charging best practice?

S

SFC

New Member
I'm pretty sure I've read that best practice for maintaining an EV's battery is to let the charge go down to 20% and then charge to 80-100%. This report from Recurrent recommends charging more frequently, when the range has dropped only 20-30%, to better maintain long-term battery life. Anybody have more insight into what's the better way to go?

Thanks!
[=sfc=]
 
SFC said:
I'm pretty sure I've read that best practice for maintaining an EV's battery is to let the charge go down to 20% and then charge to 80-100%. This report from Recurrent recommends charging more frequently, when the range has dropped only 20-30%, to better maintain long-term battery life. Anybody have more insight into what's the better way to go?
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I hate to say this but 'it depends' and is dependent upon:
  • battery management system
  • battery chemistry
  • temperature
  • mission, driving requirement
The late Jack Richards recommended keeping the operating range around 50% SOC. Based on his studies, this keeps the internal voltages away from the SOC extremes. Those voltages tend to increase lithium conversion to compounds that render part of the lithium unusable. So I typically keep my 2019 Std Rng Plus Model 3 at 67% SOC on the home charger. This gives me 'bug out' range, ~154 mi, to the nearest Fast DC chargers (SuperCharger network) North, East, South, and West.

Living in North Alabama, I prefer to defer charging until after midnight to minimize charging during the heat of the day. I only charge to 100% SOC IF I am driving the next day on a cross country trip.

Bob Wilson
 
Some EVs, such as the MINI Cooper SE I drive, have built-in buffers to prevent battery damage. Which means the SE's 100% is more like Tesla's 80%. MINI's recommendation is to drive as much as desired and always charging to 100% is fine, even with DC fast charging. What's best practice for Tesla doesn't necessarily apply to every other BEV.

You should take into consideration the recommendations from the car maker.
 
What you should do is not worry about it at all

When your car is 15 years old and has half a million miles on it someone will be pissed off at your for not being nice to your battery

If you keep the car plugged in all the time, it should not be charged to 100 percent. You shouldn't get to turtle mode every day on the ride home

Pretty much everything else is speculation based on lab tests of bare cells with no battery management or battery cooling system.

If you are heavily cycling your battery, like if you have a Mini and bring it to 20 percent or lower every single day, sure some caution is warranted as you may actually see the range drop in your ownership, but if you are driving it that much, how are you going to do that?

Worry less, drive more
 
The main things to avoid is keeping the battery fully charged or fully empty for long periods of time. Think a couple of weeks or a month or more.

If you're not using the vehicle, keep the battery charge around 50-70%.
 
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