Charging the battery to 100% with 110 volt charger harmful??

The title says it! I charge at night at home with a 240v charger, and follow the advice to stop at 80% capacity. But at work during the day, I just plug the car into the 110v outlets provided for electric cars, and let it go all the way to 100%. Why turn down free electricity? But now I am wondering if I am being penny wise and pound foolish. Will charging to 100%, even at 110v, hurt long term battery capacity?

Thanks,
Reza

Harmful is a strong word. We think that 100% charges might hasten battery degradation, but time spent at 100% matters, and you may only be spending a couple hours there. As far at 120v goes, 100% is 100% whether you charge with L1 or L2, there's no real difference. If you don't need 100%, I'd stop at 80%.

I can give you another reason to turn down free electricity. Sometimes plugging in at work is a rather hard won privilege, and some folks have had people get rather nasty about their coworkers getting "fuel for free". Personally, if I had free charging available at work, I'd only use it if I had a need. I'd at least limit it to 80% as I do at home. Not criticizing you, just a thought.

davewill said:

I can give you another reason to turn down free electricity. Sometimes plugging in at work is a rather hard won privilege, and some folks have had people get rather nasty about their coworkers getting "fuel for free". Personally, if I had free charging available at work, I'd only use it if I had a need. I'd at least limit it to 80% as I do at home. Not criticizing you, just a thought.

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Pretty good advice. People can get a bit testy about someone getting free fuel.

I frequently visit a model airplane flying club that I belong to. While I have never heard anyone complain about members spending a couple of days at the field with their RV plugged in and air conditioner running, I have heard subtle digs about charging my LEAF.

Or you can join my "say no to 80% charging" club. I have at least 1 follower...

I have been charging exclusively 100% at night and less daytime when we have no time to wait for juice and need to drive the car.

We have racked up 26,800 miles over 15 months and have NO loss of capacity, i.e. we get 73 freeway miles with every charge (more in town). Temperate weather, no AZ heat, cool at night (45-65).

I have said it many times: not charging 100% makes the battery "shrink" i.e. lose its "willingness" to charge up to 100% after being charged to 80% over and over. The electrical tendons. Gotta keep them pliable. Make sense?

All experts on the site disagree with me. I'll keep reporting on this and I'll be the first to report any loss of range or, god forbid, loss of capacity bar(s).

ILETRIC said:

All experts on the site disagree with me. I'll keep reporting on this and I'll be the first to report any loss of range or, god forbid, loss of capacity bar(s).

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Please continue your field research. I'm sure it's appreciated, the extended Leaf community has still much to learn and discover

rtaheri said:

The title says it! I charge at night at home with a 240v charger, and follow the advice to stop at 80% capacity. But at work during the day, I just plug the car into the 110v outlets provided for electric cars, and let it go all the way to 100%. Why turn down free electricity? But now I am wondering if I am being penny wise and pound foolish. Will charging to 100%, even at 110v, hurt long term battery capacity?

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I believe there was an older thread on this. All I could find is referenced below.

http://www.mynissanleaf.com/viewtopic.php?f=4&t=2078" onclick="window.open(this.href);return false;

I always go 100% when the power is free

Would it be possible to charge at home with 240v to less than 80%, then charge at work where it will be either 100%, or just 80% (if you choose), about the time work is over? That would solve the time spent at high charge problem, and it might turn out that you're getting more free electricity than the current setup.

They say that 240v charging isn't harmful, but I'm still of the opinion that 120v should then be even less harmful. Of course, I'm no lithium battery expert.

ILETRIC said:

We have racked up 26,800 miles over 15 months and have NO loss of capacity.

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What is your GID count?

No clue. All I can vouch for is range.

You can always schedule your second timer to charge to 100% with no start time, and with the end time set to the end of your work day when you leave. That way, the battery is not charged to 100% early and sits there for a while at 100% until you leave for work. As soon as it's at 100%, it's already time for you to leave for work, and the battery will be run down from 100% as soon as possible, so it doesn't spend any time sitting at 100% for very long. I think that'd be a good compromise so you can get the free electricity and not hurt the battery too much at 100%.

Does anyone know with a degree of certainty, how long is TOO LONG to keep the car charged at 100% at temperate (mild) temperature?

ILETRIC said:

No clue. All I can vouch for is range.

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OK, so by "NO loss of capacity." you mean the capacity loss is not noticeable to you but that you haven't measured it and it's not yet 15%, enough to trigger the first capacity loss bar.

All I know is that I get consistenly 73 freeway miles ever since my GOM was updated at the 15,000 battery checkup. We're now at 26,800 and we're holding steady.

When I get to drive the car I always zero the trip meter and keep an eye on miles traveled plus miles remaining on the GOM (while on level surface at a constant 65 mph) and it's nice and consistenly over 70 miles range total. Anything below 70 would mean to me I'm losing capacity.

So far - nada.

I think charging to 80% (since 100% actually means 87.5% as someone wrote on the site) is doing the battery a disservice and basically shrinks its capacity -- even in moderate temp environments. I am not a sheep. I don't follow what everybody says if I feel that there might be a problem with it. We will compare notes in the future. That's for sure.

ILETRIC said:

I think charging to 80% (since 100% actually means 87.5% as someone wrote on the site) is doing the battery a disservice and basically shrinks its capacity -- even in moderate temp environments. I am not a sheep. I don't follow what everybody says if I feel that there might be a problem with it. We will compare notes in the future. That's for sure.

