Charging Strategy - Short Shopping Trip Leaf?

[lukati]

Thank you, everybody, for your insights.



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baumgrenze

My car park looked just like yours a few weeks ago. But then I sold my Prius.

 

[thankyouOB]

very much interesting stuff in this series of posts.
BRAVO.
i wish we had actual data from Nissan about this, instead of our educated guesses.

My basic conundrum is whether to charge beyond 80% at work, where it is free. We have both L1 and L2 available.
Basically, I could charge only at work and go back and forth.
To save 50 cents a day (charge to 100%) seems like a bad bargain. My round-trip is 50 miles, and DWP rates are about 8.5 cents a kWh.
So, I typically charge to 80% at home (10 bars), run down to 6 bars going to work and recharge to 80% for the trip home.

 

[DaveinOlyWA]

very much interesting stuff in this series of posts.
BRAVO.
i wish we had actual data from Nissan about this, instead of our educated guesses.

My basic conundrum is whether to charge beyond 80% at work, where it is free. We have both L1 and L2 available.
Basically, I could charge only at work and go back and forth.
To save 50 cents a day (charge to 100%) seems like a bad bargain. My round-trip is 50 miles, and DWP rates are about 8.5 cents a kWh.
So, I typically charge to 80% at home (10 bars), run down to 6 bars going to work and recharge to 80% for the trip home.

its free juice, i would do it. time it so its 90%+ when you get off work. like plug it in at lunch or during your afternoon break. if using L2 should only need 3 hours at most to charge. if using L1 you could almost plug it in when you get there in the morning. this also allows someone commuting from farther out to use the L2

 

[thankyouOB]

do all the gearheads agree that charging to 90% is as harmless to the battery as charging to 80%--that due to the updated firmware?

 

[Stoaty]

do all the gearheads agree that charging to 90% is as harmless to the battery as charging to 80%--that due to the updated firmware?

It's all a guess, but here are some educated guesses from an old thread that suggest that 30% depth of discharge may be significantly better thank 60% depth of discharge for preserving battery capacity over time:

http://www.mynissanleaf.com/viewtopic.php?f=27&t=5331&p=125835" onclick="window.open(this.href);return false;

Read through most of the page, paying special attention to posts by surfingslovak and ericsf.

Leaves me with one conclusion: until I know different, I want to go as easy as possible on the battery without sacrificing needed functionality.

 

[thankyouOB]

do all the gearheads agree that charging to 90% is as harmless to the battery as charging to 80%--that due to the updated firmware?

It's all a guess, but here are some educated guesses from an old thread that suggest that 30% depth of discharge may be significantly better thank 60% depth of discharge for preserving battery capacity over time:

http://www.mynissanleaf.com/viewtopic.php?f=27&t=5331&p=125835" onclick="window.open(this.href);return false;

Read through most of the page, paying special attention to posts by surfingslovak and ericsf.

Leaves me with one conclusion: until I know different, I want to go as easy as possible on the battery without sacrificing needed functionality.

thank you for this, I am reading. In your post,

so, I found depth of discharge definition via google.
given that, DOD de-optimization would seem to indicate that if you are going to use 5 bars, you get a shallower DOD if you charge to 90% and run from there to 6 bars, than charge to 80% and end up with 5 bars left.

does that work for you EEs?

 

[Stoaty]

so, I found depth of discharge definition via google.
given that, DOD de-optimization would seem to indicate that if you are going to use 5 bars, you get a shallower DOD if you charge to 90% and run from there to 6 bars, than charge to 80% and end up with 5 bars left.

My understanding is that the best for the battery is to shallow cycle it and keep the charge from getting too high or too low. So for a 30% cycling, 40-70% would be the optimal range. We know that charging fully (especially at high temperature) is less than optimal, and also that fully discharging the battery isn't optimal either.

 

[planet4ever]

My understanding is that the best for the battery is to shallow cycle it and keep the charge from getting too high or too low. So for a 30% cycling, 40-70% would be the optimal range.

Why wouldn't 35%-65% be even more optimal? Based on Tony's chart, which I trust, 36% to 66% would be 3 bars to 7 bars. Here's the way I look at it for optimal cycling:

30% - 7 bars to 3 bars
40% - 8 bars to 2 bars
50% - 9 bars to 1 bar
65% - 10 bars to Low Battery
80% - 11 bars to Very Low Battery

Of course 12 bars to Turtle would be 99%, but that's hardly optimal cycling.

Personally, I aim for a 60% range: 80% charge (9.7 bars) to 20% charge (shortly below Low Battery). In my car, Low Battery comes pretty reliably at GOM=8, so I try to get home with one bar still showing, and before GOM drops to single digits.

Ray

 

[DaveEV]

My basic conundrum is whether to charge beyond 80% at work, where it is free. We have both L1 and L2 available.
Basically, I could charge only at work and go back and forth.
To save 50 cents a day (charge to 100%) seems like a bad bargain. My round-trip is 50 miles, and DWP rates are about 8.5 cents a kWh.
So, I typically charge to 80% at home (10 bars), run down to 6 bars going to work and recharge to 80% for the trip home.

