The Technology
The 'Nuts & Bolts' (or lack of)
As the title suggests, the battery cell within an EV is mechanically a lot more rudimentary than that of a conventional car. This has two main benefits - firstly there are a lot less things (1000's!) to go wrong, consequently EV's have an enviable breakdown record.
Secondly, the torque that is applied through to the wheels is full and instant. This allows EV's to more than hold their own when accelarating away in urban traffic (their playground!)
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The EV, or BEV (battery electric vehicle), is a vehicle which uses chemical energy stored in rechargeable battery packs; and electric motors and controllers instead of internal combustion engines (ICEs). The battery can re-charged overnight (saving you a queue at the petrol station) or at one of numerous charge points.
When required this energy is drawn from the electric cells and converted into motive power. The use of regenerative breaking is also key in topping up the battery every time the brakes are applied.
Charge Times & Driving Range
There are currently a number of batteries available throughout our EV range. They each have their USP's but ultimately battery makers are striving for shorter charge times and greater driving ranges.
Battery technology has come on leaps and bounds since the first non-rechargeable vehicle was assembled in 1835. The following however, is an overview of the main batteries that are powering today's EV's.
Lead Acid (PB-AC)- These have been around for a while now and provide a safe, efficient and low cost partner to any manufacturer. Recent advances in battery efficiency, capacity, materials, safety, toxicity and durability have allowed these superior characteristics to be applied to ever bigger electric cars.
Nickel-metal hydride (Ni-MH)- These batteries are now considered a relatively mature technology. Although less efficient in charging and discharging than lead-acid, they boast an energy density of 30-80Wh/kg, far higher than lead-acid. When used properly, nickel-metal hydride batteries can have exceptionally long lives.
Lithium Ion (Li-Ion)- One of the latest and potentially most viable batteries now being used in electric vehicles. Originally known for their use in smaller electrical appliances such as laptops they have now made the move to powering larger things. The cells output an impressive 160Wh/kg energy density and good power density, with near lossless charge/discharge cycles.
The future? Ultracapacitors, also known as supercapacitors, or double-layer capacitors, are electrochemical capacitors that have an unusually high energy density when compared to common capacitors. They are at present only able to store a fraction of the energy a normal cell would use to power a car but incrediby are charged in a matter of minutes. If and when these are commercialised, they will undoubtedly be taking the EV world by storm due to their quick charging (even during braking), temperature stability and excellent safety properties.