What is the lifespan of an electric car battery?

Published by on 11.27.2019 - 5 min

The rechargeable battery uses very different technology than the traditional battery, hiding its secrets under the floor of the electric car. Having recently been brought into use in modern electric vehicles, the lithium-ion battery now offers ample range and excellent durability. Read on for more about the lifespan of this vital component and contributing factors.

The average lifespan of a battery

First of all, it’s important to understand that there is not just one type of battery. These days, most vehicles use a lithium-ion model, similar to that which powers laptops and smartphones. But the battery used in electric cars has a much greater capacity!

The lifespan is stated in cycles, i.e. the number of charge/drain cycles that the battery can withstand. Depending on the type of lithium-ion battery, the number of cycles that it can take is between 1,000 and 1,500. So, if you drive a Renault ZOE every day with an average trip length of 30 km and charge the battery weekly, it will last more than 20 years. Some may question this theory with the opinion that electric cars are too new to be able to make such claims, but tests on rechargeable battery technology already show that the batteries lose very little capacity over time.

The lifespan of an electric car battery doesn’t mean that it stops dead once spent. Instead, it means a loss of capacity, which declines gradually throughout the battery’s utilization. Below a certain percentage – 75% for Renault, for example – the decline in range is deemed too great compared to its initial capacity. These days it is estimated that a battery reaches this point after 8 to 10 years, which is why the battery’s warranty term is often of a similar length. But the technology is improving all the time, so this term will get significantly longer going forwards.

RENAULT MASTER Z.E.

Battery’s second life

But this doesn’t mean that spent batteries get thrown away or forgotten. First of all, their materials can be recycled. But they can also get a new lease on life: after serving as an automotive component, there’s also life as a power pack.

For example, as part of the circular economy, Renault reuses certain battery packs to store renewable energy from wind turbines or solar panels in Belle-Île-en-Mer and Porto Santo. They are used, for example, to power forklift trucks and store energy to alleviate power outages and take the place of generators.

The charging and draining cycles of a battery

The rules of charging an electric car battery are the same as those for a smartphone battery. Charging the battery from 0 to 100% lessens its total capacity and consequently shortens its lifespan. It is therefore imperative not to let the level of charge drop below 10% or exceed 90%, with general advice being to only charge between 30 et 80% as much as possible.

The type of charge also has an impact on the battery. Fast charging delivers a large amount of energy in a short space of time, but has long-term detrimental effects. So, for the good of an electric car, it’s better to opt for slow low-voltage charging at home over ultra-fast charging stations.

What factors can cause a battery’s lifespan to vary?

new zoe charging

Quick top-ups are best, which is fortunate since electric cars increasingly use regenerative energy systems. When slowing down or braking, the vehicle generally absorbs enough energy to charge the battery by a few percent, but this can reach 10% under certain conditions (in mountainous areas). This is enough to reduce big charges a little and lengthen the lifespan.

Remember that temperature has a big impact on the battery. Too hot, and the battery’s capacity plummets permanently. Fortunately, there’s a cooling system around the battery packs to counter the effects of extreme heat. In cold weather, the range is shortened, but this doesn’t affect lifespan.

It’s also important to know that the stated capacity of the battery doesn’t necessarily apply in practical terms. Manufacturers keep a certain percentage of battery capacity ring-fenced to prevent extreme charging and maximize lifespan. So there’s a difference of several percent between usable and theoretical charge, and it varies between brands. For example, Renault states usable capacity, as with the 50 kW of New ZOE.

The capacity of the installed battery pack is a very important variable which impacts lifespan. To cover the same distance, a 20 kWh battery will logically need charging twice as often as a 40 kWh battery. So with fewer cycles, lifespan is lengthened.

What is the future for electric car batteries?

Will the future be all about “solid-state batteries“? They distinguish from lithium-ion batteries by solid – and not lquid – electrolytes, which confer greater energy storage capacities, but are not without drawbacks.

Further improvements can be made to the batteries, in particular to resolve possible overheating problems and to mitigate the risks in case of accidents. The higher capacity will also make it possible to reduce the number of charge/drain cycles, and thus lengthen the battery’s lifespan.

With a lifespan of over two decades, an electric car battery is very resistant. Its lifespan can be even longer if you are careful to charge only partially and at low voltage. This way, the battery boasts a very small carbon footprint in use, over an increasingly consistent lifetime in the vehicle. If a second life is added, outside the vehicle, to store green electricity from intermittent renewable sources, then the battery demonstrates its full potential.

 

Copyrights : Pogonici, Jean-Brice LEMAL, Frithjof OHM