Optimal Portion of Battery to Use for Longest Battery Life?

I am trying to maximize my battery life--already doing the usual things (always charge to 80%, slower acceleration, store at 50% state of charge for non-use periods of a week or more). Recently I changed my charging start time from 1:00 AM to 4:00 AM so the battery would spend less time at higher states of charge. Takes about 2:40 minutes to charge after my daily commute, so I still have almost an hour leeway before leaving for work. While I don't know how much difference these steps will make, they are easy and painless, so I figure I might as well do them.

My typical commute uses 6 bars (10 -> 4 bars currently), and the distance never varies by more than a couple of miles. Assuming I can figure out how to do it, would I be better off cutting the maximum charge to 8 bars and driving 8 -> 2 bars? I realize that we have no data to answer this question specifically for the Nissan battery, but figured that info re: similar battery chemistries might yield some insights. Any speculations welcome.

I think the bottom line is that none of what you discussed will really have any appreciable affect on battery life or capacity. I think all that really does have an appreciable effect is not constantly charging or topping up to 100 percent, not leaving the battery fully charged for many weeks at a time, and not doing too many QCs...

Stoaty said:

I am trying to maximize my battery life--already doing the usual things (always charge to 80%, slower acceleration, store at 50% state of charge for non-use periods of a week or more). Recently I changed my charging start time from 1:00 AM to 4:00 AM so the battery would spend less time at higher states of charge. Takes about 2:40 minutes to charge after my daily commute, so I still have almost an hour leeway before leaving for work. While I don't know how much difference these steps will make, they are easy and painless, so I figure I might as well do them.

My typical commute uses 6 bars (10 -> 4 bars currently), and the distance never varies by more than a couple of miles. Assuming I can figure out how to do it, would I be better off cutting the maximum charge to 8 bars and driving 8 -> 2 bars? I realize that we have no data to answer this question specifically for the Nissan battery, but figured that info re: similar battery chemistries might yield some insights. Any speculations welcome.

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I don't actually own a LEAF yet, but have been reading to learn all I can. I think by setting an end time on your charge cycle, the car will "time" the charge such that it starts its charge as late as possible. IOW :

1. Say you need a 40% charge to 80% every night based on your commute.
2. The LEAF calculates it takes 2 hours to do so
3. Your end charge time is set to 8AM (no start time needed unless you have TOU)

It will start charging at 6AM thereby leaving the battery at a lower SOC for a longer time. As an engineer, I would do this to ensure longer battery life.

Someone please correct me if I'm wrong.

-Alex

DurkaDurka said:

I don't actually own a LEAF yet, but have been reading to learn all I can. I think by setting an end time on your charge cycle, the car will "time" the charge such that it starts its charge as late as possible.

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That would be a good way to do it, except others have reported the actual end of charging to be hours earlier than the end time specified.

My take is:
Try to avoid 100% charge, 80% is good.
Stay away from the turtle.
For extended (?) storage, about 50% charge - certainly less than 80%.

Bill

Stoaty said:

DurkaDurka said:

I don't actually own a LEAF yet, but have been reading to learn all I can. I think by setting an end time on your charge cycle, the car will "time" the charge such that it starts its charge as late as possible.

Click to expand...

That would be a good way to do it, except others have reported the actual end of charging to be hours earlier than the end time specified.

Click to expand...

Well, THAT sucks. Guess I'll have some fiddling to do whenever the car finally gets built and in my garage. Will have to figure out the ideal end time so it finishes charging right when I leave. My drive to work is the same every day, so I should be able to time it just right.

-Alex

Also relevant to this thread is this link (posted on another MNL thread) about optimal battery care for the Tesla roadster:

http://www.teslamotorsclub.com/showthread.php/3848-Tesla-Roadster-Battery-Care" onclick="window.open(this.href);return false;

I wonder if battery balancing happens at the end of 80% charging in the Leaf, or just at 100%. For the Tesla, it happens at the end of charging in "standard" mode, which is an 87% charge. I assume it depends on when Nissan decides to run the balancing.

A couple of quotes from the Tesla thread:

"Allowing the car to sit plugged in after it has finished charging in Standard mode automatically balances the pack, and it may take a few rounds of this to bring an imbalanced pack back to its full potential after many partial charges. This is one of the major reasons we recommend keeping the car in Standard mode whenever possible. Partial charges in any mode, while not on their own bad for the battery, do not give the car an opportunity to balance its battery, and over time can prevent you from accessing the car’s full range potential."

