Discharge below 50%?

[SparkyEV]

What's the conventional wisdom on deep-cycling the battery for long term health? I moved up from a 2011 with 3 bars gone to a 2016 30kWh and now I'm finding that I'm getting home with 50-60% SoC remaining. Should I be concerned about not dropping below 50% on a regular basis? Should I consider only charging every other day?

So much has changed! Until 2 days ago (when I got my 2016) I was getting home after LBW every day...

 

[desiv]

I'm probably not the one to ask about wisdom, but...

I got my 2012 used just over a year ago. It was a 12 bar car.
I commute 120 miles a day (that's the round trip; 60 miles to work).

I arrive to work around 20% each day.
(During the winter, I stop at a DCFC in the middle and add about 15%. Offsets the loss from the cold weather and heater use.)

So, bottom line, I hit under (or right around) 20% twice a day. Have been for a few months over year, 5 days a week.

Car is still at 12 bars.
Now, I'm sure there has been degradation in that time. Could be up to 14% or so and still be at 12 bars.
I didn't have Leaf Spy and/or check what I should have been checking early on, so I can't tell how much.

But at least, it's not dropping bars left and right.. ;-)
And that's with letting it get lowish a lot, charging to 100% every night, and LOTS of DCFCs...

I think the key is that I'm in the PNW. Cool weather.
I think age is going to be the primary factor for my battery...

desiv

 

[LeafMuranoDriver]

I would say charge every other day if you have enough capacity.

 

[GRA]

What's the conventional wisdom on deep-cycling the battery for long term health? I moved up from a 2011 with 3 bars gone to a 2016 30kWh and now I'm finding that I'm getting home with 50-60% SoC remaining. Should I be concerned about not dropping below 50% on a regular basis? Should I consider only charging every other day?

So much has changed! Until 2 days ago (when I got my 2016) I was getting home after LBW every day...

I wouldn't worry about it (there's no memory effect), but it wouldn't hurt if you were to set your charge timer so that you had ca. 80% before you left for work. The consensus of evidence/opinion is that a generic Li-ion chemistry is happiest and will last longest if kept between 30-80% SoC. Deep cycling below 20% on a regular basis isn't to be recommended, nor is leaving the battery at 100% for more than a few hours, but other than that most variables probably fall into the noise and are swamped by normal variation.

 

[arnis]

In hot weather there is some advantage not starting charging immediately (from 50% to 80%).
First of all don't charge before midnight and switch to dual tariff meter. Night electricity costs less.
And you can set 80% end timer before night ends so for example if 7am is the beginning of
higher priced electricity set the car to finish at 7am. So it will start at 5am or after longer trips at 3am.

But in cold weather (less than 5 temperature bars) there is no difference really.
You should still charge at night to be nice to the grid and save some pennies.
Discharging below low battery warning does have some negative effects (so don't go below 20% intentionally)!

And don't use trickle charger. The faster you charge the less power is wasted on charging management.

 

[Firetruck41]

There is hidden capacity above/below the 0-100% displayed, to keep the battery from over charging/discharging, so I would not be concerned about driving down to 20%.

 

[EVDRIVER]

There is hidden capacity above/below the 0-100% displayed, to keep the battery from over charging/discharging, so I would not be concerned about driving down to 20%.

+1 . I did this for three years with no capacity loss.

 

[SparkyEV]

The 2016 model does not have the option to limit charging to 80%, which I miss. As an experiment last night, I set the end timer to 10am with no start time, but when I checked it at 8:30 this morning it was already at 100% (started at 50%). I checked my TED (power monitor for my house which has a dedicated sensor on the EVSE) and charging started at 5am and finished around 7am. Maybe it needs time to learn the charge rate.

 

[SparkyEV]

There is hidden capacity above/below the 0-100% displayed, to keep the battery from over charging/discharging, so I would not be concerned about driving down to 20%.

Is the buffer on the top end big enough to not worry about charging to "100%" on a regular basis?

 

[camasleaf]

I think it is. My wife's 2015 (a lease) spends at least 12 hours a day at 100%. She comes home, plugs it in, car starts charging.

 

[arnis]

There is hidden capacity above/below the 0-100% displayed, to keep the battery from over charging/discharging, so I would not be concerned about driving down to 20%.

