Slower charging at low temperatures to prolong cell life.

[Luk88]

Sadly my LFP cell manufacturer(Higee) does not specify max charging current at low temperatures, but I assume one can use Eve datasheets as a guide.

My cells are mostly at about ~10-15C (50-59F) in the summer and ~3-6C (37-42F) in winter. I've decided against heating to prolong calendar life.

This means I need to limit charge current. It seems Eve recommends up to 0.2C between 0 up to 10C, and then 0.5C over 10C(temp) in their LF280AH datasheet. In mb30 datasheet they suggest 0.3C up to 15C temperature.

Is there anyone else that uses cells in such temperatures long term? Any additional tips/advice?

 

[Suijkerbuijk]

Wel i use it on low temp.
I'm on a boat and the battery are under the water point in side the boat
Means the temps are low
And i do not care .
You never gone use the full load .
In my case on 1c means 150a charge and normal charger is about 0.5x means 75amps.
The max charge i can do in the summer if i do stupid thing is about .
20a dc to dc alternator.
16a by the solar
30a by the battery charger .
Well i never run that power so .
I do not care .

I think people are worry about somting .
Well if you have a small battery oke but a big battery?

In the winter inside the boat will be 15 Celsius .
So the battery wil be around 10/15 celcius.
And this systeem running now 2 years
Pics see temp

 

[Luk88]

Wel i use it on low temp.
I'm on a boat and the battery are under the water point in side the boat
Means the temps are low
And i do not care .
You never gone use the full load .
In my case on 1c means 150a charge and normal charger is about 0.5x means 75amps.
The max charge i can do in the summer if i do stupid thing is about .
20a dc to dc alternator.
16a by the solar
30a by the battery charger .
Well i never run that power so .
I do not care .

I think people are worry about somting .
Well if you have a small battery oke but a big battery?

In the winter inside the boat will be 15 Celsius .
So the battery wil be around 10/15 celcius.
And this systeem running now 2 years
Pics see temp

Thanks for answering. However as you said your chargers combined are under 0.5C so you don't have to worry with 15 Celsius

I could configure up to 120A charging on the 24V battery and 100A on 48V (both are 280ah packs). So in winter it is possible to exceed the recommended limit of 0.2C below 10 Celsius.

I currently have some overpanelling 7KW peak connected to each. My panels are at a low angle(25deg), but on a cold sunny winter day with lots of snow on the ground they could definitely produce 3.5KW necessary for the 120A charge for the 24V battery. The 100A on 48V is probably not possible.

Also, it is very likely my batteries will sit at full charge for extended amounts of time (most of the summer days probably). I've currently set it to 3.35V float and 3.4V charge. I might lower it a bit depending on use.

I realise this is not a lot of battery for this amount of solar, but I have grid and generator backup if required.

 

[Suijkerbuijk]

Thanks for answering. However as you said your chargers combined are under 0.5C so you don't have to worry with 15 Celsius

I could configure up to 120A charging on the 24V battery and 100A on 48V (both are 280ah packs). So in winter it is possible to exceed the recommended limit of 0.2C below 10 Celsius.

I currently have some overpanelling 7KW peak connected to each. My panels are at a low angle(25deg), but on a cold sunny winter day with lots of snow on the ground they could definitely produce 3.5KW necessary for the 120A charge for the 24V battery. The 100A on 48V is probably not possible.

Also, it is very likely my batteries will sit at full charge for extended amounts of time (most of the summer days probably). I've currently set it to 3.35V float and 3.4V charge. I might lower it a bit depending on use.

I realise this is not a lot of battery for this amount of solar, but I have grid and generator backup if required.

https://www.batteriesplus.com/blog/power/lithium-batteries-cold

More info about it

Personal battery are so cheap today .
And in the future more cheaper that i do not look in to it.
I have pay 4 years back 1000 euro for 150ah.
Today you have the same for 400 euro.
So that is one of the reason i do not care
And more and more upgrade of the technology come.

 

[Steve_S]

My external powerhouse is heated (gets to -35C out so) but I'm a cheap geezer and only heat to 15C. I have run tests on low temp charging and EVE doesn't fool around. I've run with the system at just over 5C (I cut off charge @ 2C and reenable it at 5C) for 2 weeks as a test. The cells themselves "slow" taking charge and boy you get to see what cells are runners (either direction). They do take 0.2C OK (56A for a 280AH) quite nicely BUT if you try to push beyond that, the Runner get's ya, pack imbalance starts quickly. After 5C the cells are reasonably happy but still "
laggy" and sluggish (you see the cells deviating). At 10C they settle down and stay more even and after 15C they operate as normal BUT are slower to charge....

