Lithium battery conversion

[booster]

Originally Posted by avanti

That video answered a question I was wondering about: Exactly what chemistry do these batteries employ that lets them advertise such a low minimum storage temperature?

The answer is "Lithium Iron Phosphate". LiFePO4 is exactly the same chemistry used by most other mainstream lithium battery providers. So what is it that allows them to make this extraordinary claim? Is there some other characteristic (packaging, some electrolyte conditioning trick, and additive...) that only they use?

Of course, it is quite possible that these batteries behave exactly the same as any other with similar chemistry at low temperatures. The claimed minimum temperature spec may be a simple calculated risk made by the marketing department. Lacking an industry standard for measuring such things, there is nothing to stop them from doing this, and it may well be that they make a lot more money from the undoubted gain in market share than they lose in the occasional warranty claim.

Who knows?

I think it is highly likely that is the case as not a lot of users are going to be storing below zero and even if the cold shortens life the batteries may still make it through the warranty period.


There is probably a lot of this with lithium at this point with things like 100% usable capacity and very high cycle life claims. They always have the "abuse" excuse to fall back on if they get lots of claims so probably a pretty low risk decision for them if it improves sales and price points.

[Boxster1971]

Originally Posted by avanti

That video answered a question I was wondering about: Exactly what chemistry do these batteries employ that lets them advertise such a low minimum storage temperature?

The answer is "Lithium Iron Phosphate". LiFePO4 is exactly the same chemistry used by most other mainstream lithium battery providers. So what is it that allows them to make this extraordinary claim? Is there some other characteristic (packaging, some electrolyte conditioning trick, and additive...) that only they use?

Of course, it is quite possible that these batteries behave exactly the same as any other with similar chemistry at low temperatures. The claimed minimum temperature spec may be a simple calculated risk made by the marketing department. Lacking an industry standard for measuring such things, there is nothing to stop them from doing this, and it may well be that they make a lot more money from the undoubted gain in market share than they lose in the occasional warranty claim.

Who knows?

The video said “Valances lithium iron phosphate chemistry”. The data sheets for Valance batteries posted earlier in this thread all refer to that chemistry as “lithium iron magnesium phosphate”. I’d guess the addition of magnesium makes the difference.

[booster]

Originally Posted by Boxster1971

The video said “Valances lithium iron phosphate chemistry”. The data sheets for Valance batteries posted earlier in this thread all refer to that chemistry as “lithium iron magnesium phosphate”. I’d guess the addition of magnesium makes the difference.

I think I remember something from quite a while ago. Valence was acquired by I assume the present owner and the chemistry was changed from the original Valence formulation to new owners chemistry that they used on their own products. It is probably on the forum somewhere.

[booster]

Here is one of their tech sheets from 2011 that is for the Magnesium lithium battery.


https://www.celltech.se/fileadmin/us..._Datasheet.pdf

[Boxster1971]

Also noticed that this news release about Lithium Werks Acquiring Valence Technologies mentions their proprietary chemistry:

“Valence’s Proprietary Lithium Magnesium Iron Phosphate intellectual property (IP)”

https://www.batterypoweronline.com/n...hnologies-inc/

Found another company that offers a -40C lithium iron phosphate batteries with special chemistry.

https://www.large-battery.com/low-temperature-battery/

I’d guess there are ways to modify the chemical formula to improve cold storage capability.

[Boxster1971]

Originally Posted by booster

I think I remember something from quite a while ago. Valence was acquired by I assume the present owner and the chemistry was changed from the original Valence formulation to new owners chemistry that they used on their own products. It is probably on the forum somewhere.

I’d say Valance was acquired by Lithium Werks in 2018 because of their proprietary chemistry and it hasn’t changed.

. . . And then in 2020 Lithion Battery, a division of Lithion Power Group, acquired the Valence branded battery module manufacturing business from Lithium Werks.

[SteveJ]

Originally Posted by booster

On page 3 they show the -40C, so they must still be saying that, at least in June 2021.

It seems to be clear as mud.

[Davydd]

Originally Posted by avanti

That video answered a question I was wondering about: Exactly what chemistry do these batteries employ that lets them advertise such a low minimum storage temperature?

The answer is "Lithium Iron Phosphate". LiFePO4 is exactly the same chemistry used by most other mainstream lithium battery providers. So what is it that allows them to make this extraordinary claim? Is there some other characteristic (packaging, some electrolyte conditioning trick, and additive...) that only they use?

