Charge timing simplified!

It's pretty simple: When you're done, you automatically add 60% to your charge state when you plug in. -OR- you hit a button to get 100% for those times when you'll need it.    Details:

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So, you're driving around in your jaunty new EV every day, and when it gets down to 20% or there'bouts on the handy battery meter (which you may have to hit some sort of menu button to see) you plug it in to your nifty home charge cord thingy and charge it. What could be simpler?

...except, you may have read that charging all the time to 100% is bad for the long term health of your battery. Keeping it between 20% and 80%, with only occasional excursions beyond those bounds, has proven to extend the life of the battery pack by a fairly large amount. Maybe even 30%, or more in hotter climates. [note that charging to 100% occasionally is actually good for it.]

"Does that mean I'm supposed to go out and remember to unplug the blasted thing at 3:AM?

Nope, there's a much simpler solution: All the EV's that we're aware of have either a charge limiting setting (Tesla's and Chevy Bolt's)  or, almost equally useful, a charge timer setting. This includes, but is not limited to Mitsubish'is, Nissan's, VW's, Kia's and some home chargers that have cellphone control apps.

Lets use the Nissan Leaf as an example since there's more of them out there than anything except Tesla. All of the above have a way to set a 'default' charge time, and generally a way to defeat that timer limit when necessary.

Here's how I did it, your mileage may vary:
The first time I got the car down to 20%,  I didn't actually plug it in until Saturday (which luckily just happened to be the next day) around 7:AM. At 1:PM it was up to 50%. By 7:PM it was at 80%, so I concluded that "12 hours of charging, on this car, with this charger equals a 60% gain in charge." where 20% to 80% is a gain of 60% eh?
With me so far? 
So, I want into the menu system on the car (after digging around in the manual) and found where to set the charge timing. I diddled the buttons to set the START time for 8:PM  and then set the STOP time for 8:AM. It took a couple times to get it right, and then I had to set that 'timer' to 'ON' and 'Default' 
Now, every time I plug in it charges up an additional 60%, unless it's above 40% to begin with.
...then it charges to 100% (40 + 60) duh.

Obviously if yours charges faster or you didn't want 60%, reduce the number of hours.

"But what if I'm driving a lot tomorrow and I want 100% charge tonight?"

On a Leaf, right near to the button that you use to open the charge door on the car is a button that disables the charge timer 'this time only' which will cause it to start charging right now and charge until it hits 100% -or- you unplug it. Simple. One button that's right near the one you had to hit to open the charge door anyway. Press it AFTER hitting the 'open door' button.

On some other cars you have to get into a menu to disable (or enable!) the charge timing, but it's usually pretty easy.

As to when to do the charging, it's generally preferred to have the charging finish up just a little while before you hop in and take off. This minimizes the time it sits at a high state of charge.
"But that's only when it's hot out right?"
Actually it's also good in the depths of a northern winter. The charging process warms up the battery. They don't like really cold temperatures any more than you do.