Battery temp management for new leaf

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lorenfb said:
johnlocke said:
lorenfb said:
A further comparison of MS battery heat versus the Leaf's (24kWhr) becomes interesting. Since the Tesla's
and Leaf's overall internal battery impedance is about the same, and the MS weighs about 1.4X the Leaf's weight,
the MS' battery will generate 2X the heat as will the Leaf's battery:

Battery Heat = Rs (internal impedance) X I (battery current)^2
Vehicle Power Losses (moderate freeway speeds - same rolling resistance + moderate drag) =
V (battery) X I (battery current)

Since the battery voltage is the same for both the MS & Leaf, the MS will require about 1.4X (MS weight)
the current than the Leaf at the same speed. Since both the MS & the Leaf have about the same internal
impedance, the MS battery will develop about 2X the battery heat as the Leaf at about the same speeds.
Not true. The model S has only slightly lower efficiency than the Leaf (330wh/mi vs 300wh/mi). So figure 10% more heat not twice the heat. Also there are 7000 cells in a Tesla battery pack as compared to 96 in a Leaf pack. There are a lot of cells in parallel in each module in a Tesla pack so the the current draw from each is much lower. The current draw on a Leaf is though 96 cells in series. Bottom line is that despite being heavier, the Tesla is nearly as efficient as a Leaf and seats up to 7 with the jump seats installed. Weight is less of a factor than aerodynamics particularly at highway speeds.

Here's my data source: https://rennlist.com/forums/mission-e/984855-probable-base-price-2.html

Where're your data to refute mine, i.e simple math based on simple electronics & NOT EPA data.
You do understand internal battery impedance (a common term used in electronics to measure battery
characteristics), right? You have been using TeslaSpy to actually measure the MS' battery output impedance too?
Or maybe you actually used a 18650 cell as was done in the link, right?

My results are NOT based on how each vehicle was driven and under what conditions, i.e. open to question,
but an actual analysis of each vehicle's battery!
Your first error is to equate vehicle weight to power consumption.

Your second error is your source for impedances. They were calculated incorrectly. They forgot to account for the fact that the cells in a Tesla are connected in parallel for the modules and the modules are in series. In a Leaf all the cells are in series even though the cells are packed as pairs. The correct values are 115.2 mohms for the Leaf and 76.5 mohms for the 95 KWH Tesla. That's using your source's figures for the battery's internal impedance. if you are driving at 60 mph on level ground power consumption is about 16KWH per hour or 42 amps current at 375VDC. In a Leaf, that 42 amps flows through each cell in the pack. Those cells had better have a very low impedance. In a Tesla pack those 42 amps are divided among 74 batteries or about 560ma each. The Leaf has a .55 c discharge rate while the discharge rate on the Tesla is .16 c. Which battery do you think is working harder?

Your third error is to dismiss the EPA numbers as irrelevant. They are run under controlled conditions in a lab setting. They do correlate to real world numbers provided by both Leaf and Tesla drivers.

Your fourth error is to state that the battery impedances for both the Tesla and the Leaf are the same. Tesla batteries have about 2/3 of the impedance of a Leaf. Teslas can be equipped with dual 275hp motors. That translates to 1100 Amps current draw and they can actually draw even more on fully charged batteries. See ludicrous mode on Youtube for a demo. Try drawing anywhere near that out of a Leaf battery. I had to do the math 3 times before I believed that current draw. It equates to 15,27 amp draw from each cell in the module.

The purpose of this thread is to discuss whether the 2018 Leaf needs a TMS in hot climates. It's already been proven that Leafs do well in cool climates like England,Canada and the northern U.S. The French Zoe with a 40KWH battery does well in Europe as well.
 
johnlocke said:

johnlocke said:
Your first error is to equate vehicle weight to power consumption.

Really? You're unaware that vehicle weight is the key factor in rolling resistance energy loss?

johnlocke said:
Your second error is to use the internal impedance of a single cell when the module is composed of 72 cells wired in parallel. If the internal resistance of the 18650 cell is 3 times higher than that of a Leaf cell as you claim then the internal resistance of a Tesla module is 3/72 or about 4% of a leaf cell. The current flow in a module is divided among the 72 cells. if you are driving at 60 mph on level ground power consumption is about 16KWH per hour or 42 amps current at 375VDC. In a Leaf, that 42 amps flows through each cell in the pack. Those cells had better have a very low impedance. In a Tesla pack those 42 amps are divided among 72 batteries or about 600ma each. The Leaf has a .55 c discharge rate while the discharge rate on the Tesla is .16 c. Which battery do you think is working harder?

