NCM vs lifepo4?

[cell_man]

http://em3ev.com/store/index.php?route=product/product&path=35&product_id=123

The above link is a shameless, deliberate lie. In their own words:

Our 14S 9P, 50V 18.5Ah Samsung SDI Battery Pack uses the SDI ICR18650-22P 4.5C rated cell.

Samsung ICR18650-22P is NOT NMC. ICR = Lithium (I) Cobalt (C) Rechargeable (R). Real life test have shown that this cell can barely tolerate 5A (2.27C) continuous discharge, let alone 9.9A (4.5C) as claimed by the seller.

Discharge curves at 2,3, & 5A ...
http://www.dampfakkus.de/akkutest.php?id=73

Worse, this misrepresentation is repeated over and over and perpetuated by members of this forum.

For true NMC 18650 cell from Samsung, look for Samsung INR18650-xxy. Note the difference, "N" instead of "C". I have tested the Samsung INR cells and they can sustain 3C comfortably. xxy is the capacity designation.

Firstly thanks,and if you don't mind I'd just like to say a few things.

First, I do not call them NMC cells, I call them NCM. That is what I am informed they are. I have a data sheet which states that the 22P cells are rated for 10A discharge.The same data sheet (which is marked as confidential) which I received from my Samsung supplier (who happen to make battery packs for some very well known and expensive brands) states a nominal capacity of 2150mAh, a minimum of 2050mAh. My own tests at real world discharge rates indicates they will do 2.05Ah or better, so that is what I use when stating pack capacity. In a Samsung brochure I picked up at a trade show it stated 3C discharge for the 22P cells, so to be perfectly honest I am not 100% sure what the true C rate is. I would never recommend they are discharged at 3, 4 or 5C, and if you look at the spec that I state for these packs, I recommend the packs are not used at anything close to 4 or 5C. For my 10.25Ah SDI 22P pack I recommend no more than a 25A controller, for the 14.35Ah pack I state no more than 35A, for the 18.5Ah pack I recommend no more than a 40A controller. Anyone that asks, I will always tell them the same thing, I do not recommend they are used at much over 2C Max and better to keep the typical continuous discharge rate below that. I personally think a 13S pack is below 48V too much of the time, so I make my packs 14S as standard instead of 13S. It would be perfectly acceptable to call a 13S 5P pack a 48V pack like most do and state the pack capacity as 10.75Ah, but I don't, we use an extra series cell and state such a pack as 10.25Ah. We recommend that pack is used with no more than a 25A controller, approx 2.5C Mac.

A very well respected Vancouver Based Ebike business uses the same cells and describes them as LiMn, 5C cells. Why don't you call them out? They have very similar suggested usage to what I recommend.

I will have to make some more inquiries regarding this INR versus ICR matter, maybe what Samsung call NCM is different from what another manufacturer states. Below is a link for the SDI ICR-18650-22F, at the bottom it states, NCM:
http://www.samsungsdi.com/battery/cylindrical-ICR18650-22F.jsp

There are several cell types that have numbers starting ICR, the ICR-18650-22F and 24F in the list below and they state NCM, the INR-18650-15R states NCA:
http://www.samsungsdi.com/battery/cylindrical-rechargeable-battery.jsp#none

I don't know why Samsung do not list many of their commonly available cell types on their website. I do not claim to know the intricate details of the cell chemistry that I source and supply and frankly it is not exactly spelled out by the manufacturers. I have already sent an email requesting clarification on this ICR, versus INR matter. If something in the product description needs to be corrected, it will be. I do not feel I over state anything, in fact I always err on the side of caution as I have zero interest in selling equipment that falls short of expectations or fails.

I will soon have the SDI 20R power cell which is 20A rated (10C plus), and the SDI 29E, which I have seen rated as 3C. Whilst I may remark at the rating when I list them on my site, I will not state such high current values are recommended for normal usage.

Good Day

 

[melodious]

I will soon have the SDI 20R power cell which is 20A rated (10C plus), and the SDI 29E, which I have seen rated as 3C. Whilst I may remark at the rating when I list them on my site, I will not state such high current values are recommended for normal usage.

Good Day

In the world of cards, that is called a trump. I wonder if the trump card gives us over 500+ cycles.

 

[SamTexas]

Your response is well balanced and you have my respect for that.

In your link for this product, you specifically said "4.5C rated". So regardless of what your further explanation is, the "4.5C rated" is stuck in your customers mind and is repeated over and over by other people.

