03 Some Issues / Problems:
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This post delves into 2 problems surrounding EVs.
1. Lack of Noise: Sound of the engine and exhaust
EVs, Unlike internal combustion engines EVs, are silent. This can seem weird to drivers used to understanding vehicle function by the sound of the engine. The silence of EVs can also be dangerous for pedestrians used to hearing cars approaching.
Many car and motorbike enthusiasts claim that EVs are too quiet for them. They like the sound of the power given by a V6 to V12 500+ horsepower sports, super cars. As of late 2009 Japan, USA and some other countries issued guidelines or approved legislation[1] on the use of sound based warning devices usually known as ‘Virtual Engine Sound Systems’ (VESS). The European Union (EU) as of 1July2019[2] passed a mandate requiring all new electric and hybrid cars to automatically use a VESS from start up to 20 to 30 km/h, and also during reversing[3]. On average, the requirement[4] is that the VESS should be 56 decibels at 10 kph and 50 decibels at 20 kph. A maximum of 75 decibels applies to any speed. EV makers like Jaguar, Audi, BMW and others have all developed their own brand specific characteristic sounds. EV sound designers such as Rudolf Halbmeir at Audi, Hans Zimmer at BMW and Richard Devine at Jaguar, have all faced the challenge of making the required car sounds. Tesla[5] have also found that some of their owners like the familiar sound of a V8, V10 or V12 engine[6]
The VESS system has also been implemented as a safety feature to protect pedestrians, cyclists and animals. Humans over the course of history have relied on their hearing to protect them from various moving vehicles, whether it was horse and carriage or loud fuel burning engines. With the advent of hybrid, electric and some could say ever quieter ‘Internal Combustion Engines’ (ICE) the need for VESS has accelerated. Companies like Harman, Sound-Booster, Soundracer and others[7] are all providing custom VESS systems.
2. A ‘Range’ Issues: Mileage per charge and charging times
Until the introduction of Li-ion batteries, the charging time of both Nickel-metal hybrid and lead acid batteries was a problem for EVs. The memory effect of the Nickel-metal batteries also contributed to making EVs unpopular in the driving world. Li-ion development has changed that. Li-ion technology still has problems but it is constantly being developed with ever better energy density. In addition, other new battery types for energy storage are under development. Some not using cobalt at all and others such as the Solid-State and Graphene batteries.
Car manufacturers are also thinking of using ultracapacitors[8] which have very good power density and their energy density is constantly increasing due to the use of modern materials such as graphene. An ultracapacitors ability to charge and discharge very quickly[9] can help batteries deal with the sudden heavy loads required in getting a car moving in the first place or acceleration both of which put a lot of stress on the battery packs and thus weaken them. So far ultra capacity technology for use in EVs has not increased to a point of being competitive. Currently an EVs battery pack energy density varies from 120 to 210 Wh/Kg[10] while ultracapicitors have an energy density of 7Wh/Kg but steadily increasing to 60Wh/Kg[11].