Joining the 80% Club

[wsbca]

So you think 93% is actually my 100%? Or do you think next time I try to "freely" charge it might be higher than 100%?
This is fun!

Carwings only shows a limited set of percentages which correspond to the bars (out of 12) that the car shows, though since 10 bars is "83%" in carwings, I would have expected 11 bars to be "92%" (11/12 rounded up), not "93". At any rate, perhaps due to temperature changes since your charge finished, you were probably slightly under 100, therefore displayed as "93". Your car likely did not literally stop charging 7% short, nor did it lose a true 7% from the time it stopped charging until the time you checked it (do you have big swings in temperature in your locale?)

 

[hobbyguy]

I set my timer for Friday and Saturday night for 100% and my other days at 80% since I have a commute of 35 miles each way and on Saturday and Sundays my freeways are wide open, I want to make sure I have enough to get back and forth and not be a hazard on the freeway.
The temps here have been in the low 60's day and 40's in the morning. So the "100% charge" I did today was in mid afternoon with temps in the high 50's. Kind of forgot about temps, will have to keep that in mind as we get warmer.

 

[smkettner]

Why fear the red bars? Is that zone really going to hurt the battery or is Nissan just giving a stong warning that the car will stop soon. Keep in mind the price of a tow is on Nissan for three years. And there is the loss of satisfaction for someone that actually gets stuck.

 

[EVDRIVER]

No one here has driven past the warning lights? Someone I know did and tried to get the car into turtle mode and drove up a very long hill and for miles and could not get the car into that mode. Regardless, it is more important to know where the total pack capacity is at any given point, that is valuable.

 

[Frank]

mwalsh, was the miles of range remaining number blinking when the Low Battery Warning popped up as specified in the service manual table shown earlier in this thread?

 

[evnow]

So you think 93% is actually my 100%? Or do you think next time I try to "freely" charge it might be higher than 100%?
This is fun!

It will charge to 100%.

 

[mwalsh]

mwalsh, was the miles of range remaining number blinking when the Low Battery Warning popped up

Yes, it was.

 

[planet4ever]

The temps here have been in the low 60's day and 40's in the morning. So the "100% charge" I did today was in mid afternoon with temps in the high 50's. Kind of forgot about temps, will have to keep that in mind as we get warmer.

In the owners manual, see page 2-9 under "Instruments and Controls". If you charge fully (12 bars) and then the battery warms up, you may drop to 11 bars just because the warmer battery can now hold more juice. Did you have the car in the garage, and was the garage gradually warming due to sun on the roof? Or maybe even a door open into the house?

 

[mwalsh]

BTW, it's worth mentioning that at no time during this experiment did I use the ECO mode. So it remains to be seen how much easier that would make it for me to become a member of the 80% club.

 

[occ]

If you ask me - it sounds like your commute (as it is now) is perfect for a 80% charge since you just barely touched the low battery warning when you got home, no? Think of it this way - you have enough juice left to get half way back to work - and that doesn't even account for turtle mode!

I think I would agree with drees, If 80% is does really prolong battery life. Of course if 80% does not prolong bat life, get the full range all the way! Don't you go out to lunch and take some co-workers for a demo ride sometimes, to promote EVs?

 

[mwalsh]

I think I would agree with drees, If 80% is does really prolong battery life. Of course if 80% does not prolong bat life, get the full range all the way! Don't you go out to lunch and take some co-workers for a demo ride sometimes, to promote EVs?

The only thing that would make me want to disagree is that I'm not comfortable with having that fuel lamp showing. I'm also compromising by driving with economy in mind, and maybe I don't really want to have to do that all the time. And, yes, that does preclude demo rides...yesterday I actually told a coworker (to whom I'd promised a ride last week) that he couldn't have one because I only had enough charge to comfortably get home.

 

[evnow]

...yesterday I actually told a coworker (to whom I'd promised a ride last week) that he couldn't have one because I only had enough charge to comfortably get home.

So, looks like 80% charging (atleast early on) will give the wrong signal to others ...

 

[LEAFer]

...yesterday I actually told a coworker (to whom I'd promised a ride last week) that he couldn't have one because I only had enough charge to comfortably get home.

So, looks like 80% charging (atleast early on) will give the wrong signal to others ...

Right.