"Think of battery degradation this way. It is very much a function of time spent at voltage and temperature. For instance, you do not want to charge a car all the way in performance mode, and then let it sit in the sun all day. Between the higher thermal limits and the high SOC, you are causing the battery a relatively high amount of degradation .In fact, the car will eventually allow itself to discharge to Standard levels if left in Performance mode to prevent inadvertent damage to the battery. If you start driving right away after charging in Performance or Range Mode, and don’t let it sit, you would minimize the damage incurred, as the time spent at these extremes is an important part of the calculation."

mogur said:

..., and not doing too many QCs...

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Manuals has quite a bit on QC. Nice they spend a lot of time on that quality as well.

LI-ION BATTERY LIFE
* Use the normal charging or trickle charging methods to charge the Li-ion battery and minimize the use of public Fast Charge or Quick Charger.
* Avoid exceeding 70-80% state of charge when using frequent (more than once per week) public Fast Charge or Quick Charging.

Quick charge (if so equipped)
NISSAN recommends that quick charging not be performed more than once a day.

Power Limitation Mode
Charging may be automatically terminated, especially with repeated quick charging in extreme hot weather.

HOW TO QUICK CHARGE (if so equipped)
When quick charging, the Li-ion battery charging rate is slower as the percentage available battery charge available increases.

When fully charged
* When 90% of a quick charge is completed

Click to expand...

DurkaDurka said:

Well, THAT sucks. Guess I'll have some fiddling to do whenever the car finally gets built and in my garage. Will have to figure out the ideal end time so it finishes charging right when I leave. My drive to work is the same every day, so I should be able to time it just right.

Click to expand...

If you are planning to charge to 80%, as you suggested in your first post, it isn't going to make a bit of difference whether it sits at that charge level for thirty minutes or three hours before you leave in the morning. The only time you might possibly want to take special action to have it below 80% is if you are letting it sit for a week or longer.

And, no, you really couldn't time it "just right" even if you wanted to. The car seems to have a mind of its own as to how fast it charges, and the Battery Management System (BMS) which controls that doesn't appear to be showing its whole hand to the console computer which is controlling the timer.

Ray

I have a Segway with Li-Ion batteries, and the recommendation from Segway is: "Leave the Segway plugged it at all times, when not in use." Even if placed in storage for months, "Leave the Segway plugged in". I have operated this way for two years, and have no issues with the batteries or the range expected.

planet4ever said:

DurkaDurka said:

Well, THAT sucks. Guess I'll have some fiddling to do whenever the car finally gets built and in my garage. Will have to figure out the ideal end time so it finishes charging right when I leave. My drive to work is the same every day, so I should be able to time it just right.

Click to expand...

If you are planning to charge to 80%, as you suggested in your first post, it isn't going to make a bit of difference whether it sits at that charge level for thirty minutes or three hours before you leave in the morning. The only time you might possibly want to take special action to have it below 80% is if you are letting it sit for a week or longer.

And, no, you really couldn't time it "just right" even if you wanted to. The car seems to have a mind of its own as to how fast it charges, and the Battery Management System (BMS) which controls that doesn't appear to be showing its whole hand to the console computer which is controlling the timer.

Ray

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Then we will have to put our full trust into the charge controller to maintain the battery that best it can.

-Alex

planet4ever said:

If you are planning to charge to 80%, as you suggested in your first post, it isn't going to make a bit of difference whether it sits at that charge level for thirty minutes or three hours before you leave in the morning.

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Do you have data to back up this statement?

Stoaty said:

Do you have data to back up this statement?

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Unfortunately, we don't have any data, with the exception of tests conducted on similar cells. I'm warming to Andy Hecker's argument BTW, and I'm less inclined to worry about the battery. The difference in the scenario you described is likely a fraction of a fraction of a percent. It's like buying three lottery tickets instead of one. The likelihood of anything happening is still small, and it only amplifies over a very long period of time. Devin asked about a charging scenario in another thread, and although these are speculative estimates at best, it looks like regardless of how he charged, it would take about 10,000 miles of doctor visits for him to see a measurable difference. If even that. That being said, it's never wrong to err on the side of caution, but I wouldn't want to spend a lot of energy on such scenarios.

Guys, remember that there are MANY different types of Li-Ion battery chemistries and what is appropriate or best for one (or hurtful for it) is NOT necessarily so for another. Thus, you can not necessarily directly compare a Segway to a Tesla to a Leaf...

NuclearLeaf said:

I have a Segway with Li-Ion batteries, and the recommendation from Segway is: "Leave the Segway plugged it at all times, when not in use." Even if placed in storage for months, "Leave the Segway plugged in". I have operated this way for two years, and have no issues with the batteries or the range expected.

Click to expand...

mogur said:

Guys, remember that there are MANY different types of Li-Ion battery chemistries and what is appropriate or best for one (or hurtful for it) is NOT necessarily so for another. Thus, you can not necessarily directly compare a Segway to a Tesla to a Leaf...