Now here's the thing I observed several times. Pack Temps do play a role within a Bank of batteries. I had a "stack" of packs on a shelf. The pack closest to the ground was of course the coolest with the pack at the top being the warmest. The temp differential between packs was just a little over 1C difference between each. When charging the bank, you could see how the "cooler" battery took charge slower that the warmer ones andit was quite obvious & measurable. The amps taken and the voltage difference is there to see. The other side of that, is during discharge, the colder packs discharged at a slower rate compared to the higher temp packs... The end result was that the packs tried to balance between themselves to make up the difference & that wasted stored energy in losses. You pay a price on both ends with packs at different temps.

I changed config to put all packs at waist height (more or less) so their temps reman even (as close as possible) and each pack acts just like the neighbour, same temps and same in/out performance. This applies wether the powerhouse is cold (15C) or hot at 35C.

Out of curiosity I took my 100AH pack and let it get below 0C and when it reached 1C I put a 50A charger on it (will deliver that to pack) and the pack only took 5A "grudgingly" but that increased as it warmed up and by 10C it was taking about 30A.

Hope it helps, Good Luck

 

[Suijkerbuijk]

How to Keep Batteries Warm in the Cold - Cell Saviors

Maintaining your battery at proper temperature is crucial for longevity and health of the pack, check out this post to learn how to.

cellsaviors.com

Some nice tip and tricks for battery in the cold.
So you can use it for the winter.

 

[Luk88]

Hope it helps, Good Luck

This is very useful information for me, thank you. I didn't realise you can actually tell you're trying to charge too fast by batteries not taking the charge fast enough, but now when you said it it is kinda obvious

I'll pay attention to it in winter.

What you said about parts of the pack being lower to the ground being colder definitely applies to my 48V battery.


The bottom, cells are very likely to be colder.

How to Keep Batteries Warm in the Cold - Cell Saviors

Maintaining your battery at proper temperature is crucial for longevity and health of the pack, check out this post to learn how to.

cellsaviors.com

Some nice tip and tricks for battery in the cold.
So you can use it for the winter.

But that is my point... I'd rather not keep them warm. I prefer longer calendar life that comes with lower temperatures, at a cost of slightly slower charging.

Today's LFP batteries are very robust in terms of surviving lots of cycles (providing they're not abused, fixtures properly etc). For me main concern is calendar life. Of course there is nothing wrong saying "who cares, battery tech is improving so in 5 years I'll buy a 5x bigger battery for a quarter of the price", but I'm approaching this from a prepper mindset. In 5 years from now I may be preoccupied with other things (war etc) and replacing the battery might be the last thing on my mind.

If everything goes well, I'll replace it with cheap as chips sodium in few years. If everything goes to hell (which in my part of the world happens at least once per generation usually) this battery may have to last me a long time. So if I can extend it's calendar life at a slight cost of performance I'm willing to try.

 

[Suijkerbuijk]

This is very useful information for me, thank you. I didn't realise you can actually tell you're trying to charge too fast by batteries not taking the charge fast enough, but now when you said it it is kinda obvious

I'll pay attention to it in winter.

What you said about parts of the pack being lower to the ground being colder definitely applies to my 48V battery.

View attachment 222819
The bottom, cells are very likely to be colder.


But that is my point... I'd rather not keep them warm. I prefer longer calendar life that comes with lower temperatures, at a cost of slightly slower charging.

Today's LFP batteries are very robust in terms of surviving lots of cycles (providing they're not abused, fixtures properly etc). For me main concern is calendar life. Of course there is nothing wrong saying "who cares, battery tech is improving so in 5 years I'll buy a 5x bigger battery for a quarter of the price", but I'm approaching this from a prepper mindset. In 5 years from now I may be preoccupied with other things (war etc) and replacing the battery might be the last thing on my mind.

If everything goes well, I'll replace it with cheap as chips sodium in few years. If everything goes to hell (which in my part of the world happens at least once per generation usually) this battery may have to last me a long time. So if I can extend it's calendar life at a slight cost of performance I'm willing to try.

LiFePO4 Temperature Range: Discharging, Charging and Storage

Temperature plays a crutial role in the performance and lifespan of LiFePO4 batteries. This comprehensive guide will delve into the temperature range when operating.

www.litime.com

More info about it.
Best temp is about 20 celcius and you have the best lifetime use really.

Hope this help.

 

[SeaGal]

Any additional tips/advice?

The EVE datasheet for LF280K also specifies different charge rate for above 70% SOC, as well as temp.

See also my posting here

Science based discussion on charging LiFePO4 below 32°F

I am not sure if any BMS has more than 2 states, on and off. Besides… Isn’t this what charge controllers are designed to do (scale current): I am not sure I would want a more complex BMS as it would likely reduce reliability. And for the last line of defence, BMSs need more reliability if...

diysolarforum.com

 

[Steve_S]

This is very useful information for me, thank you. I didn't realise you can actually tell you're trying to charge too fast by batteries not taking the charge fast enough, but now when you said it it is kinda obvious

I'll pay attention to it in winter.