Back to Mike's efficiency on the first few commute days. I don't remember, but is the fact that your drive to work is less efficient (compraed to coming home) possibly not only due to colder temps in the morning, but, did you charge to 100% in the first few days, and therefore may have "suffered" from less (or no) regen ? ( A full battery can't accept regen. )

 

[mwalsh]

Back to Mike's efficiency on the first few commute days. I don't remember, but is the fact that your drive to work is less efficient (compared to coming home) possibly not only due to colder temps in the morning, but, did you charge to 100% in the first few days, and therefore may have "suffered" from less (or no) regen ? ( A full battery can't accept regen. )

It could be all of the above. Plus it's definitely being able to drive at 65mph with the cruise control on to work vs. slow (or stop) and go traffic every night on the way home.

 

[DaveinOlyWA]

if 80% is barely making it for you, then i would do 100% no questions.

what happens when summer comes. AC is on just to survive and there is an accident ? commute takes an extra 30 minutes and you did a short detour that morning, only a few miles so you were already at the limit?

i cant, dont want or even want to think about trying to predict all my driving needs ahead of time. too hard and too unnecessary.

i am going to work on changing my charge time to where its at 95 % for those long commute days. i think that is the better way to go.

 

[TomT]

I still contend that charging to 100 percent is less stressful for the battery than discharging to 10 percent or less... This is true for almost every lithium battery ever made and I have a hard time believing that the Leaf battery would be any different.

 

[mwalsh]

if 80% is barely making it for you, then i would do 100% no questions.

It's not that it's not making it for me, just that I'm too chicken to "Kramer it"! :lol:

[youtube]http://www.youtube.com/watch?v=TuEdU_lrtZk[/youtube]

 

[planet4ever]

I still contend that charging to 100 percent is less stressful for the battery than discharging to 10 percent or less... This is true for almost every lithium battery ever made and I have a hard time believing that the Leaf battery would be any different.

But is charging to 90% less stressful than discharging to 18%? I think that is what you are really talking about. I continue to believe that the total capacity of the battery is about 30kWh with a usable charge range of 24kWh. In converting usable charge percent to total charge kWh, I contend (for a new battery at room temperature) that:

• "100% charge" is really about 27kWh
• "10% charge" is really about 5.4kWh
• "0% charge" is really about 3kWh
• The car will never let you go below about 3kWh or above about 27kWh

Note that I don't claim to know the answer to the question I asked. I only claim that it isn't "obvious" from prior lipo experience.

 

[Train]

Interesting observations.

Going 75 on AZ freeways in June with the A/C on...I'm thinking 50 miles.

 

[AndyH]

I still contend that charging to 100 percent is less stressful for the battery than discharging to 10 percent or less... This is true for almost every lithium battery ever made and I have a hard time believing that the Leaf battery would be any different.

In general, if you're talking about a raw cell, and that cell is LiFePO4, then I'll agree. If the cell is LiCo/LiPo, then I will not agree.

Because LiMn2O4 is closer to LiCo in the family tree - and industry tests conducted on LiCo clearly show that max charge voltage has a very, very significant effect on cycle life.

http://batteryuniversity.com/learn/article/explaining_lithium_ion_chemistries
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

We keep coming back to this point, though. Yes - if one has a RAW CELL they can choose to over charge and/or over discharge the cell. The info in places like battery manufacturer spec sheets is for raw cells - cells not protected by any type of management system - because the intent of those authors is to describe the cell. Places like Battery University tend to mix/match info for raw cells and complete batteries with management devices.

But we are not allowed to access either end of the Leaf's pack - NISSAN has Protected the Pack from US! As consumers, we are free to use only the capacity Nissan allows us to use.

A good low voltage cut-off point for LiCo/LiPo/LiMn2O4 if we expect a long life is 3.0V. This is what I use when building management systems for LiPo and LiMn2O4 batteries. The Leaf's battery management system will only let us come down to 3.2V-3.4V as an absolute minimum - this sets an over discharge error code that results in a 'no charge/no drive' condition. Minimum cell voltage for a 'ready' condition is between 3.3V and 3.5V. (Service manual, section EVB, P.28, P.93 and P.103)

Bottom line - the car will not let us get into low voltage danger - or into a voltage range that would shorten the cycle life of the pack.