Electric vehicle batteries
Find out how to get the most out of your EV's battery.
EV battery lifespan
EV batteries are sophisticated pieces of equipment designed to last many years. Most new EVs have battery warranties that guarantee the battery for a certain length of time (typically 5-8 years, sometimes longer) or distance (such as 100,000km).
Over time, EV battery capacity gradually decreases the more it is used, like a mobile phone. It can also happen when a vehicle is parked up and not being used.
Decreased capacity means the car won’t travel as far on a single charge. It will still work well, and is an attractive option for car buyers who don’t need to travel so far between charges.
How to assess a battery
Battery condition can be described in a number of ways including percentage of battery capacity remaining, State of Health (‘SoH’) and, for a Nissan Leaf, how many bars the car will charge to out of 12.
If buying a used EV, it’s important to get the battery properly checked. A data reader can be plugged in and a battery health check performed – you can even have the results sent to your smartphone.
The battery’s State of Health is a useful way to judge how much life a used EV’s battery has left. It describes the overall condition of a battery – not its current charge. For some vehicles, on-board diagnostics can provide data that will help you determine how much longer you can expect it to last, based on how it has been used to date.
SoH can be more useful than an odometer reading. For example, an EV may have very low mileage but a reduced SoH if it has been in storage for some time, or has been excessively fast-charged. An EV with slightly higher mileage but better SoH may be a better option.
Get the best out of a battery
As with any car, the driver of an EV has the biggest influence on its performance over time. You’ll get more out of your battery if you:
- Drive smoothly, avoiding harsh acceleration and/or braking.
- Minimise frequent fast charging. (This may differ depending on the EV model and the climate it is operating in – the EV manual or manufacturer should provide more details.)
- Only recharge the battery when needed. Many EV owners find they only need to charge every few days.
- Limit battery exposure to extreme heat or cold. In very hot weather (over 30 degrees C), park and charge in the shade or in a garage. In very cold weather (below freezing), follow battery care instructions in the manual. Some batteries have thermal management systems that use a small amount of energy to protect the battery by regulating its temperature.
- When storing an EV for a long time, follow the battery care instructions in the manual. Don’t store it with a fully charged battery.
- Follow the manufacturer’s servicing recommendations. EVs should always be serviced by a qualified technician.
Refurbishment and replacement
When an EV battery no longer provides a useful driving range – typically after many years – it can be refurbished or replaced. Sometimes it’s possible to just replace the dead cells within a battery. If a full replacement is required, you may be able to improve the range of your EV by installing a new battery with more capacity.
The used battery still has value. It can be refurbished, repurposed or recycled – for example, to store electricity from solar PV panels, or raw materials reclaimed. You may even be paid for the old battery.
Although a new battery is expensive, costing several thousand dollars, EVs are cost effective even when battery replacement is taken into account. Research by EECA shows that even if owners need to replace the battery, an EV can compete with a petrol car in terms of whole of life cost.
Members of the Motor Industry Association of New Zealand (MIA) have committed to a code of practice to have suitable systems in place for the use, capture, return, refurbishment, reuse, recycling or disposal of EV and hybrid batteries, with the aim that no batteries end up in landfill.