Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-06 Thread Paul Dove via EV
That technology is not on every vehicle manufactured. Some will never be 
willing to pay for it.

Sent from my iPhone

 On Aug 4, 2015, at 8:53 PM, Ben Goren via EV ev@lists.evdl.org wrote:
 
 On Aug 4, 2015, at 6:34 PM, Alan Arrison via EV ev@lists.evdl.org wrote:
 
 We already went round and round with this no self discharge, no BMS fellow 
 a few months ago.
 
 
 Yes, we did.
 
 I think a good analogy might be the Tire Pressure Monitoring System found in 
 every new car for ages. You could probably make a similar argument that those 
 sorts of things are utterly worthless since any idiot with a $2 pressure 
 gauge can check if the tires need air or not, so why pay the hundreds of 
 dollars it costs the manufacturers to put it in every car?
 
 If the obvious and substantial benefits of TPMS aren't obvious to somebody, 
 and if the fact that the cost-conscious penny-pinching manufacturers don't 
 try to make a few hundred dollars extra profit for themselves by leaving it 
 out of their designs isn't enough to get that person to re-think opposition 
 to TPMS...then there's basically not going to be any way to get through to 
 that person.
 
 b
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Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread via EV
It's possible he has a defective battery. Also, I still don't believe balances 
work on Lithium cells.

Sent from Outlook




On Mon, Aug 3, 2015 at 9:40 PM -0700, Bill Dube via EV ev@lists.evdl.org 
wrote:










There are too many variables to draw any strong conclusions. The two 
biggest factors are:

1) The BMS does not have as much time to balance during a fast charge.
2) The cell temperature is typically higher (for many reasons) when you 
fast charge. The cells don't like high temperatures.

Stale charge is also large factor in apparent capacity change and 
happens in all chemistries to varying degrees. It may be a factor in 
these tests on battery pack capacity. (In nicads it can be 
particularly a large stale charge effect and is commonly called 
memory effect.) Essentially, when you _gently_ and _fully_ cycle a 
battery, the apparent capacity becomes much greater after the first full 
cycle, and often grows a bit more with the second full cycle.

The longer it has been since you last accessed the full capacity of the 
battery, the worse the problem of stale charge becomes.

Batteries are very complicated chemical beasts. Simple tests often don't 
tell you the full story.

Bill Dube'




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Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Cor van de Water via EV
Hello dovepa at bellsouth.net AKA via EV,
I have no idea who you are - the message is not signed and your name is not 
showing from your email.
You can believe what you want about Lithiums, but think about that even the 
Chinese invest in a BMS
on every Lithium battery pack that they ship, while they are known to cut 
corners and reduce cost,
so there must be a reason

Cor van de Water
Chief Scientist
Proxim Wireless

office +1 408 383 7626  Skype: cor_van_de_water
XoIP   +31 87 784 1130  private: cvandewater.info
www.proxim.com


This email message (including any attachments) contains confidential and 
proprietary information of Proxim Wireless Corporation.  If you received this 
message in error, please delete it and notify the sender.  Any unauthorized 
use, disclosure, distribution, or copying of any part of this message is 
prohibited.


-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of via EV
Sent: Tuesday, August 04, 2015 5:03 AM
To: Electric Vehicle Discussion List; Bill Dube
Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

It's possible he has a defective battery. Also, I still don't believe balances 
work on Lithium cells.

Sent from Outlook




On Mon, Aug 3, 2015 at 9:40 PM -0700, Bill Dube via EV ev@lists.evdl.org 
wrote:










There are too many variables to draw any strong conclusions. The two biggest 
factors are:

1) The BMS does not have as much time to balance during a fast charge.
2) The cell temperature is typically higher (for many reasons) when you fast 
charge. The cells don't like high temperatures.

Stale charge is also large factor in apparent capacity change and happens in 
all chemistries to varying degrees. It may be a factor in these tests on 
battery pack capacity. (In nicads it can be particularly a large stale charge 
effect and is commonly called memory effect.) Essentially, when you _gently_ 
and _fully_ cycle a battery, the apparent capacity becomes much greater after 
the first full cycle, and often grows a bit more with the second full cycle.

The longer it has been since you last accessed the full capacity of the 
battery, the worse the problem of stale charge becomes.

Batteries are very complicated chemical beasts. Simple tests often don't tell 
you the full story.

Bill Dube'




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Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Paul Dove via EV
I whole heartily agree.

Sent from my iPhone

 On Aug 4, 2015, at 8:34 PM, Alan Arrison via EV ev@lists.evdl.org wrote:
 
 We already went round and round with this no self discharge, no BMS fellow 
 a few months ago.
 
 
 On 8/4/2015 5:08 PM, paul dove via EV wrote:
 Hey Mark,
 I know that seems like sounds reasonable to most people. However, a battery 
 is chemical and while you can measure resistance with a meter a battery has 
 no resistance in the electrical sense. What appears as resistance in a 
 Lithium Ion cell is really the diffusion rate of Li Ions into the graphite 
 structure. Ohm's law does not apply inside a battery. You are pushing Ions 
 into a crystal structure and as it gets full the cell transfers some of this 
 energy into heat. So holding a battery at the set point after it is full 
 just heats up the cell.
 
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Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Paul Dove via EV
I don't believe cell drift exist either. If they are unbalanced it is because 
there is a parasitic load on the cells that are unbalanced. 

