New 14s battery pack, US18650VTC6 vs NCR18650GA

docware said:
Your choice LG M36 seems to be for such case better option than Panasonic PF.
Click to expand...
Fantastic chart.

Anyone know the respective LI chemistries used?

It seems to me, the only practical differences are:

1. slightly higher voltage for each point of SoC, and

2. slightly higher capacity, assuming a 3.2V cutoff at that 1C discharge rate

As flippy keeps pointing out, acquisition cost is a non-trivial factor for most

while I would consider those two data points to be pretty unimportant.

What trusted sources would you all recommend for these two cells, for delivery to the US?

And any ideas about relative longevity? especially at under 1C rate discharge usage. . .

That to me is really the **only** factor that justifies a higher price.
 
.......
Re: LG M36 vs Samsung 36G capacity test - 3600mAh or just marketing?
by Pajda » Feb 12 2019 9:19pm

"Already finished with M36 samples from Nkon my standard 0.5C-1C 100% DoD 1000 cycle life test. In this particular test M36 performs exatly the same as MJ1. In another tests with low loads up to 0.5C charge and 1C discharge with lower DoD, the results are also almost identical. But the significant difference begins at higher loads. MJ1 performs relatively well even at 1C continuous charge rate where M36 quickly losses the capacity. Also at 3C continuous discharge test, the MJ1 hold its capacity unexpectedly well (MJ1 performs 400 cycles at 100% DoD at 3C continuous discharge - but unfortunately this is useless for battery pack use, because it is going hot as hell during 3C discharge). M36 barely make a half of this.

So M36 probably uses newer chemistry with lower manganese and cobalt than MJ1 and so it is cheaper. The drawback is that it has lost some of its robustness but still it has very good parameters for traction applications. M36 seems to be the cell with the best price performance ratio for highend e-bikes and maybe also it is the last in 18650 format because the 21700 format is coming up very quickly."


https://endless-sphere.com/forums/viewtopic.php?f=14&t=96360&p=1445173#p1445173
 
john61ct said:
docware said:
Your choice LG M36 seems to be for such case better option than Panasonic PF.
Click to expand...
Fantastic chart.
Anyone know the respective LI chemistries used?
It seems to me, the only practical differences are:
1. slightly higher voltage for each point of SoC, and
2. slightly higher capacity, assuming a 3.2V cutoff at that 1C discharge rate
As flippy keeps pointing out, acquisition cost is a non-trivial factor for most
while I would consider those two data points to be pretty unimportant.
What trusted sources would you all recommend for these two cells, for delivery to the US?
And any ideas about relative longevity? especially at under 1C rate discharge usage. . .
That to me is really the **only** factor that justifies a higher price.
Click to expand...
chemistries are irrelevant, only the actual stats that matter are relevant, once you choose the cel with the proper current, capacity, lifecycle and pricing specifications you will automagically end up with the chemistry you need for your application.

and yes, in this case apperances are quite decieving as the lifespan of this higher capacity cell is shorter and if you consider higher drains the M36 will turn into a heating element instead of a battery.
once you push into the 5A ranges and more and add a temperature gauge the picture will change considerably in favour of the PF if you factor in lifespan.
 
Chemistry is everything, but I agree monolithic categories are not to be relied upon more than evidence from IRL testing.

Especially with longevity, so rarely tested, and I do not rely on the vendor claims from their lab testing using conditions not relevant to my use cases.

So for now, we need to rely on informal reco's like yours, in favour of the PF.


What trusted sources would you all recommend for these two cells, for delivery to the US?
And any ideas about relative longevity? especially at **under 1C** rate discharge usage. . .
That to me is really the **only** factor that justifies a higher price.
Click to expand...
 
john61ct said:
Especially with longevity, so rarely tested, and I do not rely on the vendor claims from their lab testing using conditions not relevant to my use cases.
So for now, we need to rely on informal reco's like yours, in favour of the PF.
Click to expand...
companies will never give out lifecycle testing outside of lab results even if they know it -and they do-.
that is exactly why chemistries need to be ignored as lifcycle is not dependant on chemistry but actual use.
 
john61ct said:
Especially with longevity, so rarely tested, and I do not rely on the vendor claims from their lab testing using conditions not relevant to my use cases.
So for now, we need to rely on informal reco's like yours, in favour of the PF.
Click to expand...
companies will never give out lifecycle testing outside of lab results even if they know it -and they do-.
that is exactly why chemistries need to be ignored as lifcycle is not dependant on chemistry but actual use plenty of chenistries preform well in the beginning but capacity tanks simply due to the chemistry breaking down after 2~3 years and then get overtaken by a more robust cell like the 25R, PF or 29E.
 
