80% Charging???

[ranss12]

So I've had my Leaf for about a week now, but I haven't felt comfortable only charging to 80% yet. My commute is 58 miles round trip, and when I leave home, the GOM says I have about 85 miles. I use 4 bars getting to work (GOM says 62 left), about 5 bars getting back home (I live at a higher elevation than where I work - GOM says 18 miles left). My question is: If I arrive home with 1 normal bar and 2 low battery bars left after charging to 100%, could I make the round trip if I only charged to 80%. I expect that as the temperature warms up, my range will increase some and I could then make the round trip after charging to only 80%, but what about now??? I live out in the country, so if I can't make it, I don't have many options since all the chargers are at NISSAN dealers in the city.

 

[davewill]

I'd say yes, you could probably make it even now. The difference between 80% and "100%" is actually less than it sounds since the car never truly charges the battery to 100% while 80% really is 80% of the battery capacity. Also, you've probably noticed that the first bar goes much quicker than most of the others. That said, I personally wouldn't use 80% if I were in your shoes...It would leave you almost no room for the unexpected. From time to time, most people run to the mall or out to lunch or to pick up somebody without preplanning.

 

[lpickup]

I'd give it a shot. First of all you've still got an extra bar of margin. But more importantly, depending on the gradient of your "to work" commute, you'll probably benefit from some regen on the way there by charging to 80% rather than 100%. So you may even arrive back home with 2 bars. Wait for a good day (no rain or wind) and give it a shot.

Even if you find that it's too close for comfort, you can always do a quick pre-charge a half hour before you leave (possibly coupled with pre-heat/cool) and that will bump your battery up from 80% to something higher. I suspect you'll be able to narrow down the exact amount of time to give you the comfort margin you're looking for.

 

[ebill3]

Even if you find that it's too close for comfort, you can always do a quick pre-charge a half hour before you leave (possibly coupled with pre-heat/cool) and that will bump your battery up from 80% to something higher. I suspect you'll be able to narrow down the exact amount of time to give you the comfort margin you're looking for.

Good plan. That will reduce anxiety and allow you to use regen braking (if needed) on your way down.

I wish there was a 90% option. I most often charged to 80%, and sometimes to get a bit of a buffer I hit the override to get more range but preserve the regen braking.

Bill

 

[lpickup]

I wish there was a 90% option. I most often charged to 80%, and sometimes to get a bit of a buffer I hit the override to get more range but preserve the regen braking.

If they simply implemented a STOP_CHARGING CARWINGS protocol command, I guarantee in 24 hours there would be 3-4 apps and web pages that would be able to accomplish this (and an arbitrary stop at X%).

 

[garsh]

So I've had my Leaf for about a week now, but I haven't felt comfortable only charging to 80% yet. My commute is 58 miles round trip...

I am in the same exact situation! I'm doing some experimenting, trying to charge slightly less than 100%, and lowering it a little every day to see if I can actually make it work down to 80%. I'm too afraid to just charge to 80% and "give it a try".

 

[DaveEV]

I use 4 bars getting to work, about 5 bars getting back home (I live at a higher elevation than where I work - GOM says 18 miles left). My question is: If I arrive home with 1 normal bar and 2 low battery bars left after charging to 100%, could I make the round trip if I only charged to 80%.

If you consistently make it back home with 3 bars left, 80% should be fine. It might be cutting it a bit close. If road/traffic is suitable, drive 5 mph slower than normal if possible to pick up some additional range. Definitely a 90% option would be ideal for you.

Do you know what your typical mi/kWh is for the trip? Reset the dash meter for a few days and see what you get - will help figure how much energy you are using over 58 miles. Do you ever need to take any detours?

One thing you can do as others have mentioned is to use the end timer to end the charge close to your departure time. This will minimize time spent at 100%, but do note that it will tend to finish charging an hour or two before your end time. You could also use the 80% timer and then manually charge before you leave as you see fit. It takes 90 minutes to go from 80% to 100%.

 

[LEAFfan]

Also, you've probably noticed that the first bar goes much quicker than most of the others.

By first bar did you mean the top 12th bar after a 100% charge or the top tenth bar after an 80% charge? For me, I always get more miles (14 is my best) from the very top (12th) bar than any other. For the 80%, it all depends on how full that tenth bar is as to how quick it goes.