Sent from my iPhone

 On Aug 4, 2015, at 4:49 PM, Cor van de Water via EV ev@lists.evdl.org wrote:
 
 Hi Paul,
 Thanks for putting a name to the message.
 I have a bit of experience with Lithiums and the unbalance in (self)
 discharge,
 so I am very much in favor of using a BMS to balance cells, even if this
 is the
 possibly not entirely perfect matching them in max charge voltage.
 For example, I have a battery operated stage light (American DJ QA-5
 bar)
 that has a 6Ah 24V battery to run it approx 6 hours long at full power.
 I bought one second hand and its battery cut out after 1.5 hours while
 displaying
 that it should still have about 70% capacity left. What happened?
 Simple - from the 6 series sets of 3 parallel cells, one was unbalanced
 so much
 that after delivering approx 30% of the expected capacity, its voltage
 fell to 2.5V
 and the BMS opened the output to prevent over-discharge.
 I tried to recharge and cycle it several times and it seemed to gain a
 little bit
 but not significantly, so I wanted to know if this was a case of 2
 failed cells
 in the 3 parallel configuration or a badly discharged set.
 I opened the pack and found that I could put 4Ah into the low cells to
 bring them up
 to the same 4.1V that the other cells were after a charge. Then the
 battery was
 working again as specified, running the light close to 6h at full power.
 So, having a BMS that balances (even if at top voltage) and turns the
 voltage off
 when a cell threatens to go outside voltage spec, saves the pack and
 avoids
 fiery disasters and it might even prevent the extreme unbalance in the
 first place,
 because this pack was not limited by the weakest cell, it was limited by
 the unbalance.
 Hope this gives some insight.
 
 Cor van de Water
 Chief Scientist
 Proxim Wireless
 
 office +1 408 383 7626Skype: cor_van_de_water
 XoIP   +31 87 784 1130private: cvandewater.info
 www.proxim.com
 
 
 Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack
 balancing
 
 Hello Cor van de Water,
 My name is Paul Dove, thus dovepa.  I don't know you either. Just
 knowing your name or where you work does not make me know you.
 It is not really relevant who uses a BMS. People used to use x-rays to
 measure their shoe size and it had a viewer so you could see your feet
 x-rayed real time. They figured out this was dangerous eventually but
 non-the-less everyone was doing it.
 Now, with everyone is doing it argument out of the way..
 The CC/CV charging methodology was arrived at by experimentation.
 Researchers were trying to determine the method that would put the most
 capacity in the cell. They tried multiple CV values and recommend the
 value that put the most into the cell.
 Actual capacity has to be calculated by current times time. It cannot be
 determined by voltage. The voltage set point is part of a procedure to
 maximize the energy in the cell. 
 
 In series the current is the same through all the cells. A balancer will
 attempt to shunt part of this current off of the cell to let other cells
 come up to the CV value while keeping this cell from exceeding the CV
 value. In my opinion, having not analyzed every BMS out there, a BMS
 would need to shunt enough energy to keep the voltage from rising above
 this voltage set point or have the ability to command the charger to
 lower the current. 
 
 So the balancer would have to hold cells individually at the CV level by
 reducing current into each cell independently.
 
 Now, even if it can achieve this feat according to the manufacturers
 recommended cc/cv procedure this does not balance the cells. Ok, maybe
 it's a semantics issue on the word balanced. What is balanced? All cells
 at the same voltage? All cells at the same capacity? I think the goal is
 to have maximum capacity not balancing.
 That aside, do you actually have more capacity? If so, how much more?
 When you discharge the car will cut off when the lowest capacity cell
 reaches it's cutoff voltage so by holding it at the set point voltage
 while the others fill up didn't gain any pack capacity advantage sine
 you still cutoff based on the lowest capacity cell. You pack size is the
 size of your lowest or weakest cell. No way around that. 
 
 In addition, the amount of energy put into the cell during the constant
 current part of the charge is less than 5%.
 So on 70Ah cells we are talking 3 miles range. That's if you cut off
 when the first cell reaches the set point voltage. So if you took the
 current down to C/20 based on the lowest capacity cell you would mt
 likely loose no capacity or if I'm wrong possibly 1% or less than a mile
 range.
 The whole concept of balancing comes from other battery technology such
 as Lead Acid cells where it makes much more sense. You want all the
 batteries to boil to get maximum capacity.
 I have

Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Cor van de Water via EV
Hi Paul,
Thanks for putting a name to the message.
I have a bit of experience with Lithiums and the unbalance in (self)
discharge,
so I am very much in favor of using a BMS to balance cells, even if this
is the
possibly not entirely perfect matching them in max charge voltage.
For example, I have a battery operated stage light (American DJ QA-5
bar)
that has a 6Ah 24V battery to run it approx 6 hours long at full power.
I bought one second hand and its battery cut out after 1.5 hours while
displaying
that it should still have about 70% capacity left. What happened?
Simple - from the 6 series sets of 3 parallel cells, one was unbalanced
so much
that after delivering approx 30% of the expected capacity, its voltage
fell to 2.5V
and the BMS opened the output to prevent over-discharge.
I tried to recharge and cycle it several times and it seemed to gain a
little bit
but not significantly, so I wanted to know if this was a case of 2
failed cells
in the 3 parallel configuration or a badly discharged set.
I opened the pack and found that I could put 4Ah into the low cells to
bring them up
to the same 4.1V that the other cells were after a charge. Then the
battery was
working again as specified, running the light close to 6h at full power.
So, having a BMS that balances (even if at top voltage) and turns the
voltage off
when a cell threatens to go outside voltage spec, saves the pack and
avoids
fiery disasters and it might even prevent the extreme unbalance in the
first place,
because this pack was not limited by the weakest cell, it was limited by
the unbalance.
Hope this gives some insight.

Cor van de Water
Chief Scientist
Proxim Wireless

office +1 408 383 7626  Skype: cor_van_de_water
XoIP   +31 87 784 1130  private: cvandewater.info
www.proxim.com


Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack
balancing

Hello Cor van de Water,
My name is Paul Dove, thus dovepa.  I don't know you either. Just
knowing your name or where you work does not make me know you.
It is not really relevant who uses a BMS. People used to use x-rays to
measure their shoe size and it had a viewer so you could see your feet
x-rayed real time. They figured out this was dangerous eventually but
non-the-less everyone was doing it.
Now, with everyone is doing it argument out of the way..
The CC/CV charging methodology was arrived at by experimentation.
Researchers were trying to determine the method that would put the most
capacity in the cell. They tried multiple CV values and recommend the
value that put the most into the cell.
Actual capacity has to be calculated by current times time. It cannot be
determined by voltage. The voltage set point is part of a procedure to
maximize the energy in the cell. 