Of course, it is quite possible that these batteries behave exactly the same as any other with similar chemistry at low temperatures. The claimed minimum temperature spec may be a simple calculated risk made by the marketing department. Lacking an industry standard for measuring such things, there is nothing to stop them from doing this, and it may well be that they make a lot more money from the undoubted gain in market share than they lose in the occasional warranty claim.

Who knows?

Well I think I know. I have the batteries. Where do you get your opinion? You don't have lithium ion batteries of any kind so you are basing you opinions on others. I doubt the marketing department would make those claims which were not in the video. Who makes a claim of 144ah in a Group 27 battery? It says 138ah but the video is old they changed it. I know from experience. Who has reporting (5 screens on my Silverleaf which is one screen of the computer read out they show in the video) of most every aspect of the batteries? I know. I haven't seen it from any manufacturer. I have it. ARV is being cautious though. They did install a heating plate under the batteries even though I have never experienced -40F in Minnesota ever but have driven in -15F. So, if you are basing your opinion on that one temperature aspect wouldn't you have caution if you store outside with no shore power you mention time and again.

I don't know what others are doing with lithium ion batteries but I have faith in what ARV does with 8 years of experience in the most extreme of weather. You have been coy in not even saying who is building your van or what lithium lon system you are employing. I'm tired of your implications.

[booster]

I think a lot of the questions of the -40* storage come from the idea that in the early days of lithium almost all the manufacturers claimed that kind of low temp ability, but now many/most of them have backed off to the now common -4* specification.


It does make one wonder why some have not, I think.


Very few will be storing in that cold of weather, so the warranty risks are very, very small to those who claim a colder temp than the batteries could handle, as was mentioned early. That would give them little incentive to charge the claims if it helps sales at all due to perceived quality.

[JohnnyFry]

The minimum charging temperature is 0ºC...the same as every other LiFePO4 battery on the market. This is the only critical temperature limitation because charging at temperatures lower than 0ºC causes "Spicules" to grow on the membrane eventually puncturing it and ruining the cell. Discharge can occur at much lower temperatures because this phenomenon does not occur on the discharge cycle. Minimum storage temperature is probably limited more by the case materials than battery chemistry.(the storage temp statement is speculation on my part)

[avanti]

Originally Posted by Davydd

Well I think I know. I have the batteries. Where do you get your opinion?

Actually, I don't think I expressed an opinion. I said "Who knows?".

I have never experienced -40F in Minnesota ever but have driven in -15F.

We were talking about storing a vehicle unpowered at -40F, not inhabiting it, which I agree is implausible.

You have been coy in not even saying who is building your van or what lithium lon system you are employing.

I am certainly not trying to be coy.

I know that a few folks are curious about my upfitter. When the time comes, I will document my experience thoroughly, both the good and the bad. I have chosen not to prematurely identify the upfitter, since we really won't know how satisfied we are until we take delivery (which will not be long, now, BTW). It seems obvious that what I write will depend fundamentally on our opinion of the result, so there is no point in talking about the details yet. You will get my best effort at a balanced report -- good or bad. So far, so good, though.

In any event, we are talking about weeks now, not months. I think some will find the results interesting. In the mean time, I would be perfectly glad to discuss any technical details of the design. (E.g., the 24V electrical system is 100% Victron, except for the DC-AC-DC engine charging system driven by the very capable Ford dual alternator). Please post any such questions on my build thread, so as not to hijack this one).

Otherwise, stay tuned...

[booster]

I think that it should be brought out that it is highly, highly unlikely, assuming the -4*F safe to store temp is largely correct, that there is a hard cutoff at -4* or at -40* if that is more appropriately accurate.


Nearly all this kind of stuff is more like a progressive thing that happens. Probably a progression in the rate of failure as it get colder and perhaps a max amount of damage that could occur at any given temperature.


Is -4* a whole lot better than -5*, not likely. Is -39* totally safe, but -40* is a disaster, not likely for those that are rated at -40*.


I just don't see this as a hard cutoff, especially with all the different ratings we have seen over the years since lithium entered the picture.



If anyone has any hard data on this it would be interesting to see as I would think it would be pretty easy to test under lab conditions and with good equipment. The manufacturers probably already have this information, but they also would not be likely to release it.

[avanti]

Originally Posted by booster

I think that it should be brought out that it is highly, highly unlikely, assuming the -4*F safe to store temp is largely correct, that there is a hard cutoff at -4* or at -40* if that is more appropriately accurate.

I think you are probably right. However, it isn't necessarily true. It depends on the mechanism.

There certainly exist hard thresholds in physics. The freezing point of water is an example. The phase transition takes place quite abruptly, and any damage done due to freezing may well happen suddenly. If the damage in a lithium battery is caused by such a phase transition, it could well be hard threshold.