 

[Ingineer]

I hope to add selectable end charge point to LEAFSCAN soon, I'll keep everyone posted.

You will still be able to manually restart charging as you can now. It may even be possible to add a "toggle" so you can also stop charging via CarWings.

-Phil

 

[lpickup]

I hope to add selectable end charge point to LEAFSCAN soon, I'll keep everyone posted.

I think I could probably live without LEAFSCAN based on its current functionality, but if this feature is added, it would definitely push me over the edge.

For the record though, what I would want is this: the ability to be able to initiate a charge to bring me up to X% SOC (via an override or some other kind of button), but then have my normal timer take over and get me up to 80 or 100% during off-peak times.

 

[planet4ever]

My question is: If I arrive home with 1 normal bar and 2 low battery bars left after charging to 100%, could I make the round trip if I only charged to 80%.

I cringe when I read statements like this. There are no "low battery bars"' there are 12 normal available charge bars. The two red bars are part of a separate battery capacity gauge which, so far as I know, still shows 12 bars for everyone all the time.

If you are unwilling to let the available charge drop to two bars, you are throwing away about a third of the battery capacity! The car will give you two low battery warnings, but the first one (that we call LBW) will come after you drop to a single charge bar, and the second one (that we call VLBW) some time after all of the bars have disappeared. And you can still travel a number of miles after you get the VLBW before the turtle lights up.

Driving between 12 bars and 2½ bars uses roughly the same amount of energy as driving between "80%" and the first low battery warning. Except - as lpickup and ebill3 have pointed out - you lose energy when you are above 10 bars because you can't recapture much while slowing down. Between 80% and LBW is the sweet spot for the battery. It charges faster, stays cooler, and ages less.

I predict that if you continue driving as you are now, with the weather as it is now, but charge to 80%, you might occasionally see and hear the first low battery warning, but that is absolutely nothing to be worried about. If you are half a dozen miles or less from home, just keep driving as you were. If you are less than 10 miles from home, slow to 55. If you slow to 45 you can probably go 15 more miles. Shucks, if you slow to 30 and hold a steady speed you could probably go 25 miles more! Worst case, you get home maybe 20 minutes later than you expected. If you slow from 65 to 55 for the last 9 miles you lose a whole 90 seconds.

Ray

 

[RegGuheert]

I hope to add selectable end charge point to LEAFSCAN soon, I'll keep everyone posted.

You will still be able to manually restart charging as you can now. It may even be possible to add a "toggle" so you can also stop charging via CarWings.

-Phil

Awesome! Since our typical trip is 25 to 30 miles with the car occassionally sitting for a couple of days and simce I am all about getting absolutely the longest calendar life out of the battery that is possible, I would use this feature to charge the car to 70%, or perhaps even 60%. That would give about a 50-mile range to allow for some margin for extra running around, etc.

But thinking of this a little further, I would probably always be fiddling with it to adjust for cold weather, etc. Since LEAFScan also has access to battery temperature data, how about a Charge-to-Useable-Capacity option instead of going to a particular state-of-charge? Essentially this would be a temerature-compensated state-of-charge setting. That would allow me to dial in, say, 10 kWh and on warmer nights it would charge to a lower state-of-charge while on colder nights it would charge to a higher value. Perhaps with programmable limits for upper and lower end (I might use 90% and 50%, personally).

With such a feature in place, I could set up my LEAF for approximately 50 miles of daily range and it would go to a very high state-of-charge during those 15-degree winter nights, but the battery would tend to sit around 50% to 60% when it is soaking in 95-degree temperatures during the hottest part of the summer, thus minimizing wear on the battery.

I also think such a capability woul help out the OP with his issue.

So, what say you, Phil? Is this a possibility?

 

[ebill3]

Ray (planet4ever) has on occasion recommended that LEAF'ers ought to purposely go to LBW to experience what is available. I concur.

I hit LBW for the first time yesterday less than a half mile from my garage and decided to cruse around the local area to see what happens. I drove around at 30-40 MPH. VLBW showed up 11.2 miles after LBW. I parked in the garage at 14.3 miles from LBW, still no turtle. I was going to drive around in my ghetto until turtle, but since the speed limit is 10 MPH, it wouldn't tell me much.

