PCM material for DIY pack builders ... where to get?

[migueralliart]

If someone with knowledge in this subject can chime in and provide some info that might be helpful.

I've seen optibike call it Cool Carbon Technology
Then Allcel calls it PCM

I understand the concept but where to search for this type of material?

 

[wesnewell]

http://www.acronymfinder.com/PCM.html
Suspect you're looking for Phase Change Materials, not Pulse Code Modulation.
http://www.pcmproducts.net/

 

[migueralliart]

I know what it means and what the material does... I'm trying to source it for some battery packs I'm making.

 

[Kin]

Any reason why you're trying to source it?

I bet some of the early academic papers talk about it. I think the typical kind, like Allcell, is a wax mixed with other materials.

But why do you want it? If you're building a pack for Ebikes, I think in most cases you're better off just keeping your heat down. There are few applications for ebikes that I can think of that could use PCM material that wasn't just wasting weight the majority of the time.

 

[migueralliart]

Any reason why you're trying to source it?

I bet some of the early academic papers talk about it. I think the typical kind, like Allcell, is a wax mixed with other materials.

But why do you want it? If you're building a pack for Ebikes, I think in most cases you're better off just keeping your heat down. There are few applications for ebikes that I can think of that could use PCM material that wasn't just wasting weight the majority of the time.

I wanna test it by my own at various discharge rates using high power 18650 cells. I just don't trust the graph that ALLCELL has in their website. If I can source it then I can test it and if it works then i'll make some packs for myself using it.

 

[SamTexas]

I just don't trust the graph that ALLCELL has in their website.

Good for you! And not just the graph, almost all other data provided are wishful/imaginary.

That said, I think if cooling is necessary/required for any type of cells then it's time to either add more capacity or look for another cell type designed for higher discharge.

 

[999zip999]

Agree.

 

[docnjoj]

I just don't trust the graph that ALLCELL has in their website.

Good for you! And not just the graph, almost all other data provided are wishful/imaginary.

That said, I think if cooling is necessary/required for any type of cells then it's time to either add more capacity or look for another cell type designed for higher discharge.

Yes to all comments here! It is too bad that there is a lack of data, not only from Allcell but from Sphere members. I have only seen 2 people write about these batteries and both people and batteries were new.
I do like the idea of American assembly but not at the level of performance that we seem to believe is the case here.
I wonder what the rate of returns under warantee is and whether Allcell backs their product, since with all those small cells it does not look easy to fix.
otherDoc

 

[migueralliart]

I'm gonna test it with some Samsung INR18650-20R cells. These are brand NEW and apparently don't have as much sag as the ones allcell uses. The reason I wanna use the PCM material is to extend life and thermal build up and I'm not concerned that the cells area heating too much. I myself have not given up the 18650 format yet I think it has got a lot of potential. These new cells can put out 20Amps each and have a low IR with a capacity of 2Ah. My configuration will be 15S4P 8Ah so capable of "80 amps" discharge for briefs moments and sustained 40 amps. A member in the budget light forum posted graphs for 20A 10A 7.5A and 5A and I think for my application they are perfect. I'll post my findings when I finish the pack.

 

[Kin]

If you have relatively low density 18650 cells, why stick with 18650? You have a lot of terminals and components that can break, plus the minor loss of density with the cylindrical shells.


To me, 18650 seems to have its best benefit from either freely available (see: darkangel & samtexas) or ultra high density (e.g, with panasonic 3+Ah cells. Which are way too hard to source, unfortunately) But with 2Ah cells you are not in the realm of high density, though you get more reasonable discharge rate.


I feel like I'm just saying negative things though, so dont let me discourage you. Keep looking for the PCM material.

 

[agniusm]

what about them:
http://www.pcmproducts.net/Solid_Solid_PCMs.htm
http://www.teappcm.com/products.htm

 

[migueralliart]

If you have relatively low density 18650 cells, why stick with 18650? You have a lot of terminals and components that can break, plus the minor loss of density with the cylindrical shells.


To me, 18650 seems to have its best benefit from either freely available (see: darkangel & samtexas) or ultra high density (e.g, with panasonic 3+Ah cells. Which are way too hard to source, unfortunately) But with 2Ah cells you are not in the realm of high density, though you get more reasonable discharge rate.


I feel like I'm just saying negative things though, so dont let me discourage you. Keep looking for the PCM material.

Thanks for your opinions ... the thread tittle should give you an idea of what I am looking for; a SOURCE for PCM material that's all.

In my quest for knowledge I've used pretty much all formats except pouch NMC and headway's. I'm well aware of the pro's and cons of the 18650 cells and I'm not looking for an opinion on these for that we have multiple threads that bash them so let's stick to the main topic which is PCM.

 

[Kin]

You're right. I commend your effort in experimentation.


In case my messages crowded out Agnesium's response, make sure to note his link above my thread (a few potential sources.)

 

[migueralliart]

what about them:
http://www.pcmproducts.net/Solid_Solid_PCMs.htm
http://www.teappcm.com/products.htm

Thanks for that !

