Possibly overcharged, Leaf wouldn't start this morning

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Nov 14, 2023
I recently bought a 2019 Leaf off Carvana. I have long wanted an EV, this is my first. I've only had it a couple of weeks and am still learning.

I had a Tesla home charger installed, which unfortunately seems to charge at a faster rate than any of the charge rate estimates on the Leaf's estimates. I have not yet installed the phone app (mean to but my days have been busy lately, including having to get a new phone) so I'm reliant on the charge display screen on the Leaf telling me how many hours to charge to a certain point, I'm using the 6800 estimate. Monday (yesterday) I ran the battery down to the 30 percentile charge, and the charge timer display showed it would take 5 hours to charge to the 75% mark, and 5 more hours to get to 100%, so I felt safe setting the timer to charge for 5 hours (7 PM - midnight). I noticed the weather forecast called for frost, so I set climate timer to heat the car so it would be warm by the time I leave for work at 3:30 AM (after it should have stopped charging).

When I woke up and went out, I admit I enjoyed the sight of my car all nice and thawed for me (I've never had a car with a climate timer feature before) but it turned to a bit of a shock as I did brake + power to turn the Leaf on, and it showed I had a 100% charge. I quickly unplugged the charging cable, but the display showed a red error that the battery had no charge and EV service was required. I tried turning the car off and on a few times, but unfortunately I was forced to resort to starting my old gas car I was getting ready to sell to get to work.

I think perhaps the car had overcharged during the climate activation, perhaps this overheated the battery and prevented it from starting.

I forgot my work access badge in the Leaf. I'm a truck driver with a local delivery route, and fortunately my route for the day went past my house, so I decided to take my lunch at home to retrieve my badge, and while I was at it, I checked and the car started fine. I'm obviously not plugging it in as its at 100%, but I am putting on the climate timer again as its supposed to be frosty. I'll honestly feel a bit better if that knocks the charge down a bit when I start it.

Has the Leaf been tested to ensure the climate timer wouldn't overcharge the battery if it activates after the battery has already been at 100%? Or has that been tested and its impossible? How much would it cost to have an expert check the battery for overcharge damage?

Thank you so much for answering my question.
Welcome. You don't have to worry about a damaging overcharge - the car will only accept as much charge as it takes to reach 100%, plus a little more to equalize the battery if needed. It isn't recommended that you leave a Leaf sitting at 100% in hot weather, or leave it that way for weeks, but that's because of long term degradation of the battery, not because of any immediate damage.
Something about the combination of a timed charge and timed climate had the car in a state where it would not start in the morning, but it was able to start later. It was a nonspecific message saying it had no charge, even as the meter said 100%. A few hours later, it was able to start. About the only thing I could think of that might have cleared in that time is battery temperature. What else could it have been?

And again I did not intentionally charge it to 100%, but the Tesla home charger I have seems to charge faster than the Nissan estimated timer for the 6.6k, that plus the charge it applied from the climate timer put it to 100%, and the car would not start. It was the first time I had set the battery charge and climate timers.
If the car is left plugged in for many hours after charging ends, that can drain the 12 volt battery, and THAT can result in bizarre errors and error messages. More on charging: think of the charging cable or station as a smart wall outlet. It checks for ground faults and an unreliable power supply, but it's the car's onboard charger that does the actual charging. It's like plugging a toaster into a wall outlet at home. Just because the house can provide 240 volts and hundreds of amps, that doesn't force the toaster to use the full amount. You can stop worrying about that.
The estimated charge time on my 2019 SL Plus is always longer than it actually takes to charge. As LeftieBiker said, there is no way to overcharge the car. Something caused a glitch to create the EV system error--that should not have happened from charging, using climate control timer, and unplugging while climate control timer was active. The system error glitch was apparently cleared by the time you returned at lunch time. I would use the charge and climate control timers normally and not worry about it unless the glitch happens again.
I would get that Tesla app up and running just so you can monitor/adjust it to match the charging rate you want to provide. It's just peace of mind seeing & knowing what is going on.

As others men though, the car itself has the actual charger onboard. And it determines the charge rate.

I don't really rely on the dashboard time estimate for changing. Instead I use the Nissan Connect smartphone app to show me the HV battery SOC.
I also use the EVSE smart app to start/stop or schedule a start/stop charging event. As well as the Amp rate I want to supply the car with.

It's second nature now to charge the car at night to ~80-85%

And finally, I'd keep an eye out on the 12V battery as mentioned. That dang thing is far more likely to strand you than the HV battery is.

Enjoy your new to you Leaf!
I'm about 4 months in with a 2018 model. It's been a great experience. Fantastic bargain, in my opinion. And I'm learning a lot about EV ownership that I otherwise wouldn't have.
Based on your explanation of your situation, maybe:
1) You have a weak 12V battery.
2) Cold temperatures reduced the effectiveness of 12V battery further = no functionality on your first attempt at 3:30 AM.
3) Warmer temperature? when you returned allowed 12V battery to have enough spunk to turn the car on.

I would get your 12V battery tested. Most autoparts stores will do this for you for free.