Reading about the new supercar from VW, I distinctly noticed when the author specifically mentioned shifting to "drive". I know the car in article is an automatic, but it got me thinking. Is it possible to have a manual car with an electric motor?
Sure the flexible torque characteristics of the electric motors used for EVs mean that you do not need a gearbox .But the weight and cost of electric motors is a strong function of Torque .Street cars have wide ratio gears so the difference between top and low could be say 3:1 .If you are doing a conversion and you remove the gearbox then you will want the electric motor to make at least 3 times the peak torque of the ICE that is going to be pulled out .This is a minimum for plausible performance .The total weight of your car will increase if you want a reasonable range because lithium batteries still weigh much more than petrol.This is why people often keep the manual transmission when they are doing a home conversion .Series wound DC Brush motors make good torque and are happy at 5000rpm or less which means that the standard diff ratio can stay .If you are a commercial manufacturer and doing things from ground up you can do an AC motor which makes less torque and revs a lot higher and makes more horsepower. It is normal for this type of EV to have a drive ratio of more than 10:1 .The power losses in a typical manual gearbox are less than 5% so it is a trade off .
Yes, a simple method to convert a car from petroleum to electric involves removal of the engine and mounting of the motor to the transmission with an adaptor plate. Manual transmissions are preferred because with automatic transmissions the shift points would be all wrong.
2nd and 3rd gears seem to be the most popular. 1st would make the wheels spin too much, and 4th or 5th hurts acceleration. Reverse gear is optional if the electronics can reverse the voltage.
Strictly speaking, a clutch is not necessary, because a motor with no voltage applied will spin according to the synchronizer. However, the clutch can manually disconnect the motor in case the switches fail closed.
It is possible but given that electric motor achieves maximum torque at zero RPM, it is usually not required. The maximum power is usually obtained at 50% of maximum RPM (max RPM is the RPM at which no torque is anymore produced). An intelligent controller (for AC motors, variable frequency drive and for DC motors, variable voltage drive) may change this characteristic that 50% of maximum RPM is the maximum power point, and the limitation of power can actually be in the battery and not in the motor if the battery is small.
So, manual transmission could perhaps in some cases result in slightly faster 0-100 km/h acceleration due to producing more power at low wheel RPMs. It is a good question whether the extra time required to shift to another gear results in more harm than the good the more power at low wheel RPMs result. In any case, the optimal number of gears in an electric car would be much, much lower (perhaps two).
Usually, electric cars are built with no transmission whether it is automatic or manual. In hybrids, the situation is different. In Toyota hybrids, the electric motors (two of them) are the transmission! So, there is no traditional transmission but rather a clever electrically controlled CVT-like system. Some Mercedes hybrids have an automatic transmission.
Some Lexus high-end hybrids have a second planetary gearset with two clutches that effectively works as a two-speed automatic transmission. This is to achieve good power at low wheel RPMs and extremely high maximum speeds, like 250 km/h or so. So, not all Toyota-like hybrids are eCVT only: there may be effectively a two-speed automatic transmission in there.
Another matter are cars that have been converted from gasoline/diesel to electric. In this case, it is possible the transmission isn't removed at all and there are thus quite many gears. More than needed, I would say.
Actually, there was at least one such crazy contraption, called Flybo Total Electric... 4 speed manual gearbox, complete with clutch and all.
It was reviewed by the Hungarian Totalcar magazine.
To sum it up: the title of the video says "I'm scared of this" says all.
Yes, it makes DIY homebrewing an EV much easier.
The presence of a manual transmission washes away much of the engineering needed to torque-match the motor to the application.
It's very easy in a homebrew EV to find that your motor lacks the torque to climb a hill, or has way more torque than you need for hill-climbing, but "revs out" when you get to highway speed.
With a manual transmission, you have to do some cursory sanity-checks... but there isn't need for a lot of sharp-pencil engineering. You can build the EV, and then figure out which gear ratio is the best fit for the motor and the car's weight and usage.
That makes homebrewing an EV much more achievable.