JRP3
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Sun Oct 21, 2012 5:45 am

Yup, paralleled cell pairs will show the same voltage.

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gbarry42
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Sun Oct 21, 2012 10:45 am

TonyWilliams wrote:LEAFscan will allow us mere mortals to see the 96 cell PAIR voltages (that's how Nissan has configured it).
He did say "cell", but I expect it's really at the (half) module level, as you say. After all, they get the data off the same CAN bus as any other monitor would.
And there goes the first capacity bar! At 24,000 mi on 9/9/2013.
Second bar at 30,500 mi on 2/7/2015.

evchels
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Mon Oct 22, 2012 11:39 am

thankyouOB wrote:yes, and the LEAF service manager at Power Nissan in LA did not know that leaving a battery at 100% was not recommended for the car....imagine what they are doing to all those LEAFs sitting on the lot.
Based on what I've seen and heard, the whole dealer process and training needs to be overhauled and refreshed.

However, it's really sort of silly that if it's that important to only charge to 80% (and while I'm not doubting, I'd love to see some data on the real-world effects, esp if only on Level 2), that the car doesn't automatically default to that mode and require an override to go to 100% when desired, a la Tesla's "range mode" for charging. Anything that crucial shouldn't be left up to the knowledge of the newest lot porter, or body shop employee, or valet, etc...

(I'm sure there's a thread about this or discussion that's already been had- happy to read up if someone wants to point me in the right direction! :) )

EatsShootsandLeafs
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Mon Oct 22, 2012 11:53 am

evchels wrote:
thankyouOB wrote:yes, and the LEAF service manager at Power Nissan in LA did not know that leaving a battery at 100% was not recommended for the car....imagine what they are doing to all those LEAFs sitting on the lot.
Based on what I've seen and heard, the whole dealer process and training needs to be overhauled and refreshed.

However, it's really sort of silly that if it's that important to only charge to 80% (and while I'm not doubting, I'd love to see some data on the real-world effects, esp if only on Level 2), that the car doesn't automatically default to that mode and require an override to go to 100% when desired, a la Tesla's "range mode" for charging. Anything that crucial shouldn't be left up to the knowledge of the newest lot porter, or body shop employee, or valet, etc...

(I'm sure there's a thread about this or discussion that's already been had- happy to read up if someone wants to point me in the right direction! :) )
I strongly suspect it's because the real range of this car is 73 miles @ 100%, so at 80% you've now basically got its EPA range in the 50's, which is really not great for marketing.

evchels
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Mon Oct 22, 2012 11:59 am

EatsShootsandLeafs wrote:
evchels wrote:
However, it's really sort of silly that if it's that important to only charge to 80% (and while I'm not doubting, I'd love to see some data on the real-world effects, esp if only on Level 2), that the car doesn't automatically default to that mode and require an override to go to 100% when desired, a la Tesla's "range mode" for charging. Anything that crucial shouldn't be left up to the knowledge of the newest lot porter, or body shop employee, or valet, etc...
I strongly suspect it's because the real range of this car is 73 miles @ 100%, so at 80% you've now basically got its EPA range in the 50's, which is really not great for marketing.
No, but having a default charge mode to 80% until the customer overrides it doesn't change the EPA #s- though the new driver certainly needs to know that what's happening and to expect range in the 50's without the override.

Then again, so much about communication to date isn't great for marketing either! :?

TEG
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Mon Oct 22, 2012 12:24 pm

evchels wrote:However, it's really sort of silly that if it's that important to only charge to 80% (and while I'm not doubting, I'd love to see some data on the real-world effects, esp if only on Level 2), that the car doesn't automatically default to that mode and require an override to go to 100% when desired, a la Tesla's "range mode" for charging. Anything that crucial shouldn't be left up to the knowledge of the newest lot porter, or body shop employee, or valet, etc...
(I'm sure there's a thread about this or discussion that's already been had- happy to read up if someone wants to point me in the right direction! :) )
Start with this: 80% or 100% charge?

I myself charge only to 80% with rare exceptions (doing a rare long distance trip.)

Seems opinions run the range with regards to the importance of using 80%.
My take is it is OK to go to 100% now and then as long as you start using that full charge soon.
Leaving the car at 100% for long periods, particularly with high ambient temps is not good for the battery.
(But I will have to disclaim this, saying it is only my opinion since we seem to have plenty who will claim that 100% is OK/fine all the time.) On the other hand, why did Nissan even bother to provide an 80% charge mode if they didn't think it was helpful in some way...