Read the analysis in the above link, that may help you understand how the equivalent series resistance/impedance
of the overall battery is determined. It's is a very simple analysis, i.e. a series/parallel resistance equivalency.

johnlocke said:
Your third error is to dismiss the EPA numbers as irrelevant. They are run under controlled conditions in a lab setting. They do correlate to real world numbers provided by both Leaf and Tesla drivers.

1. Fact - The MS weighs 1.4X heavier than the Leaf.
2. Fact - Power loss (consumed) while moving is the result of rolling resistance & drag. (neglecting motor efficiency) plus battery power loss (heating - battery series resistance)
3. Fact - Power loss = Battery Voltage X Battery Current
4. Fact - Battery Power loss = Battery resistance X battery current squared

The above facts then determine each vehicle's theoretical efficiency the result of losses.

johnlocke said:
Your fourth error is to state that the battery impedances for both the Tesla and the Leaf are the same. Teslas can be equipped with dual 275hp motors. That translates to 1100 Amps current draw and they can actually draw even more on fully charged batteries. See ludicrous mode on Youtube for a demo. Try drawing anywhere near that out of a Leaf battery. I had to do the math 3 times before I believed that current draw. It equates to 15,27 amp draw from each cell in the module.

Again, please read the link and then comment. I said the overall battery effective resistance is basically
the same for the MS & Leaf, i.e. NOT that each MS cell & each Leaf cell has the same resistance.

johnlocke said:
The purpose of this thread is to discuss whether the 2018 Leaf needs a TMS in hot climates. It's already been proven that Leafs do well in cool climates like England,Canada and the northern U.S. The French Zoe with a 40KWH battery does well in Europe as well.

You challenged my analysis, so please read the link and show mathematically how to determine the effective
internal series resistance of a multiple cell battery, e.g. knowing the single cell value of the MS or Leaf,
as presented in the link.

If you really want to refute the MS' effective battery resistance, then invalidate the methodology used in the
link to calculate the 18650 cell's internal resistance. I've assumed the writer a knowledgeable Tesla insider/consultant.
His overall mathematics are correct, notwithstanding his determination of the single 18650 cell resistance.
 
lorenfb said:
johnlocke said:

johnlocke said:
Your first error is to equate vehicle weight to power consumption.

Really? You're unaware that vehicle weight is the key factor in rolling resistance energy loss?

johnlocke said:
Your second error is to use the internal impedance of a single cell when the module is composed of 72 cells wired in parallel. If the internal resistance of the 18650 cell is 3 times higher than that of a Leaf cell as you claim then the internal resistance of a Tesla module is 3/72 or about 4% of a leaf cell. The current flow in a module is divided among the 72 cells. if you are driving at 60 mph on level ground power consumption is about 16KWH per hour or 42 amps current at 375VDC. In a Leaf, that 42 amps flows through each cell in the pack. Those cells had better have a very low impedance. In a Tesla pack those 42 amps are divided among 72 batteries or about 600ma each. The Leaf has a .55 c discharge rate while the discharge rate on the Tesla is .16 c. Which battery do you think is working harder?

Read the analysis in the above link, that may help you understand how the equivalent series resistance/impedance
of the overall battery is determined. It's is a very simple analysis, i.e. a series/parallel resistance equivalency.

johnlocke said:
Your third error is to dismiss the EPA numbers as irrelevant. They are run under controlled conditions in a lab setting. They do correlate to real world numbers provided by both Leaf and Tesla drivers.

1. Fact - The MS weighs 1.4X heavier than the Leaf.
2. Fact - Power loss (consumed) while moving is the result of rolling resistance & drag. (neglecting motor efficiency) plus battery power loss (heating - battery series resistance)
3. Fact - Power loss = Battery Voltage X Battery Current
4. Fact - Battery Power loss = Battery resistance X battery current squared

The above facts then determine each vehicle's theoretical efficiency the result of losses.

johnlocke said:
Your fourth error is to state that the battery impedances for both the Tesla and the Leaf are the same. Teslas can be equipped with dual 275hp motors. That translates to 1100 Amps current draw and they can actually draw even more on fully charged batteries. See ludicrous mode on Youtube for a demo. Try drawing anywhere near that out of a Leaf battery. I had to do the math 3 times before I believed that current draw. It equates to 15,27 amp draw from each cell in the module.

Again, please read the link and then comment. I said the overall battery effective resistance is basically
the same for the MS & Leaf, i.e. NOT that each cell within each the battery pack has the same resistance.

johnlocke said:
The purpose of this thread is to discuss whether the 2018 Leaf needs a TMS in hot climates. It's already been proven that Leafs do well in cool climates like England,Canada and the northern U.S. The French Zoe with a 40KWH battery does well in Europe as well.

