Joining the 80% Club

[TomT]

Technically, both L1 and L2 are trickle charging based on the C value of the battery...

Another possible reason is the efficiency of trickle charging is much less than that of level 2 because of all the static overhead required to charge is running for much longer.

 

[ebill3]

I am quite sure L1 charging is not detrimental. It is a use thing. Consider a person who has an eight hour work day and a commute that requires using near full battery capacity. Add a couple of hours travel time, and there are not enough hours in the day to be able to L1 charge and use the car every day.

Small point, but I sure wish Nissan did not use the term "trickle charge" for the 120 volt L1 charge. To the best of my knowledge, trickle charge is normally used to describe a charge rate that is just sufficient to replace capacity lost due to self discharge. For example, emergency lighting systems in public buildings - they are on trickle charge.

Bill

 

[jwatte]

Based on all this data, should I be plugging in L1 at the office every day to prolong my battery life? I'm in the 80% club every day except Friday. Generally, I go 100% on Fridays because I'll go far, and also top up during the stay at the office on those days, but not most other days. I'll go from 80% to about 25% going there and back on a normal day, so if I topped up, would I be gentler to the battery?

Also, is there some way to trickle only up to 80%?

 

[Stoaty]

Based on all this data, should I be plugging in L1 at the office every day to prolong my battery life? I'm in the 80% club every day except Friday. Generally, I go 100% on Fridays because I'll go far, and also top up during the stay at the office on those days, but not most other days. I'll go from 80% to about 25% going there and back on a normal day, so if I topped up, would I be gentler to the battery?

No, 80% to 25% is pretty much ideal for using the central 50% (55% actually) of the battery.

Also, is there some way to trickle only up to 80%?

Yes, you can do it by setting one of the two charging timers to only charge to 80%.

 

[rwherrick]

There has been much talk here about 80% charging vs. 100% charging, but other than the fact that Nissan "recommends" the 80% level, I have seen no information that tells me what kind of tradeoff I am making if I charge to 100% each time.

There is some indication that when the Leaf is charged to full 12 bars, the battery is about 90% full. Likewise, when the Leaf stops dead after crawling in turtle mode, the battery likely still holds about 10% charge. These are approximations, since Nissan does not publish actual numbers, but this would roughly correspond to a 80% depth of discharge cycle (DOD). Should that be the case, then anyone charging from 0 to 12 bars is already doing pretty well. However, it would be better to shallow cycle the battery. How shallow a cycle you ask? As shallow as your usage patterns allow. A 50% DOD cycle, often referenced in the literature and achieved by keeping the battery between 2 to 10 bars, can prolong battery life by a factor of three when compared to a full 100% DOD cycle. It's roughly a difference between driving 50K miles or 150K miles on one battery pack. This is well worth doing.

There was a really nice post on this topic on the Tesla forum. I believe that it originated with Dan Myggen at Tesla and a lot of what's been said there is directly or almost directly transferable to the Leaf:

http://www.teslamotorsclub.com/showthread.php/3848-Tesla-Roadster-Battery-Care?highlight=battery+warranty

For what it's worth, the Engineer at Nissan that I talked to told me that only charging to 80% most of the time would roughly double battery life when compared to 100% charging every day. And he told me to stop worrying about the "memory effect". So I went from charging every other day to having it on a timer, and charging to 80% every night. He also said that I shouldn't worry about L2 charging reducing life compared with L1 charging; he said the battery is so large, and so well heat sunk to the chassis that it's not really getting all that hot except during L3 charging. Obviously, there are some people who have longer commutes who can't afford to start at 80% charge. But for the rest of us, it sounds like a good idea.

- Bob

 

[jwatte]

Also, is there some way to trickle only up to 80%?

Yes, you can do it by setting one of the two charging timers to only charge to 80%.

Well, I already have the two timers set to 80% for most nights, and 100% for Thursday nights (Friday morning). When I trickle at work, I have to hit the override button, which AFAICT always goes to 100%, unless I monitor it through the web.

That charging timer UI seriously needs some re-do. How about a weekly schedule, with 1-hour increments (or even 3-hour increments) where each increment can be set to "allow charge to X%," or "do not charge." That would be SO much easier to use -- and also fix the "you missed the turn-on-time" problem.

 

[Volusiano]

I agree that the Leaf limit of only 2 timers is very primitive. They should design the timer similar to the Blink charging station, where you can add as many timers as you want.

 

[jwatte]

Why timers at all? What you really care about is time ranges. With a timer, if you miss the start time, you're SOL and empty in the morning.

 

[LEAFfan]

Also, is there some way to trickle only up to 80%?

Yes, you can do it by setting one of the two charging timers to only charge to 80%.

When I trickle at work, I have to hit the override button, which AFAICT always goes to 100%, unless I monitor it through the web.

So with 120V charging, you need to push the 'timer off' switch? I've never used the 120, but I don't have to do that with the 240 when I charge somewhere else;it always goes to 80% (83%).

 

[jwatte]

Do you have timers on? For me, it won't charge at all, only say "connected," unless I hit the timer override button.

 

[Volusiano]

When I trickle at work, I have to hit the override button, which AFAICT always goes to 100%, unless I monitor it through the web.

So with 120V charging, you need to push the 'timer off' switch? I've never used the 120, but I don't have to do that with the 240 when I charge somewhere else;it always goes to 80% (83%).