0% and 100% are weighted limitations. There is no such thing as hidden capacity on Leaf. Hidden capacity is something that can
be "taken into use" by user or vehicle. But it can not. Even if battery degrades it is not used. For example GM Volt does use hidden capacity on both sides of 0% and 100%. Those limits are user accessible. Real limits are only car accessible. For example regen is possible at 100% but not charging. Voltage of the cells is something like 4V at 100%. Power is available at 0% but no electric only driving. Limit values are restored as soon as possible by running a generator or using excessive capacity for driving.

"down to 20%" and "below 20%" are not the same things.

"I did this for three years with no capacity loss." - Leaf does not support that function
Capacity is not measured in bars.

Is the buffer on the top end big enough to not worry about charging to "100%" on a regular basis?

100% state of charge is considered much more healthier than 0%. 0% is designed to be used in extreme situations (running out of charge should be temporary and rare event) having vehicle charged to 100% on the other hand is not designed to be that rare on Leaf.
For example Tesla's 100% is more than 100% on Leaf. Tesla defaults back to 90% charge if user does not switch back from range charge for days. Leaf does not do that.

Are you absolutely sure that you can not choose 80% when you set up a charging timer? Are you sure there is no "long battery mode" deep hidden in menus?

 

[desiv]

Capacity is not measured in bars.

Not sure I understand that..

How are the bars on the far right not a representation of capacity?
When someone is down do 8 bars, how is that not showing he has less capacity than someone with the full 12 bars?

Now, it's not a totally accurate capacity gauge, as the first bar covers 15% ish or so, and the rest around 10% or so.

For instance, I still have 12 bars. Doesn't mean I haven't loss capacity, I'm sure I have. So that's not too telling there..
But, compared to someone whose car is at 10 bars, a 12 bar car has more capacity.

Of course, assuming we're all talking the same scale (24kWh or 30kWh).

It is important to note the difference between the bars on the far right (what I'd call capacity) and the ones JUST to the left (what I'd call the percentage of charge of that capacity).

desiv

 

[dhanson865]

The 2016 model does not have the option to limit charging to 80%, which I miss. As an experiment last night, I set the end timer to 10am with no start time, but when I checked it at 8:30 this morning it was already at 100% (started at 50%). I checked my TED (power monitor for my house which has a dedicated sensor on the EVSE) and charging started at 5am and finished around 7am. Maybe it needs time to learn the charge rate.

I'd set a timer with no end time, and a start time 30 minutes before you normally leave. If you charge drops below 40% at any point in the day move the start time forward 10 minutes and run like that to see if it increases or decreases. If it is increasing you found the right level and can leave it there until you hit 100% one day and then shorten it by 10 minutes and run like that until you see 40% again. If it is still decreasing move the start time forward another 10 minutes to increase the charge time by 10 minutes. Keep making small adjustments to the start time until you find the level that works.

So long as you have excess range you don't need to charge exactly enough to cover your days trips. You can run a slight deficit or surplus and adjust over the long term instead of thinking about it on a daily basis.

I do similar with a 24 kWh leaf that only does 35 miles a day. I don't like to get below the charge I need for a one way trip in case I have to skip a charge session. I don't like to sit above 60% charge when I'm not charging (since a round trip will only use 40%). I try to get my >60% charge to occur right as I'm about to leave and I never charge above 80%.

Depending on your attitude towards degradation you could worry about it less than I do. Just keep enough range to make your daily trip and let the SOC% fluctuate. Avoid 100% charges if you can. Definitely don't let it sit at a full charge.

 

[Firetruck41]

There is hidden capacity above/below the 0-100% displayed, to keep the battery from over charging/discharging, so I would not be concerned about driving down to 20%.

Is the buffer on the top end big enough to not worry about charging to "100%" on a regular basis?

Seems to be debatable on this board, but I always charge to 100%, in my mild climate my battery has stayed at ~86% SOH since I bought it 6 months ago.

 

[DaveEV]

Seems to be debatable on this board, but I always charge to 100%, in my mild climate my battery has stayed at ~86% SOH since I bought it 6 months ago.