You challenged my analysis, so please read the link and show mathematically how to determine the effective
internal series resistance of a multiple cell battery, e.g. knowing the single cell value of the MS or Leaf,
as presented in the link.

If you really want to refute the MS' effective battery resistance, then invalidate the methodology used in the
link to calculate the 18650 cell's internal resistance. I've assumed the writer a knowledgeable Tesla insider/consultant.
Please see the revised post . I did check your source who is a contributor on a Porsche website. I have no idea about his expertise but his math has errors. He also didn't seem to realize that the Leaf cells are all in series despite being in paired modules.

As to weight vs power consumption, yes weight increases rolling resistance but at speeds over 30-40 mph aerodynamics trumps all other effects. Since both the EPA results and real word data from both Tesla and Leaf drivers seem to agree as to power consumption, I'l take their word over yours.
 
@johnlocke ,
This article
https://cleantechnica.com/2016/01/06/a-tale-of-3-battery-packs/
says that the 24 kWh LEAF has 192 cells. Since we know it has a 96S arrangement, it must have a 2P arrangement

I had earlier posted that I expected the 40 kwh pack to have as poor a longevity as the 24 kWh, but given the tighter packing in the same volume and therefore higher impedance, I'm now wondering if the dense packs will do even worse.
 
SageBrush said:
@johnlocke ,
This article
https://cleantechnica.com/2016/01/06/a-tale-of-3-battery-packs/
says that the 24 kWh LEAF has 192 cells. Since we know it has a 96S arrangement, it must have a 2P arrangement

I had earlier posted that I expected the 40 kwh pack to have as poor a longevity as the 24 kWh, but given the tighter packing in the same volume and therefore higher impedance, I'm now wondering if the dense packs will do even worse.

To make it simple to understand comparatively:

1. The Leaf has 96 cells stacked in series at about 12.5 Whrs per cell, about 4.1V per cell.
There are essentially 20 parallel stacks (or 2 groups with 10 parallels) resulting in 1920 cells for a total capacity of 24kWhrs.
2. The MS has 96 18650 cells essentially stacked is series and assuming about 12.5 Whrs per cell .
There are essentially 70 parallel stacks resulting in 6720 cells for a total capacity of 84kWhrs.

The key point from the noted reference is that the internal battery resistances are essentially equal:

The P95D pack is 96S74P, so (96/74)*(59 mOhm) = 63.5 mOhm. Altogether the bolted joints and busbars and such come to another 0.5 mOhms, for a net 64 mOhms per pack.

The Nissan Leaf uses pouch cells that are laserwelded together; these particular pouches are optimized for impedence at the expense of energy density at around 1.2mOhm and 30Ah per cell. This makes cooling significantly easier (and therefore the pack much cheaper), and there are 48x 2S2P modules. The net resistance is (48*2/2)*(1.2mOhm) = 57.6mOhm.

So given that both battery packs have essentially the same internal resistance but the Tesla weighs 1.4X the Leaf,
it will theoretically use 2X power (1.4X the current) of the Leaf for its rolling resistance at moderate speeds
(~ 40 - 50 MPH).

Use this for power losses: http://ecomodder.com/forum/tool-aero-rolling-resistance.php
 
johnlocke said:
I have no idea about his expertise but his math has errors. He also didn't seem to realize that the Leaf cells are all in series despite being in paired modules.

Re-read it.

johnlocke said:
As to weight vs power consumption, yes weight increases rolling resistance but at speeds over 30-40 mph aerodynamics trumps all other effects. Since both the EPA results and real word data from both Tesla and Leaf drivers seem to agree as to power consumption, I'l take their word over yours.

So weight is a factor in power consumption. Read here to calculate the crossover between rolling resistance
and drag: http://ecomodder.com/forum/tool-aero-rolling-resistance.php

A point that should now become more apparent relative to battery TMS is the battery's internal resistance,
i.e. heat generated internally besides externally from ambient. Factors such as vehicle weight, speed, length
of QCing, & etc., all play a role in whether to have TMS or not. As the reference noted, capacity density at the
expense of higher internal resistance was likely a factor contributing to use of TMS in the Tesla.
 
I don't know why you are harping about weight and ignoring everything else.
Just look at the EPA MPGe figures. The packs will generate similar amounts of heat and require similar amounts of power.

The LEAF pack will heat up in warm weather and the Tesla will be cooled down by its TMS.
 
SageBrush said:
I don't know why you are harping about weight and ignoring everything else.

Where did I ignore "everything else"?

SageBrush said:
The packs will generate similar amounts of heat and require similar amounts of power.

