DaveinOlyWA
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Re: Battery Upgrades are very possible

Sat Jun 13, 2020 5:48 pm

Marktm wrote:
Sat Jun 13, 2020 5:08 pm
mux wrote:
Fri Nov 15, 2019 1:07 am
Well, that's going to take another year at least then.
mux;
After watching the "LG install video" from evbatteryrebuilds, it appears physically, they are doing the conversion. I'd sure like your opinion on the reality of pack construction, connector viability (appears quite "home built"), vibration resistance, heat dissipation, re-wiring techniques, BMS fit for service, potential CAN bridge success, etc. etc. The fact that they had no safety process and used a fork lift for assembly make me question the reality of their eventual viability as a professional supplier. I guess if it's just a prototype...........
I have concerns as well. It "appears" they are stacking cell pouches with no air gap whatsoever. Notice the one view where it appears there are a dozen or more pouches stacked up against each other?
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 11,333.1 mi, 93.73% SOH
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LeftieBiker
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Location: Upstate New York, US

Re: Battery Upgrades are very possible

Sat Jun 13, 2020 7:19 pm

It is actually common practice to pack pouch type cells tightly together. This makes it more difficult for them to swell under unfavorable conditions. Once a pouch swells it is both useless and dangerous - you can't reverse the process. It's counter-intuitive, like using ice to keep something warmer in a really cold environment, but it apparently works. Converting a Vectrix maxi-scooter like mine involves building a horizontal 'stack' of Leaf modules that are held tightly together much like the pack in the video: with long threaded rods, nuts and washers. My conversion (not done by me but by the bike's original owner) is about 5 years old now, with <knocks on wood> no problems so far.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

coleafrado
Posts: 291
Joined: Fri Oct 11, 2019 11:58 pm

Re: Battery Upgrades are very possible

Sat Jun 13, 2020 9:35 pm

LeftieBiker wrote:
Sat Jun 13, 2020 7:19 pm
It is actually common practice to pack pouch type cells tightly together. This makes it more difficult for them to swell under unfavorable conditions. Once a pouch swells it is both useless and dangerous - you can't reverse the process. It's counter-intuitive, like using ice to keep something warmer in a really cold environment, but it apparently works. Converting a Vectrix maxi-scooter like mine involves building a horizontal 'stack' of Leaf modules that are held tightly together much like the pack in the video: with long threaded rods, nuts and washers. My conversion (not done by me but by the bike's original owner) is about 5 years old now, with <knocks on wood> no problems so far.
It's really important, when stacking pouch cells, for there to be even pressure across the whole cell surface and a physical barrier between the cells to contain any out-of-control thermal reactions. Without even pressure, any internal gas pressure from evolved hydrogen within the cell can strain the pouch and cause puffing or short-circuits across the separators. The Vectrix works fine because the Leaf cells already have that addressed at the module level: the steel case contains and constrains the cells with even pressure while air gaps prevent excess heat from flowing through the stack rather than out of it. As long as you b0lt the cells together and compress them with the OEM compression plates, nothing too bad can happen.

EVBatteryRebuilds has assembled a pack with no inter-cell barriers, no air gaps, no emergency vents, no cell-level fusing, no cooling, and no apparatus for applying even pressure to the cells. Not only that, but they compromised the structural integrity of the battery case (by removing the central crossbar) just so they could pack more cells in. It's cool and all that it's 64 kWh, but this an incredibly bad battery design, perhaps the worst ever documented.

http://www.formula-hybrid.org/wp-conten ... _guide.pdf (p. 33-41)

https://www.researchgate.net/publicatio ... 4/download

https://researchbank.swinburne.edu.au/f ... Thesis.pdf

mux
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Leaf Number: 6177

Re: Battery Upgrades are very possible

Sun Jun 14, 2020 11:59 am

Preface: I have a competing product so I'm going to always look like I'm promoting my own company by passing judgement on competitors. The following is the opinion of Emile Nijssen, not of MUXSAN as a whole, and off the cuff/badly edited/probably wrong.

