Best charging strategy?

[johnrhansen]

I will use the bicycle directions on google maps (it shows altitude) or topograpy on google earth to determine altitude. No one does that with trip planning on a gas car!

 

[LeftieBiker]

Are you sure you still have 12 "capacity" bars? These are the small bars just to the right of the 12 long "charging" bars.

I was unaware that the small bars represented capacity. I thought they were just there to help you judge how many long bars you were at (i.e. one down from the top is easier to see than 11 up from the bottom). But yes, there are 12 short bars.

Not to belabor the point, but are any of the short capacity bars greyed out, or have little lines running through them? As I understand it, you can still see the one or ones that have been lost.

 

[cwerdna]

Are you sure you still have 12 "capacity" bars? These are the small bars just to the right of the 12 long "charging" bars.

I was unaware that the small bars represented capacity. I thought they were just there to help you judge how many long bars you were at (i.e. one down from the top is easier to see than 11 up from the bottom). But yes, there are 12 short bars.

http://electricvehiclewiki.com/File:Scott_3_bars_s.jpg" onclick="window.open(this.href);return false; shows a car w/3 capacity bars lost.

 

[bguisti]

I will use the bicycle directions on google maps (it shows altitude) or topograpy on google earth to determine altitude. No one does that with trip planning on a gas car!

Nice tip. Google maps shows a net elevation increase of 318 ft between my home and work.

 

[bguisti]

There is a very simple summary for you to follow:

1. Charge such that your average SOC during your daily use is 50% (i.e. if you know you will use 65%, charge to 82.5%, and get home with 17.5% remaining).

2. Charge as late as you can (i.e., if you are going to charge to 82.5%, then time it so that you hit 82.5% just as you are about to leave).

Thanks for this. Sounds like a reasonable strategy. Any thoughts on charging in stages? For instance, I could plug in right when I get to work, set the end-time of the timer to stop charging after 30-60 minutes (to get to around 30% and avoid leaving the battery in a low SOC), then set the start-time on the timer to a few hours before I leave to finish charging.

 

[2k1Toaster]

There is a very simple summary for you to follow:

1. Charge such that your average SOC during your daily use is 50% (i.e. if you know you will use 65%, charge to 82.5%, and get home with 17.5% remaining).

2. Charge as late as you can (i.e., if you are going to charge to 82.5%, then time it so that you hit 82.5% just as you are about to leave).

Thanks for this. Sounds like a reasonable strategy. Any thoughts on charging in stages? For instance, I could plug in right when I get to work, set the end-time of the timer to stop charging after 30-60 minutes (to get to around 30% and avoid leaving the battery in a low SOC), then set the start-time on the timer to a few hours before I leave to finish charging.

Unless you enjoy the game of eeking out imperceptible differences in pack life, just plug and go. Get there and plug in, unplug when you leave, that's it. A brand new pack from the dealership is $5K. Is that really worth all the trouble of babying them? The Prius pack was/is $2.5K from the dealership. You can buy a salvaged pack on eBay with another decade of life left in it for $300. By the time your Leaf needs a new pack, there will probably be a few sitting in junk yards or you can just go to Nissan and get a new one.

Your time is worth something as is your ability to just go for it. I treat the Leaf like a big cell phone. When I get somewhere I can plug in, I do. Simple as that, the car takes care of the rest.

 

[GRA]

I will use the bicycle directions on google maps (it shows altitude) or topograpy on google earth to determine altitude. No one does that with trip planning on a gas car!

Nice tip. Google maps shows a net elevation increase of 318 ft between my home and work.

If you want to see the whole profile in more detail, you can transfer the Google map details by clicking on the 'gear wheel' icon, then on 'share and embed map', then click on the 'Short URL' box and copy the resulting URL over to gps visualizer:

http://www.gpsvisualizer.com/profile_input" onclick="window.open(this.href);return false;

Paste the URL into the box on the right labelled 'Or provide the URL of data on the Web', select 'U.S.' instead of 'Metric' in the 'Units' box on the left, and then click on 'Draw the Profile' bottom right.

 

[dgpcolorado]

...Your time is worth something as is your ability to just go for it. I treat the Leaf like a big cell phone. When I get somewhere I can plug in, I do. Simple as that, the car takes care of the rest.