Jan-Erik-86 said:
So, only questions remaining, with an average load of 12-14A and short peek loads of ~50A:
1) Will the LG M29, Samsung 29E (E6 that would be, nkon don't have enough E7 in stock), or Panasonic PF perform more or less identical, or does one stand out as a better option (ignore the price)?
2) Will a M29/29E/PF cell have significantly increased IR after some years? Do i, in a few years, risk hitting LVC if i have ~30% left and hit the throttle?
3) What's the capacity loss of a M29/29E/PF cell after ~500 and ~1000 cycles?
Click to expand...

I must say that this is one of the best formulated technical question. Hope that someone will reply you with relevant informations :wink:
 
flippy said:
docware said:
"anything higher capacity will die off quicker" ..... that is only flippy ´s opinion, as he prefers 29E above all. Read again Pajda´s reports. He has biggest collection of really tested cells, bigger than anybody else here.
Click to expand...

sorry, but its not a opinion, its a measured fact. anyone that has done lifecycle testing or can read a datasheet can verify this.
and by comparison: a 2500mAh will generally outlive a 2900mAh. but the price per Wh is worse so 2900 is the sweet spot right now. when that changes i will change my recommendation.
Click to expand...

In my beggining with battery testing I was looking for simple "rules of thumb" to predict what influence have cell capacity, chemistry, internal design (HE vs HP) or manufacturer on cycle life and DCIR rise. But after years of testing and almost hundred of different cell types I am saying that there is no reliable dependence :? There are to many exlusions so I am now using a rule which in Czech means "I don't believe in data I haven't falsified myself". This means tons of standardized test for each cell (yes, my tests are laboratory based, but for full rating each type of cell is now passing more than 10 standardized test under different conditions). It of course takes tons of time, mostly because I do not have hundreds of test channels. Big issue is also that you must detect fakes and also original cells over the years are going through the development.
 
flippy said:
..this is partially also the reason why tesla still uses a 3350mAh cell in the model S instead of 3500+mAh.
it would give a tesla 10kWh extra storage but it would absolutely murder the lifespan of the battery.
Click to expand...

First I must say, that I have not already tested cells from "100"kWh Tesla battery pack. But my opinion is that 3350 mAh is the maximum rated capacity already produced by Panasonic/Sanyo for 18650 cells with decent DCIR. I'd bet a penny that "100" kWh pack cells are using Sanyo GA chemistry which is rated at the same 3350 mAh. (as the "85" battery cells using BE and BM cells) So they are actually using the highest available(from Panasonc/Sanyo production) energy density cells.

And even if Tesla will use cells with rated "3500" capacity then still it will be only gain of 0.4 Wh per cell which means 3.3 kWh gain at best.
 
flippy said:
so far i have detailed data about the 29E(6 and 7), PF, GA, BD, 35E, 25R, MH1 and probably a couple i forgot. and ofcouse a crapload of chinese junk.

and my tests are realistic or done on cells that have been in use for years of daily cycles so that is actual usable data and it does give a better idea on what to expect in terms of realistic lifespan. no pink glasses data.

next week i am planning on taking a couple new GA's, PF and 29E's and stuff them in a test mount and dunk them in a fridge set to slighty above freezing and run them hard and see how they cope.
Click to expand...

flippy I think that I finaly find the reason why you are to sceptical about HE cells. All above mentioned cells (I have tested them all) does not have excellent cycle life by my standards. My evaluation is good at best (MH1 and 29E are very close to excellent under partcular conditions). If I can give you an advice order from Nkon samples of LG M36 (excellent/ballbusting up to 1C continuous discharge) and particularly M29(excellent) and run the same cycle life test as with 29E. I have understand that you prefer cells with excellent price/performance ratio and then it makes perfect sense that you are looking into "2900" capacity range. I will looking forward to your evaluation of LG M29.
 
999zip999 said:
Pajda what is your favorite cell 18650 high discharge long life ?
Click to expand...

It depends on many factors and applications so there is no clear favorite, but on the other hand, you can't choose completely wrong. If we are talking about 18650 size, "3000 mAh" capacity then we have LG HG2, Samsung 30Q and Sony VTC6. If you are looking for extra long life (>500 full cycles) then HG2 is the leader, but you will pay with the significant capacity drop and slightly higher DCIR from the beginning, so in first ca 300 cycles the 30Q and VTC6 are better, but after passing this border both are outperformed by HG2 in all mentioned parameters.