In series the current is the same through all the cells. A balancer will
attempt to shunt part of this current off of the cell to let other cells
come up to the CV value while keeping this cell from exceeding the CV
value. In my opinion, having not analyzed every BMS out there, a BMS
would need to shunt enough energy to keep the voltage from rising above
this voltage set point or have the ability to command the charger to
lower the current. 

So the balancer would have to hold cells individually at the CV level by
reducing current into each cell independently.

Now, even if it can achieve this feat according to the manufacturers
recommended cc/cv procedure this does not balance the cells. Ok, maybe
it's a semantics issue on the word balanced. What is balanced? All cells
at the same voltage? All cells at the same capacity? I think the goal is
to have maximum capacity not balancing.
That aside, do you actually have more capacity? If so, how much more?
When you discharge the car will cut off when the lowest capacity cell
reaches it's cutoff voltage so by holding it at the set point voltage
while the others fill up didn't gain any pack capacity advantage sine
you still cutoff based on the lowest capacity cell. You pack size is the
size of your lowest or weakest cell. No way around that. 

In addition, the amount of energy put into the cell during the constant
current part of the charge is less than 5%.
So on 70Ah cells we are talking 3 miles range. That's if you cut off
when the first cell reaches the set point voltage. So if you took the
current down to C/20 based on the lowest capacity cell you would mt
likely loose no capacity or if I'm wrong possibly 1% or less than a mile
range.
The whole concept of balancing comes from other battery technology such
as Lead Acid cells where it makes much more sense. You want all the
batteries to boil to get maximum capacity.
I have no problem with a BMS to monitor individual cell voltage an
temperature and controlling charge based on this.  My arguments are
against shunt balancer circuits.
Both their effectiveness and the necessity.

  From: Cor van de Water via EV ev@lists.evdl.org
 To: Electric Vehicle Discussion List ev@lists.evdl.org
 Sent: Tuesday, August

Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Cor van de Water via EV
Believe it or not,
I have seen (measured) cell drift between cells that were connected to nothing
and at the same temp, sitting idle next to each other in my garage,
only attaching a DVM from time to time to measure them and I saw about
a 2:1 spread in their self-discharge rate.

Cor van de Water
Chief Scientist
Proxim Wireless

office +1 408 383 7626  Skype: cor_van_de_water
XoIP   +31 87 784 1130  private: cvandewater.info
www.proxim.com


This email message (including any attachments) contains confidential and 
proprietary information of Proxim Wireless Corporation.  If you received this 
message in error, please delete it and notify the sender.  Any unauthorized 
use, disclosure, distribution, or copying of any part of this message is 
prohibited.


-Original Message-
From: Paul Dove [mailto:dov...@bellsouth.net] 
Sent: Tuesday, August 04, 2015 3:02 PM
To: Cor van de Water; Electric Vehicle Discussion List
Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

I don't believe cell drift exist either. If they are unbalanced it is because 
there is a parasitic load on the cells that are unbalanced. 

Sent from my iPhone

 On Aug 4, 2015, at 4:49 PM, Cor van de Water via EV ev@lists.evdl.org wrote:
 
 Hi Paul,
 Thanks for putting a name to the message.
 I have a bit of experience with Lithiums and the unbalance in (self) 
 discharge, so I am very much in favor of using a BMS to balance cells, 
 even if this is the possibly not entirely perfect matching them in max 
 charge voltage.
 For example, I have a battery operated stage light (American DJ QA-5
 bar)
 that has a 6Ah 24V battery to run it approx 6 hours long at full power.
 I bought one second hand and its battery cut out after 1.5 hours while 
 displaying that it should still have about 70% capacity left. What 
 happened?
 Simple - from the 6 series sets of 3 parallel cells, one was 
 unbalanced so much that after delivering approx 30% of the expected 
 capacity, its voltage fell to 2.5V and the BMS opened the output to 
 prevent over-discharge.
 I tried to recharge and cycle it several times and it seemed to gain a 
 little bit but not significantly, so I wanted to know if this was a 
 case of 2 failed cells in the 3 parallel configuration or a badly 
 discharged set.
 I opened the pack and found that I could put 4Ah into the low cells to 
 bring them up to the same 4.1V that the other cells were after a 
 charge. Then the battery was working again as specified, running the 
 light close to 6h at full power.
 So, having a BMS that balances (even if at top voltage) and turns the 
 voltage off when a cell threatens to go outside voltage spec, saves 
 the pack and avoids fiery disasters and it might even prevent the 
 extreme unbalance in the first place, because this pack was not 
 limited by the weakest cell, it was limited by the unbalance.
 Hope this gives some insight.
 
 Cor van de Water
 Chief Scientist
 Proxim Wireless
 
 office +1 408 383 7626Skype: cor_van_de_water
 XoIP   +31 87 784 1130private: cvandewater.info
 www.proxim.com
 
 
 Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack 
 balancing
 
 Hello Cor van de Water,
 My name is Paul Dove, thus dovepa.  I don't know you either. Just 
 knowing your name or where you work does not make me know you.
 It is not really relevant who uses a BMS. People used to use x-rays to 
 measure their shoe size and it had a viewer so you could see your feet 
 x-rayed real time. They figured out this was dangerous eventually but 
 non-the-less everyone was doing it.
 Now, with everyone is doing it argument out of the way..
 The CC/CV charging methodology was arrived at by experimentation.
 Researchers were trying to determine the method that would put the 
 most capacity in the cell. They tried multiple CV values and recommend 
 the value that put the most into the cell.
 Actual capacity has to be calculated by current times time. It cannot 
 be determined by voltage. The voltage set point is part of a procedure 
 to maximize the energy in the cell.
 
 In series the current is the same through all the cells. A balancer 
 will attempt to shunt part of this current off of the cell to let 
 other cells come up to the CV value while keeping this cell from 
 exceeding the CV value. In my opinion, having not analyzed every BMS 
 out there, a BMS would need to shunt enough energy to keep the voltage 
 from rising above this voltage set point or have the ability to 
 command the charger to lower the current.
 
 So the balancer would have to hold cells individually at the CV level 
 by reducing current into each cell independently.
 