I just provided an example where that's not the case. You and others might find it trivial, but the analysis
makes a point about what contributes to battery thermal increases besides ambient on both the MS & Leaf.

SageBrush said:
The LEAF pack will heat up in warm weather and the Tesla will be cooled down by its TMS.

That's true. Just like you, I don't have all the Nissan engineering data related to using TMS and what the cost
trade-offs are. So at this point, we are all just guessing.
 
Oils4AsphaultOnly said:
This.

After my discussions with lorenfb, where (s)he only saw a few degrees temp increase from QC'ing less than 15 mins, I saw an almost 30 degree increase from a 27 min QC. QC'ing that 40kwh pack will make for even higher temp increase from the higher sustained fast charging.

the temp rise especially from LEAF Spy readings takes time to equalize and as always the rise has to do with starting temp as it relates to ambient so your statement needs a lot more info to mean anything.
 
DaveinOlyWA said:
Oils4AsphaultOnly said:
This.

After my discussions with lorenfb, where (s)he only saw a few degrees temp increase from QC'ing less than 15 mins, I saw an almost 30 degree increase from a 27 min QC. QC'ing that 40kwh pack will make for even higher temp increase from the higher sustained fast charging.

the temp rise especially from LEAF Spy readings takes time to equalize and as always the rise has to do with starting temp as it relates to ambient so your statement needs a lot more info to mean anything.

It was in my discussion with lorenfb. Here's the relevant posting: http://mynissanleaf.com/viewtopic.php?f=55&t=24379&p=504979#p504979

Following that chain will provide the context. It was a very warm day that day.

I think one other poster said it best. Those of us in hot areas should just protect ourselves and NOT consider the leaf.
 
Oils4AsphaultOnly said:
DaveinOlyWA said:
Oils4AsphaultOnly said:
This.

After my discussions with lorenfb, where (s)he only saw a few degrees temp increase from QC'ing less than 15 mins, I saw an almost 30 degree increase from a 27 min QC. QC'ing that 40kwh pack will make for even higher temp increase from the higher sustained fast charging.

the temp rise especially from LEAF Spy readings takes time to equalize and as always the rise has to do with starting temp as it relates to ambient so your statement needs a lot more info to mean anything.

It was in my discussion with lorenfb. Here's the relevant posting: http://mynissanleaf.com/viewtopic.php?f=55&t=24379&p=504979#p504979

Following that chain will provide the context. It was a very warm day that day.

I think one other poster said it best. Those of us in hot areas should just protect ourselves and NOT consider the leaf.

oh ok... another waylaid conversation courtesy of one of the poorest designed sites on the web...

Yeah, couple things; I did a "few" charges during very warm weather and noticed very fast temperature drops after the charge was over like 8-10º within 10 mins after leaving the charger under what would normally not be an easy "battery drive"

This leads me to believe that some sensors are not positioned well to give a good overall temperature reading of the pack

the only other conclusion is the movement of the car was causing the temps to drop quickly which would imply some sort of venting and well all know that can't possibly be true...
 
lorenfb said:
SageBrush said:
@johnlocke ,
This article
https://cleantechnica.com/2016/01/06/a-tale-of-3-battery-packs/
says that the 24 kWh LEAF has 192 cells. Since we know it has a 96S arrangement, it must have a 2P arrangement

I had earlier posted that I expected the 40 kwh pack to have as poor a longevity as the 24 kWh, but given the tighter packing in the same volume and therefore higher impedance, I'm now wondering if the dense packs will do even worse.

To make it simple to understand comparatively:

1. The Leaf has 96 cells stacked in series at about 12.5 Whrs per cell, about 4.1V per cell.
There are essentially 20 parallel stacks (or 2 groups with 10 parallels) resulting in 1920 cells for a total capacity of 24kWhrs.
2. The MS has 96 18650 cells essentially stacked is series and assuming about 12.5 Whrs per cell .
There are essentially 70 parallel stacks resulting in 6720 cells for a total capacity of 84kWhrs.

The key point from the noted reference is that the internal battery resistances are essentially equal:

The P95D pack is 96S74P, so (96/74)*(59 mOhm) = 63.5 mOhm. Altogether the bolted joints and busbars and such come to another 0.5 mOhms, for a net 64 mOhms per pack.

The Nissan Leaf uses pouch cells that are laserwelded together; these particular pouches are optimized for impedence at the expense of energy density at around 1.2mOhm and 30Ah per cell. This makes cooling significantly easier (and therefore the pack much cheaper), and there are 48x 2S2P modules. The net resistance is (48*2/2)*(1.2mOhm) = 57.6mOhm.

