How To Extend the Life of Your Electric Vehicle Battery Pack
Many potential (or current), electric car owners have seemingly legitimate concerns over the likely battery life expectancy of EVs. Previous experience of small consumer devices and old(er) battery powered tools, suggests the batteries in our EVs won't last too long and will render the car uneconomical to run or repair within a short time of ownership.
The truth is, modern EV's battery management systems are tuned to extend the life of the battery pack, which is how some manufacturer warranties can be extended to as long as 8 years. That said, there are still steps you can take to save and protect your battery and 'sweat the asset'. ;-)
1. Avoid full charging when you can.
One reason that batteries in mobile devices only last a couple years, is that they are being pushed to their maximum capacity—frequently getting fully charged and fully drained. Consumer products are advertised by their battery operation time, not their battery lifespan. This means that every possible electron will be shoved in there. Charging to maximum capacity might give you the possible use for that one charge, but it is one of the worst things that you can do to lithium batteries.
This is the reason, for example, that smartphone batteries may only last a couple of years. That's generally acceptable because small consumer devices aren't expected to last much longer than 2-3 years anyway. We expect slightly longer than that out of our electric vehicles!
Top Tip! In the 2011 Nissan LEAF EV, there is a Long Battery Life setting that tells the car to stop charging at 80 percent. This reduces the available range, but could greatly increase the lifespan of your battery pack. If your normal daily driving can be done with less than an 80 percent charge, or you can top up during the day then this mode may be for you. This simple setting is one of the easiest things that you can do to increase the battery’s lifespan.
One additional advantage of not charging up all the way is that it leaves room to store energy from regenerative braking. Consider this option if, for example, you live at the top of a hill, often when the batteries are full or near full, regen will be disabled to avoid overcharging the batteries.
2. Avoid deep discharging your battery pack.
Lithium-ion packs prefer a partial cycle rather than a deep discharge. Since lithium-ion chemistries do not have a memory effect, there is no harm using a partial discharge. Not only will this avoid excessive wear it will also mean that—with a little planning—you will arrive at your destination with range to spare.
Granted a partial cycle is much easier if you have a bigger battery pack (e.g. Tesla or the Bolt) but it's still very possible especially if you have regular options to charge throughout the day.
3. For plug-in hybrids (PHEVs), consider “save” for climbs or long highway drives.
In a plug-in hybrid like the Mitsubishi Outlander PHEV, or a range-extended electric vehicle such as the Holden Volt, it’s more common to use all of the available battery capacity before switching to petrol power. Fortunately, the EV’s battery management system knows when to stop drawing from the battery—to avoid deep cycling. But you can help the system by taking control of battery vs petrol use.
If you know that your planned route includes a long hill climb, switch to 'Save'—which kicks on the petrol engine and saves the battery—at least 20 minutes before you start the climb. This will ensure that the batteries are not deep discharged during a long steep climb, and you’ll have all the power you need to pass as you go up the mountain.
Of course, you're always best using the EV mode for town (rather than highway) driving.
4. On a hot day, try to park in the shade & during the winter, park in a garage, rather than on the street.
Many electric cars have thermal management—via air or liquid—that is great for keeping your batteries comfortable, but it comes at a price. Running fans and AC compressors use energy. On a hot day, if you were to park your car on a hot asphalt car park, the thermal management system may run continually to keep the battery temperature in check. If it did, hours later when you came back, your batteries could be somewhat drained from cooling themselves You have no control over this other than to perhaps minimize the heat impact in the first place by finding a cooler spot to park.
Top Tip! If your electric vehicle has thermal management and the weather is extreme, plug in whenever you can.
This will, of course, charge your batteries, but more importantly, it will engage the thermal management system continuously without draining the batteries. Remember that lithium batteries like the same temperature ranges that you and I do. If you had to sit in the sun in a hot parking lot, would you want the AC turned on? Yes, you would and so would your vehicle’s batteries.
5. Plan ahead for a period of extended storage.
Lithium cells like to be at a left at a mid voltage level if they're to be stored for extended periods of time. While the Tesla Roadster has a “storage mode.” most EVs do not. If your plug-in vehicle has a special storage mode, use it.
If not, and you will not be driving your plug-in electric car for a month or more, here is what we recommend:
1. Store the vehicle in a cool, but not freezing, location;
2. Charge to 60 percent;
6. To maximize battery life, minimize the use of DC quick charge.
This is the best way to save your batteries, avoid DC quick-charging!
While fast charging is very useful it really hurts the batteries. Unless you really need to fast charge (such as on a stop off during a long journey), the recommendation is to charge more often with slower (AC) Chargers.
Regular use of fast charging will cost you about 1 percent of capacity per year. For example, if you avoid EV fast charging, you may have 80 percent capacity after 10 years of normal use. However, if fast charging is your primary fueling method, then your capacity would be 70 percent after 10 years. While the cost to the battery’s lifespan may not be as much as you may think, fast charging still takes a toll that should be avoided when possible.
These tips can extend the life of an electric car’s batteries, but you can choose to ignore everything. With modern plug-in vehicles, you can simply plug them in anytime and drive it any way that you see fit but you may see accelerated degradation within your ownership. However, make a few changes to your behaviour and you'll get more out of your battery pack long term and have a better chance of a healthy resale value when it's time to change up.