What you said about parts of the pack being lower to the ground being colder definitely applies to my 48V battery.

View attachment 222819
The bottom, cells are very likely to be colder.


But that is my point... I'd rather not keep them warm. I prefer longer calendar life that comes with lower temperatures, at a cost of slightly slower charging.

Today's LFP batteries are very robust in terms of surviving lots of cycles (providing they're not abused, fixtures properly etc). For me main concern is calendar life. Of course there is nothing wrong saying "who cares, battery tech is improving so in 5 years I'll buy a 5x bigger battery for a quarter of the price", but I'm approaching this from a prepper mindset. In 5 years from now I may be preoccupied with other things (war etc) and replacing the battery might be the last thing on my mind.

If everything goes well, I'll replace it with cheap as chips sodium in few years. If everything goes to hell (which in my part of the world happens at least once per generation usually) this battery may have to last me a long time. So if I can extend it's calendar life at a slight cost of performance I'm willing to try.

If you really want to max out lifecycles then you have major issue right there in front of you.
1) Get that pack in the proper orientation, Cell Vents UP - not on the sides ! That is the biggest Murphy's Laws invitation right there... the botten cells WILL leak. (we have seen a LOT of that failure - several companies are now out of business because of it - commercial packs that even had UL/CSA/ETL certifications. Just fact that some do not want to admit).
2) Get it at least 60cm (2') off the ground ! and level... That way all cells will remain at same temp, They cannot in that config, the bottom cells will always be colder. no matter what.
3) LFP LOVES the same temps humans do and are happiest @ 25C/77F and are quite content to be between 18C-32C and will produce happily without issues.

Also, with ESS very few ever do a full 0.5C Charge Rate and it gets a lot harder when you also have a bank of packs sucking it all in. I have the ability to "push" 350A Charge (with hassle) but not much point. ESS has the benefit of non-mobile & arrays that produce through the sun hours.. We had a poll a while back - possibly an extended thread, I forget ATM. For an ESS installation, many people are charging around 0.2C-0.3C.

 

[SeaGal]

I've currently set it to 3.35V float and 3.4V charge. I might lower it a bit depending on use.

The issue with charging at less than 3.4V is that you'll never give the BMS an opportunity to balance the cells.

Also with regard to temperature, as well as all the good points @Steve_S made, you'll achieve more storage capacity at 20-25 degrees C than at (say) 5 degrees C.

 

[SoggyShoes]

My external powerhouse is heated (gets to -35C out so) but I'm a cheap geezer and only heat to 15C. I have run tests on low temp charging and EVE doesn't fool around. I've run with the system at just over 5C (I cut off charge @ 2C and reenable it at 5C) for 2 weeks as a test. The cells themselves "slow" taking charge and boy you get to see what cells are runners (either direction). They do take 0.2C OK (56A for a 280AH) quite nicely BUT if you try to push beyond that, the Runner get's ya, pack imbalance starts quickly. After 5C the cells are reasonably happy but still "
laggy" and sluggish (you see the cells deviating). At 10C they settle down and stay more even and after 15C they operate as normal BUT are slower to charge....

Now here's the thing I observed several times. Pack Temps do play a role within a Bank of batteries. I had a "stack" of packs on a shelf. The pack closest to the ground was of course the coolest with the pack at the top being the warmest. The temp differential between packs was just a little over 1C difference between each. When charging the bank, you could see how the "cooler" battery took charge slower that the warmer ones andit was quite obvious & measurable. The amps taken and the voltage difference is there to see. The other side of that, is during discharge, the colder packs discharged at a slower rate compared to the higher temp packs... The end result was that the packs tried to balance between themselves to make up the difference & that wasted stored energy in losses. You pay a price on both ends with packs at different temps.

I changed config to put all packs at waist height (more or less) so their temps reman even (as close as possible) and each pack acts just like the neighbour, same temps and same in/out performance. This applies wether the powerhouse is cold (15C) or hot at 35C.

Out of curiosity I took my 100AH pack and let it get below 0C and when it reached 1C I put a 50A charger on it (will deliver that to pack) and the pack only took 5A "grudgingly" but that increased as it warmed up and by 10C it was taking about 30A.

Hope it helps, Good Luck

Wow. That is amazing how much even small temperature variations make big differences.
Thanks Steve.

 

[featherlite]

I'm approaching this from a prepper mindset.

10++

 

[Luk88]

If you really want to max out lifecycles then you have major issue right there in front of you.
1) Get that pack in the proper orientation, Cell Vents UP - not on the sides ! That is the biggest Murphy's Laws invitation right there... the botten cells WILL leak. (we have seen a LOT of that failure - several companies are now out of business because of it - commercial packs that even had UL/CSA/ETL certifications. Just fact that some do not want to admit).