I basically share the opinions of the other previous posts on their battery wholeheartedly. This is a very, VERY badly engineered product and I hope this is just a demonstrator. As a demo pack, just for getting some PR buzz, it's totally fine and I will happily concede that I've done similar rush jobs in the past just to show a proof of concept. But this is not a safe EV battery system - this is a heap of cells.

You're going to get incredibly poor cycle life without compression frames, without interstitials and without an adequate BMS. Additionally, they don't have thermal management. The Leaf's batteries aren't bad chemically, the cells are perfectly competent NMC cells capable of excellent service life. Their life is cut drastically short by poor BMS algorithms and absent thermal management. These LG cells are not great cells to begin with, especially for EV purposes, so they're going to need a much better BMS to get decent performance out of them in the long term.

Additionally, they're simply not charging enough money for this. At MUXSAN, we're aware our prices aren't the lowest, but that is part of our sustainable business model. We're in it for the long haul, charging a bit extra so we can support our products. If I go by BOM costs, RdS/EVBatteryRebuilds is operating on 20%ish margins at best, or maybe even barely breaking even because they rely on selling the old cells for cashflow. This inevitably means that they'll go under in 2 years, leaving a few dozen customers with unsupported, low production volume and thus inherently buggy hardware.

Lastly, we're quite worried that these kinds of stunts are going to eventually cause either the shutdown of this cottage industry or heavy regulation with little opportunity to adapt (effectively regulating us out of business). We're already working hard to essentially become a bona fide car parts manufacturer with all the certifications and compliance work necessary, but that's going to take 2ish years to complete (if you include a complete supply chain audit etc.).

I don't want to end this on too much of a downer. They're doing good work in principle and definitely learning from the experience. EVBatteryRebuilds is not a lost cause or something that can never work. The principle is... fine. Their mission is great. This is not a company that has to be stopped or that deserves hate in any form, but they need a couple of decent engineers and maybe somebody with some business sense to help them.

knightmb
Posts: 491
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Re: Battery Upgrades are very possible

Sun Jun 14, 2020 12:30 pm

mux wrote:
Sun Jun 14, 2020 11:59 am
This is not a company that has to be stopped or that deserves hate in any form, but they need a couple of decent engineers and maybe somebody with some business sense to help them.
I think that last statement is important, from what I see, a lot of time is put into the electronics part of the build (battery setup, wiring, electronics, etc.) but many of these don't have someone who is knowledgeable in battery chemistry or physics to help. I think too many people want to treat a EV like a flashlight where you simply change out the batteries and everything else will just work out for the best. :roll:
2013 Leaf SV

LeftieBiker
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Re: Battery Upgrades are very possible

Sun Jun 14, 2020 12:36 pm

coleafrado wrote:
Sat Jun 13, 2020 9:35 pm
LeftieBiker wrote:
Sat Jun 13, 2020 7:19 pm
It is actually common practice to pack pouch type cells tightly together. This makes it more difficult for them to swell under unfavorable conditions. Once a pouch swells it is both useless and dangerous - you can't reverse the process. It's counter-intuitive, like using ice to keep something warmer in a really cold environment, but it apparently works. Converting a Vectrix maxi-scooter like mine involves building a horizontal 'stack' of Leaf modules that are held tightly together much like the pack in the video: with long threaded rods, nuts and washers. My conversion (not done by me but by the bike's original owner) is about 5 years old now, with <knocks on wood> no problems so far.
It's really important, when stacking pouch cells, for there to be even pressure across the whole cell surface and a physical barrier between the cells to contain any out-of-control thermal reactions. Without even pressure, any internal gas pressure from evolved hydrogen within the cell can strain the pouch and cause puffing or short-circuits across the separators. The Vectrix works fine because the Leaf cells already have that addressed at the module level: the steel case contains and constrains the cells with even pressure while air gaps prevent excess heat from flowing through the stack rather than out of it. As long as you b0lt the cells together and compress them with the OEM compression plates, nothing too bad can happen.