No, that's not what he said. There's no difference between 120V and 240V when it comes to the "timer off" switch. He's only saying that the only way you can program to 80% charge is via 1 of the 2 timers (or both), and he already had it programmed for at home, so he doesn't want to mess with them for the 120V at work, and therefore he has to resort to using the "timer off" switch to activate the charging and not being able to have it automatically stop at 80% charge for him. Had he had a 240V outlet at work, he would have still faced the same dilemma anyway.

 

[Volusiano]

Why timers at all? What you really care about is time ranges. With a timer, if you miss the start time, you're SOL and empty in the morning.

Timer is the only way you can automatically restrict the charge to complete at 80%. If you turn off the timers then it'll always charge to 100%.

 

[LEAFfan]

Do you have timers on? For me, it won't charge at all, only say "connected," unless I hit the timer override button.

My 80% on/off timers are 6AM to 6AM Sun.-Sat. and it has never failed to charge even though the Blink goes on the blink with the '502' error. It just doesn't always record the charge data.

 

[LEAFfan]

When I trickle at work, I have to hit the override button, which AFAICT always goes to 100%, unless I monitor it through the web.

Had he had a 240V outlet at work, he would have still faced the same dilemma anyway.

That's what I thought, but since I hadn't tried the 120, I didn't know if it behaves the same way. So if jwatte sets up his 80% timers correctly, it should be no problem.

 

[jwatte]

Why timers at all? What you really care about is time ranges. With a timer, if you miss the start time, you're SOL and empty in the morning.

Timer is the only way you can automatically restrict the charge to complete at 80%. If you turn off the timers then it'll always charge to 100%.

Yes, but that's dumb! We were talking about a better UI for specifying when I allow the car to charge, and how much to charge it. Here's what I'd like to see:

If the car is plugged in during a time slot where it's set to a particular charge level, and the charge level is less than specified, the car charges. No "start" or "stop" times. Great flexibility on when you want to charge how much. And still a timer override button if you really need it.


Now, how would I set up my timers to get it to do this? Note: I don't have a Blink charger; I have the Ecototality Nissan-branded one that you got to order when you ordered the car back in November, even though I didn't actually get it until after the California money ran out :-(

 

[Volusiano]

]Timer is the only way you can automatically restrict the charge to complete at 80%. If you turn off the timers then it'll always charge to 100%.

Yes, but that's dumb!

I fully agree that it's dumb. For such a sophisticated car, the Leaf's timer options are primitive in my opinion. I don't see how you can set up the schedule like you want above using only 2 timers on the Leaf.

 

[jwatte]

There must be something I'm missing here.

First, I want to set these timers once, and then never change them. Fiddling with the UI of that screen after I'm where I want to go is a losing proposition.

Second, I believe that my Leaf does not charge if I'm within a particular time period, but I wasn't plugged in when the "on" time arrived -- it's an event, not a time interval.

Third, the schedule I show has a lot of "do not charge during this time" that won't work with only the two timers that are available. Especially note the Friday changes in 80% and 100% allowed schedule.

To make it very clear: I'd be happy to be proven wrong in any of my assumptions above. If the Leaf would charge when plugged in during "on" time, no matter what the "start" time, and if I was OK with charging during the blank no-charge intervals, then I would set Friday 00-18 as 100%, and the rest of the time as 80%, and it would work. But I believe that wouldn't actually work, even disregarding the time-of-day issues.

Also, my argument is that the table I posted should BE the UI. Tap on a time slot to change the setting for that slot. Or perhaps tap on a setting (0/80/90/100) and "paint" ranges of that particular setting -- now that would be something!

And if you really need better than 3 hour resolution, slicing them up into 1-hour intervals would still fit pretty well on the current screen; I think there's enough pixels for that.

 

[Volusiano]

Second, I believe that my Leaf does not charge if I'm within a particular time period, but I wasn't plugged in when the "on" time arrived -- it's an event, not a time interval.

The Leaf timer is interval-based and not event-based. For example, if your ON time is 1-5pm, but you're not plugged in until 2pm, the Leaf should have recognized that it just got plugged in during the ON interval and turn on the charger. It doesn't care that the ON event is at 1pm because it's not event-based in the first place. If your Leaf timer doesn't work like the example above, then something is wrong and you need to take it in to the dealership to take a look at.

 

[patrick0101]

Why timers at all? What you really care about is time ranges. With a timer, if you miss the start time, you're SOL and empty in the morning.

Timers can shift your energy use to times when it is cheaper AND it means your batteries spend less time in the full state. Less time above 80% is a good thing for the battery life.

 

[planet4ever]

Frankly, this discussion seems to be divided between people who have time-of-use metering at home, and those who don't, and it appears that neither of these two groups has any understanding of what the other group is trying to say, nor any appreciation of their problems.

From my perspective (a time-of-use guy) Nissan has tangled two very different requirements into one control, and there is no way that it can be made to work reasonably, no matter what you do to the user interface. In fact I'll go further. Even apart from the 80% entanglement, the only way a charge timer control is ever going to work nicely for me is if the car follows two sets of rules depending on whether it is at my home or not.

What I would like to see is:

• a percent of charge touch-screen menu that comes up automatically when I ask the charge bay door to be opened. It should have a default that I can set via an option.
• a table of times/days when charging at home is allowed. It would be independent of the first point and would apply only when the car is at its home location.

But going back to my opening statement, it's obvious that I don't understand the needs people like jwatte are expressing, because my proposals wouldn't satisfy him.

Ray