And I keep my cell phone (and laptop) in the middle charge range to help the battery last longer. And do the same with my LEAF since there is zero chance I will qualify for the capacity warranty. For my usage pattern it isn't a big deal to do this. YMMV.

For someone with a regular commute, I think donald's advice makes a lot of sense. One doesn't have to be precise in implementing it, but the OP did ask for the "best charging strategy" and that's pretty much it.

 

[dgpcolorado]

Thanks for this. Sounds like a reasonable strategy. Any thoughts on charging in stages? For instance, I could plug in right when I get to work, set the end-time of the timer to stop charging after 30-60 minutes (to get to around 30% and avoid leaving the battery in a low SOC), then set the start-time on the timer to a few hours before I leave to finish charging.

If you are above 20% don't bother to charge immediately unless you expect to need the range soon. The battery should be fine in that charge range. If you are down to 10% I would put a little charge into it to get it to 20%.

Bear in mind that if you need the car to make a sudden trip you will be SOL. If that is a concern, you might just want to start charging when you arrive. It's up to you.

Unless something has changed, you will not be able to do two charge cycles in the same day ("end time", later "start-time") unless you reprogram the timer in between, which has a high nuisance value. You might be able to use Carwings to start the second charge.

 

[donald]

Thanks for this. Sounds like a reasonable strategy. Any thoughts on charging in stages? For instance, I could plug in right when I get to work, set the end-time of the timer to stop charging after 30-60 minutes (to get to around 30% and avoid leaving the battery in a low SOC), then set the start-time on the timer to a few hours before I leave to finish charging.

I have done this strategy, but it is for when I am not sure if I will need the car the next day. I would charge up to, say, 60% and then you can leave the car with no fear of SOC induced life issues, yet if/when I need it, I can top up as much as I will need for the next trip - often just an hour or two more, which I can do when I get up in the morning, plug in straight away, have breakfast, get to 90%+ and be ready to go.

There are no life-ageing issues arising from leaving the battery in a low SOC (so long as it does not then self-discharge below the lowest safe voltage, which it will never do overnight unless something is badly wrong). It is when the cells are charged up and subject to voltage stress at high SOC that you will find ageing mechanisms are accelerated. So it is fine to leave your car at 10% overnight before a timed charge starts, no problem at all.

 

[bguisti]

If you are above 20% don't bother to charge immediately unless you expect to need the range soon. The battery should be fine in that charge range. If you are down to 10% I would put a little charge into it to get it to 20%.

Bear in mind that if you need the car to make a sudden trip you will be SOL. If that is a concern, you might just want to start charging when you arrive. It's up to you.

Unless something has changed, you will not be able to do two charge cycles in the same day ("end time", later "start-time") unless you reprogram the timer in between, which has a high nuisance value. You might be able to use Carwings to start the second charge.

Carwings usually tells me I'm at 17% when I arrive.

I actually tried the timer today in the configuration that I mentioned and it worked. I had the start time at 11:30 am and the end time at 8:30 am. I plugged in at 8:00 am, it charged until 8:30 am, then started again at 11:30 am and charged to 80%.

There is the issue of needing the car during the day, but that pretty much never happens so it doesn't concern me much.

 

[bguisti]

There are no life-ageing issues arising from leaving the battery in a low SOC (so long as it does not then self-discharge below the lowest safe voltage, which it will never do overnight unless something is badly wrong). It is when the cells are charged up and subject to voltage stress at high SOC that you will find ageing mechanisms are accelerated. So it is fine to leave your car at 10% overnight before a timed charge starts, no problem at all.

Great to hear. Thanks.

 

[dgpcolorado]

Carwings usually tells me I'm at 17% when I arrive.

Carwings does not give an accurate %SOC. Rather, it measures the fuel bars and extrapolates that to a crude percent. If you charge to 80% and show ten fuel bars, Carwings will say 83% because that is 10/12 of 100%. Yes, it really is that stupid. So, don't pay much attention to the percentage given by Carwings.

I actually tried the timer today in the configuration that I mentioned and it worked. I had the start time at 11:30 am and the end time at 8:30 am. I plugged in at 8:00 am, it charged until 8:30 am, then started again at 11:30 am and charged to 80%.