That's a bummer :-( I thought orientation doesn't really matter with these cells as it is not mentioned in any datasheets (or I missed it...).

I was under an impression when a vent bursts that cell is a goner so what is the difference if it bursts venting up vs to the side (there is steel cover planned there so it doesn't vent into someone's face.

You clearly have a lit of experience with these. Could you say more about the reasoning for having the vent up. Is this to lower the impact on the surroundings from a leaking cell? (vents some gas vs sprays flammable liquid around)

I have very little space in that cellar. Having cells vertically is one of the "important" design elements for me to be able to expand this very soon. If I have to rearrange the vents this suddenly becomes almost impossible to fit in the space I have. I'd have to build some racking, put them maybe 4 per level, then I'd have every 4th busbar longer than others... And so on. All just to point the vents up.

2) Get it at least 60cm (2') off the ground ! and level... That way all cells will remain at same temp, They cannot in that config, the bottom cells will always be colder. no matter what.

That cellar has at most 3C difference floor to ceiling at the hottest time of the year. In the winter it is more like 1C. Thanks to your earlier reply I'm not that worried about the bottom cells being cooler unless the pack starts going out of balance. I think I'll attempt to fix it with add on (removable) insulation if it happens in winter.

(unless the vent situation forces a redesign)

3) LFP LOVES the same temps humans do and are happiest @ 25C/77F and are quite content to be between 18C-32C and will produce happily without issues.

This is commonly accepted. However, we know calendar aging is caused by chemical processes that are faster and slower with temperature. So it seems logical if one adjusts charge/discharge rates to match a cell/pack should last longer stored in lower temperatures (below the sweet spot)

So why is there a sweet spot? Well, perhaps the damage caused by charging at lower temperatures (even at slower speeds) is far worse that any potential benefit of low temperature storage. If this is the case I definitely should insulate both of my batteries and add heaters if required.

I've looked for research articles, but I couldn't find any.

Also, with ESS very few ever do a full 0.5C Charge Rate and it gets a lot harder when you also have a bank of packs sucking it all in. I have the ability to "push" 350A Charge (with hassle) but not much point. ESS has the benefit of non-mobile & arrays that produce through the sun hours.. We had a poll a while back - possibly an extended thread, I forget ATM. For an ESS installation, many people are charging around 0.2C-0.3C.

This is what I also set. 80A max or slightly under 0.3C. If I expand the pack which I plan on doing soon this will drop to around 0.2C at most. This is a factor in not doing any insulation for the larger of my packs.

The issue with charging at less than 3.4V is that you'll never give the BMS an opportunity to balance the cells.

I'm planning to charge higher occasionally. Once I have my automation system I'll be able to set to 3.45 once a couple of weeks.

In the meantime I'm hoping if it gets out of balance the runners will exceed 3.45 despite the pack being lower and the BMS will have a chance to discharge balance, but that's just an idea.

Also with regard to temperature, as well as all the good points @Steve_S made, you'll achieve more storage capacity at 20-25 degrees C than at (say) 5 degrees C.

Indeed. It is difficult to quantify this too. From what I read If you're discharging fairly slowly that decrease may not be much. But if you want to pull a lot of power off the cold pack the voltage will tank until the pack heats up. I'm interested in knowing which "uses up" more energy. Heating the pack with heaters. Or just letting it heat itself up (assuming that voltage drop doesn't cause you to go below low voltage cut off in which case heaters win every time).

 

[SeaGal]

I'm interested in knowing which "uses up" more energy. Heating the pack with heaters.

It will largely depend on the amount of insulation you have and how much charge/discharge you are putting through the cells. For my 14.3kWh pack, I have 50mm of PIR insulation and just 20W of heaters - these are only on about 30% of the time when it's -5 degrees C ambient.

 

[Steve_S]

The cells internally is a really long microthin copper foil with the compound on it rolled into a tight jelly roll, then the electrolyte is added, they are then part charged & vented off & then sealed. The Electrolyte is not "right to the top" there is space for gasses etc.. hence when you shake an LFP cell you get a flushing sound and you ca squeeze then between your fingers... They are "almost" as tough as a pop can. When laying on the sides, the upper layers of the jelly roll will not be covered and exposes in the "gas area". THIS IS SIMPLIFIED - You want Hard Techie I'll give you links to the Battery University info... Stacking 16 cells (5.5kg bricks) on on top of another puts a hell of a lot of pressure (just from gravity) onto he bottom cells. We have seen NUMEROUS examples of this and how they end up leaking. Companies like Iron Edison went BANKRUPT cause of it and many more. 300 kgf per Centimeter (not per meter) is not a lot of pressure but some wizbangs can't get that (Compression topic beaten to death & revived too many times). Bottom Line: Proper Orientation is essential for safe longterm use.