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I don't know where you got that "87.5%" figure. I believe that Ingineer has measured the "100%" charge at about 94-95% of the maximum, the 80% is really 80%, and shutdown is about 2%:

Ingineer said:

FYI, a "full" charge is typically around 94-95% SoC, while an 80% charge is actually to 80% SoC. My last "full" charge stopped at just over 94% SoC which was 278 "Gids" or 22240 watt-hours. Also keep in mind, the battery contactor opens at around 2% SoC, so you only get about 92% usable per full charge. I've calculated that 100% SoC (if you could reach it) would be 23512 watt-hours. (on my car anyway) Knowing the top ~5% (1176wH) and the bottom ~2% (470wH) can't really be used, that leaves 21866wH actual usable from "full" to turtle, and 18340wH usable from 80% to turtle. Since there is a significantly wide variation from one "full" charge to the next, it's not an accurate test to charge to full and expect repeatable results. It would be more accurate to charge to 80%.

-Phil

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http://www.mynissanleaf.com/viewtopic.php?f=31&t=8437&start=1

ILETRIC said:

I think charging to 80% (since 100% actually means 87.5% as someone wrote on the site) is doing the battery a disservice and basically shrinks its capacity -- even in moderate temp environments. I am not a sheep. I don't follow what everybody says if I feel that there might be a problem with it. We will compare notes in the future. That's for sure.

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I know you've exchanged views with more than one doubter on this forum, but I'm not familiar with the full dialog, so bear with me if any of this has already been covered.

I'm curious to know what you anticipate with regard to your future battery performance, assuming you continue charging to 100%. Do you expect no loss of capacity at all? Do you expect some loss, but less than most of those who regularly charge to 80%? Some other scenario?

I admit to having some fascination with a person who seems utterly unpersuaded by the laws of physics or chemistry, at least as they have been demonstrated with respect to current lithium battery technology. I'm also curious to know what you do for a living (but will not be offended if you choose not to share that information). Again, this may already have been asked, but where do you live (for determining relevant climate information only)?

However unpopular your theory of battery life extension may be, there is no doubt many of us must envy the performance yours appears to be providing you.

ILETRIC said:

Or you can join my "say no to 80% charging" club. I have at least 1 follower...

I have been charging exclusively 100% at night and less daytime when we have no time to wait for juice and need to drive the car.

We have racked up 26,800 miles over 15 months and have NO loss of capacity, i.e. we get 73 freeway miles with every charge (more in town). Temperate weather, no AZ heat, cool at night (45-65).

I have said it many times: not charging 100% makes the battery "shrink" i.e. lose its "willingness" to charge up to 100% after being charged to 80% over and over. The electrical tendons. Gotta keep them pliable. Make sense?

All experts on the site disagree with me. I'll keep reporting on this and I'll be the first to report any loss of range or, god forbid, loss of capacity bar(s).

Click to expand...

there very well could be a method to your madness. a lot of motors thrive on near constant or heavy use. remember one of the degrading factors is time.

i have always wondered assuming good weather/temps how much different the degradation would be with someone who drove 80-100 miles a day charging twice a day to 100% but never having it at 100% much more than a few hours verses someone who averages say 20 miles a day.

over time would the difference be significant enough to park the LEAF for gas option? I wonder because TaylorSF is in the former category. he has a 65 mile one way commute and charges to 100% on L2 twice a day. he is up to 53,000 miles after about 14 months or so and says he has "some" loss but is still doing that 65 miles on the highway

now, up to this past spring, i rarely charged to 100% but since then, i now average 100% 3-4 times a week. i am guessing i have maybe 2-4% degradation of range per GID count. i dont know what loss i have as far as usable range since i feel that running to very low SOC is worse than charging to 100% but who knows?? could be my Lead Acid experience talking...

but the other thing is that why chance running low enough to generate concern if i dont have to? even when i was working at job that was a 50 mile RT commute. i got home with 30-35% SOC remaining so i could have done 80% charging and made it but why cut it that close? having that extra gives me the leeway to side trip it for any unexpected things that life tends to throw at me.

ILETRIC said:

Does anyone know with a degree of certainty, how long is TOO LONG to keep the car charged at 100% at temperate (mild) temperature?

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short answer; no. most feel up to 4-8 hours is more than fine.

my feeling is not letting car sit at 100% thru a relatively large temperature swing. the pack temp changes the internal resistance which is why (i think) that they dont actually charge to 100%.

so if you charge at night, the pack is relatively "cooler" but heats up a bit during charging, so BMS stops charge a bit before 100% to insure no overcharging is caused by thermal changes.

then the charge is completed at 4 am when its cool, the Sun rises, the pack starts to heat up and then you run a risk of overcharging without being plugged in?

ya, i know its a stretch but in extreme temp situations...

luckily the pack seems to be well...insulated. sealed up, slow to dissipate heat which has kinda backfired i think

http://daveinolywa.blogspot.com/2012/10/longevity-verses-safety.html" onclick="window.open(this.href);return false;

The downside of charging to 100% at 120 V could be that more time would be spent at a higher SOC, since you would have to start charging earlier to reach 100%. This assumes the use of an "end timer" whereby you tell the car when you want it to be done charging. I suspect this was discussed at length elsewhere, though...

Thanks, everyone, for the detailed responses. I think I have learned something new: it isn't the process of charging to 100% that is the problem, it is sitting idle at 100%, right? If so, I might have the best of all worlds: I charge at home to 80% at nights. After my 22-mile commute to work, which is almost exclusively on the highway, I am down to 5-6 bars. I plug into the 110v, which charges at the rate of around 6% per hour, right? Well when I come back after 8-10 hours, I am either at 11 bars, or had just finished charging. So the car never sits at 100% for more than an hour or so. It sounds like this is an OK situation, right?

Thanks a lot,
Reza

Correct, the less "sitting" at 100%... the better.

But it's easier to just recommend 80% "for the masses"... since you are bound to see less savvy folks leaving their car at 100% for days at a time, maybe even in hot weather. :?