How Long Do Electric Car Batteries Last?

EV batteries, like the ones used in consumer electronics, degrade a little every time they’re charged. The good news is studies have proven EV batteries degrade very little due to provisions like active thermal management systems, smart software and ‘top buffers’. For example, famous EV YouTuber, Bjørn Nyland tested the battery in his 2013 Tesla Model S and found it had only degraded 11 per cent (8.1kWh loss) or around 100km less driving range than new after seven-years and 260,000km driven.

Avoiding degradation is close to impossible, there however certain factors which will accelerate the degradation of your battery if not managed within the ideal parameters.

Heat

Regular exposure to extreme heat will accelerate battery degradation. This is the reason why all modern EVs have advanced thermal management systems, typically liquid-cooled, to ensure the batteries stay within the optimal temperature ranges. The first generation Nissan Leaf did not feature liquid cooling, instead, it relied on air cooling, meaning that EVs in hot climates degraded more quickly than expected and many did need to have a battery replacement.

Fast Charging

Fast charging a battery will result in more heat than slow charging, accelerating the degradation of an EV's battery, this has been supported by several studies. This study found that regular use of fast charging can reduce NMC battery life by 10% compared to regular charging at home. To minimise degradation of the battery, an EV's battery management system will often limit the charge power during a fast charging session. This is the reason why the charging curve of electric cars is not a flat line (at the max rate) but a curve that tapers off as the charge level nears 80%.

If using fast charging networks is your main source of energy, you should not be too deterred from using them due to concerns about degradation. The energy savings that you'll accrue from using an electric car will far exceed the 'cost' of degradation'. Furthermore, your car will likely lose greater value from technology obsolescence and general depreciation than from battery degradation.

Depth of Discharge

The higher depth of discharge the higher the degradation. Do this on a regular basis and you will accelerate the degradation of your battery. This is the reason why most EV manufacturers recommend setting the charge limit to 80% to 90% to ensure it stays within a range which minimises degradation.

The recommendations for the BYD Atto 3 and Tesla Model Rear-Wheel-Drive, which use LFP battery packs, deviate from the above recommendations and instead recommend charging to 100% regularly.

LFP batteries are still exposed to degradation from a higher depth of discharge, just less so compared to other chemistries such as NMC. The recommendation to charge to 100% is to allow the BMS to properly calibrate and provide accurate range estimates. The justification here is that the benefit of accurate range estimates exceed the cost of additional degradation caused by charging the battery to 100%.

Battery Cycles

Like all battery-operated consumer electronic devices, the more times you charge it (cycles), the more it will degrade. Ever notice your iPhone which you’ve owned for a few years doesn’t hold a charge for as long as it used to? That’s due to the degradation caused from cycling.

The battery chemistry of the EV will be the key determinant of the number of battery cycles that a given EV model is capable of. LFP batteries will often be capable of two to three times the number of cycles compared to NMC and NCA. Based on the modeling below, an LFP battery will be capable of over one million kilometres before it hits the 80% capacity threshold.

Most EV batteries in Australia are warranted for at least 8 years, suggesting at a minimum manufacturers are confident their batteries will last this duration There is however mounting evidence from data collected that many modern EV batteries will last beyond the warranty period, likely between 10 to 20 years. One of the reasons for this improvement is driven by the use of battery chemistries such as LFP which have a cycle life of up to 2.5 times that of NMC and NCA chemistries which is still found in the majority of EV models.

Battery manufacturer CATL is on the cusp of producing a 'million mile' battery that lasts 16 years and 2 million kilometers (1.24 million miles).

Electric car battery warranties typically cover the battery pack for a number of years or a number of kilometres, whichever comes earlier. The warranty may also cover the reduced capacity of the battery if it drops below a certain percentage e.g. 70%.

Below we’ve listed popular electric car models and their respective battery warranty terms.

The key factors affecting battery health include: how often you drive, operating temperatures, charging cycles, frequency of DC fast charging, and more. Each manufacturer may have slightly different recommendations for maintaining battery health - it is best to check the owner's manual of your specific model.

Our top general tips for maintaining the battery health of your electric car:

• Minimise fast charging on a regular basis;
• Minimise exposure to extreme temperatures when parked; and
• Minimise frequency of 100% state of charge (for some chemistries).

With the evolution of electric vehicle battery technology the probability of having to replace your battery within a typical ownership period is going to be very low.

Let's say however you need to replace the battery in your electric vehicle, how much will it cost? It varies and very much depends on your EV model. EV models which use the LFP chemistry will have a significantly lower cost. The complexity of the battery pack integration will dictate the labour costs involved to swap the battery out.

By way of example, we've seen total replacement costs (including labour) for the Tesla Model 3 RWD for its 57.5 kWh battery for $17,000. The replacement cost for the Hyundai Kona Electric's 64 kWh battery has been quoted at $13,500 plus labour. Replacement costs for the 1st gen Nissan Leaf's 24 kWh battery have been quoted at $12,000 including labour.