I have no idea who or what Vancouver Based Ebike business is? But I suspect you are referring to the owner of this board, Justin. I have never looked at his battery specs, but if what you are saying is true, then I am calling his battery out too!

I have also called out batteries from AllCellTech/ChicagoElectricBicycles as well
http://www.allcelltech.com/products/electric-bike
http://www.chicagoelectricbicycles.com/Batteries.html

And my contempt for HobbyKing RC LiCo cannot get anymore disgusting.

Not trying to be your friend or your enemy, but your misrepresentation is very mild compared to AllCellTech/ChicagoElectricBicycle. Next to HobbyKing, you are almost an angel.

I respectfully ask you to tone down your description for this Samsung cell. You have a solid reputation on this board, why not try to maintain it or even make it better?

 

[dnmun]

-1

 

[etriker]

NCM, NMC, what the heck ?

Cellman, why did you give up on the rugged tried and true A123m1 cells that last 1000s of cycles and have big Cs ?

Those are the cells that made you famous ?

 

[mvly]

In my onion the future is NCM. I distinctly remember LFP stating this sometime. Though I don't agree with him all the time, I think he got a point on NCM. LiFEPO4 is old tech in terms of development. Not much improvements on it lately. Also it is heavier and has lower C compared to NCM unless you are using A123 cells. NCM is also higher capacity. Overall I would get NCM if comparable in price.

Now for lipo. Just for the facts. I have nanotreh and am at 300 cycles. The battery is still good. But 2 out of the 8 sticks I had is gone. Had to remove them because I did not want the bad cells from those to destroy the good cell on the good pack. They sag like crazy now even at 2C even though they are rated at 25C-50C. I never abused them and go from 3.6-4.1V. Now I go to 4.15V just to get a bit extra out of them.

@etriker, I remember LFP promoting nanotech lipo because of the high power ability and low price at the time. Now however, they are pretty shitty. I recently got some new ones are they already have cell imbalance. I would stay away from them if possible. I also distinctly remember LFP stating the nanotech having around 250 cycled or so before they were useless to him.

He does promote stuff before testing it fully. But he did redact it later on in some post.

Again for all those people who love lipo. Sure go ahead and keep using it. But now NCM and LiFePO4 is comparable to lipo, I would go for for he safer chemestry. In the long run, running these battery instead of lipo is better for your pocketbook. The stories is all the same with lipo.
1) It is dangerous
2) expect to care for it. I.e. no abusing it
3) expect to run at most 80% or less capacity discharge unless you don't care about cycle count
4) expect to replace bad cells
5) If you are getting them from HobbyKing, expect to buy more than you need just to take into account the shortly quality assurance they have.
6) expect to read up on a lot of information on lipo just to get going with it.

That being said, lipo has its uses. If people are comfortable with it, I recommend they keep using it. Just know what they are getting themselves into. For me, I am migrating away from lipo. There are better lithium technology out there and cheaper too... In the long run.

 

[999zip999]

Best packs are made out the strongest cells A123's. A great balance. Still a little heavy as 24s20ah heavy. At 10ah to 12ah for a bike with these strong cells sould work out fine for a bike. Plug and play.

 

[etriker]

In my onion the future is NCM. I distinctly remember LFP stating this sometime. Though I don't agree with him all the time, I think he got a point on NCM. LiFEPO4 is old tech in terms of development. Not much improvements on it lately. Also it is heavier and has lower C compared to NCM unless you are using A123 cells. NCM is also higher capacity. Overall I would get NCM if comparable in price.

Now for lipo. Just for the facts. I have nanotreh and am at 300 cycles. The battery is still good. But 2 out of the 8 sticks I had is gone. Had to remove them because I did not want the bad cells from those to destroy the good cell on the good pack. They sag like crazy now even at 2C even though they are rated at 25C-50C. I never abused them and go from 3.6-4.1V. Now I go to 4.15V just to get a bit extra out of them.

@etriker, I remember LFP promoting nanotech lipo because of the high power ability and low price at the time. Now however, they are pretty shitty. I recently got some new ones are they already have cell imbalance. I would stay away from them if possible. I also distinctly remember LFP stating the nanotech having around 250 cycled or so before they were useless to him.

He does promote stuff before testing it fully. But he did redact it later on in some post.

