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Most electric cars lack a variable-ratio transmission. At some point and you only have the final drive to reduce the speed of the electric motor. The final dri
by ferongr 10y ago
Most electric cars lack a variable-ratio transmission. At some point and you only have the final drive to reduce the speed of the electric motor.
The final drive has to strike a balance between torque for negotiating inclines and top speed, as the electric motor cannot rev to infinity, neither can the power systems handle infinite power though them.
An electric car with a two-ratio gearbox would be ideal for both taking off from a standstill and top speed.
- Roritharr 10y agoWhat does the Model S use then?
- ferongr 10y agoA way more powerful motor and power electronics that allow for a "taller" (smaller reduction ratio) final drive.
- ahakki 10y agoIIRC the AWD versions (recognizable by a 'D' at the end of the model name, as in P90D) use 2 motors, one for the front and one for the rear. These two motors have different gear ratios, so one is more opimized for torque and the other for high speed. The rear wheel drive versions have a single ratio which has to strike a balance between speed and torque. This is also the reason that the AWD versions are faster than the RWD even though they are heavier due to the additional motors.
- andruby 10y agoTesla wanted to use a 2-gear transmission for the original roadster, but they couldn't find one that could handle the massive torque, so they ended up with a single ratio gearbox. Source: http://www.autoblog.com/2008/01/23/breaking-tesla-has-a-solution-for-their-transmission-woes-get/ http://www.autoblog.com/2008/01/23/breaking-tesla-has-a-solu... and Ashley Vance's biography of Elon Musk.
- awjr 10y agoOne of the concerns I have is that many of the EVs that are being released are not capable of towing significantly. I own a horse and we need something that can tow a braked 3.5T trailer. This market in the EU is primarily serviced by diesel 4x4s. I can see a future where the diesel engine is banned and only at that point will something fall out of the woodwork to cope with that towing capacity.
- ollie87 10y agoExtra battery in the floor of the trailer? Hooks into the car and gives it some extra juice, why wouldn't that work?
- Klathmon 10y agoIIRC it's not the battery power as much as it is the cooling. Many of the parts on electric cars overheat when pushed pretty quickly, and while adding cooling similar to a traditional ICE seems to be the answer, it adds even more weight and complexity to a platform which is already fighting to save every oz. Even the Tesla Model S can't do more than a single lap around many tracks without overheating.
- jgust 10y agoThe diesel-electric locomotive comes to mind. The road has different challenges than rail, but the application is proven.
- mikeash 10y agoI have heard that the more recent Model Ss (Models S?) are a lot better about being able to keep up with power output on tracks, although what you say was definitely true for a long time.
- camiller 10y agoI think that there will always be some internal combustion driven vehicles for tasks such as these.
- 10y ago