Just because it's "free" to you, does not mean that it's that's the best time to charge. Charging at work during the day (especially in the afternoon) means charging when electricity rates are highest and the least efficient power plants are running. Personally, I would just charge to 80% at both work/home with a 24-hour charging time frame and forget about it. This gets you charged back up to 80% before lunch when grid loads are low and minimizes depth of discharge for your driving.

If you want to maximize your charge at work, I would instead change your charge end-time to 2-3 hours past your scheduled departure time on weekdays (will take a bit of fine tuning to get the end-charge right - figure about 45 minutes per bar to start with). That should get you to work with ~2 bars remaining.

 

[Stoaty]

Why wouldn't 35%-65% be even more optimal? Based on Tony's chart, which I trust, 36% to 66% would be 3 bars to 7 bars. Here's the way I look at it for optimal cycling:

30% - 7 bars to 3 bars
40% - 8 bars to 2 bars
50% - 9 bars to 1 bar
65% - 10 bars to Low Battery
80% - 11 bars to Very Low Battery

That is getting to be too much work, even for me. Also, remember that it is time and temperature at higher charge that is less than optimal for the battery. I charge to 80% starting at 4:30 AM to a bit after 7:00 AM. When I get to work I am down to about 60% charge, so the higher SOC is only about 1.5 hours, and this also occurs when temperatures are lower. Cycling between 80% and 35% by the Gid-o-meter for my normal work commute also leaves me additional wiggle room in case I need to go somewhere else, and for about 20 hours per day the battery is in the range of 35-65%. On weekends, I don't charge to more than 8 bars, since I don't drive as much. This plan is:

1) Near optimal for the battery
2) No trouble for me to implement
3) Easy on the grid since my charging is done at times which are low usage

 

[lukati]

Here's the way I look at it for optimal cycling:

30% - 7 bars to 3 bars
40% - 8 bars to 2 bars
50% - 9 bars to 1 bar
65% - 10 bars to Low Battery
80% - 11 bars to Very Low Battery

I use my LEAF almost exclusively for commuting during the week, with both 25 mile legs requiring about equal energy and no charging at work. With this scenario, there is a simple way to optimize battery use: arrive at work with a SOC of about 50%.

You are at 50% SOC when the time to charge (in the dash display) is ~8.5 hours (charging to 80%) or ~12.5 hours (charging to 100%).

 

[jhorgelinkin]

I also do a variation on a partial charge: when I come home almost empty I want to charge a bit to put the battery pack back into the middle range, so I just charge via override for an hour or hour and a half by setting a kitchen timer. Then I unplug/replug and allow the car to go back to the 80% timer set for midday, so that I can use my solar power directly on sunny days (or middle of the night if it is cloudy). If I am already in the middle of the battery pack and don't need the range I will skip charging entirely.

I'm going to have to remember Stoaty's 25 minutes-per-bar rule-of-thumb. That's helpful.

Thats really great work! Its quite helpful to use solar power on sunny days. I will definitely work this on, thanks for sharing with us and keep posting!

 

[Herm]

Personally, I aim for a 60% range: 80% charge (9.7 bars) to 20% charge (shortly below Low Battery). In my car, Low Battery comes pretty reliably at GOM=8, so I try to get home with one bar still showing, and before GOM drops to single digits.

I like the way you do it, it must be a coincidence how Nissan helps you to do it just that way.. they give you an 80% charge setting and just drive until all the warnings start screaming.

65% seems to be the magical number used by GM, Hyundai and Toyota for cycling their batteries.

 

[paulchurchley]

I have taken the view that I bought the car from Nissan and trust that they have built the car to look after the battery as much as possible so I just charge when I need to. I realise that I might get a bit more life out of the battery over a number of years by following the kinds of charging strategies mentioned here but I feel that the savings are minimal at best and I have better things to think about than worrying about when to charge, stop charging etc.

I set the timer to stop at 80% and it charges everyday unless I didn't use the car that day. If I know I have a longer trip next day I charge to 100%. If I need to fast charge, even several times a day, then I do but I do keep an eye on battery temps.

I have had the car a year and done 11,000 miles and so far range has not reduced any noticable amount.

 

[saywatt]

+1

I have taken the view that I bought the car from Nissan and trust that they have built the car to look after the battery as much as possible so I just charge when I need to. I realise that I might get a bit more life out of the battery over a number of years by following the kinds of charging strategies mentioned here but I feel that the savings are minimal at best and I have better things to think about than worrying about when to charge, stop charging etc.

I set the timer to stop at 80% and it charges everyday unless I didn't use the car that day. If I know I have a longer trip next day I charge to 100%. If I need to fast charge, even several times a day, then I do but I do keep an eye on battery temps.

I have had the car a year and done 11,000 miles and so far range has not reduced any noticable amount.

 

[ERG4ALL]

I was told by Nissan Tech that the degradation of the battery being charged to 100%, or "topped off" as they put it, is the amount of time that the battery sits while it's at 100%. Thus, if you need 100% it is better to top it off just before you are going to use the car. I was setting it the night before and so the car would sit for several hours before I used it. I've now changed that procedure.