Again for all those people who love lipo. Sure go ahead and keep using it. But now NCM and LiFePO4 is comparable to lipo, I would go for for he safer chemestry. In the long run, running these battery instead of lipo is better for your pocketbook. The stories is all the same with lipo.
1) It is dangerous
2) expect to care for it. I.e. no abusing it
3) expect to run at most 80% or less capacity discharge unless you don't care about cycle count
4) expect to replace bad cells
5) If you are getting them from HobbyKing, expect to buy more than you need just to take into account the shortly quality assurance they have.
6) expect to read up on a lot of information on lipo just to get going with it.

That being said, lipo has its uses. If people are comfortable with it, I recommend they keep using it. Just know what they are getting themselves into. For me, I am migrating away from lipo. There are better lithium technology out there and cheaper too... In the long run.

I would think.

Right now Zero motorcycles is letting the customers test out some of the new stuff ?

https://encrypted.google.com/#gs_rn=22&gs_ri=psy-ab&gs_mss=zero%20motorcycle%20battery%20&pq=famous&cp=30&gs_id=6l&xhr=t&q=zero+motorcycle+battery+recall&es_nrs=true&pf=p&sclient=psy-ab&oq=zero+motorcycle+battery+recall&gs_l=&pbx=1&bav=on.2,or.r_qf.&bvm=bv.49784469,d.eWU&fp=53c4f867b3a83ae3&biw=1015&bih=391

They seem to have a problem keeping them dry ?

They should test them in Florida. It rains almost every day lately.

 

[Tommy L]

Nice post, Tommy!

Thank you fellow HAM Op! VE7 TAC says.....very good! lol

I don't know everything, but there are basics or foundations that should be known.
Going in totally blind may not be the correct approach in the somewhat expensive hobby.

Thank you for the kind comment......Whiskey Bravo Niner Kilo

Tommy L sends....

 

[etriker]

Nice post, Tommy!

Thank you fellow HAM Op! VE7 TAC says.....very good! lol

I don't know everything, but there are basics or foundations that should be known.
Going in totally blind may not be the correct approach in the somewhat expensive hobby.

Thank you for the kind comment......Whiskey Bravo Niner Kilo

Tommy L sends....

Fuse size too. Don't forget that.

For example. I have an etrike with an A123m1 cell 11s 5p pack. 60amp controller that will do 60 amps for a short time at startup if I gas it all the way.

40 amp fuse is the smallest that will not blow so that is what I use.

Testing found this number for the fuse size for my size (165lbs).

I always use fuses to protect.

 

[wb9k]

Thank you fellow HAM Op! VE7 TAC says.....very good! lol

I don't know everything, but there are basics or foundations that should be known.
Going in totally blind may not be the correct approach in the somewhat expensive hobby.

Thank you for the kind comment......Whiskey Bravo Niner Kilo

Tommy L sends....

Fuse size too. Don't forget that.

For example. I have an etrike with an A123m1 cell 11s 5p pack. 60amp controller that will do 60 amps for a short time at startup if I gas it all the way.

40 amp fuse is the smallest that will not blow so that is what I use.

Testing found this number for the fuse size for my size (165lbs).

I always use fuses to protect.[/quote]

See now, that's the kind of content we need to see more of. When one of these systems fails, it's tempting to point to the cells, probably because they cost so much and are prone to becoming collateral damage. Too many guys can't tell cause from effect after things go awry, and it's not just on this board. This is a young industry, and everyone involved is learning on a constant basis, of this I am sure. But your points about pack impedances OUTSIDE the cells are critical and seem to be lost on many. The whole system has to work together, and you should try to size everything in a way that is very conscious of the intended application, and put multiple safeguards in place (like your carefully selected fuse) that will let you know when something goes wrong sooner rather than later. Cells (at least A123 cells) will chug right along for quite some time while being abused mildly. By the time a performace issue is noticed, it's often impossible to tell how long the problem's really been going unless you have pretty robust data collection over the life of the pack. How many guys here have that? My experience with literally thousands of "failed cells" suggests that the cells themselves are rarely the cause of the problem. Control, environmental, and pack design issues (cell abuse, basically) are all far more common problems than cell defects at this point in time. So I appreciate reading a perspective that reflects the reality I myself have experienced.

Rock on, and 73!

 

[spinningmagnets]

Thanks for responding, Paul. I know you are very busy and I appreciate you taking the time.

I will soon have the SDI 20R power cell which is 20A rated (10C plus),

Please PM me when you have beta packs available, I will gladly pay full retail for the opportunity to test them.

