Regarding good EV charging practices… let me explain.
Since I upgraded recently from a Tesla with LFP batteries to one with the more common Nickel-Manganese-Cobalt (NMC) battery chemistry, I had to rethink my battery charging advice. And the conclusion I came up with is the NMC chemistry is different enough that I needed to start following some very specific rules to maximize my battery’s longevity. But before I go there, I need to dispell the common response from anyone who ‘leases’ a Tesla, and that is “Who cares – you only ‘own’ the car for a short time and let battery life be somebody else’s problem, not yours.” Yeah, there is that. But what if it’s so easy to treat your battery right that you should just do it anyway – save the planet and all that? So that’s my thinking…
So, what to do? I’m glad you asked. And since you did ask, I recommend you start here:
Best practice electric vehicle (EV) charging for low mileage drivers from Mark at This Electric Life.
I’m a low mileage driver, and Mark’s video speaks directly to my use case and battery technology. Mark presents the chart shown below which was borrowed from Battery University‘s BU-808 (How to Prolong Lithium-Base Batteries) findings.
In summary, discharging and charging a lithium battery within the ‘goldilocks zone’ in the middle of the State of Charge (SoC) range, AND charging roughly 10% with each charge, appears to increase the number of DST (dynamic stress test) cycles to ‘infinity and beyond’. Well, not exactly, but in this example Mark extrapolates the orange line to 23-years of battery life, without even crossing the 90% capacity retention line. And that’s pretty good!
So this is what I’m doing. I set my SoC max charge limit to 50% and always plug in after a drive (usually ~40% SoC when I plug in) and so far the results are kind of interesting. I use a service called Recurrent to track my battery state over time. And when I ‘View Insights’ for my 2025 Model 3 RWD Long Range, I get this result:
Granted, I only have 4000 miles on this car to date. But who knew that 103% was even possible? And with an ‘expected range’ of 368 miles for this car, a 50% SoC still gives me 184 miles of range, and a battery that will outlive me. Not bad…
In closing, if you’re in the majority and don’t really drive that many miles each day, consider giving your battery a break and charge regularly in the goldilocks zone, and keep your car plugged in whenever it’s not in use. Your battery will appreciate it, as will your grand kids.
** update **
One more thing: Like many Tesla owners, I use Tesla’s Wall Connector to charge my Model 3 at home. What I didn’t mention above was that I usually keep my Wall Connector’s charge amperage set to 8 amps. Why, you might ask, do I charge so slowly? Well, since you asked, I charge at the slower rate a) because I can, b) because I have the time to do it since I don’t drive that many miles each day, and c) because I believe charging at a lower amperage is better for your battery over the long term than charging at a higher rate, when faster charging is unnecessary. But, as we say in our Tesla Owners classes, “do what you gotta do”. This advice works for me, my car, and the miles I drive each day. Your situation might be quite different…