EVBatteryRebuilds has assembled a pack with no inter-cell barriers, no air gaps, no emergency vents, no cell-level fusing, no cooling, and no apparatus for applying even pressure to the cells. Not only that, but they compromised the structural integrity of the battery case (by removing the central crossbar) just so they could pack more cells in. It's cool and all that it's 64 kWh, but this an incredibly bad battery design, perhaps the worst ever documented.

http://www.formula-hybrid.org/wp-conten ... _guide.pdf (p. 33-41)

https://www.researchgate.net/publicatio ... 4/download

https://researchbank.swinburne.edu.au/f ... Thesis.pdf
Ahhh, that isn't good. I didn't watch the video closely enough to see they had ditched the modules and were just installing pouches in a more or less exposed fashion. You are correct, of course.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

User avatar
Marktm
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Re: Battery Upgrades are very possible

Sun Jun 14, 2020 1:36 pm

coleafrado wrote:
Sat Jun 13, 2020 9:35 pm

It's really important, when stacking pouch cells, for there to be even pressure across the whole cell surface and a physical barrier between the cells to contain any out-of-control thermal reactions. Without even pressure, any internal gas pressure from evolved hydrogen within the cell can strain the pouch and cause puffing or short-circuits across the separators. The Vectrix works fine because the Leaf cells already have that addressed at the module level: the steel case contains and constrains the cells with even pressure while air gaps prevent excess heat from flowing through the stack rather than out of it. As long as you b0lt the cells together and compress them with the OEM compression plates, nothing too bad can happen.

EVBatteryRebuilds has assembled a pack with no inter-cell barriers, no air gaps, no emergency vents, no cell-level fusing, no cooling, and no apparatus for applying even pressure to the cells. Not only that, but they compromised the structural integrity of the battery case (by removing the central crossbar) just so they could pack more cells in. It's cool and all that it's 64 kWh, but this an incredibly bad battery design, perhaps the worst ever documented.

http://www.formula-hybrid.org/wp-conten ... _guide.pdf (p. 33-41)

https://www.researchgate.net/publicatio ... 4/download

https://researchbank.swinburne.edu.au/f ... Thesis.pdf
Great references - so much to learn about Li battery pack designs. The recommendation that FEA be done on any commercial AMP20 (pouch) battery pack design probably suggests the need for extraordinarily carefully constructed and tested final products. OTOH, I wonder if the cylindrical designs get around the dimensional stability issues?
2012 Leaf SL; 46,000 miles. Battery replaced November 1st, 2016.

coleafrado
Posts: 291
Joined: Fri Oct 11, 2019 11:58 pm

Re: Battery Upgrades are very possible

Sun Jun 14, 2020 3:08 pm

Now that they've de-unlisted their video, it's reached over 100,000 views and 150 comments. I'm seeing about 100-300 views per hour. :|

A few recent comments from EVBR:
The max temp reached in Fast Charging was 51º

It's ABS. Plastic parts are only aesthetic covers, nothing related with security on the pack

Almost impossible to add cooling to this pack... Nissan fault!
The 51º they mentioned must be centigrade, i.e. 128 degrees Fahrenheit, in which case they are literally playing with fire. Even a first-gen 24 kWh pack doesn't get anywhere near that hot unless it's fast charged 3 or 4 times in a row within a span of a couple hours. Who even knows where they're measuring that temperature? If that's the external shell temperature, the center of the pack could easily have passed 80ºC. Ordinary cells that spend lots of time sitting near 50ºC usually don't last long: https://sci-hub.tw/https://www.cell.com ... 19)30481-7
Marktm wrote: Great references - so much to learn about Li battery pack designs. The recommendation that FEA be done on any commercial AMP20 (pouch) battery pack design probably suggests the need for extraordinarily carefully constructed and tested final products. OTOH, I wonder if the cylindrical designs get around the dimensional stability issues?
There's a reason we haven't seen a thermally managed aftermarket pack from anyone yet. Designing this stuff, iterating on it with FEA, building and blowing up prototypes and then mass-producing it takes years even with "unlimited" resources and dozens of engineers. As far as I know, zero of the companies working on Leaf batteries have more than ten employees let alone ten engineers.