So given that both battery packs have essentially the same internal resistance but the Tesla weighs 1.4X the Leaf,
it will theoretically use 2X power (1.4X the current) of the Leaf for its rolling resistance at moderate speeds
(~ 40 - 50 MPH).

Use this for power losses: http://ecomodder.com/forum/tool-aero-rolling-resistance.php
The Leaf has 96 cells arranged in series. 96*4=386vdc. at 1.2 mohm a piece that's 115.2 mohm. A 95 KWH Tesla battery is arranged with 74 cells in parallel. At 59 mohms each 74 cells in parallel, 59/74=.797 mohms. 96 modules * .797 =76.54 mohms. Since your source knows that the Leaf module is comprised of two cells in a single module, I'll assume that he tested an individual cell for the internal resistance value given. I'm done with this conversation.
 
DaveinOlyWA said:
Oils4AsphaultOnly said:
DaveinOlyWA said:
the temp rise especially from LEAF Spy readings takes time to equalize and as always the rise has to do with starting temp as it relates to ambient so your statement needs a lot more info to mean anything.

It was in my discussion with lorenfb. Here's the relevant posting: http://mynissanleaf.com/viewtopic.php?f=55&t=24379&p=504979#p504979

Following that chain will provide the context. It was a very warm day that day.

I think one other poster said it best. Those of us in hot areas should just protect ourselves and NOT consider the leaf.

oh ok... another waylaid conversation courtesy of one of the poorest designed sites on the web...

Yeah, couple things; I did a "few" charges during very warm weather and noticed very fast temperature drops after the charge was over like 8-10º within 10 mins after leaving the charger under what would normally not be an easy "battery drive"

This leads me to believe that some sensors are not positioned well to give a good overall temperature reading of the pack

the only other conclusion is the movement of the car was causing the temps to drop quickly which would imply some sort of venting and well all know that can't possibly be true...

Okay. Do you think my sensors are placed too close to the core of the cells? Because in my case, the temp only dropped about 4 degrees F in the 45 min drive home (stop and go traffic at the beginning too).
 
Oils4AsphaultOnly said:
DaveinOlyWA said:
Oils4AsphaultOnly said:
It was in my discussion with lorenfb. Here's the relevant posting: http://mynissanleaf.com/viewtopic.php?f=55&t=24379&p=504979#p504979

Following that chain will provide the context. It was a very warm day that day.

I think one other poster said it best. Those of us in hot areas should just protect ourselves and NOT consider the leaf.

oh ok... another waylaid conversation courtesy of one of the poorest designed sites on the web...

Yeah, couple things; I did a "few" charges during very warm weather and noticed very fast temperature drops after the charge was over like 8-10º within 10 mins after leaving the charger under what would normally not be an easy "battery drive"

This leads me to believe that some sensors are not positioned well to give a good overall temperature reading of the pack

the only other conclusion is the movement of the car was causing the temps to drop quickly which would imply some sort of venting and well all know that can't possibly be true...

Okay. Do you think my sensors are placed too close to the core of the cells? Because in my case, the temp only dropped about 4 degrees F in the 45 min drive home (stop and go traffic at the beginning too).

no, my situation was likely more to do with greater delta from ambient. I blogged where I dropped from 126º to 120º in literally a few miles. OAT mid 80's, freeway speed 70 mph. Temps were 116-118º in roughly 15 mins.

That was a 4 charge day

In your case, stop and go on asphalt pretty much means ambient temps are out the window.
 
DaveinOlyWA said:
Oils4AsphaultOnly said:
DaveinOlyWA said:
oh ok... another waylaid conversation courtesy of one of the poorest designed sites on the web...

Yeah, couple things; I did a "few" charges during very warm weather and noticed very fast temperature drops after the charge was over like 8-10º within 10 mins after leaving the charger under what would normally not be an easy "battery drive"

This leads me to believe that some sensors are not positioned well to give a good overall temperature reading of the pack

the only other conclusion is the movement of the car was causing the temps to drop quickly which would imply some sort of venting and well all know that can't possibly be true...

Okay. Do you think my sensors are placed too close to the core of the cells? Because in my case, the temp only dropped about 4 degrees F in the 45 min drive home (stop and go traffic at the beginning too).

no, my situation was likely more to do with greater delta from ambient. I blogged where I dropped from 126º to 120º in literally a few miles. OAT mid 80's, freeway speed 70 mph. Temps were 116-118º in roughly 15 mins.

That was a 4 charge day

In your case, stop and go on asphalt pretty much means ambient temps are out the window.