OTOH, if the mechanism involves mechanical failure due to the contraction of a solid (within a phase), the damage likely won't be all-or-none. I actually think that this is the actual mechanism of Lithium battery freeze damage. I think it has to do with cold-driven contraction degrading the connections between the cathode and the surrounding matrix (or some such), which is not all-or-none.

[booster]

I seem to remember seeing someplace I don't recall saying it was some sort of damage to the cells themselves on the the cathode or anode. Some kind of growth, I think. I wish I had saved a link to where I saw it, as it was new to me.

[MobileCabin]

booster,

I think that freezing effect was in a materials paper that is summarized here:

https://www6.slac.stanford.edu/news/...ng-performance

Pat

[GeorgeRa]

Originally Posted by booster

I seem to remember seeing someplace I don't recall saying it was some sort of damage to the cells themselves on the the cathode or anode. Some kind of growth, I think. I wish I had saved a link to where I saw it, as it was new to me.

These are dendrites which can grow during low temperature charging and can cause shorts. Cold storage limitation could be related to phase change, dimension change due to temperature or discharge which could cause electron flow related formation of some kind dendrites (see previous comments). Metal migration induced by electron flow can deposit as dendrites (whiskers) ultimately causing short. Happens often as a result from corrosion on printed circuit boards.
https://www.batterypoweronline.com/n...ging%20process.

[GeorgeRa]

Originally Posted by MobileCabin

booster,

I think that freezing effect was in a materials paper that is summarized here:

https://www6.slac.stanford.edu/news/...ng-performance

Pat

I think cathode is a crystalline material versus anode which is graphite. This could explain why cathode is more fragile.

[booster]

I did some reading on the topic of cold damage last night. The study mentioned earlier by MobileCabin was in 2021 and seemed to be the defining point of more understanding. Earlier searches before this study brought up much less information on the topic.



Cold shrinking of the spherical structures of the cathode could cause cracks in those spherical structures, was the conclusion of the study. The cracks could be either new or expansions of existing cracks. Having cracks in the spheres can interfere with the energy storage and giving up energy processes and reduces the capacity and lowers the charge and discharge rates, it stated.


The damage appears to be a function of buildup of damage over time, and there were some references to the cracks also being able to cause more damage to the battery during subsequent charge and discharge cycles.


So, if this idea is correct, the results would get worse faster the colder the temps got and would accumulate over time and cold cycles. Add in the possible damage from charges and discharges and more accumulation of damage.



I didn't find anything on how fast or how much capacity would be lost however, but I didn't pay to read the entire tech paper from 2021 so it might be there.


There is a lot more information around about the effects of high temps for lithium, with high temp defined as being some of the normal temps for RV batteries, depending on where they are located.


It appears that Avanti was correct in speculating about thermal stresses, although it is not the kind I normally would run across in whole parts shrinking and causing breaks in continuity. It is more in the metallurgical structures themselves affecting their properties and ability to transfer ions.


A couple of related things I ran across were that a couple of articles claimed that at -40*C a lithium battery has lost nearly all of its SOC which I found surprising. I assume that capacity, or most of it anyway unless the damage mentioned above was large, would come back when warmed up.


There were also mentions of being extra careful in handling very cold lithium batteries as they may be even more prone to bumps and such damage than they are when warmer.


None of what I found was for LiFePO4 batteries specifically or even mentioned, so probably all the information was more in line with vehicle or backup power lithium batteries.

[@Michael]

Originally Posted by booster

The damage appears to be a function of buildup of damage over time, and there were some references to the cracks also being able to cause more damage to the battery during subsequent charge and discharge cycles.


So, if this idea is correct, the results would get worse faster the colder the temps got and would accumulate over time and cold cycles. Add in the possible damage from charges and discharges and more accumulation of damage.

Perhaps this is why one of the major manufacturers (forgot which one) allows for low-rate charging when below freezing?

[Boxster1971]

Originally Posted by avanti

. . . I know that a few folks are curious about my upfitter. . .

. . . In any event, we are talking about weeks now, not months. I think some will find the results interesting. In the mean time, I would be perfectly glad to discuss any technical details of the design. (E.g., the 24V electrical system is 100% Victron, except for the DC-AC-DC engine charging system driven by the very capable Ford dual alternator). Please post any such questions on my build thread, so as not to hijack this one).

Otherwise, stay tuned...

How about a link to your build thread? I searched a bit and could not find it.

Thanks,
- - Mike