 Now, even if it can achieve this feat according to the manufacturers 
 recommended cc/cv procedure this does not balance the cells. Ok, maybe 
 it's a semantics issue on the word balanced. What is balanced? All 
 cells at the same voltage? All cells at the same capacity? I think the 
 goal is to have

Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Roland via EV
   
I also saw a increase of capacity after each charge cycle by reading how much 
ah is use per mile on the same road and temperature using 33.3 ah Li Ion cells 
connected six cells in parallel for about 200 ah for 216 volts or about 4.0 
volts per cell which is 95% of the maximum cell voltage.  Only discharge to 90% 
SOC.  

 

The first cycle was in the high 2 ah range and now after 256 cycles is now 1.6 
ah.

 

The most negative cell still reads about 0.01 volt higher than the most 
positive cell.  These batteries are not group in one large block.  There are 
three battery packs that are space 6 inches apart and 2 inches from the battery 
box container.  

 

The aluminum case cells are setting on a heat sink which is setting on a 
insulator board cushion by rubber nut dampers fasten to the fiberglass box. 

 

Roland 

 

Each cell is space 0.1875 inches apart to allow air flow between the cell 
modules.  There is a incoming air blower, a exhaust air blower and a in battery 
box air circulator.  

 

 


- Original Message - 

From: via EVmailto:ev@lists.evdl.org 

To: ev@lists.evdl.orgmailto:ev@lists.evdl.org 

Sent: Monday, August 03, 2015 5:19 AM

Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing



I believe he is experiencing temporary capacity fade mostly. I did a recent 
test after all the battery discussion we had last month.
I had some CALB gray cells 60ah in my garage. I had left them at 2.5 volts 
which every one tells me is a no no. They sat in my garage over a year at that 
voltage. When I check them some had dropped in voltage one down to 1.8 volts. I 
became concerned the others were correct in their theories.
I charged this one cell up to 3.65 volts. Then discharged it and got 25 ah. Now 
I became very concerned but not convinced. I repeated the process and each time 
I was discharging at 0.5C and charging at 1/6 C or 30amps and 10 amps. The 
second time I got 25ah the third I got 45ah the fourth time I got 61,75. Ah and 
the fifth time I got 62.5 ah. The paperwork from CALB says it's a 62 ah cell.
I heard from another user that you can wake these cells up by slow cycling them 
and the paper I shared with the group stated that this type of capacity loss 
could be recovered.
Now after this inadvertent experiment I am convinced that this mechanism is 
real and there can be apparent capacity loss from not exercising the cell all 
the way and the speed of charge seems to matter for this particular situation.
I realize one test is not enough but as I said this is documented by 
researchers in the pAper I shared before. 

Sent from Outlook

_
From: brucedp5 via EV ev@lists.evdl.orgmailto:ev@lists.evdl.org
Sent: Monday, August 3, 2015 2:32 AM
Subject: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing
To:  ev@lists.evdl.orgmailto:ev@lists.evdl.org




'“It’s fine to Supercharge,” she said “Just don’t do it too much.”
Tesla Service Center “pack balancing” ... they do it all the time.
“Discharge it as close as you can to zero, and then charge it as slow as
possible all the way up to 100 percent,” ... “You’ll probably get some
capacity back.”'

% Is it the pack, guessometer, or both that is reset? %

http://www.greencarreports.com/news/1099280_life-with-tesla-model-s-does-supercharging-cut-battery-capacityhttp://www.greencarreports.com/news/1099280_life-with-tesla-model-s-does-supercharging-cut-battery-capacity
Life With Tesla Model S: Does Supercharging Cut Battery Capacity?
By David Noland  Jul 28, 2015

[images  
http://images.thecarconnection.com/med/tesla-model-s-electric-car-road-trip-upstate-new-york-to-southern-california-photo-david-noland_100500010_m.jpghttp://images.thecarconnection.com/med/tesla-model-s-electric-car-road-trip-upstate-new-york-to-southern-california-photo-david-noland_100500010_m.jpg
Solar panels at Supercharger in Barstow, CA, during Tesla Model S road trip 
/ David Noland

http://images.thecarconnection.com/med/tesla-model-s-lithium-ion-battery-pack-in-rolling-chassis-photo-martin-gillet-via-flickr_100481091_m.jpghttp://images.thecarconnection.com/med/tesla-model-s-lithium-ion-battery-pack-in-rolling-chassis-photo-martin-gillet-via-flickr_100481091_m.jpg
Tesla Model S lithium-ion battery pack in rolling chassis  / Martin Gillet
via Flickr

http://images.thecarconnection.com/med/2013-tesla-model-s-at-supercharger-station-on-ny-to-fl-road-trip-photo-david-noland_100454642_m.jpghttp://images.thecarconnection.com/med/2013-tesla-model-s-at-supercharger-station-on-ny-to-fl-road-trip-photo-david-noland_100454642_m.jpg
2013 Tesla Model S at Supercharger station on NY-to-FL road trip  / David
Noland

http://images.thecarconnection.com/med/2013-tesla-model-s-at-supercharger-station-on-ny-to-fl-road-trip-photo-david-noland_100454644_m.jpghttp://images.thecarconnection.com/med/2013-tesla-model-s-at-supercharger-station-on-ny-to-fl-road-trip-photo-david-noland_100454644_m.jpg
]

[image] Tesla Model

Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread paul dove via EV
Hello Cor van de Water,
My name is Paul Dove, thus dovepa.  I don't know you either. Just knowing your 
name or where you work does not make me know you.
It is not really relevant who uses a BMS. People used to use x-rays to measure 
their shoe size and it had a viewer so you could see your feet x-rayed real 
time. They figured out this was dangerous eventually but non-the-less everyone 
was doing it.
Now, with everyone is doing it argument out of the way..
The CC/CV charging methodology was arrived at by experimentation. Researchers 
were trying to determine the method that would put the most capacity in the 
cell. They tried multiple CV values and recommend the value that put the most 
into the cell.
Actual capacity has to be calculated by current times time. It cannot be 
determined by voltage. The voltage set point is part of a procedure to maximize 
the energy in the cell. 

