How do you take care of your electric car battery?

This guide puts together some handy tips and advice on how to maximise the life and performance of your electric vehicle battery.

Electric car batteries will last a long time, but there are things you can do to maintain and extend your EV battery's life.

 

Quick tips to maintain an electric car battery:

1. Keep the “State of Charge” between 20-80%
2. Only charge fully for long trips
3. Minimise rapid charging
4. Avoid leaving your car in hot places
5. Get your EV serviced
6. Use pre-conditioning

 

How long does an EV battery last?

We're at a point now where we have over 10 years of data on mass market electric vehicle lithium ion batteries following on from Nissan pioneering ahead with the market with the launch of the Leaf back in 2010.

Typical manufacturer warranties on EV batteries are around eight years/100,000 miles, which is even more substantial compared with internal combustion engines (ICE).

Answering definitively how long electric car batteries will last is difficult due to various factors, but the same would go for a petrol or diesel engine too.

A poorly maintained petrol or diesel engine won't last. Some variables to think about might include understanding how the battery has been charged over the life of the vehicle so far? What kind of EV battery technology has the vehicle got?

An electric car battery condition is called its state of health (SOH) and they will start with 100% SOH and over time they will deteriorate.

Geotab, the fleet software and telematics business, has analysed over 6,300 fleet and consumer EVs, representing 1.8 million days of data.

The data shows that EV batteries are generally exhibiting high levels of sustained health.

Geotab says that if these same battery degradation rates continue, the vast majority of EV batteries will outlast the vehicle.

Geotab's data shows that across those 6,300 vehicles there was an average battery deterioration of 2.3% per year.

This would mean if you had a 150 mile range EV, it would lose around 17 miles of accessible range after five years. How important that level of degradation is will vary from person to person and how many miles they do on a regular basis.

The data from Geotab is obviously an average too, so there will be a difference in degradation depending on the make and model of the vehicle, as well as the battery chemistry and thermal management technology it has.

Older EVs are likely to have more dated technology, while the latest EVs will also have the most up-to-date battery technology.

If you're planning on keeping your EV for many years or you're looking for a used EV, battery degradation is something to consider, although the impact on range might not be as dramatic as you were expecting. Keep that 2.3% figure in mind and use that as a bit of a guide when you're looking at vehicles.

However, if you're someone that changes your car regularly (the average ownership cycle in the UK is around four years), any battery degradation is likely to be pretty negligible over that kind of time frame.

 

Tips to maintain an electric car battery

As detailed above your EV's battery will degrade over time, although it should be at a fairly negligible rate.

However, there are steps you can take to help minimise degradation and the great thing here is that higher vehicle use does not equal higher battery degradation.

 

Keep the “State of Charge” between 20-80%

Avoid keeping your battery empty or completely full. Batteries don't like extreme states of charge, so letting it run completely flat will put a strain on the battery, as will consistently charging an EV to 100%.

Instead, change the settings on your car or car charger to limit the charge to around 80% and keep it above 20% if you can. Most daily or weekly driving is easily covered by the range of most EVs.

If you need to do a longer trip, it's fine to charge to 100%, but once you've got a bit of a feel for driving an EV and managing your weekly mileage it will be a lot easier to keep it in that 20-80% range.

Research by Altelium, an EV battery warranty provider, actually found that leaving a car sat for long periods of time unused with a battery between 70%-80% caused the steepest curve of battery degradation.

Altelium's data shows EV batteries stored at 70-80% could lose up to four to eight per cent of capacity to hold charge at the end of one year.

It's something to keep in mind if you're planning on leaving your EV parked for a number of days, like at an airport car park.

 

Only charge fully for long trips

As explained above, it's better for your EV's battery to keep it between 20% and 80%, but sometimes you might need more range.

Charging to 100% occasionally is OK, but try and limit this to only when you really need it.

Most electric cars have in-built navigation that will tell you if you can reach your destination with the current state of charge, or plan ahead to see if you need to charge to 100% or not.

 

Minimise rapid charging

Consistently rapid charging can cause faster EV battery degradation in the long term.

Passing high currents of energy through the EV's battery can increase the temperatures the battery is exposed to, which can speed up degradation if it's something that's done consistently.

Geotab's data shows that a vehicle that has never been rapid charged shows a slower rate of degradation. This means charging all electric vehicles at home with a 7kW charger using smart scheduling and management is the best long-term option to maintain the health of your EV's battery.

The data shows that EVs that are rapid charged up to three times a month show a 5% decrease in degradation rate over four years compared with a vehicle that has never been rapid charged.

This increases to almost 20% over four years if you're consistently DC charging your EV more than three times a month.

Even in that scenario that would still leave you with 80% SOH after four years, so in a scenario where you had a BYD Seal with a potential range of 354 miles, this might go down to 283 miles after year four. That's still a good amount of range, depending on what kind of trips you need to do.

 

Exposing EVs to extreme temperatures

EV batteries that are exposed to higher temperatures can experience a faster rate of battery degradation, compared with somewhere that is more temperate.

Geotab's data shows a faster decline in sustained temperatures of over 27°C. The good news is that average temperatures in the UK are usually below that level for the majority of the year (there can obviously be some peaks in the summer).

Where possible, try and avoid parking in the hot sun and if you really have to, try and make sure the battery is not charged above 80% in that scenario.

 

Get your EV serviced at least once a year

Properly qualified technicians will be able to monitor the health of your EV's battery with regular annual checks.

Workshops should have the proper diagnostic tools and software licences available to check on your EV and make sure everything is in a good condition.

 

Utilise pre-conditioning if possible

Some EVs will have a pre-conditioning feature that can get the battery ready for a charge. If it's too cold or too hot outside, this pre-conditioning can heat or cool the battery to an optimum temperature to receive a charge and help extend the life and health of your EV's battery.

The Ohme Home Pro and ePod chargers both feature functionality through the company's charging app that can trigger pre-conditioning.

 

How much does it cost to replace an EV battery?

The cost of battery production represents a fair chunk of the manufacturing cost of an EV, with a replacement EV battery costing approximately £10,000 or more.

However, it's possible to repair the modules within an EV battery pack at a much lower cost to improve battery capacity and its overall health.

The cost of a battery repair is dependent on the number of modules required.

Early Nissan Leaf batteries have two cells per module, while 2018 models have four cells per module - both have 96 cells in their battery packs total.

As a general rule only one module will require replacing and can be sourced used or new (in the case of the later cells).

The total job can cost around £1,000 as a general rule of thumb, but following the above tips to keep your battery in good condition would mean it's unlikely you would need to repair modules or replace your battery.

 

What happens to EV batteries when they die?

An electric car battery pack can be reused in different ways when the vehicle it has been in is no longer viable.

EV batteries can be used together to create "second life" renewable energy storage at businesses and homes.

For example, a solar powered array on a building can be linked to a battery storage solution made up of used EV batteries.

When batteries can no longer be used, even for a second life application, they can then be recycled.

Vehicle manufacturers can strip and recycle up to 90% of a battery's raw materials, including the lithium, nickel, manganese and cobalt. These materials can then be used to produce more EV batteries once they have been chemically processed.

For more detailed information about EV battery recycling and second-life uses, read our full guide here.