Regarding "real world data". Seems Nissan is the only entity that really has access to the data there, and they don't seem in a hurry to say a whole lot about it. I think they are a little bit twisted up about what is the right message to use. On the one hand, they want to say "The car is easy to live with... don't worry about trying to charge only to 80%... Quick charge as much as you want... The car is smart and will do the right thing." on the other hand, they probably have engineers begging to get the message out that the customer can help the car last longer by following certain charging protocols... But you can't have engineers dictate directly to customers how the customers should use the product, can you?

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DaveEV
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Mon Oct 22, 2012 12:37 pm

TEG wrote:(But I will have to disclaim this, saying it is only my opinion since we seem to have plenty who will claim that 100% is OK/fine all the time.) On the other hand, why did Nissan even bother to provide an 80% charge mode if they didn't think it was helpful in some way...
Not only that, but they also say to avoid topping off the battery back to full until you're below 80%. They even ding you for this on the battery report. And they say to store the car charged to 80% (not 100%). This is plenty of evidence that Nissan fully knows that time spent above 80% will cause premature capacity loss.

There is simply no evidence that increasing the amount of time spent at higher SOC levels is inconsequential, while plenty of evidence that avoiding it is beneficial.

TEG
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Mon Oct 22, 2012 12:40 pm

Perhaps anecdotal, and more hearsay, but here are some related suggestions:

plugin-cars: Eight Tips to Extend Battery Life of Your Electric Car
#1: Avoid full charging when you can.
...
#4: Use timers to minimize the time spent at a high state of charge.
...
#8: To maximize battery life, minimize use of DC quick charge.

TEG
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Mon Oct 22, 2012 12:54 pm

I think it is basically "well known" that at higher SoCs there is more "internal resistance" and a more significant percentage of the charge turns into heat instead of being stored energy in the cell. It is also well known that prolonged high heat causes chemical breakdown in the cell. I think many of us have "put 2 and 2 together" and made our own conclusions regardless if they don't attempt to explain the technical reasons to "Joe Sixpack".


Back in "the early days" (at LEAF launch), I think there was an inadvertent mixed message.

Those coming from previous ERA NiMH EVs (such as old RAV4EV, or Ford Ranger EV), or thinking in terms of Ni-Cad devices would ask about charging with questions "how often do you need to deep cycle to avoid the 'memory effect' ". The response would be "No memory effect with Li-Ion! Top off whenever you want! Do opportunistic public charging whenever you get a chance." That may have been true from a short term standpoint, but longer term doing a lot of 90%->100% SoC charging could cause different sorts of degradation.
Ni-Cad and NiMH with reduced SoC range due to "memory effect" could be "reconditioned" and regain some of their former range, but Li-Ion that has been overheated repeatedly is probably irrecoverably "toasted".
Last edited by TEG on Mon Oct 22, 2012 12:57 pm, edited 2 times in total.

Stoaty
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Re: Andy Palmer and Chelsea Sexton Discuss the Nissan LEAF

Mon Oct 22, 2012 12:56 pm

drees wrote:Not only that, but they also say to avoid topping off the battery back to full until you're below 80%. They even ding you for this on the battery report. And they say to store the car charged to 80% (not 100%). This is plenty of evidence that Nissan fully knows that time spent above 80% will cause premature capacity loss.

There is simply no evidence that increasing the amount of time spent at higher SOC levels is inconsequential, while plenty of evidence that avoiding it is beneficial.
All true, but oddly enough while my battery aging model doesn't (yet) account for this it seems to be pretty accurate in many cases. I haven't yet run into a case where charging to 100% was the factor that made the prediction model too optimistic. For example, I was surprised that when I checked Azdre/opossum my current model nailed their capacity loss almost exactly. As I recall, they charged to 100% most of the time. Everything I have read indicates it isn't good for the battery to leave it at high SOC for any length of time. Perhaps the initial loss of capacity (first year) is so rapid in places like Arizona from the effects of heat that the effects of high SOC tend to be lost in the noise. It may be more of a factor in subsequent years.
2011 Leaf with 62,000 miles given to Nephew
2013 Tesla Model S85 with 251 miles rated range at full charge
Leaf Spy Manual
Battery Aging Model Spreadsheet

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