The motivation for electric vehicles: Mechanical design
Mechanical design
It was believed that after the century-long development of the ICE car that greatly contributed to better understanding of automobile mechanical technology used in automobiles, knowledge would be sufficient to make the mechanical transformation to electric, and the primary devotion would need to be on the power system. It turns out that during this most recent decade and the one before, this hypothesis has been pretty valid—the weakest area of the EV industry is still in the power system. Still, there are some problems in the mechanical designs that took us by surprise.
The suspension system
Suspension refers to the system of "cushions", such as the tires and shock absorbers that ties the frame of the vehicle to its wheels. The design of the suspension for ICE cars tends to be mostly the same because the distribution of the weight is the same—it is now settled for the most part that the weight should be either in the front of the vehicle, where the engine is located, or in the back of the vehicle, where a more complicated mechanical design is needed. Most traditional car companies make cars with front-wheel drive, primarily for safety reasons (reducing the chance of a flip). This setup meant the engine was effectively pulling the rest of the vehicle forward.
After the arrival of the electric vehicle, innovative companies were excited to begin using a rear-wheel drive approach (it helps with terrain, it's more balanced, better traction, etc.). However, the addition of an incredibly heavy battery underneath the car threw our previously established setup out of the window. Due to the sheer density and weight of the large traction battery under the car, a upper-lower weight distrubution analysis proved to be more useful than a front-back approach.
As the heaviest component of the entire vehicle, weighing in at around 900 lb (400 kg), the lithium-ion battery's only possible and resonable location is under the floor. While this improves stability (it isn't generally safe or sensible to be carrying top-heavy loads in life), this means that over longer periods of time, the suspension would have to deal with a constant downward push by the heavy battery. Given the clearly novel situation, it seems reasonable to advocate for a complete overhaul of the suspension system. It would be necessary to strengthen the front of the car for front-mounted electric motors or pay close attention to the back for rear-mounted electric motors.
The Nissan LEAF chose to stick with a front suspension, inheriting historical technology, now with some parts of the front suspension under greater stress due to the increased weight. While serious concerns for danger is largely minimal, problems could definitely reoccur here and it is worth ameliorating the increased strain in future designs. On the other hand, Tesla's suspension in particular also leads to problems elsewhere, such as in the running gear and the alignment. Although many different solutions have been tested (air suspension, adaptive automatic suspension, intelligent/real-time adjustment), the fundamental difficulties remain.
The brake system
ICEs rely on hydraulic and braking systems to do their job, but some were skeptical that these systems could be replicated in their function with electric vehicles. In recent years, such doubts have been erased—the electric braking system is far more reliable than hydraulic pipes.
Nevertheless, the initial high cost of traction batteries made it necessary for regenerative braking to become a vital baked-in feature for EVs, and it is now a permanent feature, even after the cost fell later on. It is quite important that this early emphasis on energy efficiency happened; it paves the way for greater economy in energy transfer. In fact, this also greatly reduces the working intensity of the braking system, meaning that the brake pads and discs that previously wore away incredibly quickly on ICEs can now last much longer, a definite benefit to traffic safety.
This current vehicle's regenerative braking system is still rather conservative. As of today (December 2023), the vehicle has had two brake pad replacements and one brake disc replacements, but the brake pads on the front of the vehicle have only been replaced once. In newer models, this system is even further enhanced, and the newest models can even do one-pedal driving.
Environment control of passenger compartment (heating and A/C)
While initially considered a difficult problem for EVs many years ago, the electrification of climate control is not a big issue in running electric vehicles today—it is, once again, saving electricity and maximizing energy efficiency. In this specific vehicle, it is one of the larger problems.
In ICE cars, the heating system directly relies on waste heat from the engine's exhaust gas, introducing it into the vehicle's interior, and warming the air. In electric batteries, there is no exhaust, and so a new heating method must be found. Designing such a method requires remembering conservation of energy. Nissan chose, for the LEAF, the most traditional method—harnessing the heat produced by a wire's resistance. Upon initial inspection, the energy consumption was too high for too little results, so resistance heating was added to the seats and the steering wheel. In practice, it was found that using this method for heating had a huge negative impact on performance because pushing hot air with fans is wildly inefficient. Nissan actually recommends that you use the seat warmers instead of the climate control's heat setting. Subsequent companies have learned this lesson and moved to a heat pumps with the seat warmers.