Technology

Frightened about EV battery degradation? Don’t be so

Welcome to SHIFT Basics, a collection of tips, explanations, guides, and advice to keep you up to date on mobility technologies.

Get in and buckle up, partner – because it’s story time.

My first real encounter with an electric vehicle was when BMW launched its i3. I remember watching the car roll silently into the showroom and thinking it was some kind of personal transportation system from the future.

When interested drivers stormed into the showroom on the opening night of the vehicles, one question seemed to echo more than any other in the room … “How long will it be?”

When talking to the group of valued guests, it became clear that they were actually referring to two things: range and battery life.

Range

How much your EV has depends on the type of EV itself and the size of the battery. The bigger and heavier the EV, the worse its range compared to a lighter and more aerodynamically slimmer vehicle – provided both cars have the same battery size.

EV batteries are specified in kWh (kilowatt hours). That is how much electricity they can store. For more information on how to do this, see this handy guide. As a rule of thumb, however, the bigger the battery, the more range the EV has.

There are an increasing number of electric vehicles that can travel over 200 miles on a single charge, but 100 miles was the norm in the i3’s launch days.

Software optimization can also affect the range of an electric vehicle, but not significantly. Tesla previously released a wireless software update that added 9 miles to the range of some Model 3s.

Battery degradation

While many of the evening’s guests focused on how far the car could go, they were also concerned about how long the battery would last before it became unusable. This phenomenon is known as battery deterioration.

A lithium-ion battery is considered charged and discharged, it worsens. Remember the laptop that used to last all day and is now dead at lunchtime? It’s the same as that, but only on a much larger scale.

Many potential EV buyers worry that this will happen to their car. So let’s look at how important it should be to us.

Fortunately, we have a lot more user data than we did five years ago, and as EVs get older, it’s becoming clear how much charge they can lose.

Some of the worst hit by battery degradation are former Nissan Leafs owners, especially those that were made more than seven years ago.

The problem stems from a technical decision Nissan made for its early generation Leaf vehicles, which opted for passive air cooling instead of active battery cooling. Air cooling is much cheaper to manufacture, but is far less effective at controlling battery thermal systems and can cause larger temperature fluctuations. As a result, Nissan Leafs in the early edition is known to suffer from above average battery deterioration with age.

Photo credit: Wikimedia – CCA cross-section of the Nissan Leaf batteries mounted in the bottom pan of the car. Nissan Leafs fast charging according to the CHAdeMO standard.

However, things have improved a lot. Battery degradation doesn’t seem that much of a problem anymore.

Tesla has proven that actively cooling batteries – and using cylindrical cells instead of pouch-style lithium-ion packs – can improve their overall lifespan. It’s a format many new electric vehicles are adopting, and you can often hear how an electric car’s cooling system works when it’s plugged into charging on a hot day.

The state of charge

Let’s take a look at what people are saying right now. In a study by British consumer advice magazine Which? Over 1,000 EV drivers were surveyed last year, and the results were pretty clear.

An average EV that is three years old only loses 2% of battery capacity. By the age of six, the battery has lost about 8% of its charge.

We also have to remember a six year old dare uses six year old technology. If you buy a brand new electric vehicle today, it will likely do even better in six years than it did in this survey.

There is also another point of view. If you are buying a new electric vehicle, you are likely buying the car under a lease. Most of the time on lease plans, drivers return the car for a new one, so battery degradation will never be a problem for these drivers.

Battery degradation is more likely to be a problem for used electric vehicle buyers. However, it is quite easy to test the range of a used electric vehicle and check the battery condition in the vehicle diagnostics. If the battery has deteriorated noticeably, it should definitely be reflected in its price.

While battery degradation does occur, it never seems to be a problem for the majority of EV drivers.

This also includes the admired BMW i3 * admirers. You shouldn’t have worried at all. As it turns out, not a single battery has had to be replaced since the i3 was launched due to premature aging or a significant loss of range.

* Damn it, I love this car

Do electric vehicles excite your electrons? Do e-bikes make your wheels spin? Are you being charged by self-driving cars?

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Published on March 3, 2021 – 14:59 UTC

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