Temp mismanagement & orientation is HARMING the cells and reducing calendar life. Sorry, it is as simple as that, I won't screw around with your money (some love to do so) and so I am blunt about it. There are just some basic facts that a few people love to "debate/argue" seemingly for fun. I personally blame lack of soap opera shows and bored people looking to entertain themselves.

I am well aware of the numerous formats that a battery pack can be built into. Below is one of my most common handouts showing some choices. Would a "Block" format fit into your space ? Can you also not use a Foam Insulation sheet (type with foil on both sides) underneath to provide a Thermal Break to prevent the concrete acting like a Cold Sink ? Operationally you should NOT stress your cells by operating at the low temp thresholds, get them up to at LEAST 10C if not 15C.

 

[Brucey]

We have seen NUMEROUS examples of this and how they end up leaking. Companies like Iron Edison went BANKRUPT cause of it and many more. 300 kgf per Centimeter (not per meter) is not a lot of pressure but some wizbangs can't get that (Compression topic beaten to death & revived too many times).

Iron Edison went bankrupt because of leaking LFP cells? I thought they did NiFe cells?

 

[Steve_S]

Iron Edison went bankrupt because of leaking LFP cells? I thought they did NiFe cells?

They used subcontractors to make wall mont packs. MANY MANY leaked, some caught fire too... with warranty claims the failures resulting in losses and bad management - all combined. GSL from China was one such contractor... Funny thing happened at their factory... They changed up and now are starting to make Wall Mount Packs with cells in an UPRIGHT position...

 

[Luk88]

The cells internally is a really long microthin copper foil with the compound on it rolled into a tight jelly roll, then the electrolyte is added, they are then part charged & vented off & then sealed. The Electrolyte is not "right to the top" there is space for gasses etc.. hence when you shake an LFP cell you get a flushing sound and you ca squeeze then between your fingers... They are "almost" as tough as a pop can. When laying on the sides, the upper layers of the jelly roll will not be covered and exposes in the "gas area".

Yes, this makes sense. I imagine there is some wicking and capillary action going on through the electrodes(lfp and graphite), but if parts of the roll become starved of the electrolyte I can definitely see how it can cause huge problems in the end.

Now, an obvious question would be "so why manufacturers of these cells(eve for one) repeatedly say they can be used in any orientation" they also make EV car packs where these cells are flat on the short edge (BYD "blade" battery). Then, there are manufacturers like Tesla and their prismatic LFP pack for model 3 that has vents facing upward.

The answer may simply be "they haven't gotten the memo yet". Things are considered accepted knowledge until evidence mounts to the contrary. They may well be evidence that putting these cells on their side (long or short) is detrimental. It's just being collected. Probably better to err on the side of caution. It's just a huge shame I haven't known that before I built my cellar, a building on top, planned entire layout and I've built a battery. Oh well, I guess these are the perils of DIY with cutting edge tech.

I have to research this topic a lot more.

THIS IS SIMPLIFIED - You want Hard Techie I'll give you links to the Battery University info... Stacking 16 cells (5.5kg bricks) on on top of another puts a hell of a lot of pressure (just from gravity) onto he bottom cells.

These cells a little lighter, but let's take 5.5kg. The recommended 300kg of force given for the compression fixture is on a surface of one cell, not per cm (that would crush them easily) or per sq. meter (that would be only about a half of 1psi). Let's take 15 cells on top of one. That would be 82.5kg.

So a good argument can definitely be made one should back off the fixture force by these 82kg. This means cells on top will be under recommend pressure, but I'd rather have not enough than too much. I'll be doing that tonight.

However if I back the pressure off and there is no "leaning tower of Pisa" situation I don't think crushing is causing it. Perhaps it is a factor.

Maybe it's a combination of a couple of things, a single one of each would seem not enough to cause failure?

We have seen NUMEROUS examples of this and how they end up leaking.

Can't argue with that. But I'd love to find out more. Were these packs using compression fixtures? If so, did they use springs, or screws, or something else?

Also, we're they leaking from the vents, or were corners separated etc?

Companies like Iron Edison went BANKRUPT cause of it and many more. 300 kgf per Centimeter (not per meter) is not a lot of pressure but some wizbangs can't get that (Compression topic beaten to death & revived too many times). Bottom Line: Proper Orientation is essential for safe longterm use.

Indeed it has. I'm compressing my cells with springs, but 300kg/cm is an insanely high pressure. That's about 104 tons on top of one cell. It would look like a squished empty pop can The correct value is 300kg total.