It wasn't that bad, dropped to 90F when charging started near sunset, but I hadn't considered that the asphault probably retained a substantial amount of heat and might've been near 100F still.

All the same though, I still saw a considerable amount of temp increase from doing a 27 min QC (because didn't want to make multiple stops with passengers and bigger battery permitted this). The 40kwh leaf can only see a worse situation, as someone is more likely to charge from LBW to 80% with that battery, and taking ~40 mins to do so. Factoring in a best case of 5% charging loss (assuming it's drawing 45kw max), that's ~2.2kw of power that goes into heating the battery pack.
 
johnlocke said:
The Leaf has 96 cells arranged in series. 96*4=386vdc. at 1.2 mohm a piece that's 115.2 mohm. A 95 KWH Tesla battery is arranged with 74 cells in parallel. At 59 mohms each 74 cells in parallel, 59/74=.797 mohms. 96 modules * .797 =76.54 mohms. Since your source knows that the Leaf module is comprised of two cells in a single module, I'll assume that he tested an individual cell for the internal resistance value given. I'm done with this conversation.

Your 115.2 mohm value for the Leaf is 2X what it actually is. Get and use LeafSpy and you'll find you're wrong.
Remember: Battery internal resistance = Delta Voltage (a change) divided by Delta Current (a change)

If you have access to the LeafDD device (like LeafSpy), it calculates mohms every time a hard acceleration is done
from a stop, i.e. a basic 'launch mode'. As I said before, I've been monitoring it for a number of years:

11/20/14 -13,700 miles, 76 mohms per LeafDD, 20 Deg, 73% SOC
11/27 -13,800 miles, 67 mohms per LeafDD, 25 deg, 63% SOC
11/30 - 13,900 miles, 56 mohms per LeafDD, 27 deg, 71% SOC
12/2 - 14.100 miles, 55 mohms per LeafDD, 28 deg, 67% SOC
12/16 - 14,500 miles, 89 mohms per LeafDD, 15 deg, 93% SOC
12/27/14 - 14,800 miles, 103 mohms per LeafDD, 11 deg, 24% SOC
3/10/15 - 17,400 miles, 60 mohms per LeafDD, 30 deg, 73% SOC
3/14 - 17, 550 miles, 56 mohms per LeafDD, 32 deg, 47% SOC
4/14 - 19,100 miles, 59 mohms per LeafDD, 25 deg. 38% SOC
5/4 - 19,989 miles, 64 mohms per LeafDD, 24 deg. 48% SOC
5/15 - 20,400 miles, 73 mohms per LeafDD, 20 deg. 41% SOC
5/22 - 20,700 miles, 58 mohms per LeafDD, 28 deg. 50% SOC
12/10/15 - 28,000 miles, 90 mohms per LeafDD, 19 deg. 92% SOC
4/5/16 - 32,000 miles, 74 mohms per LeafDD, 24 deg, 55% SOC
5/16 - 33,700 miles,89 mohms per LeafDD, 22 deg, 47% SOC
5/16 - 33.700 miles, 58 mohms per LeafDD, 31 deg, 76% SOC
10/5 - 39,300 miles, 100 mohms per LeafDD, 22 deg, 50% SOC
10/6 - 39,400 miles, 61 mohms per LeafDD, 30 deg, 51% SOC
10/7 - 39,500 miles, 80 mohms per LeafDD, 25 deg, 56% SOC
10/15 - 40,000 miles, 71 mohms per LeafDD, 27 deg, 45% SOC
10/30 - 41,000 miles, 74 mohms per LeafDD, 23 deg, 66% SOC
12/26/16 - 43,000 miles, 110 mohms per LeafDD, 13 deg, 77% SOC
6/10/17 - 49,600 miles, 89 mohms per LeafDD, 19 deg, 70% SOC
7/1/17 - 51,000 miles, 62 mohms per LeafDD, 33 deg, 44% SOC
8/15/17 - 53,400 miles, 61 mohms per LeafDD, 35 deg, 57% SOC

As can be noted, the internal resistance has increased, i.e. like a typical battery, as it ages.
 
Oils4AsphaultOnly said:
DaveinOlyWA said:
Oils4AsphaultOnly said:
Okay. Do you think my sensors are placed too close to the core of the cells? Because in my case, the temp only dropped about 4 degrees F in the 45 min drive home (stop and go traffic at the beginning too).

no, my situation was likely more to do with greater delta from ambient. I blogged where I dropped from 126º to 120º in literally a few miles. OAT mid 80's, freeway speed 70 mph. Temps were 116-118º in roughly 15 mins.

That was a 4 charge day

In your case, stop and go on asphalt pretty much means ambient temps are out the window.