All known studies show that keeping the average SOC of a lithium battery does in fact reduce the rate of capacity loss. I was pretty diligent about charging only to 80% and then topping off as late as possible for the first 4 years of my LEAF and now as a result it appears that I will just miss the capacity warranty when most others around here who were not so diligent (or changed their charging habits sooner) will make the capacity warranty.

So I think there's good evidence that it makes a noticeable difference all else being equal. It just doesn't make as much of a difference as moving the battery to a significantly cooler climate.

 

[RonDawg]

In hot weather there is some advantage not starting charging immediately (from 50% to 80%).
First of all don't charge before midnight and switch to dual tariff meter. Night electricity costs less.
And you can set 80% end timer before night ends so for example if 7am is the beginning of
higher priced electricity set the car to finish at 7am. So it will start at 5am or after longer trips at 3am.

But in cold weather (less than 5 temperature bars) there is no difference really.
You should still charge at night to be nice to the grid and save some pennies.
Discharging below low battery warning does have some negative effects (so don't go below 20% intentionally)!

And don't use trickle charger. The faster you charge the less power is wasted on charging management.

Arnis, a couple of things:

1. Not everybody in the US has access to a Time of Use plan in which cheap(er) night charging is offered in exchange for a high daytime rate. And for those of us who have it as an option, it's not necessarily the most economical one. For example, my local utility's ToU plan is only slightly cheaper at night than the regular plan, but MUCH more expensive during the day. People who work a night shift, or have family members who are at home all day (such as retired workers, or stay at home parents) would often not benefit from such a plan.

2. For US and Canadian market Leafs, Nissan removed the long-life (80% charging) feature starting with model year 2014.

 

[arnis]

Thanks for information.
Nr2 is really weird. Looks like American weird laws are responsible for that s*it.
So what about Tesla. It has charge limit 50% to 100%. Law is just stupid enough to
not apply there? :lol:

To fix that "facepalm" Nissan could just rename 80% charge to "storage mode".

In Europe there is two ways to activate 80% limit, either 80% long battery life mode in
settings or via charging timer charge percentage. Both of them are removed in US?

 

[GRA]

Thanks for information.
Nr2 is really weird. Looks like American weird laws are responsible for that s*it.
So what about Tesla. It has charge limit 50% to 100%. Law is just stupid enough to
not apply there? :lol:

To fix that "facepalm" Nissan could just rename 80% charge to "storage mode".

In Europe there is two ways to activate 80% limit, either 80% long battery life mode in
settings or via charging timer charge percentage. Both of them are removed in US?

The reason Nissan removed the 80% setting is because it was 'recommended' for long life, so the EPA took the max range at both 80% and 100% and averaged them for the EPA sticker, giving the 2013 LEAF an EPA range of 75 miles (versus the 2011-2012's EPA range of 73). Getting rid of the 80% charge meant that they were able to claim the range at the full 100% charge, or 84 miles EPA. The RAV4 and B-class were also subject to this range averaging stupidity. Tesla, because it allowed any setting between 50% and 100%, wasn't, possibly because they didn't actually say that a 'normal' charge (ca. 90%) was better for the battery than a 'range' charge - it's always been a little murky why they were able to avoid this. If you think that's dumb, you should read the threads on the i3's crippled range extender and fuel capacity, crippled solely to meet a CARB requirement that BMW lobbied for.

 

[rcm4453]

What's the conventional wisdom on deep-cycling the battery for long term health? I moved up from a 2011 with 3 bars gone to a 2016 30kWh and now I'm finding that I'm getting home with 50-60% SoC remaining. Should I be concerned about not dropping below 50% on a regular basis? Should I consider only charging every other day?

So much has changed! Until 2 days ago (when I got my 2016) I was getting home after LBW every day...

I also recently got a 2016 30kwh Leaf. I charge to 100% every night because I've noticed that once I get below 50% SOC my range goes down a lot quicker then 100% to 50% SOC. I skipped charging one day and almost went into turtle mode because I assumed I'd get the same range going from 50% down that I got going from 100% to 50%. Maybe it's just my car I don't know but that second half of the battery goes quick for me. This was the same route to work I always take so it couldn't have been that.

 

[tkdbrusco]

I think it is healthy to drain the battery to a low SOC from time to time and then do a full recharge cycle. The only thing that I would actively avoid would be topping off the charge when it is already at a high SOC, such as 70% or more.