It should be noted:
- 300 full cycles is "a lot" for many applications
- cycling at 50% DoD average makes almost all cells on the market practically immortal.
- many HE cells significantly outperforms those HP cells even at 100% DoD in cycle life when they are used properly (HG2 is an exception :wink: )
 
Good news for Jan-Erik-86 : also first data from cycling LG M36 and Panasonic PF are more favourable for M36. Cycling parameters are similar to the real conditions : charge 1 A to 4,1 V, discharge 2,5 A to 3,3 V (PF) or 3,4 V (M36), ambient temperature 25 ± 2°C.


Panasonic PF cycling.jpg


LG M36 cycling.jpg
 
docware said:
Good news for Jan-Erik-86 : also first data from cycling LG M36 and Panasonic PF are more favourable for M36. Cycling parameters are similar to the real conditions : charge 1 A to 4,1 V, discharge 2,5 A to 3,3 V (PF) or 3,4 V (M36), ambient temperature 25 ± 2°C.
Click to expand...

That is what I am talking about... :thumb: This is exactly why the cycle life tests should look like. For the full information there is missing only rated capacity test each 50 cycles (in most cases 0.5C charge - 0.2C discharge at 100% DoD).

I never figured out why Panasonic PF is considered in many forums as an extraordinary cell. :?
 
Pajda said:
That is what I am talking about... :thumb: This is exactly why the cycle life tests should look like. For the full information there is missing only rated capacity test each 50 cycles (in most cases 0.5C charge - 0.2C discharge at 100% DoD).

I never figured out why Panasonic PF is considered in many forums as an extraordinary cell. :?
Click to expand...

Originally the standard capacity test was planned each 50 cycles. But because it means 100 % DOD, I finally decided to not affect course of the „normal“ cycling.
I am now learning that LG cells seems to be really good, as Pajda was always declaring. :)
 
From my point of view the most expensive are always the measured data in quality which posted docware in this topic. So you can decide if the price of the cell worth its real parameters. To do such measurement costs a lots of effort (=money) where the most expensive item is not the equipment but to train the skills of person which performs measurement to "expert" level. In this particular case it is not about the battery chemistry knowledge, but about the knowing measuring principles, dealing with errors, data processing and so one. In other words, the "expert" should recognize that he sometimes measured a nonsense - I know it myself. :wink:
 
john61ct said:
Are they comparable in price?
Click to expand...

Well, before answer this question we should remind that cells constitute only part of the whole battery price.

M36 and MJ1 price is 20 % higher than PF. But also have 20% higher capacity. Having 20 % higher capacity and better lifetime at the same battery pack size and weight is for ebike especially important, isn´t it ?

QueenBattery is offering even slightly better price for M36 and MJ1 than for PF.

However, clinging to the cell lowest price seems to be rather shortsighed to me, when consider ebike battery. I would prefer capacity and lifetime instead.
 
It is just one factor, but most do need to take it into account. For me, energy density is important, as is Ah per cell, high as possible, really would prefer 6+Ah

discharge rate over 0.5C is irrelevant, but

longevity - ideally 1000+ cycles - is critical.

I do not think nkon is relevant for the US market.
 
Some people chasing the price factor use old laptop cells. Then spend significant amount of time and money trying to keep such battery pack alive.

I agree that longevity is critical, therefore I will not consider cells like PF.
 
Thank you very much for the update on this thread guys! :)

It seems the M36 was indeed a much better choice then the PF. Not only does the capacity loss more or less stall after ~50 cycles on the M36 (at least in coimparison with the PF), but also the DCIR increase appears to have stalled after ~150 cycles on the M36 while it keeps on increasing on the PF.

So far I'm very happy with my M36 pack. I've insulated the battery box, and keep room temp at no less then 15c while i have it parked and charging. The last couple of days it's been around -2c here, but there have been no issues with battery performance for the ~35 minute commute.
 
Good to hear you are satisfied with your choice. Keeping cells at high enough temperature during operating period (charge, discharge) should be your highest priority now.
 
Unfortunately, I have realized that IEC DCIR data can be also interesting a little be late, started from cycle No 100. Have no initial data.
 
Simultaneously with LG M36 and Panasonic PF, also Sanyo GA and Samsung 29E are cycled, 29E started later than others. My favourite GA doesn´t do very well. :(
Willy-nilly, I am confirming Pajda´s conclusions more and more.

There is interesting course of 29E DCIR having at 150 cycles slightly lower value than at 100 and also higher capacity between the given interval 4,1 – 3,3 V is interesting, however there is probably too early to make any conclusion.


Sanyo GA cycling.jpg

Samsung 29E.jpg
 
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