It wasn't that bad, dropped to 90F when charging started near sunset, but I hadn't considered that the asphault probably retained a substantial amount of heat and might've been near 100F still.

All the same though, I still saw a considerable amount of temp increase from doing a 27 min QC (because didn't want to make multiple stops with passengers and bigger battery permitted this). The 40kwh leaf can only see a worse situation, as someone is more likely to charge from LBW to 80% with that battery, and taking ~40 mins to do so. Factoring in a best case of 5% charging loss (assuming it's drawing 45kw max), that's ~2.2kw of power that goes into heating the battery pack.

well, "anything" is possible and trust me, I have seen sillier things but lets examine the scenarios and we will ignore the multistate road trip (why anyone would not fly is beyond me unless its simply a road trip drive around which I do do...)

You now have 150 miles of range so you can drive till LEAF is comatose, charge up an hour or drive till you don't feel like driving and stop and pee or get coffee or better yet... Donuts and coffee!. plug in 30 mins or until you are tired of not driving any more. So you gain about 80-90 miles of range back so you might have stopped with 40 miles left so now you are at 120ish and have been waylaid 30 mins plus (detour right?) But lets face it; it does not take 30 mins to pee and get donuts unless its Voodoo Donuts in Portland (one a good day, you might get out in less than an hour!)

So you probably only charged 15 mins and got 50 miles of range so you leave with 90 miles of range. But the reality is... you are only 20 miles from your destination on your planned 260 mile trip. So you spend the day doing what you went for and leave, driving back to this station or even better the next one down the road cause you have enough range and charge up 30 mins while you eat

or you could have hit a station in town and charged while eating, etc.

But that is what range does for you. It gives you options and yeah, some people will camp out for an hour watching that last 3 kwh trickling in for 10 minutes (that is still nearly 20 KW) thinking they did it right then have to stop and pee at the McDonalds 100 miles up the road and walk right past the QC in the parking lot thinking.... "hmmm??"
 
DaveinOlyWA said:
Oils4AsphaultOnly said:
DaveinOlyWA said:
no, my situation was likely more to do with greater delta from ambient. I blogged where I dropped from 126º to 120º in literally a few miles. OAT mid 80's, freeway speed 70 mph. Temps were 116-118º in roughly 15 mins.

That was a 4 charge day

In your case, stop and go on asphalt pretty much means ambient temps are out the window.

It wasn't that bad, dropped to 90F when charging started near sunset, but I hadn't considered that the asphault probably retained a substantial amount of heat and might've been near 100F still.

All the same though, I still saw a considerable amount of temp increase from doing a 27 min QC (because didn't want to make multiple stops with passengers and bigger battery permitted this). The 40kwh leaf can only see a worse situation, as someone is more likely to charge from LBW to 80% with that battery, and taking ~40 mins to do so. Factoring in a best case of 5% charging loss (assuming it's drawing 45kw max), that's ~2.2kw of power that goes into heating the battery pack.

well, "anything" is possible and trust me, I have seen sillier things but lets examine the scenarios and we will ignore the multistate road trip (why anyone would not fly is beyond me unless its simply a road trip drive around which I do do...)

You now have 150 miles of range so you can drive till LEAF is comatose, charge up an hour or drive till you don't feel like driving and stop and pee or get coffee or better yet... Donuts and coffee!. plug in 30 mins or until you are tired of not driving any more. So you gain about 80-90 miles of range back so you might have stopped with 40 miles left so now you are at 120ish and have been waylaid 30 mins plus (detour right?) But lets face it; it does not take 30 mins to pee and get donuts unless its Voodoo Donuts in Portland (one a good day, you might get out in less than an hour!)

So you probably only charged 15 mins and got 50 miles of range so you leave with 90 miles of range. But the reality is... you are only 20 miles from your destination on your planned 260 mile trip. So you spend the day doing what you went for and leave, driving back to this station or even better the next one down the road cause you have enough range and charge up 30 mins while you eat

or you could have hit a station in town and charged while eating, etc.

But that is what range does for you. It gives you options and yeah, some people will camp out for an hour watching that last 3 kwh trickling in for 10 minutes (that is still nearly 20 KW) thinking they did it right then have to stop and pee at the McDonalds 100 miles up the road and walk right past the QC in the parking lot thinking.... "hmmm??"

I was thinking more like apt dweller who can now consider a leaf, because they can fast charge once a week while grocery shopping. QC'ing isn't just to make a long distance trip.
 
Oils4AsphaultOnly said:
DaveinOlyWA said:
Oils4AsphaultOnly said:
It wasn't that bad, dropped to 90F when charging started near sunset, but I hadn't considered that the asphault probably retained a substantial amount of heat and might've been near 100F still.