Obviously, your results may differ.

Bill

 

[KJD]

In the Nissan web chat a couple of days ago there was this statement.

Mark Perry: To maximize your battery health you should try to stay between 20-80% state of charge. You aren't hurting the battery if you go to 100% or drop below 20% but after 10 years of use you may see a bit more gradual loss of capacity

It seems to me that this is good advice. My commute is short so most of the time I only charge to 80%. However when my wife drives the Leaf her commute is longer and she likes to go out for lunch so then I charge to 100% with timer set to finish at 7AM. I would rather have the car at 100% SOC for a short period of time than worry about her not making it home one night.

In the years prior to owning a Leaf I used to build EV conversions. Several of the EV builders in this area had Lithium packs and they all said that for Lithiums to have a long life you wanted to avoid discharging down to near zero. Most of them made an effort not to go below 20% state of charge.

Have you guys ever thought that driving all the way to Turtle mode might be stressing your battery pack ?

 

[garygid]

If there is ANY question of Range, just charge "to 100%" (of usable). As you get more experience with your car, you will become better able to judge what "works", and you will begin to find out how much "unused" fuel you have, and your "comfort zone" will grow. But on new destinations, going exploring, etc. just start with a "full tank".

If the "80% charging" works easily for your needs, use that. Generally, there is no benefit from charging to anything less than 80% (unless starting the trip by going DOWN a lot).

In a "new-battery" car (with up-to-date firmware), the LBW occurs near the bottom end of the lowest Fuel-Bar. As the battery capacity "gradually" decreases, I suspect that the LBW will occur gradually higher in the Fuel Bars, since (I believe that) the fuel Bars will "shrink" (each represent less fuel). The 12 Fuel-Bars will still represent a "full" tank, but the "tank" will have shrunk in size (less capacity).

Generally using up most of the last (bottom) Bar is no problem, and going lower on occasion is OK, but it can be a bit un-nerving to have no more visible "fuel" or Range (GoM is "---") information. Yes, the VLBW is still available as a "hint", but our SOC-Meter (which shows the car's estimate of the remaining usable energy, or fuel) has been helpful to many.

When it becomes available, the LEAFSCAN should be able to display "the same" information.

 

[Stoaty]

Generally, there is no benefit from charging to anything less than 80% (unless starting the trip by going DOWN a lot).

I don't think we have the data to back up that statement. In our previous discussions, similar battery chemistries have shown a significantly less degradation over time when using shallower depth of discharge. In the absence of any data, I think it is safer to assume that it may make a difference for the Leaf also. Thus when I am not driving much on a weekend, I cycle between 40% and 60% SOC. Of course, I don't hesitate to charge to 80% or 100% if I need it.

 

[garygid]

No data to the contrary either.

 

[Stoaty]

No data to the contrary either.

Agreed.

 

[Herm]

My guess is that going into the low end of the battery wont hurt anything.. usually the battery will generate more waste heat at low and high SOC (both charging and discharging), but there are 600lbs of thermal mass and a watchful BMS to moderate things. It would be nice to see some actual temperatures.

 

[surfingslovak]

No data to the contrary either.

I would beg to differ. While the anecdotal evidence we are seeing points to minimal cycling losses, and we might see high-mileage cars with little capacity degradation, storing the battery at a high state of charge will lead to more pronounced gradual capacity loss. If the car is driven regularly and frequently, it might not spend enough time at this potential for us to see material difference.

However, based on lab reports and commonly accepted practices, you can be sure that cycling the battery between 40 and 60% in a temperate climate will maximize its useful life. Likewise, we would expect a battery, which has spent more of its life at a lower average state of charge, to retain more capacity. This is commonly used in both military and space applications, which depend on the longevity of their batteries.

Obviously, we don't live in a lab, and things are a bit more wiggly in the real world. The Leaf has only been out for a year or so, and we don't have a large and conclusive body of data to base our decisions on. However, this does not mean that some common principles don't apply to us or that the Leaf was somehow exempt from them. I had to cringe yesterday when an experienced and prominent EV driver gave a novice the advice to charge his car to 100% before going on a four-week vacation. (This happened outside of this forum, in case you were wondering.)