I'll go in and do some reading and dig out my thermodynamic class notes ... getting the rust out

 

[velias]

PCM material, that stuff is a bunch of hogwash just so that company can sell more cells to kool-aid drinkers.
Does anyone's batteries in an e-bike application really get much more than warm?
This is a waste of time.
Its like drag racers putting icepacks on their engines to get some sort of miniscule performance increase.
If it made any performance or life difference then everyone would be using it.

 

[migueralliart]

PCM material, that stuff is a bunch of hogwash just so that company can sell more cells to kool-aid drinkers.
Does anyone's batteries in an e-bike application really get much more than warm?
This is a waste of time.
Its like drag racers putting icepacks on their engines to get some sort of miniscule performance increase.
If it made any performance or life difference then everyone would be using it.

Here's what I ultimately want ;
1-Wrap a single 18650 cell in a PCM rectangle then take that cell to it's max discharge capability until the capacity is depleted
2- Do the same to a cell without PCM.
3- Log temperature for both cells throughout the test.
4- Compare the results

My thinking is that if you can take a cell and discharge it and mantain it cool then it's IR would not increase significantly until the capacity reduces. Therefore you will get a higher voltage and possibly higher cycle life.

Now would I pay 400$ for such PCM material. HELL NO. Is it worth to me to investigate how much will it cost to implement it to my packs and do some simple tests ... well YES.

 

[SamTexas]

So all you want to prove is whether a cell performs better at a lower operating temperature. For that you only one or two cpu or power supply fans.

 

[migueralliart]

So all you want to prove is whether a cell performs better at a lower operating temperature. For that you only one or two cpu or power supply fans.

That's one of the problems of this forum... people who just believe what they "think" some other guy's gut feel is.

Truth is I wanna see the data... this is the same thing that happens every time someone says ohh you should vent a hub motor this way or the other.
In the end the guy that logged data and made conclusions from it is the one that really learned something.

Having said that all I asked was for someone with EXPERIENCE with PCM to bring to the table a source to buy such a material. I emailed some of the companies from the earlier posts to see if I can get somewhere with this.

 

[SamTexas]

So all you want to prove is whether a cell performs better at a lower operating temperature. For that you only one or two cpu or power supply fans.

That's one of the problems of this forum... people who just believe what they "think" some other guy's gut feel is.

WTF are you talking about? When did I say I say that!??? I was suggesting to use the fans to cool the cell so you can get whatever the heck you were looking for. Why do I care about your gut feel? It's irrelevant and meaningless to me.

 

[migueralliart]

So all you want to prove is whether a cell performs better at a lower operating temperature. For that you only one or two cpu or power supply fans.

That's one of the problems of this forum... people who just believe what they "think" some other guy's gut feel is.

WTF are you talking about? When did I say I say that!??? I was suggesting to use the fans to cool the cell so you can get whatever the heck you were looking for. Why do I care about your gut feel? It's irrelevant and meaningless to me.

Point taken ... It is not what I'm looking for.

Back on topic;

I think another member with id hillzofvalp has used these before but I'm not sure whom else.

 

[battman]

PCM material, that stuff is a bunch of hogwash just so that company can sell more cells to kool-aid drinkers.
Does anyone's batteries in an e-bike application really get much more than warm?
This is a waste of time.

Kool-aid drinker here :wink: ...
This summer the ambient temperature will reach 110F and possibly more here in Phoenix.
Under these weather conditions my pack could get warm enough to potentially degrade the cells.
I am looking at experimenting with wrapping my pack in PCM material (maybe a couple of laptop cooling pads sown together, I'm still researching) to help reduce cell heating during the 45 minute journey to/ from work.

Its like drag racers putting icepacks on their engines to get some sort of miniscule performance increase.
If it made any performance or life difference then everyone would be using it.

It may make a performance or life difference, but may not be practical for everyone to use.
It is somewhat a PITA to have to stick the 'blanket' in a freezer then wrap the pack before every journey. Not everyone may have access to a freezer at work. Some people might even keep food in their freezer and not have room for stuff like this anyway. My pack is quick release, so I keep it indoors and safe from the inferno when not travelling. If someones pack is sitting outside all day strapped to their bike, PCM isn't going to help in this climate.

If I get anywhere with this project, I'll post results here. Plan would be to stick a thermometer in pack and see how temperature changes on days of similar heat with and without the PCM blanket. Also if anyone does find a convenient source of material (perhaps in larger panel with smaller regular size squares that could be trimmed to fit custom needs) that would avoid cobbling laptop cooling pads together I'd be interested to know.

 

[rf]

I was thinking about the earlier comment about dragsters and ice packs. And how that would be an easier way to do this particular testing of battery packs vs. temperature. Cool them down with ice or something like that. Or surround them with water at your desired testing temperature. (Preferrably with a plastic barrier to keep them dry.)

But, I'm pretty sure that all Lithium chemistries perform better when warm. The Lifepo's I've used (and abused) have never gone beyond warm during use.

I've browsed the Allcell ebike web pages and keep asking myself: What for?


Richard