All the same though, I still saw a considerable amount of temp increase from doing a 27 min QC (because didn't want to make multiple stops with passengers and bigger battery permitted this). The 40kwh leaf can only see a worse situation, as someone is more likely to charge from LBW to 80% with that battery, and taking ~40 mins to do so. Factoring in a best case of 5% charging loss (assuming it's drawing 45kw max), that's ~2.2kw of power that goes into heating the battery pack.

well, "anything" is possible and trust me, I have seen sillier things but lets examine the scenarios and we will ignore the multistate road trip (why anyone would not fly is beyond me unless its simply a road trip drive around which I do do...)

You now have 150 miles of range so you can drive till LEAF is comatose, charge up an hour or drive till you don't feel like driving and stop and pee or get coffee or better yet... Donuts and coffee!. plug in 30 mins or until you are tired of not driving any more. So you gain about 80-90 miles of range back so you might have stopped with 40 miles left so now you are at 120ish and have been waylaid 30 mins plus (detour right?) But lets face it; it does not take 30 mins to pee and get donuts unless its Voodoo Donuts in Portland (one a good day, you might get out in less than an hour!)

So you probably only charged 15 mins and got 50 miles of range so you leave with 90 miles of range. But the reality is... you are only 20 miles from your destination on your planned 260 mile trip. So you spend the day doing what you went for and leave, driving back to this station or even better the next one down the road cause you have enough range and charge up 30 mins while you eat

or you could have hit a station in town and charged while eating, etc.

But that is what range does for you. It gives you options and yeah, some people will camp out for an hour watching that last 3 kwh trickling in for 10 minutes (that is still nearly 20 KW) thinking they did it right then have to stop and pee at the McDonalds 100 miles up the road and walk right past the QC in the parking lot thinking.... "hmmm??"

I was thinking more like apt dweller who can now consider a leaf, because they can fast charge once a week while grocery shopping. QC'ing isn't just to make a long distance trip.

not sure there is any evidence that shows short duration heat being a significant cause of degradation. if it was, I would have lost about 7-8 bars by now! Been in the red a few dozen times but been at 9-10 TBs "at least" 100 times....
 
DaveinOlyWA said:
Oils4AsphaultOnly said:
DaveinOlyWA said:
well, "anything" is possible and trust me, I have seen sillier things but lets examine the scenarios and we will ignore the multistate road trip (why anyone would not fly is beyond me unless its simply a road trip drive around which I do do...)

You now have 150 miles of range so you can drive till LEAF is comatose, charge up an hour or drive till you don't feel like driving and stop and pee or get coffee or better yet... Donuts and coffee!. plug in 30 mins or until you are tired of not driving any more. So you gain about 80-90 miles of range back so you might have stopped with 40 miles left so now you are at 120ish and have been waylaid 30 mins plus (detour right?) But lets face it; it does not take 30 mins to pee and get donuts unless its Voodoo Donuts in Portland (one a good day, you might get out in less than an hour!)

So you probably only charged 15 mins and got 50 miles of range so you leave with 90 miles of range. But the reality is... you are only 20 miles from your destination on your planned 260 mile trip. So you spend the day doing what you went for and leave, driving back to this station or even better the next one down the road cause you have enough range and charge up 30 mins while you eat

or you could have hit a station in town and charged while eating, etc.

But that is what range does for you. It gives you options and yeah, some people will camp out for an hour watching that last 3 kwh trickling in for 10 minutes (that is still nearly 20 KW) thinking they did it right then have to stop and pee at the McDonalds 100 miles up the road and walk right past the QC in the parking lot thinking.... "hmmm??"

I was thinking more like apt dweller who can now consider a leaf, because they can fast charge once a week while grocery shopping. QC'ing isn't just to make a long distance trip.

not sure there is any evidence that shows short duration heat being a significant cause of degradation. if it was, I would have lost about 7-8 bars by now! Been in the red a few dozen times but been at 9-10 TBs "at least" 100 times....

But the apt dweller with his 40kwh leaf QC'ing during grocery shopping, isn't doing a short-duration charge. This would be his weekly charge from 20% to 90%, because he doesn't have charging at home. This use case is most definitely long-duration QC.

Edit: By the way, 150 mile range isn't comatose driving, that's a 2-hr trip to san diego or to visit friends for a day. A QC will be needed for the return trip in case there's no L2 at the destination.

Edit 2: Since this thread is about battery management, my point is that larger batteries encourage people to use the car in ways that would call for longer QC sessions, not shorter ones, ergo the need for better battery management.
 
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