Cylindrical cells are better, yes - their steel cases eliminate the need for constant external compression and protect the actual cells from physical damage - but they come with their own issues. Cooling is more complicated since it usually requires access to the curved sides of the cells rather than flat faces like pouches. Tesla runs pre-formed extruded aluminum microchannel between every other row of cells, then plumbs them all together. The tooling to produce that plumbing is not cheap. Electrical assembly is harder, too, since cylindrical cells require specialized 3D busbars and wirebonding at two points per cell. Not something you can make with a drill press and some copper stock.

It's not impossible, of course. The Model 3 proved that you can do cylindrical cells cheaply if you're willing to sacrifice repairability. But the setup costs for automated assembly are in the ~tens of millions unless you're willing to spend 100-200 hours per car in manual labor costs putting together just the battery. There's a reason Tesla has their module assembly line right next to their cell production line. Even at sub-$80/kWh cell costs, Tesla barely breaks even on their cars and Panasonic is basically making 0%.
Last edited by coleafrado on Mon Jun 15, 2020 4:25 am, edited 1 time in total.

ramdoor
Posts: 2
Joined: Tue Sep 27, 2011 3:43 pm
Delivery Date: 27 Sep 2011

Re: Battery Upgrades are very possible

Sun Jun 14, 2020 4:55 pm

Hello friends!

I am Jesus Toucedo, owner of Renovables del Sur, and also of evbatteryrebuilds.com, but now I write as one more user of the forum that has been mentioned.

I have read the last posts about the battery update and it seems that our video has caused quite a stir.

I want to start by saying that I agree on quite a few things discussed here, but there are others that I would like to qualify and answer for allusions.

First of all, I want to thank Emile for his contribution with the can bus bridge PCB, if none of this would have been possible or would have been a little more difficult than it has already been. We started testing with Raspberry and its solution has been by far much more elegant, professional and automotive grade.

Second, I want to confirm to Emile that indeed, this battery has only been a prototype, a proof of concept, and that in all probability it will never make a battery like this again. As a business I assure you that it is not profitable as Emile says, and we have only lost 90 days of our time, but you know that, it has been great, someone had to do it. Everything we have done in this battery has been agreed with its owner, who is aware of its limitations and virtues.

Having said this, I want to mention some commented points that I think are important to clarify:

Regarding the stacking of cells, I have access to the LG Chem technical manual on these cells, and the only mention it makes about the stacking is that a tightening with M6 screws and nuts greater than 10kgf x cm must be maintained. I can assure you that the cells have the correct compression, regardless of the number of them stacked.

Regarding the vibrations, well indeed it is a homemade pack, and it could never be a professional one, but we have done many tests and the car has been driven for 4000 km before being delivered. We have subjected it to all possible dynamic tests, acceleration, braking, inertia, potholes, and heavy off road, and after all the tests we have reopened the pack. As expected, absolutely nothing has moved, and has behaved in a stable way. Only time will tell how it goes. We can open this thread in 5 years and take some photos of the inside of the battery if it has not yet exploded :D

Regarding the space between cells, who said there should be? We all know that the Nissan leaf pack is a disaster dissipating heat, we also know that it is airtight and there is no air circulation inside it, nor is it possible to install a cooling system due to the design. Seriously, what else do you think I can do?

Regarding the temperature, someone asked where the probes have been placed, the probes are obviously between the LG cells. In no test have we gone from 51º celcius in Chademo fast charge, even with temperature days at 35º.

I don't know where you live, but in the south of Spain, 51º is reached by the battery in the first and only fast charge.

