[edmondpogi]

or do i have to wait until its half-full?

 

[coneslayer]

Lithium-ion batteries, whether in your phone or car, like to be kept at a medium state of charge in order to have the longest useful life before replacement. Going down to 0% or charging to 100% are harder on them, and over time can shorten their life. So you might try to keep it between 20% and 80% most of the time. Small, frequent charges vs. fewer, larger charges doesn't really matter as long as you're avoiding the extremes. So 20 to 80% once a week, or 60% to 70% every day, is up to you. If you need to take a long trip, then of course charge to 100% -- that's what it's there for -- but try to finish as close to departure time as possible.

On the other hand, battery chemistry is always improving, to reduce the impact of low or high states of charge. And car manufacturers lie about what 100% is and keep some in reserve, so you never actually charge the battery to 100%, so it's hard to say how much it matters. But as general advice (akin to "don't redline the engine when it's cold"), I think it's best to avoid the extremes when your plans permit.

 

[Steverino]

GM has long recommended keeping the Volt, Spark EV and Bolt EV plugged in when not being driven. GM has also stated that the new Ultium batteries can be charged to 100% with no degradation.

If you have an EV from someone else, check the owner's manual instructions.

 

[hellsop]

And there's lot of small reasons to not charge much past half as a matter of efficiency in one way or another, but the important thing is to have the charge you need for the trip when you set out, so that you charging can happen at home as much as possible: that's generally the cheapest way to get electricity into the battery. "Full" covers as many unexpected circumstances as possible.

 

[CTAPRN]

For most use-case scenarios, there's little reason to charge to 100% for daily driving anyway. Example, my wife mainly uses our ID.4 - VW recommended keeping between 20-80% when possible for daily use. Her commute is 40 miles round trip. Even in winter, when we've been averaging 2.9 mi/kWh that's about 223 miles total (compared to 255 EPA estimate for my year/trim). If keeping between 20-80% for daily use, that's keeping within 60% of the battery and in these temps would be about 134 miles between charges. So, if not plugging in every day, that's plugging in ever 3 days as the extra range just isn't needed. If you really want to go all out, some recommend certain battery chemistries being best between 40-60% so you could just plug it in every day but tell your car to stop charging at 60% and to start charging when it gets below 40% and if it's not in those parameters plugging in still will help to use energy from the wall to pre-heat/cool the cabin prior to leaving so you can avoid using cabin heating/cooling during the drive to maximize range. For longer trips, as mentioned above, using hopefully shortly after reaching 100%. However, with that said, it really depends on where your first charging spot will be. If your first charger will use 60% of your battery, starting at 100% actually doesn't help you with time, because you'll be drawing energy at a slower rate from DCFC at 40% compared to 20%, so sometimes it's actually beneficial to not charge to 100% on a longer trip if you want to maximize trip efficiency. Of course, range anxiety is real, so just do what's comfortable, but generally as mentioned above, follow what the manual says. I've seen people say on many forums, "it's your car, do what's best for you" but I think that really only applies if you: a) have a lease and plan on trading up afterwards; b) you purchased but plan selling in the next 5 years when battery degradation isn't significant (dependent on miles driven). However, if you plan on owning the care past the warranty, it may be beneficial to maintain according to manufacturer's suggestions. On that, some have said, "that's what the battery is for" but even lower quality batteries on older Leafs, some people have noted that they didn't qualify for the warranty because by the time they reached the warranty limit, their battery hadn't passed the threshold of degradation to qualify. If it did, though, there's some concern that the manufacturer could look at stats from your car's computer and see that it was DCFC'd exclusively and charged to 100% every time.

Ultimately, some questions:

• Do you need the range every day?
• Does the manufacturer recommend against it?

If the answers are no, then simply setting the car to charge to 80% should be sufficient.
If you do need the range, well, you need the range...just make sure to start driving not too long after hitting 100% (you can set departure times on most EVs for charging, so easy peasy)

 

[obermd]

There's a practical issue with charging to 100%. For those of us who live on top of a hill we want some battery buffer at the top available for regenerative braking. Charging to 100% doesn't allow this.