Temp mismanagement & orientation is HARMING the cells and reducing calendar life. Sorry, it is as simple as that, I won't screw around with your money (some love to do so) and so I am blunt about it. There are just some basic facts that a few people love to "debate/argue" seemingly for fun. I personally blame lack of soap opera shows and bored people looking to entertain themselves.

Some people for sure do. No doubt it is a fact what you said about temp mismanagement. You said to keep it at about 15C. This is a safe default.

I've found this research article today. It is showing visually effects of charging/discharging at various low temperatures. https://app.jove.com/t/57501/the-ef...ells-at-different-temperatures-on-degradation

Based on the above anyone can decide what temperature is appropriate for their pack (where does cost of heating/insulation outweight the benefits of few % less deterioration).

I am well aware of the numerous formats that a battery pack can be built into. Below is one of my most common handouts showing some choices. Would a "Block" format fit into your space ?

Not without serious redesign of everything else, but if I find more supporting info I'll have to do it. Probably not very soon, but probably in a couple of months time at most.

Can you also not use a Foam Insulation sheet (type with foil on both sides) underneath to provide a Thermal Break to prevent the concrete acting like a Cold Sink ?

Yes, this is a very good idea to insulate from concrete.

Operationally you should NOT stress your cells by operating at the low temp thresholds, get them up to at LEAST 10C if not 15C.

At the moment they are above 10C (14~16 today as we're having a heatwave, 13C seems average). I have good few months to consider this before I decide.

They used subcontractors to make wall mont packs. MANY MANY leaked, some caught fire too... with warranty claims the failures resulting in losses and bad management - all combined. GSL from China was one such contractor... Funny thing happened at their factory... They changed up and now are starting to make Wall Mount Packs with cells in an UPRIGHT position...

Is there a diagram of the old pack floating somewhere? (the one with issues).


Edit: Adding some useful links regarding cell orientation, but this topic probably deserves its own thread.
- regarding amount of free electrolyte in LFP cells: https://iopscience.iop.org/article/10.1149/2.1151904jes/pdf The article analysed few cell types some with lots of free electrolyte (that makes that sloshing around) sound and some with barely any. In all cases all electrode components were well wetted. Not really surprising as they are very porous. But a very useful thing to know.
- regarding cell construction: https://www.sciencedirect.com/science/article/pii/S001346862301513X discussing Tesla 3 cell showing air space on sides rather than up top - if it is not filled with electrolyte fully the jelly roll almost certainly is not fully submerged (as there is no gas space above the roll).
- influence of cell orientation of li-ion aging in big prismatic cells (not lfp, but useful) https://www.sciencedirect.com/science/article/abs/pii/S037877532100762X (ask me for text if needed). These guys show different thermal behaviour in cells aged in diffrent orientation. Their recommendation is to have all cells in the same orientation, but they don't say which.

Last one, I promise. Not directly related to cells on their side, but "temperature and pressure gradients" in general.
- https://www.researchgate.net/public...drical_cells_revealed_by_post-mortem_analysis

Excerpt from the abstract:
The most remarkable result is that both cycled cells displayed highly uneven aging primarily of the graphite electrodes, showing large differences between the central parts of the jellyroll compared to the outer parts. The aging variations are identified as differences in capacity and impedance of the graphite electrode, associated with different SEI characteristics. Loss of cyclable lithium is mirrored by a varying degree of lithiation in the positive electrode and electrode slippage. The spatial variation in negative electrode degradation and utilization observed is most likely connected to gradients in temperature and pressure, that can give rise to current density and potential distributions within the jellyroll during cycling.

 

[Brucey]

They used subcontractors to make wall mont packs. MANY MANY leaked, some caught fire too... with warranty claims the failures resulting in losses and bad management - all combined. GSL from China was one such contractor... Funny thing happened at their factory... They changed up and now are starting to make Wall Mount Packs with cells in an UPRIGHT position...

Eg4 power walls and Ruixu amongst others are producing 14-16kWh batteries with horizontal cells.

Are you saying they will fail because of that? I would say that the failure of one manufacturer doesn't mean it's a defective design.

 

[Steve_S]

Now, an obvious question would be "so why manufacturers of these cells(eve for one) repeatedly say they can be used in any orientation" they also make EV car packs where these cells are flat on the short edge (BYD "blade" battery). Then, there are manufacturers like Tesla and their prismatic LFP pack for model 3 that has vents facing upward.

There are NUMEROUS documents out there and sadly many often refer to docs that are outdated. EVE, CATL etc all update this material quite regularly, especially when a new product hits.

BLADE cells are NOT primsmatics and are designed for their application. Additionally, they are NOT easy to get and won;t be for a while yet... Their production is being consumed by EV's at an increasing rate.

An A-Typical EVE 280AH cell is about 5.5kg, I used that as a commonly known & used example.