 

[migueralliart]

While those 20R cells are good for 10C they sag too much at that rate. 5C they're happy with all day long. I now have 2 packs full time running (one on my trike and one on my new commuter bike) the third one is bigger but I haven't got the time to finish it up yet.

There seems to be a capacity increase at 3C-5C due to the cell heating up. Another thing is that they're 2AH so just having 5P will get you 10AH but the capability to run 50amps all day (5C) and pushing 90-100amps is doable for a couple of seconds.

They are definitely my favorite cell. Been using them for a while and I like em. There is also an equivalent cell made by sanyo but I have not tested it.

I also have no clue about cycle life but to me anything is better than LIPO at the moment.

 

[wesnewell]

Oh man, i have to worry about the amps of the controller too? I thought I just needed to match the volts & watts to the motor hub!

Size of motor doesn't matter. Volts of motor doesn't matter either. It doesn't care what voltage it gets. The battery needs to be matched to the controller, For that you need to know the max amp draw of the controller. Put a 15A (not AH) rated battery pack on a 40A max rated controller and you will kill the battery pack in no time if you are heavy handed on the throttle. This is one of the reasons I don't like Lnmc or lifepo4. Most of them are 1-2C rated. C rate is the amps you can draw from the battery. C rate times AH give max rated amps.

 

[wb9k]

C rate is the amps you can draw from the battery. C rate times AH give max rated amps.

No, absolutely not. C-rate is a fundamental characteristic of any battery. The definition you give here of C rate is simply not correct. By extension, the second sentence is also incorrect. Try looking up C rate somewhere authoritative like BatteryUniversity.com. You'll see that C rate is the amount of constant current required to drain a cell from 100% to 0% SOC in exactly one hour. Cells are generally rated in relation to that C-rate. Let's say a cell can deliver 2.3 Amps in one hour to go from 100 to 0% SOC. That is a 2.3 Ah cell. If it can deliver a max of 4.6 Amps continuously, the constant current rating of the cell corresponds to a rate of 2C for that cell. If it delivers a maximum of 1.15 Amps continuously, the cell is only good for 0.5C. Max current can be more or less than the actual C rate. A max current rating of 0.5C means a cell cannot be fully discharged from 100% in less than 2 hours, even though the C-rate is a number for a one-hour discharge.

Making sense?

 

[major]

C is charge. Charge units are Coulombs or more commonly for us Ampere hours (Ah). One Ah = 3600 Coulombs. A Coulomb is the amount of charge delivered by one Ampere in one second. Or one Ampere is one Coulomb per second. So current is charge divided by time or the rate of charge.

So if the cell’s charge is C, then the rate of C is current, or C-rate is current. It is used in describing cells to normalize current between different size cells or cells of differing capacities. The C-rate is simply the current through the cell stated in terms of its rated capacity.

Since the capacity of the cell (C) is given in Ah, the current (or C-rate) is just charge (C) divided by the time (h). So both a 2Ah cell and a 20Ah cell can be rated at 3C. That would be 6A for the 2Ah cell and 60A for the 20Ah cell. Even though the absolute current values differ (6A and 60A), the C-rate is the same for both cells (3C), hence normalized. Both cells discharge completely from full in 1/3 hours at 3C.

 

[melodious]

Back to LiFEPO4 vs. NCM. I hit you take in added space you suffer for choosing NCM is negligable in the total scheme of things in personal transport. The electric magic that suddenly disappears with the latter chemistry's discharge curve is what really bugs me in the end. As a personal matter of taste, I like the small incremental increase of sag you get with NCM I can live with, as I don't need to be coddled. I have two legs. I'm not young, but I'm not exactly an old geezer either d-('_')z I'll just give more effort :wink:

We're still talking electric bikes right? :|

 

[torqueon]

I read somewhere that NCM batteries will self balance in a series pack ?? Is that true.

 

[migueralliart]

I believe those are the konion cells. LiMn ? I'm not sure thou.

 

[SamTexas]

Please guys, stop perpetuating old wive tales. No lithium battery self balance. NONE, not even the Konion. Doctorbass has been spreading this bullshit long enough. Let's stop it.

 

[999zip999]

I don't think konion's have a magic number that they self balance at. After 530 cells.

 

[liveforphysics]

I what ways are they safer or more stable? And why would GM use A123 cells for the Spark if the Volt's cells are superior? I heard a different story about why A123 wasn't in the Volt, and while I can't say for sure if it's true, it's very plausible in the context visible from my perspective.

