Sähköautot - Nyt!

There are a lot of pros and cons. One larger motor is usually much cheaper than four smaller ones. Only one controller is required and a simple control. A fancy control system providing the exact required balance of power to each wheel does have advantages in terms of handeling, and anti-skid. However the cost goes up and if one wheel drive should fail there must be a safety interlock to remove the matching one also to avoid torque steer. The main thrust of this project is to provide a low-cost conversion, not build the highest performance car, therefore a single motor is the best choice.

If you connect the left and right side motors in series, that will effectively work as a differential. It balances itself automatically, because when you drive into a corner, one motor is slowed down while the other speeds up. This effectively changes the voltage distribution between the motors and thus redistributes the power so that the car doesn't try to pull itself straight. Exactly what the mechanical differential is supposed to do.

And conversely, if you connect the motors in parallel, it works as if the differential was locked.

The only difficulty you have then is to provide front-back balancing of power. Or if you're content with two wheel drive, you can do with one controller only, perhaps with a throw-over switch to lock your "differential" in case you get caught up in snow or something.

Wiring two motors in series as described sounds ideal. However it pre-supposes that the motors are DC. Now the proposed motor is a DC Brushless design, which means that there is an internal AC controller so you are already paying for two controllers! If the motor was a brushed DC motor then you have lower efficiency, more maintenance and lower power.

As far as brushless designs are concerned, they function just the same as their mechanically commutated counterparts. Try taking two ordinary DC fans from a computer and connect them in series. See what happens when you stop one or the other.

From my experience, those little brushless DC motors do exactly what they're supposed to do. In series configuration, both turn at a low rate since their voltage is now halved, and when you stick your finger in one, the other one speeds up. The other one won't get up to full speed, though, since these kind of motors present a significant resistance to the current even when stopped. A high power high amperage motor would practically short circuit when you jam it.