A high voltage battery powers the driving motor and the heater. A secondary, low voltage battery powers everything else, as in a Petrol or Diesel vehicle. The main battery will charge the secondary battery.
They can be expected to last 10 years or more and are usually Warrantied for 5 or 8 years by the vehicle manufacturer.
EV Batteries are, like mobile phone batteries Lithium-Ion, in fact they consist of a large number of cells. Individually these cells may fail causing the State of Health (SoH) to reduce. However this will be over a very large number of charging cycles. The individual cells can be replaced as part of a refurbishment.
Batteries are currently sized from 24 to 64kWh. Note that 24 and 30kWh are no longer available for new cars.
Not all batteries with the same capacity are equal, as there are different Battery management techniques which impact degradation.
A key factor is the Battery Management system to relieve the stress on the battery, particularly during Rapid charging. A form of Active Battery Management is necessary.
There are various causes of Battery degradation, including a poor Battery management system and charging at a higher than the optimum for the battery.
The cost of electric vehicle batteries has fallen some 87% over the last ten years to an average of US$156/kWh (£123/kWh), and is on a trajectory to reach around US$100/kWh by 2023.
The UK plans to build huge batteries to store renewable energy – but there’s a much cheaper solution quoting BloombergNEF’s Battery Pack Prices Fall As Market Ramps Up With Market Average At $156/kWh In 2019.