Home > News > Maximizing Your EV Battery’s Longevity

An electric vehicle’s (EV’s) battery system is likely its most costly component. Like any other battery, an EV’s battery will eventually degrade. (The same can be said for just about any device.) Fortunately, there are things that you can do to optimize the life of your car’s battery. A good example is Tesloop’s Model S, an EV with over 200,000 miles and only 6% battery degradation. Additionally, modern EVs have really sophisticated systems to maximize the longevity of their batteries – they have temperature management systems and software to optimize charging activities and help you avoid damaging conditions.

There are several articles written on this topic (see below) but I’d like to share a few pointers that are relevant to EV ownership on our island.

Select the Right Electric Vehicle

Before purchasing an EV, understand your driving requirements – round trip commute distances, driving frequency, and even the terrain that you expect to travel in. These factors will help make sure that you buy an EV with enough driving range. If most or all of your commute is in-town, e.g., within Hilo or Kona, an EV with a less than a 100-mile range is sufficient. If you expect to make trips between East and West Hawaii, then I recommend an EV with 200+ mile range. For most of us, a daily commute of around 50 miles is the norm so many of the available EVs will suffice.

The ability for your EV to meet your daily driving requirements while maintaining an ideal 20%-80% ‘state of charge’ (more on this below) will help extend your EV’s battery life. This means that you should not go merely by the manufacturer’s range estimates. These estimates take into account the car’s full battery capacity whereas you should minimize situations where you fall below 20% while driving and situations where you have to charge beyond 80%. This does not mean that you must never fall outside of the range – it should just not be the norm. Having a right-sized EV will mean that you should rarely need for your battery to be outside the ideal range.

Keep it Between 20 and 80

This refers to the level of charge in your EV’s battery. To optimize your battery’s life, it is recommended that you keep its ‘state of charge’ (SoC or charge level) to between 20% and 80%. Modern EVs make it easy for you to know what your SoC is – each make will have a number of indicators on the dashboard to let you know what the charge level is. Since your EV may allow for you to toggle the display between ‘miles’ and ‘%’, you may have to change a setting to see the actual percentage.

Additionally, EVs offer the ability to set the maximum charge rating. This allows you to charge up to a predefined limit. This varies by manufacturer – in the NISSAN LEAF, you can set for 80% or 100% (no limit), while Tesla EVs offer the ability to set in smaller increments all the way to 100%.

Avoid ‘0’ and ‘100’

This is related to the previous tip. While it is sometimes impossible to avoid being outside of the ideal SoC of 20-80%, there are extreme situations that you’ll want to avoid – draining the battery or keeping at 100% for a long period.

Draining your EVs battery pack is a lot harder to do with modern EVs as there are several warnings that users will receive as the vehicle gets to this extreme situation – there are very visible indicators on the dash, severe drop in performance (e.g., the LEAF goes into ‘turtle mode’ where it literally crawls), and you may even get a notification from the manufacturer. Additionally, manufacturers have (wisely) created some buffer to avoid a complete drain.

That said, it is possible to fully drain the battery of some EVs and when this happens, there can be irreversible damage. For instance, there have been reports of Tesla Roadsters with ‘bricked’ batteries. In these situations, the vehicles were essentially ignored or not managed (Roadsters give out many visible and audible warnings, and Tesla contacts owners if connectivity exists with the cars so it’s really hard to ‘brick’ their batteries).

On the other hand, keeping your EV’s battery charged at 100% for an extended period is also bad and can eventually result in accelerated degradation. This can happen if your EV is plugged into your charging station and the maximum charge setting is set to 100%. If you must charge to 100% in preparation for a road trip, set your charge timer so that you’re able to start using your car as soon as possible after it reaches 100% SoC. (If you have a ‘right-sized’ EV, you’ll rarely need to charge to 100% here in Hawaii.)

Keep it Cool

Accelerated degradation will result in batteries that are subject to extremes in temperature. This is less of an issue with newer EVs where batteries where active thermal management is employed (these EVs cool or heat the battery pack, depending on the temperature.) When the NISSAN LEAF was first introduced, owners in Arizona reported that they were quickly losing ‘bars’ (range). While this affected a small percentage of the early LEAFs (2011 and 2012), the situation was attributed to the temperature management system in the car. NISSAN responded with enhancements to the battery system and an enhanced warranty that offered a replacement should the battery capacity drop below a certain level within a certain period or before 50,000 miles were reached. (We shared our battery replacement in an earlier post. You can read about it here.)

In Hawaii, the challenge can be heat – it may not be scorching as in the deserts of the southwest, but it can get hot. Park your car in the shade or in a parking structure, where possible. Also, try to avoid charging your car in a hot setting, e.g., at noon in a spot exposed to the hot sun. Ideally, you’ll have the opportunity to charge when you’re at home and after the car has had a chance to cool down.

Slower May Be Better

DC Fast Chargers offer EV owners the convenience of rapid charging. Big Island EV owners have a growing number of these stations to select from (4 in operation and 2 being installed). These stations are equipped with CHAdeMO and CCS plugs. (Teslas must have an adapter to use these stations.) While the use of a DC Fast Charger may be convenient and unavoidable, it has been suggested that its use is minimized. A number of studies comparing the impact of charging using Fast Chargers vs. Level 2s have been done. The outcomes suggest a negligible difference between them – there should be minimal impact to your battery when using DC Fast Chargers.

Note that there is a good amount of heat that is produced when using this type of charger so it is not advisable to use it on EVs with inadequate battery thermal management, e.g., early model NISSAN LEAFs. EVs with advanced thermal management should be able to handle the output of the Fast Charger. Examples of these include Tesla (Model S, Model X, and Model 3), Chevy Bolt, and BMW i3. Teslas appear to have an advantage when dealing with high power charging. They, after all, are built to take the output of the Tesla Supercharger (with even higher output than the DC Fast Charger).

In general, occasional use of a DC Fast Charger should be fine. It can help you get back on the road a LOT sooner than a Level 2. On the other hand, level 2 charging in a relatively cool location may help prolong the life of your battery.

Right-Size is Best

A theme that you’ll notice above is that a properly sized EV will allow you to maintain optimal conditions for the car’s battery and maximize your ownership experience. With today’s high-range, affordable EVs, e.g., the Tesla Model 3, Chevy Bolt, and 2018 NISSAN LEAF, it should more feasible for you to get the ‘right-sized’ electric car in Hawaii.

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