In series the current is the same through all the cells. A balancer will 
attempt to shunt part of this current off of the cell to let other cells come 
up to the CV value while keeping this cell from exceeding the CV value. In my 
opinion, having not analyzed every BMS out there, a BMS would need to shunt 
enough energy to keep the voltage from rising above this voltage set point or 
have the ability to command the charger to lower the current. 

So the balancer would have to hold cells individually at the CV level by 
reducing current into each cell independently.

Now, even if it can achieve this feat according to the manufacturers 
recommended cc/cv procedure this does not balance the cells. Ok, maybe it's a 
semantics issue on the word balanced. What is balanced? All cells at the same 
voltage? All cells at the same capacity? I think the goal is to have maximum 
capacity not balancing.
That aside, do you actually have more capacity? If so, how much more?
When you discharge the car will cut off when the lowest capacity cell reaches 
it's cutoff voltage so by holding it at the set point voltage while the others 
fill up didn't gain any pack capacity advantage sine you still cutoff based on 
the lowest capacity cell. You pack size is the size of your lowest or weakest 
cell. No way around that. 

In addition, the amount of energy put into the cell during the constant current 
part of the charge is less than 5%.
So on 70Ah cells we are talking 3 miles range. That's if you cut off when the 
first cell reaches the set point voltage. So if you took the current down to 
C/20 based on the lowest capacity cell you would mt likely loose no capacity or 
if I'm wrong possibly 1% or less than a mile range.
The whole concept of balancing comes from other battery technology such as Lead 
Acid cells where it makes much more sense. You want all the batteries to boil 
to get maximum capacity.
I have no problem with a BMS to monitor individual cell voltage an temperature 
and controlling charge based on this.  My arguments are against shunt balancer 
circuits.
Both their effectiveness and the necessity.

  From: Cor van de Water via EV ev@lists.evdl.org
 To: Electric Vehicle Discussion List ev@lists.evdl.org 
 Sent: Tuesday, August 4, 2015 10:48 AM
 Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing
   
Hello dovepa at bellsouth.net AKA via EV,
I have no idea who you are - the message is not signed and your name is not 
showing from your email.
You can believe what you want about Lithiums, but think about that even the 
Chinese invest in a BMS
on every Lithium battery pack that they ship, while they are known to cut 
corners and reduce cost,
so there must be a reason

Cor van de Water
Chief Scientist
Proxim Wireless

office +1 408 383 7626         Skype: cor_van_de_water
XoIP  +31 87 784 1130         private: cvandewater.info
www.proxim.com


This email message (including any attachments) contains confidential and 
proprietary information of Proxim Wireless Corporation.  If you received this 
message in error, please delete it and notify the sender.  Any unauthorized 
use, disclosure, distribution, or copying of any part of this message is 
prohibited.


-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of via EV
Sent: Tuesday, August 04, 2015 5:03 AM
To: Electric Vehicle Discussion List; Bill Dube
Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

It's possible he has a defective battery. Also, I still don't believe balances 
work on Lithium cells.

Sent from Outlook




On Mon, Aug 3, 2015 at 9:40 PM -0700, Bill Dube via EV ev@lists.evdl.org 
wrote:










There are too many variables to draw any strong conclusions. The two biggest 
factors are:

1) The BMS does not have as much time to balance during a fast charge.
2) The cell temperature is typically higher (for many reasons) when you fast 
charge. The cells don't like high temperatures.

Stale charge is also large factor in apparent capacity change and happens in 
all chemistries to varying

Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Mark Grasser via EV
To be simple it is not all about just the fact that all cells get the same 
amount of current, thus a BMS is not needed. If this were true then the 6 cells 
in a FLA would not go into horible unbalance as they do.

So to be simple, as I am, it also includes internal resistance, then by math, 
volts and watts. The differneces in internal resistance will directly affect 
the cells ability to accept charge. This will directly affect balance. Please 
understand that the internal resistance during discharge will not be the same 
as during recharge.

One for the non balancing side, if you only charge to 80% and only discharge to 
30% you might never need to balance. MANY of my boating customers do this as it 
fits their needs, they simply charge underway when needed. EVs are a different 
story. Here some of us want to charge as close to 100% as possible and 
discharge as low as they can. In this instance it is important to balance as 
going to far over voltage or going negative in discharge is obviously not a 
good thing.

To say that simply because the current is the same through the entire bank of 
batteries is proof thay the cells can not unbalance, is incorrect.

Mark Grasser


 



Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

Hello Cor van de Water,
My name is Paul Dove, thus dovepa.  I don't know you either. Just knowing your 
name or where you work does not make me know you.
It is not really relevant who uses a BMS. People used to use x-rays to measure 
their shoe size and it had a viewer so you could see your feet x-rayed real 
time. They figured out this was dangerous eventually but non-the-less everyone 
was doing it.
Now, with everyone is doing it argument out of the way..
The CC/CV charging methodology was arrived at by experimentation. Researchers 
were trying to determine the method that would put the most capacity in the 
cell. They tried multiple CV values and recommend the value that put the most 
into the cell.
Actual capacity has to be calculated by current times time. It cannot be 
determined by voltage. The voltage set point is part of a procedure to maximize 
the energy in the cell. 

In series the current is the same through all the cells. A balancer will 
attempt to shunt part of this current off of the cell to let other cells come 
up to the CV value while keeping this cell from exceeding the CV value. In my 
opinion, having not analyzed every BMS out there, a BMS would need to shunt 
enough energy to keep the voltage from rising above this voltage set point or 
have the ability to command the charger to lower the current. 

So the balancer would have to hold cells individually at the CV level by 
reducing current into each cell independently.

Now, even if it can achieve this feat according to the manufacturers 
recommended cc/cv procedure this does not balance the cells. Ok, maybe it's a 
semantics issue on the word balanced. What is balanced? All cells at the same 
voltage? All cells at the same capacity? I think the goal is to have maximum 
capacity not balancing.
That aside, do you actually have more capacity? If so, how much more?
When you discharge the car will cut off when the lowest capacity cell reaches 
it's cutoff voltage so by holding it at the set point voltage while the others 
fill up didn't gain any pack capacity advantage sine you still cutoff based on 
the lowest capacity cell. You pack size is the size of your lowest or weakest 
cell. No way around that. 