The current pack heats up equal to or less than the original, please give its owner some time to report his experience, I am sure that soon he will have a lot to say.

I suppose you have your opinion and of course I have mine, but I want to comment on these points:

"EVBatteryRebuilds has assembled a pack with no inter-cell barriers, no air gaps, no emergency vents, no cell-level fusing, no cooling, and no apparatus for applying even pressure to the cells."

LG cells already have their own emergency ventilation system, what else can I do? Put them in a can for even less refrigeration? I don't see the point.

Air Gaps? I have not read anything about that in the LG assembly manual .. in fact in its professional assemblies for other vehicles I have never seen air gaps between the cells.

Cell Level fusing? No refrigeration? Does Nissan use it? I didn't do the engineering for this battery pack! It would have been nice to put it .. I'm sure it would.

"no apparatus for applying even pressure to the cells." What do you mean? They have 22 pressure points on each side, calibrated to deliver the necessary pressure to each cell.

As I said before, I hope it is the last battery of this type that we make, but I want you to know that we are proud of it, although of course it is not a professional system, but on the other hand, it is impossible.

We have our way and we are going to follow it. We think that putting a lot of cells in the trunk is not a good idea for the safety of the occupants, or to keep the center of gravity of the car, and other problems related to insurance and authorities, but we are glad that at least their Users who for sure are aware of their limitations can once again enjoy their Leafs. I firmly believe that this is the true reason that unites us, to see all the Leafs of the planet on the road again. In the meantime, we will try to learn and improve with each step we take.

coleafrado
Posts: 291
Joined: Fri Oct 11, 2019 11:58 pm

Re: Battery Upgrades are very possible

Sun Jun 14, 2020 5:54 pm

Jesus, thank you for posting to the forum!
ramdoor wrote:
Sun Jun 14, 2020 4:55 pm
Hello friends!

I am Jesus Toucedo, owner of Renovables del Sur, and also of evbatteryrebuilds.com, but now I write as one more user of the forum that has been mentioned.

I have read the last posts about the battery update and it seems that our video has caused quite a stir.

I want to start by saying that I agree on quite a few things discussed here, but there are others that I would like to qualify and answer for allusions.

First of all, I want to thank Emile for his contribution with the can bus bridge PCB, if none of this would have been possible or would have been a little more difficult than it has already been. We started testing with Raspberry and its solution has been by far much more elegant, professional and automotive grade.

Second, I want to confirm to Emile that indeed, this battery has only been a prototype, a proof of concept, and that in all probability it will never make a battery like this again. As a business I assure you that it is not profitable as Emile says, and we have only lost 90 days of our time, but you know that, it has been great, someone had to do it. Everything we have done in this battery has been agreed with its owner, who is aware of its limitations and virtues.
This is great to hear, thank you for the clarity.
Having said this, I want to mention some commented points that I think are important to clarify:

Regarding the stacking of cells, I have access to the LG Chem technical manual on these cells, and the only mention it makes about the stacking is that a tightening with M6 screws and nuts greater than 10kgf x cm must be maintained. I can assure you that the cells have the correct compression, regardless of the number of them stacked.
The concern with the cells is that those specifications are for a single cell stack - i.e. five or ten cells on top of each other, with bolts all around. It's pretty easy to create an even gradient of pressure when the bolts are only 3-5 inches apart, the stack height does not matter too much. But with the cells next to each other, and no space for bolts between the stacks, the only way you can apply pressure is from the edges of the modules (30cm minimum separation). It is quite visible in the video that the plates bend upwards towards the center of the stacks. Unless you can find an infinitely rigid top plate, or create an asymmetric spacer pad, the possibility of pouch puffing or other mechanical failure in the stacks is higher than it should be. I hope this is clear enough.
Regarding the vibrations, well indeed it is a homemade pack, and it could never be a professional one, but we have done many tests and the car has been driven for 4000 km before being delivered. We have subjected it to all possible dynamic tests, acceleration, braking, inertia, potholes, and heavy off road, and after all the tests we have reopened the pack. As expected, absolutely nothing has moved, and has behaved in a stable way. Only time will tell how it goes. We can open this thread in 5 years and take some photos of the inside of the battery if it has not yet exploded :D
It is explained elsewhere, but the amount of movement necessary to cause mechanical damage to a pack this large is so small that it's not really noticeable by eye. I have seen pouch cells suddenly explode from relatively minor (and ultimately invisible) asymmetry in their compression.
Regarding the space between cells, who said there should be? We all know that the Nissan leaf pack is a disaster dissipating heat, we also know that it is airtight and there is no air circulation inside it, nor is it possible to install a cooling system due to the design. Seriously, what else do you think I can do?