Indeed it has. I'm compressing my cells with springs, but 300kg/cm is an insanely high pressure. That's about 104 tons on top of one cell. It would look like a squished empty pop can The correct value is 300kg total.

I will post the answer and I will NOT get into another long hauled argument over it (Too much of that shit has happened and not going there again) The SIMPLE MATH (proper - not interpreted like everyone wants to do) IF ANYONE WANTS TO GET INTO IT GOTO the Compression Thread - NOT HERE !

M6 Screw/Nut tightened to 10Nm = 1000kgf
M6 tightened to 3Nm = 300kgf

6 Screws applying pressure to a plate: Divide Nm x # of screws
6x M6 tightened to 0.5Nm = 300kgf "collectively"

Essential "Snug" enough to prevent movement of cells but not so much to interfere with normal Expansion & Contraction during cycling at various temperature ranges.
--------------
YES, companies are producing wall mounts with side mounted cells and it's their liability. EVEN GSL and others are changing their designs. 2 of my suppliers are now working on cases (wall mount & otherwise) to ensure that cells are UPRIGHT (should be available within a month) as they are presently prototyping & testing.

TBH, I have been at this a while and seen many things and really, you could NOT pay me to put a battery pack in service with cells on their sides, not for anything thanks. If I was using Blade or other Pouch format cells, I would work with those formats per specs and a lot of those are long, narrow & now very tall with terminals on the sides as part of the design. Even our current Steel Case offerings (used for Prismatics) would need mods for that.

I have provided the information and the rest is up to you... Ultimately choices, decisions & consequences are yours as is the financial part. Where I live I see 40C to -35C, I've beaten abused gear with hard & nasty "thrash" tests pushing things to operational limits. I'm ex Military IT Engineering + and approach things in that fashion) Rule of 3 applied, production, backup & redundant backup but applied to all things whenever possible.

When you say a Failure by one manufacturer is not an indication. Several manufacturers hit this wall and continue on. Others see & are taking corrective action. If a car company builds a car and does something really stupid resulting in harm (injuries /death) they are forced to change by law & pressure from outside. Other companies take note of that and correct it before doing it themselves (no one likes law suits) yet several still build bombs on wheels. And people buy them anyways. Do you want TRABANT or a real car ? Don't build a Trabant ! (My Spouse is Polish, I am Canadian Hungarian and know) .

 

[Luk88]

@Steve_S you know my first car was a Trabant 601 with a 2 stroke engine. The car was 18 years old and I paid $170 (at today's conversion rate) for it Yes, it was a bit of a comedy car with its high revving two stroke and composite body, but there was a saying "you could repair it with a push-bike repair kit" and it was mostly true. If you put the lead-replacement additive and oil in the fuel properly it was very reliable (except electrics - I had to start it with a screwdriver bridging the starter terminals many times). There was of course a 4 stroke, metal bodied and much heavier Trabant and the owners of these consider the two stroke variant a toy But I digress, let's go back to the original topic...

I will post the answer and I will NOT get into another long hauled argument over it (Too much of that shit has happened and not going there again) The SIMPLE MATH (proper - not interpreted like everyone wants to do) IF ANYONE WANTS TO GET INTO IT GOTO the Compression Thread - NOT HERE !

Essential "Snug" enough to prevent movement of cells but not so much to interfere with normal Expansion & Contraction during cycling at various temperature ranges.

Agreed, no need to debate it again here. I just pointed out an obvious typo for the sake of someone taking it and cranking down on their cells until the juice comes out...

Personally I prefer springs, but anyone seeking more info will find plenty on the subject.

--------------
YES, companies are producing wall mounts with side mounted cells and it's their liability. EVEN GSL and others are changing their designs. 2 of my suppliers are now working on cases (wall mount & otherwise) to ensure that cells are UPRIGHT (should be available within a month) as they are presently prototyping & testing.

Sadly these companies are extremely light on technical details about their battery construction in public (maybe they distribute better materials to prospects). The pictures of open batteries I could find all had vertically arranged cells with vents up (a rack battery, and one "power wall" style).

I would appreciate any more details, which of their battery/s was using side mounted cells? (so I can look up more info).

TBH, I have been at this a while and seen many things and really, you could NOT pay me to put a battery pack in service with cells on their sides, not for anything thanks. If I was using Blade or other Pouch format cells, I would work with those formats per specs and a lot of those are long, narrow & now very tall with terminals on the sides as part of the design. Even our current Steel Case offerings (used for Prismatics) would need mods for that.

I have provided the information and the rest is up to you... Ultimately choices, decisions & consequences are yours as is the financial part.

Thank you, I find this first hand information very valuable. The fact I'm considering serious redesign after I've put this system almost fully in service is a big deal for me.