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Wait a minute, the Segway appears to be using NiMH batteries, which is another ball game altogether. There is a lithium option though, so it's tough to know for sure what the poster has at home. I'm more inclined to listen to what Tesla says, even though they built and manage their pack quite differently, because their cell chemistry is closer to ours (lithium cobalt vs lithium manganase). But you are right, it's appropriate to take these comparisons with more than the proverbial grain of salt.

I think Segways lithium is LiFePO4 and that is totally different, very hard to kill those. Following Tesla procedures would be good for a Leaf's battery life, a major difference is that the Tesla's cells are a bit more delicate and sometimes burst into flames.

The Roadster forums have excellent advice on battery care, sorry I dont have any links.

DurkaDurka said:

I don't actually own a LEAF yet, but have been reading to learn all I can. I think by setting an end time on your charge cycle, the car will "time" the charge such that it starts its charge as late as possible. IOW :

1. Say you need a 40% charge to 80% every night based on your commute.
2. The LEAF calculates it takes 2 hours to do so
3. Your end charge time is set to 8AM (no start time needed unless you have TOU)

It will start charging at 6AM thereby leaving the battery at a lower SOC for a longer time. As an engineer, I would do this to ensure longer battery life.

Someone please correct me if I'm wrong.

-Alex

Click to expand...

Nothing wrong with the procedure. However I wouldn't do it this way, what if there is a storm during the night and the charge either doesn't start or gets interrupted half way through? May not have a charge enough to get to work. Now that would suck.

I believe leaving the car at full charge from say 10pm to 6am will have minimal impact on the life. Getting the battery hot through 100% charging and driving hard on hot days would be more damaging by orders of magnitude.

I think it's really overkill to purposefully not charge the car to 80% right away at first opportunity so that it's always at the "Ready to Go" state as often as possible, just for the sake of MAYBE prolonging the battery life (or maybe not true).

What if you have an emergency situation and need to use it? Even if it's not an emergency, what if you all of a sudden have an unplanned errand you want to run late at night? Like go to a pharmacy for some medicine, or go pick up your kids from a sleepover because they got sick, or run to a Walmart for something you suddenly need, etc?

The purpose of a car is to be ready to serve you at any moment's notice. A car without sufficient range to serve you is a no-good car. We didn't buy the car so we can keep it out of commission half of the time to try to maybe prolong its battery life. We buy the car so we can drive it at any time we need it. So it'd better always be ready to serve us.

Unless Nissan says that it's not healthy for the battery otherwise, I'm going to charge my car at the first opportunity available to 80% right away. The only delay I would allow is to wait until the off peak time to start charging.

Volusiano said:

I think it's really overkill to purposefully not charge the car to 80% right away at first opportunity so that it's always at the "Ready to Go" state as often as possible, just for the sake of MAYBE prolonging the battery life (or maybe not true).

What if you have an emergency situation and need to use it? Even if it's not an emergency, what if you all of a sudden have an unplanned errand you want to run late at night? Like go to a pharmacy for some medicine, or go pick up your kids from a sleepover because they got sick, or run to a Walmart for something you suddenly need, etc?

The purpose of a car is to be ready to serve you at any moment's notice. A car without sufficient range to serve you is a no-good car. We didn't buy the car so we can keep it out of commission half of the time to try to maybe prolong its battery life. We buy the car so we can drive it at any time we need it. So it'd better always be ready to serve us.

Unless Nissan says that it's not healthy for the battery otherwise, I'm going to charge my car at the first opportunity available to 80% right away. The only delay I would allow is to wait until the off peak time to start charging.

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My sentiments exactly, we need to be able to use it when we need to, not when it's convenient for the cars battery pack.

The extraordinary ends folks are going to to try and conserve their batteries life, is a direct result of not have a reassuring warranty from Nissan. 'Battery life anxiety' if communicated to the general public, will help kill the idea of EV's. I believe Nissan should announce a pro-rated cost replacement schedule like they do with tires and 12v batteries to let us know they will help us out if our batteries experience more than normal loss of life/capacity.

The glass half-full in me tells me they will act appropriately once they have enough data. They did help out CVT transmission owners when high out of warranty repair costs caused consternation with their customer base. Let's hope they take care of us if that time comes.

I'm visiting the Nissan factory in Japan and I was able to meet with their senior battery engineer Shiro Lithimoto and after speaking with him for more than an hour he told me the 80% charge level was there to protect the pack in high heat climates during equalization and those in temperate climates will not benefit form this mode. He maintains that for the longest pack life one should attempt to discharge the pack no more than 90% and try to use the area between 40% and 50% SOC as little as possible so don't leave it sitting in that range and drive fast when at 50%. to get below 40% quickly. He also said charging at 120V will shorten the pack life by 27% based on their testing because the cells don't like 120V, only 240 and above.