Regarding the temperature, someone asked where the probes have been placed, the probes are obviously between the LG cells. In no test have we gone from 51º celcius in Chademo fast charge, even with temperature days at 35º.

I don't know where you live, but in the south of Spain, 51º is reached by the battery in the first and only fast charge.

The current pack heats up equal to or less than the original, please give its owner some time to report his experience, I am sure that soon he will have a lot to say.

I suppose you have your opinion and of course I have mine, but I want to comment on these points:

"EVBatteryRebuilds has assembled a pack with no inter-cell barriers, no air gaps, no emergency vents, no cell-level fusing, no cooling, and no apparatus for applying even pressure to the cells."

LG cells already have their own emergency ventilation system, what else can I do? Put them in a can for even less refrigeration? I don't see the point.
The emergency vents on the cells are intended to be used in conjunction with pack vents - i.e. burst discs or plastic breakable vents that can release any built-up gases in a safe direction. As you said, the battery case is air-tight; if one cell activates its emergency vent, the rest may follow, and it would be bad news if the battery case itself were to burst.
Air Gaps? I have not read anything about that in the LG assembly manual .. in fact in its professional assemblies for other vehicles I have never seen air gaps between the cells.

Cell Level fusing? No refrigeration? Does Nissan use it? I didn't do the engineering for this battery pack! It would have been nice to put it .. I'm sure it would.
The Chevy Bolt uses either the same or very similar cells to what you're using, but they're implemented very differently. Each Bolt stack is made up of several modules, each module being several cells welded together and enclosed in a steel or aluminum case with vents and liquid cooling plates. Not only does the steel shell on each module protect the cells, it slows any possible spread of fire or heat.

It's the difference between a seawall made of sandbags and a seawall made of sand. Compartmentalization is very important for large batteries; the criticism of your prototype is that there are only three compartments (left, right, rear) in the whole thing. The lack of cooling and mechanical rigidity just compounds that.

see here: https://www.youtube.com/watch?v=54SshSAH_k0

Nissan doesn't use cell-level fusing or refrigeration because they're idiots. Why repeat their mistakes? Essentially everyone else uses cell-level fusing and cooling.
"no apparatus for applying even pressure to the cells." What do you mean? They have 22 pressure points on each side, calibrated to deliver the necessary pressure to each cell.

As I said before, I hope it is the last battery of this type that we make, but I want you to know that we are proud of it, although of course it is not a professional system, but on the other hand, it is impossible.

We have our way and we are going to follow it. We think that putting a lot of cells in the trunk is not a good idea for the safety of the occupants, or to keep the center of gravity of the car, and other problems related to insurance and authorities, but we are glad that at least their Users who for sure are aware of their limitations can once again enjoy their Leafs. I firmly believe that this is the true reason that unites us, to see all the Leaf of the planet on the road again. In the meantime, we will try to learn and improve with each step we take.
I can assure you that Nissan and GM made, at one point, prototype batteries that were no less dangerous! The crucial part is that they didn't sell them until they were certain they wouldn't injure anyone. Thermal runaway on a cell phone battery (Note 7, anyone?) is bad enough. Multiply that by a factor of a few hundred and it should make sense why we would discourage this kind of pack design.

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