In addition, the amount of energy put into the cell during the constant current 
part of the charge is less than 5%.
So on 70Ah cells we are talking 3 miles range. That's if you cut off when the 
first cell reaches the set point voltage. So if you took the current down to 
C/20 based on the lowest capacity cell you would mt likely loose no capacity or 
if I'm wrong possibly 1% or less than a mile range.
The whole concept of balancing comes from other battery technology such as Lead 
Acid cells where it makes much more sense. You want all the batteries to boil 
to get maximum capacity.
I have no problem with a BMS to monitor individual cell voltage an temperature 
and controlling charge based on this.  My arguments are against shunt balancer 
circuits.
Both their effectiveness and the necessity.

  From: Cor van de Water via EV ev@lists.evdl.org
 To: Electric Vehicle Discussion List ev@lists.evdl.org
 Sent: Tuesday, August 4, 2015 10:48 AM
 Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing
   
Hello dovepa at bellsouth.net AKA via EV, I have no idea who you are - the 
message is not signed and your name is not showing from your email.
You can believe what you want about Lithiums, but think about that even the 
Chinese invest in a BMS on every Lithium battery pack that they ship, while 
they are known to cut corners and reduce cost, so there must be a reason

Cor van de Water
Chief Scientist
Proxim Wireless

office +1 408 383 7626 Skype

Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread paul dove via EV
Hey Mark,
I know that seems like sounds reasonable to most people. However, a battery is 
chemical and while you can measure resistance with a meter a battery has no 
resistance in the electrical sense. What appears as resistance in a Lithium Ion 
cell is really the diffusion rate of Li Ions into the graphite structure. Ohm's 
law does not apply inside a battery. You are pushing Ions into a crystal 
structure and as it gets full the cell transfers some of this energy into heat. 
So holding a battery at the set point after it is full just heats up the cell.




  From: Mark Grasser via EV ev@lists.evdl.org
 To: 'Electric Vehicle Discussion List' ev@lists.evdl.org 
 Sent: Tuesday, August 4, 2015 3:37 PM
 Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing
   
To be simple it is not all about just the fact that all cells get the same 
amount of current, thus a BMS is not needed. If this were true then the 6 cells 
in a FLA would not go into horible unbalance as they do.

So to be simple, as I am, it also includes internal resistance, then by math, 
volts and watts. The differneces in internal resistance will directly affect 
the cells ability to accept charge. This will directly affect balance. Please 
understand that the internal resistance during discharge will not be the same 
as during recharge.

One for the non balancing side, if you only charge to 80% and only discharge to 
30% you might never need to balance. MANY of my boating customers do this as it 
fits their needs, they simply charge underway when needed. EVs are a different 
story. Here some of us want to charge as close to 100% as possible and 
discharge as low as they can. In this instance it is important to balance as 
going to far over voltage or going negative in discharge is obviously not a 
good thing.

To say that simply because the current is the same through the entire bank of 
batteries is proof thay the cells can not unbalance, is incorrect.

Mark Grasser


 



Subject: Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

Hello Cor van de Water,
My name is Paul Dove, thus dovepa.  I don't know you either. Just knowing your 
name or where you work does not make me know you.
It is not really relevant who uses a BMS. People used to use x-rays to measure 
their shoe size and it had a viewer so you could see your feet x-rayed real 
time. They figured out this was dangerous eventually but non-the-less everyone 
was doing it.
Now, with everyone is doing it argument out of the way..
The CC/CV charging methodology was arrived at by experimentation. Researchers 
were trying to determine the method that would put the most capacity in the 
cell. They tried multiple CV values and recommend the value that put the most 
into the cell.
Actual capacity has to be calculated by current times time. It cannot be 
determined by voltage. The voltage set point is part of a procedure to maximize 
the energy in the cell. 

In series the current is the same through all the cells. A balancer will 
attempt to shunt part of this current off of the cell to let other cells come 
up to the CV value while keeping this cell from exceeding the CV value. In my 
opinion, having not analyzed every BMS out there, a BMS would need to shunt 
enough energy to keep the voltage from rising above this voltage set point or 
have the ability to command the charger to lower the current. 

So the balancer would have to hold cells individually at the CV level by 
reducing current into each cell independently.

Now, even if it can achieve this feat according to the manufacturers 
recommended cc/cv procedure this does not balance the cells. Ok, maybe it's a 
semantics issue on the word balanced. What is balanced? All cells at the same 
voltage? All cells at the same capacity? I think the goal is to have maximum 
capacity not balancing.
That aside, do you actually have more capacity? If so, how much more?
When you discharge the car will cut off when the lowest capacity cell reaches 
it's cutoff voltage so by holding it at the set point voltage while the others 
fill up didn't gain any pack capacity advantage sine you still cutoff based on 
the lowest capacity cell. You pack size is the size of your lowest or weakest 
cell. No way around that. 

In addition, the amount of energy put into the cell during the constant current 
part of the charge is less than 5%.
So on 70Ah cells we are talking 3 miles range. That's if you cut off when the 
first cell reaches the set point voltage. So if you took the current down to 
C/20 based on the lowest capacity cell you would mt likely loose no capacity or 
if I'm wrong possibly 1% or less than a mile range.
The whole concept of balancing comes from other battery technology such as Lead 
Acid cells where it makes much more sense. You want all the batteries to boil 
to get maximum capacity.
I have no problem with a BMS to monitor individual cell voltage an temperature 
and controlling charge based

Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Alan Arrison via EV
We already went round and round with this no self discharge, no BMS 
fellow a few months ago.



On 8/4/2015 5:08 PM, paul dove via EV wrote:

Hey Mark,
I know that seems like sounds reasonable to most people. However, a battery is 
chemical and while you can measure resistance with a meter a battery has no 
resistance in the electrical sense. What appears as resistance in a Lithium Ion 
cell is really the diffusion rate of Li Ions into the graphite structure. Ohm's 
law does not apply inside a battery. You are pushing Ions into a crystal 
structure and as it gets full the cell transfers some of this energy into heat. 
So holding a battery at the set point after it is full just heats up the cell.





