an axle
just a wire to power them. I like the idea of a motor that doesnt need a redrive/transmission.
What do people use for an electronic differential???I mean a control that slows one motor down and speeds the other one up for cornering etc.?
You are talking about hub motors
Nobody uses them

The reason is that Torque is (very roughly) proportional to motor mass
Something like a Tesla uses a 30 kg motor and a 10:1 gearbox

To get the same torque without the gearbox you would need a 300 kg motor
 

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Discussion Starter #6
understood
got any pics/link to nice homebuilt arrangements with engine assist and electronic differentials
not mechanical ones..
 

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What do people use for an electronic differential???I mean a control that slows one motor down and speeds the other one up for cornering etc.?
got any pics/link to nice homebuilt arrangements with engine assist and electronic differentials
not mechanical ones..
Very few EVs - production or DIY - use separate motors per wheel, although there will be more of them. A separate controller is needed per motor. There are some controllers which are designed to work as a pair, with logic to coordinate with each other (Curtis has a feature for this). The other approach is to just provide the same accelerator pedal input to each controller, so both wheels get the same torque... as long as there is a speed limiter so if one wheel spins (due to lack of traction) it doesn't turn too fast.

Few if any homebuilt EVs have anything like the traction control, stability control, and other features of a normal modern production car.
 
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