LFP has been putting out misinformation about batteries ever since I have been reading this forum.

He is for sure the worst guru on our forum.

He bragged up using hk lipo for a long time and when I was a newbee I bought some.

Worst batteries I ever bought and wasted money.

I should have never read any of his posts.

He is bad for the ebike movement. A total joker that does not help people understand but confuses people.

Somebody linked me to this thread for the LOL value, which is fantastic, thank you.

RC LiPo isn't for n00bs, morons, or people who aren't willing to keep the battery in a safe place for it to burn etc (this seemed to be something made painfully clear by this entire forum and the various painful experiences etc). It's for people looking to make the highest performance EV's at the cost of most every non-performance attribute a battery can have. There is a place for that, kinda like using Nitro-methane for fuel, there is no match for it if your goal is to haul-ass, but just because you see top-fuel dragster pro's using and delivering the results they want back doesn't mean you're going to have much luck just filling your family sedan's tank with it and hoping for the best.

It would nice if before you could click "add to cart" you had to pass some IQ test minimum.

For a commuter pack, it's not the chemistry that plays the big role in how it will perform over time. It's cells that are made right from quality materials, QC processes that filter out the duds/hazards, and finally a pack design and architecture and management to keep the cells happy over time. Look at the Tesla Roadster, Lithium Cobalt cells (same chemistry in RC LiPo), I've never heard of one burning, and the packs have been lasting a long time. Look at the Fiskar Karma, many fires, and A123 LiFePO4 cells. It's because they obviously didn't do some things right, I've got no doubt a safe pack can be made with either.

NMC/NCM (same thing) is currently about the top of the pile as something to base building a safe cell around and still have good energy density. This means you can still make a super crappy NCM cell if you like, because as mentioned above, the chemistry choice is a pretty small piece of the big picture on a cells safety and performance. NCA makes a better cathode material in most attributes than NCM, and as the material tech and processes are better refined you will see it replacing many other chemistry choices soon.

The fundamental issue with a thread like this (not that I don't like this thread, I got many good belly-laughs from it), is comparing chemistry to chemistry is pointless and misses the big picture.

What cell makes a pack that suits your needs is the real question to ask. Do you need to draw 200A from a high voltage tiny pack that weighs just a few lbs? Better start looking at RC LiPo if those are your needs. If you want to pull 30A from a 25lbs low voltage battery, but have it last thousands of cycles, now RC LiPo seems like an absurd choice to make.

Different horses for different courses. Seems weird you even have to say it.

 

[wb9k]

LFP, I agree with most of your post, but have say something about this tidbit:

"Look at the Fiskar (sic) Karma, many fires, and A123 LiFePO4 cells. It's because they obviously didn't do some things right..."

Not one of the Fisker fires was cause by the HV battery. All of them were in the 12V system, either in the overheating ICE cooling fans or the steering column electronics setting the magnesium on fire in the Superstorm Sandy event. Every one of those cars was examined by our guys and none of those batteries ever burned. Period. The Texas and California fire packs were still charged and fully functional when removed from those cars.

It seems to me you should know better....

 

[johnrobholmes]

This is it here. If I'm going cheap and proto, hobby city packs. My 20mph commuter gets a ping cause its easy and reliable enough. My offroad 45lb machine will get lipo, my daily use scooter will get eig cells for a long term pack. Pay now, pay later, there is no spoon.

 

[wb9k]

C is charge. Charge units are Coulombs or more commonly for us Ampere hours (Ah). One Ah = 3600 Coulombs. A Coulomb is the amount of charge delivered by one Ampere in one second. Or one Ampere is one Coulomb per second. So current is charge divided by time or the rate of charge.

So if the cell’s charge is C, then the rate of C is current, or C-rate is current. It is used in describing cells to normalize current between different size cells or cells of differing capacities. The C-rate is simply the current through the cell stated in terms of its rated capacity.

Since the capacity of the cell (C) is given in Ah, the current (or C-rate) is just charge (C) divided by the time (h). So both a 2Ah cell and a 20Ah cell can be rated at 3C. That would be 6A for the 2Ah cell and 60A for the 20Ah cell. Even though the absolute current values differ (6A and 60A), the C-rate is the same for both cells (3C), hence normalized. Both cells discharge completely from full in 1/3 hours at 3C.

I like yours better than mine.