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Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-04 Thread Ben Goren via EV
On Aug 4, 2015, at 6:34 PM, Alan Arrison via EV ev@lists.evdl.org wrote:

 We already went round and round with this no self discharge, no BMS fellow 
 a few months ago.


Yes, we did.

I think a good analogy might be the Tire Pressure Monitoring System found in 
every new car for ages. You could probably make a similar argument that those 
sorts of things are utterly worthless since any idiot with a $2 pressure gauge 
can check if the tires need air or not, so why pay the hundreds of dollars it 
costs the manufacturers to put it in every car?

If the obvious and substantial benefits of TPMS aren't obvious to somebody, and 
if the fact that the cost-conscious penny-pinching manufacturers don't try to 
make a few hundred dollars extra profit for themselves by leaving it out of 
their designs isn't enough to get that person to re-think opposition to 
TPMS...then there's basically not going to be any way to get through to that 
person.

b
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Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-03 Thread ph...@bill-collins.net via EV
I see a couple of things wrong here that make me question the whole article:
 
1) The author seems to think that supercharging will be harder on the pack than
fast charging a LEAF because the supercharger is higher rate. BUT, compared to
total pack capacity, the supercharger is the lower of the two rates. (and the
Tesla has better thermal management than the LEAF)
 
2) I don't see how the 98% capacity estimate could have been accurate
immediately after supercharging.  I don't know the specifics of the Tesla
battery, but I would expect the estimated capacity to be high before the battery
has had a chance to cool down from supercharging.
 
Bill
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Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-03 Thread Bill Dube via EV
There are too many variables to draw any strong conclusions. The two 
biggest factors are:


1) The BMS does not have as much time to balance during a fast charge.
2) The cell temperature is typically higher (for many reasons) when you 
fast charge. The cells don't like high temperatures.


Stale charge is also large factor in apparent capacity change and 
happens in all chemistries to varying degrees. It may be a factor in 
these tests on battery pack capacity. (In nicads it can be 
particularly a large stale charge effect and is commonly called 
memory effect.) Essentially, when you _gently_ and _fully_ cycle a 
battery, the apparent capacity becomes much greater after the first full 
cycle, and often grows a bit more with the second full cycle.


The longer it has been since you last accessed the full capacity of the 
battery, the worse the problem of stale charge becomes.


Batteries are very complicated chemical beasts. Simple tests often don't 
tell you the full story.


Bill Dube'




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[EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-03 Thread brucedp5 via EV


'“It’s fine to Supercharge,” she said “Just don’t do it too much.”
Tesla Service Center “pack balancing” ... they do it all the time.
“Discharge it as close as you can to zero, and then charge it as slow as
possible all the way up to 100 percent,” ... “You’ll probably get some
capacity back.”'

% Is it the pack, guessometer, or both that is reset? %

http://www.greencarreports.com/news/1099280_life-with-tesla-model-s-does-supercharging-cut-battery-capacity
Life With Tesla Model S: Does Supercharging Cut Battery Capacity?
By David Noland  Jul 28, 2015

[images  
http://images.thecarconnection.com/med/tesla-model-s-electric-car-road-trip-upstate-new-york-to-southern-california-photo-david-noland_100500010_m.jpg
Solar panels at Supercharger in Barstow, CA, during Tesla Model S road trip 
/ David Noland

http://images.thecarconnection.com/med/tesla-model-s-lithium-ion-battery-pack-in-rolling-chassis-photo-martin-gillet-via-flickr_100481091_m.jpg
Tesla Model S lithium-ion battery pack in rolling chassis  / Martin Gillet
via Flickr

http://images.thecarconnection.com/med/2013-tesla-model-s-at-supercharger-station-on-ny-to-fl-road-trip-photo-david-noland_100454642_m.jpg
2013 Tesla Model S at Supercharger station on NY-to-FL road trip  / David
Noland

http://images.thecarconnection.com/med/2013-tesla-model-s-at-supercharger-station-on-ny-to-fl-road-trip-photo-david-noland_100454644_m.jpg
]

[image] Tesla Model S in Albuquerque's 'snowstorm' during NY-to-California
road trip  / David Noland

Last month, my wife and I took my 2013 Tesla Model S on a day trip from our
home in New York’s Hudson Valley to Brattleboro, Vermont, a distance of 180
miles.

We picked up our daughter, charged the 85-kilowatt-hour battery up to 98
percent at the Brattleboro Supercharger, and returned home via a longer,
more scenic route of 210 miles.

To my surprise, the return trip took almost every electron the battery could
muster. We pulled into the driveway with only 5 percent capacity
remaining—roughly 15 miles of range.

At first I attributed the close call to a headwind on the way home. But the
efficiency readout for the return leg had showed a respectable 302
watt-hours per mile.

That was only a bit worse than the 290 Wh/mi of the outbound leg, and well
within my normal range for summer Interstate cruising.

Diminished battery capacity
Looking more closely, what caught my eye was the dashboard readout for total
energy used for the 210-mile return leg: 63.5 kWh.

I had started with 98 percent battery and finished with 5 percent. Thus the
63.5 kWh amounted to 93 percent of the total battery capacity.

That suggests the 100-percent capacity was 68.3 kWh.

Wait a minute: Wasn’t this supposed to be an 85-kWh battery? What the heck
had happened to the other 17 kWh?

Too much Supercharging?
There has long been speculation that Supercharging--and DC fast charging of
any electric car--can cause long-term loss of Model S battery capacity.

And there is credible research to support the general idea.

A 2014 study by Idaho National Laboratory of two 2012 Nissan Leafs concluded
that, after 40,000 miles, the Nissan Leaf that used 50-kW fast charging
exclusively had 3 percent less battery capacity than the one that used
standard 6.6-kW charging.

At 120-135 kW, the Tesla Superchargers are more than twice as powerful as
the Leaf fast-chargers. It stands to reason that its effects on long-term
battery capacity might be even greater.

Was my apparent loss of battery capacity due to too much Supercharging?

[image] Tesla Model S electric-car road trip, Route 66 Museum, Elk City,
Oklahoma  / David Noland

As it happens, I’ve done a lot of Supercharging in the past six months. 