There is the issue of needing the car during the day, but that pretty much never happens so it doesn't concern me much.

If I understand it correctly, your charge regimen sounds as if you are spanning two days ("11:30 am to 8:30 am") in which case it should work, as you have seen. That seems like a clever solution for your situation!

 

[bguisti]

Not to belabor the point, but are any of the short capacity bars greyed out, or have little lines running through them? As I understand it, you can still see the one or ones that have been lost.

I checked again and all 12 bars seem equally clear and bright.

 

[bguisti]

Carwings does not give an accurate %SOC. Rather, it measures the fuel bars and extrapolates that to a crude percent. If you charge to 80% and show ten fuel bars, Carwings will say 83% because that is 10/12 of 100%. Yes, it really is that stupid. So, don't pay much attention to the percentage given by Carwings.

I had noticed that when I charge to 80% Carwings tells me that I'm either at 75% or 83%. Where can I get more reliable data? Leaf Spy?

 

[bguisti]

There are no life-ageing issues arising from leaving the battery in a low SOC (so long as it does not then self-discharge below the lowest safe voltage, which it will never do overnight unless something is badly wrong). It is when the cells are charged up and subject to voltage stress at high SOC that you will find ageing mechanisms are accelerated. So it is fine to leave your car at 10% overnight before a timed charge starts, no problem at all.

I gather that charging to 100% is particularly bad when it will stay charged for a long period of time. Would I be safe charging to 100% daily if I drive it within an hour or two of reaching full charge? I ask because I can charge for free at work and a 100% charge at work would mean that I have less charging to do at home.

 

[dgpcolorado]

I had noticed that when I charge to 80% Carwings tells me that I'm either at 75% or 83%. Where can I get more reliable data? Leaf Spy?

Yes. Leaf Spy or another aftermarket meter device is necessary to get detailed information about a 2011 LEAF.

I gather that charging to 100% is particularly bad when it will stay charged for a long period of time. Would I be safe charging to 100% daily if I drive it within an hour or two of reaching full charge? I ask because I can charge for free at work and a 100% charge at work would mean that I have less charging to do at home.

Yes, that won't hurt anything and many people here charge to 100% within a few hours of driving the car. There really isn't any good evidence that this affects the battery in any significant way, versus charging to 80%.

 

[donald]

I gather that charging to 100% is particularly bad when it will stay charged for a long period of time. Would I be safe charging to 100% daily if I drive it within an hour or two of reaching full charge? I ask because I can charge for free at work and a 100% charge at work would mean that I have less charging to do at home.

That is my understanding. There are phase changes in the electrodes as the cell voltage passes 4V/cell so it is still appropriate to charge to less if you can. However, you should take that with a pinch of salt because if you are driving off very soon after 100% every time, such that your battery still averages a low-SOC over its lifetime, then the difference in battery life to one treated like that and one that is only ever charged to 90% will be indistinguishable. So, yeah, a small effect maybe, but it will be swamped by the effects of any hot summers, or very low operating temperatures, the car might experience during its lifetime.

Ultimately, a battery with a very short life will most likely arise because one or two cells start going bad, due to thermal ageing. Whether you charge to 100% all the time or not will still not be a big factor in the early death of a battery pack, only if there were some poor cells in there in the first place, and if there were some poor cells then you will probably have an early pack failure in any case. So in one way, maybe it is actually better to reasonably 'exercise' the battery in the first year or two which will help show up if the pack has got susceptible cells, and then after a few years you might well have settled down to a slightly difference, 'gentler', charging routine anyway.

 

[bguisti]

Leaf Spy or another aftermarket meter device is necessary to get detailed information about a 2011 LEAF.

Any suggestions?

 

[bguisti]

There are phase changes in the electrodes as the cell voltage passes 4V/cell so it is still appropriate to charge to less if you can.

Are these phase changes in the lattice structure of the material (just asking out of curiosity...I worked with a crystallography group in college)?

Ultimately, a battery with a very short life will most likely arise because one or two cells start going bad, due to thermal ageing.

Is there any way to replace just the bad cells if you're able to identify them?