Electric Vechicles get us independence from gas and gas prices and remove all sorts of unnecessary engine parts, noise and maintenance. But they also bring in a new technology with advanced Lithium-ion battery packs that need some special handling.
Here are the top 5 things you can do to extend the life of your battery:
1. Never charge your battery to 100% and let it sit.
Most EVs have an option of a “Standard” charge or a “Range” or “Max” charge. By all means, do the maximum charge when you need it, but do it right before you start using the battery for the trip. Most EVs have charge timers to help you plan for this. If your EV doesn’t have that, do an overnight standard charge and then charge the last 10-20% in the AM before departure. Leaving a battery pack at max charge for even relatively short periods of time can reduce its life. As a rule of thumb, try never to let your battery sit at maximum charge for longer than 8 hours.
2. Never let your battery sit at a very low charge state for an extended period.
Leaving your battery in a discharged state for an extended period will also reduce its life. Most vendors protect batteries from becoming completely discharged as that can effectively “brick” the battery to make it completely useless. The general rule of thumb is to plug in and charge whenever you can. That doesn’t mean going out of your way for a few kW of charge, but it does mean plugging your car in nightly and maintaining a reasonable charge level.
What is a low state of charge? Under 30% charge is generally considered low and a state that you should probably not let your car sit in for an extended period. Also be aware that EVs lose charge state even when they sit unused. With the Model S, it loses about 1% of its charge per day.
3. For daily use, charge to your vendors 90% limit or less
While you may be able to time your max charges and departure times well, daily charging to 100% is stressful to your battery. This is why most vendors offer “standard” or “normal” charge levels that don’t provide the maximum range quoted for your vehicle. If you don’t need the max charge then don’t use it. Generally lithium-ion batteries do best when they operate in the 30% to 90% range for state of charge. Much time spent above or below that range will lead to a shorter pack life.
4. Don’t store your EV fully charged.
If you’re going away on vacation or for a business trip the best thing for your car is to set the charge level to 50% and leave it plugged in. If you’re leaving your EV at the airport or somewhere where you can’t leave it plugged in be aware that you’re going to lose some charge per day. Charge to a level where you can get to the airport, let it sit for the trip and then still have charge and margin to get home. Don’t let it sit for days at the airport at a 90% charge state if you can avoid that. Still, sitting at 90% is better for the battery (and you) than sitting at 10% and coming back to find the battery completely discharged.
5. Periodically fully charge your battery.
While lithium-ion batteries are designed to minimize the “memory” issues of older technologies, battery packs in EVs are more complex and are often comprised of multiple individual batteries — as many as 7,000 cells in the Model S. Battery balancing is about maximizing your battery’s capacity to get full capacity out of it increase the battery’s life by evening out the charge distribution. Modern EV battery packs include a automatic battery balancing component, but you can help too. While you may never need the maximum range that your battery can provide and you may never take long trips, a periodic range or max charge is helpful to your battery’s management system. I’d suggest doing this about once every 3 months or so and keep in mind that after you fully charge you should not let it sit, that would be a violation of battery management rule #1.
Disclaimer: Since we’re dealing with expensive components and i’m no expert I want to point that that fact. Read the manuals for your EV, search your EV forums, develop your own rules and be consistent and adjust as needed. The rules above are general rules for any EV that will likely extend the life and health of your battery but your own mileage (range!) may vary.