In January, I drove my Model S to California, using Superchargers most of
the way. During a two-month stay, we made several Supercharged road trips
along the West Coast.

Then I drove the car back to New York, Supercharged all the way along I-70.

And for the past few weeks, I’ve done some local Supercharging at a new
station that recently opened near me.

Overall, I’d estimate that of the last 10,000 miles I’ve driven the Model S,
8,000 of them have been Supercharged.

No problem, Tesla says

Has this Supercharging frenzy come back to haunt me?

Tesla says no. (In fact, one Tesla tech rep I consulted almost shouted,
“Absolutely not!”) The official company line is that Supercharging has no
deleterious effect on the battery, period.

But a funny thing: all three Tesla reps I talked to, including the shouter,
hedged their bets.

After assuring me there was absolutely no problem, each one advised me
that--all else being equal--slower charging was better for the battery in
the long run.

 “It’s fine to Supercharge,” one of them told me. “Just don’t do it too
much.”

When I pointed out the thundering contradiction in that statement, she just
shrugged.

So can I just Supercharge up to the point where I start to lose range?

Sudden capacity loss
Before I left for California, I’d 

Re: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing

2015-08-03 Thread via EV
I believe he is experiencing temporary capacity fade mostly. I did a recent 
test after all the battery discussion we had last month.
I had some CALB gray cells 60ah in my garage. I had left them at 2.5 volts 
which every one tells me is a no no. They sat in my garage over a year at that 
voltage. When I check them some had dropped in voltage one down to 1.8 volts. I 
became concerned the others were correct in their theories.
I charged this one cell up to 3.65 volts. Then discharged it and got 25 ah. Now 
I became very concerned but not convinced. I repeated the process and each time 
I was discharging at 0.5C and charging at 1/6 C or 30amps and 10 amps. The 
second time I got 25ah the third I got 45ah the fourth time I got 61,75. Ah and 
the fifth time I got 62.5 ah. The paperwork from CALB says it's a 62 ah cell.
I heard from another user that you can wake these cells up by slow cycling them 
and the paper I shared with the group stated that this type of capacity loss 
could be recovered.
Now after this inadvertent experiment I am convinced that this mechanism  is 
real and there can be apparent capacity loss from not exercising the cell all 
the way and the speed of charge seems to matter for this particular situation.
I realize one test is not enough but as I said this is documented by 
researchers in the pAper I shared before. 

Sent from Outlook

_
From: brucedp5 via EV ev@lists.evdl.org
Sent: Monday, August 3, 2015 2:32 AM
Subject: [EVDL] EVLN: Offset Supercharging degradation w/ pack balancing
To:  ev@lists.evdl.org




'“It’s fine to Supercharge,” she said “Just don’t do it too much.”
Tesla Service Center “pack balancing” ... they do it all the time.
“Discharge it as close as you can to zero, and then charge it as slow as
possible all the way up to 100 percent,” ... “You’ll probably get some
capacity back.”'

% Is it the pack, guessometer, or both that is reset? %

http://www.greencarreports.com/news/1099280_life-with-tesla-model-s-does-supercharging-cut-battery-capacity
Life With Tesla Model S: Does Supercharging Cut Battery Capacity?
By David Noland  Jul 28, 2015

[images  
http://images.thecarconnection.com/med/tesla-model-s-electric-car-road-trip-upstate-new-york-to-southern-california-photo-david-noland_100500010_m.jpg
Solar panels at Supercharger in Barstow, CA, during Tesla Model S road trip 
/ David Noland

http://images.thecarconnection.com/med/tesla-model-s-lithium-ion-battery-pack-in-rolling-chassis-photo-martin-gillet-via-flickr_100481091_m.jpg
Tesla Model S lithium-ion battery pack in rolling chassis  / Martin Gillet
via Flickr

http://images.thecarconnection.com/med/2013-tesla-model-s-at-supercharger-station-on-ny-to-fl-road-trip-photo-david-noland_100454642_m.jpg
2013 Tesla Model S at Supercharger station on NY-to-FL road trip  / David
Noland

http://images.thecarconnection.com/med/2013-tesla-model-s-at-supercharger-station-on-ny-to-fl-road-trip-photo-david-noland_100454644_m.jpg
]

[image] Tesla Model S in Albuquerque's 'snowstorm' during NY-to-California
road trip  / David Noland

Last month, my wife and I took my 2013 Tesla Model S on a day trip from our
home in New York’s Hudson Valley to Brattleboro, Vermont, a distance of 180
miles.

We picked up our daughter, charged the 85-kilowatt-hour battery up to 98
percent at the Brattleboro Supercharger, and returned home via a longer,
more scenic route of 210 miles.

To my surprise, the return trip took almost every electron the battery could
muster. We pulled into the driveway with only 5 percent capacity
remaining—roughly 15 miles of range.

At first I attributed the close call to a headwind on the way home. But the
efficiency readout for the return leg had showed a respectable 302
watt-hours per mile.

That was only a bit worse than the 290 Wh/mi of the outbound leg, and well
within my normal range for summer Interstate cruising.

Diminished battery capacity
Looking more closely, what caught my eye was the dashboard readout for total
energy used for the 210-mile return leg: 63.5 kWh.

I had started with 98 percent battery and finished with 5 percent. Thus the
63.5 kWh amounted to 93 percent of the total battery capacity.

That suggests the 100-percent capacity was 68.3 kWh.

Wait a minute: Wasn’t this supposed to be an 85-kWh battery? What the heck
had happened to the other 17 kWh?

Too much Supercharging?
There has long been speculation that Supercharging--and DC fast charging of
any electric car--can cause long-term loss of Model S battery capacity.

And there is credible research to support the general idea.

A 2014 study by Idaho National Laboratory of two 2012 Nissan Leafs concluded
that, after 40,000 miles, the Nissan Leaf that used 50-kW fast charging
exclusively had 3 percent less battery capacity than the one that used
standard 6.6-kW charging.

At 120-135 kW, the Tesla Superchargers are more than twice as powerful as
the Leaf fast-chargers. It stands to reason that its effects on long