If I was doing it again I'd put them with vents up just to be safe.

I'm trying to get as much detail about this as you're willing to give. Sadly there has been not much input from others here, but I realise side mounting cells like this is uncommon in DIY space so the only real source of info can be had from installers/owners of commercial systems. And not many frequent this board...

Where I live I see 40C to -35C, I've beaten abused gear with hard & nasty "thrash" tests pushing things to operational limits. I'm ex Military IT Engineering + and approach things in that fashion) Rule of 3 applied, production, backup & redundant backup but applied to all things whenever possible.

So I have multiples of my equipment too. My other "big" battery is vertical side mounted too, but it's in a wheeled tool case (it's only an 8S) so if I had the space I could just lie it down to put vents up.

When you say a Failure by one manufacturer is not an indication. Several manufacturers hit this wall and continue on. Others see & are taking corrective action.

I wouldn't say a failure by one manufacturer is not an indication. It is exactly an indication, but ideally one would have more information. There may be other reasons at play. I'm not saying this to argue with your experience. I'm saying it to describe my thought process. Perhaps someone finds it useful.

Imagine this, you're a commercial manufacturer and you design your product with side mounted cells (you don't know any better at this stage). You don't really care about compressing cells as the uncompressed life expectancy is good enough, but you don't want them to shift in the case. You don't want to add elastomers because it will compromise your fire rating or is bulky/expensive. So you design the "fixture" to gently snug the bolts by hand when at storage charge.

Then the packs get manufactured and Mr Zhang a factory worker sees your design sheet and thinks "are these westerners idiots? Do they really want us to just snug the bolts by hand? Don't they know these cells will come loose in the case in transport and how long it takes to do by hand anyway?" He picks a cordless driver and sets it 3 clicks from the lowest setting.

These packs then go into their service life with very varying fixturing pressure. Some are torqued as spec'ed. Some are overtorqued. A lot. And some go to hot climate where even "snug by hand" in 10C factory proves too much.

If compression is too high, which cells will fail? Ones on the bottom of course which have the weigh on top of them.

What is the cause, orientation, too much pressure, uneven pressure, all these things and harsh use at the same time? Who knows? So we gather as much info as we can and make our decisions based on that. U

 

[Steve_S]

hahaha on the 601 ! What a pain to push up hill in the Carpathians... I Know you KNOW what I mean... hehehe Imagine putting a Tesla motor & batteries into one (for kicks & giggles because of the attention it would get hahaha).

I'm trying to get as much detail about this as you're willing to give. Sadly there has been not much input from others here, but I realise side mounting cells like this is uncommon in DIY space so the only real source of info can be had from installers/owners of commercial systems. And not many frequent this board...

Many are reading this thread and pondering/considering... It happens. We have Manufacturers & Vendor/Suppliers lurking, reading & watching. There are a couple who actually listen, hear & take the ideas.suggestions and incorporate them if sensible & reasonable. Vender & Maker interaction got "squelched" a while back because after it started & some of us helped them to help improve products etc things got out of control with manipulators/users/abusers. For a little while at least, there was a great exchange & excellent interaction that actually resulted in new better products for everyone to benefit from. Several even gave an extra discount to the membership here. It was shortly after that that things got fugly and it had to all be shutdown. It's a shame because because we saw rapid development, testing & refinement almost realtime for a bit... a Great Loss really. There is a very serious Talent pool lurking here.

BTW a bit of clarity.
Tesla Powerwalls are still not LFP "yet". Commercial Wall Mounted packs come in many flavours. More & more are changing to LFP or LMFP and BYD is now making a family with Blade Cells even (good luck finding them LOL). Cylindrical (All Chemistries) and Pouch are different beasts but the bigger companies are going that way. IF I was looking for "Commercial" Wall Mounted / Stackables I'd get BYD's dropped at my door.

 

[Brucey]

BTW a bit of clarity.
Tesla Powerwalls are still not LFP "yet". Commercial Wall Mounted packs come in many flavours. More & more are changing to LFP or LMFP and BYD is now making a family with Blade Cells even (good luck finding them LOL). Cylindrical (All Chemistries) and Pouch are different beasts but the bigger companies are going that way. IF I was looking for "Commercial" Wall Mounted / Stackables I'd get BYD's dropped at my door.

Tesla Power wall 3s are using LFP cells.

Tesla releases more details on Powerwall 3, confirms cheaper stack coming

Tesla has released more details about Powerwall 3, its new generation home energy storage system, and there’s some more good...

electrek.co

 

[kappa7]

Just for info the new Huawei LUNA S1 has 8 280Ah cells per block lying horizontal on the bigger side. The older LUNA S0 has 16 50Ah cells lying horizontal on the smaller side. Sadly I don't know the cells manufacturer of both batteries.