Charger timer starts too early

[Calaveras]

I recently bought a used 2016 S
When level 2 the timer is fine, finishes charging when set.
When level 1 charging at home it starts a couple hours early so it is at 100% for hours before I leave.
Any ideas?

[LeftieBiker]

They all do that. I think it's because the timer was originally using Japan's 208 volt grid to estimate times, and they never fixed the L-1 estimate for the US market. Maybe they also use less than 120 volts. 110? Anyway, set the timer to finish half an hour after you leave when using L-1 and you'll be fine.

EDIT: Japan uses 100 volts. That explains it.

[Calaveras]

I set it for two hours later and it was at 98%

[LeftieBiker]

I set it for two hours later and it was at 98%

Hmm... you have a 30 kwh pack. The known error is about 60-90 minutes early for the 24kwh pack. I winder if the original, uncorrected error got amplified by being applied to a larger pack...?

[Calaveras]

Actually a 24kw battery. If others are seeing a 90 minute error I am close to that.
I will change the timer another hour forward, because I would like to stop it before 90%.

[baustin]

There is nothing wrong with charging to 100%. In fact, it needs done regularly to balance the cells. Sitting for a couples hours at 100% is not a big deal, unless you are in a warmer climate or the car is in a hot garage. I would suggest adjusting the timer so that it finishes about 15 to 30 minutes before departure. It is best for the battery to have it between 25% and 80% while it is sitting idle during the day. If your drive to work does not get it from 100% down to 85% or less, then consider not charging every day.

[cwerdna]

Actually a 24kw battery.

Battery capacity is measured in kWh, not "kw".

kW and kWh are very different metrics. It's the same as confusing gallons with horsepower. Think of kW = horsepower, kWh = gallons.

If one charges at 1 kW (or 1000 watts) for 6 hours, 6 kWh came out of the wall. If it's at 6 kW for 1 hour, it's also 6 kWh. If it's 1 watt for 6000 hours, it's also 6 kWh.

One pays for electricity at home in cents per kWh. There are a few utilities w/residential plans where they not only bill per kWh but also have demand charges, but that's rare and complicates calculations. (Demand charges aren't unusual on many commercial plans.)

24 kWh Leaf has ~21 kWh usable battery but since charging isn't 100% efficient, it takes more than 21 kWh out of the wall to fully charge a dead Leaf.

(BTW, 1 hp = ~0.746 kW. And, many .gov sites say 1 gallon of gasoline=33.7 kWh.)