Panasonic vs Samsung cell pack

[thegrizz]

2600mAh Samsung cells
or
2200mAh Panasonic

with the pack dimensions I'll have 11Ah on the Panasonic and 10.5Ah on the Samsung

I'm asking because the cost per cell on Panasonic are considerably more expensive. I've heard about the "QC" aspect but as far as I can tell Samsung cells seem to be holding up just fine.

Thoughts? Something I missed?

 

[thegrizz]

***
the reduction in Ah in the denser Samsung cells is due to them being highly recommended to be placed in "heat dissipating" material....

 

[neptronix]

What cells are we comparing? samsung and panasonic make all sorts of various cells.

You also need to consider the amp load. Most of these cells are for laptops, so they'll only put out 1C, if that. Are you gonna run a 10-11 amp controller?

 

[thegrizz]

The controller was packaged with a Bafang 500W motor. No marking other than 15mosfet 48V 500W motor controller.

Both cells are 18650 rated at 1C discharge
The cell model listed for Samsung is 18650 26C

I don't have a specific model on the Panasonic until I receive a reply from seller.

 

[dnmun]

the small cells end up weighing a lot and producing little power for the weight. also the multiple connections are liable to failure, and the number of connections increases the probability of failure. best to go with something like a ping pack which is already assembled if you are new to the game. jmho.

 

[Kin]

Ok, so the samsung and panasonic cells are both 18650, and somehow your estimates give you 10.5ah for the 2600mah batteries, and 11ah for the 2200mah batteries...Something is quite funky.

But that is besides the point. My opinion would be similar to those here that laptop cells are designed for quite low C rate and although I hope to oneday use them, the suitable application scenarios are very limited. For 10ah pack you should only be running them 185watts, maybe 370watts burst, but quite seriously not above 1C from the experiences of everyone who talked while I was asking about laptop cells earlier in the year. (A 500watt controller would be running them at 1.35C and also quite possibly above that, since many of those controllers burst a bunch above 500 watts).

 

[chilledoutuk]

Decent 18650 cells perform fine at 2c they sag a little but other than that they perform well and are very reliable.

I have built a few packs out of 18650 cells recently i used some 2400mah sanyo cells rescued from laptop packs.

Originally i ran them in 10s 3p config on my 9c 6x10 they sagged a bit but they didn't get hot or anything now i am running them in 4p and they sag very little.

The sanyo cells hold about 3.5v plus per a cell under a 5a load after being discharged at that until they are flat they get a little hot but in use on the ebike they barely ever get warm.

I solder screw terminals on the ends of my cells so that i can reconfigure packs easily in the future if any cells get any problems without having to de-solder and re-solder cells.

 

[migueralliart]

I've built 2-3 packs for my ebikes made exclusively from samsung 2.6Ah cells and found the following.

THEY sag if you load them improperly
Don't do 1.5C or more. Try building a pack with the same capacity as .66 the current rating of your controller. ie if your controller draws 20 amps make sure you have at least 13.3 AH + of capacity or more. The more the BETTER. I run my ebike mostly on flats so I carry 2 36V 15.6 AH Packs in parallel total of 31.2Ah. I've discharged 40 amps from this pack but I don't do often because I tend to love range so I ride mostly @ 22mph.

THEY tend to stay balanced

THEY heat up way faster if discharged past that 1.5C or trying

Don't try to fast charge them, I charge them at 8 amps each pack with ichargers and meanwell supplies. It takes a couple of hours but I've read that if you charge at a lower rate you prolong the cell life so it is good practice.


As a side note I really like these packs for commuters because the cells are good to work with and also offer good cycle life. The problem lies with the discharge rate and price. In my case I bought from a seller hundreds of these paired cells and found that aprox 7 out of 10 were in really good condition. If you cruise a lot at a low discharge rate (15 amp/hrs or less) note that I said CRUISE. Then these cells are really good.


Edit: I forgot to mention that the weight of these packs as built is 6.5 lbs each so with less than 14 lbs give it or take I have 31.2 AH at 36V now even if I use only 70% of that capacity the weight is good. My next project will be a kMX trike for long distance commuting, I would probably build two more of these packs so that I can have 62.4Ah and install it on a custom ABS box behind the seat. A good efficient motor to propel me @ 22mph will suffice and range should be amazing.

Just my 2 cents

 

[thegrizz]

Originally i ran them in 10s 3p config on my 9c 6x10 they sagged a bit but they didn't get hot or anything now i am running them in 4p and they sag very little.

Has there been an increase in dead cells since bumping to 4p?
It sounds like they are getting hotter.

I agree -

(A 500watt controller would be running them at 1.35C and also quite possibly above that, since many of those controllers burst a bunch above 500 watts).

I haven't found out a specific Panasonic model yet but I was seeking a more experienced opinion as far as convincing myself if the price increase in what seems like a similar 18650 cell is truly a better performing cell.

Though Ping is in no means over priced, I wanted to take a shot at a cheaper angle and see how they perform, charge, etc.

 

[SamTexas]

18650 LiCo: Samsung 2.6Ah vs Panasonic 2.6Ah: Panasonic is a better choice (cooler discharge temp, less sag).

Is 18650 LiCo (laptop cells) a good choice for ebikes?
Definitely NOT: If you plan to completely discharge the battery is less than 60 minutes.
Good choice: If you plan to completely discharge the battery in 60 to 90 minutes.
The BEST choice, bar none: 120 minutes or more. You would have the smallest (volume) and lightest battery pack.

Discharge rates:
4C burst: 15 secs max. i.e. quick start from stop.
2C burst: 60 secs max. i.e. Climbing a steep hill at high speed
1C continous: Indefinitely, but the cell will get warm, about 15 to 20F above ambient.
0.5C forever: cell remains cool, about 5 to 10F above ambient.

Sag:
About 10% sag at 1C discharge.
15% at 2C
25% at 4C

 

[chilledoutuk]

Technically why would you want to specify how quickly you want to discharge your battery pack?

what is important is how much power it can put out at a certain weight and volume.

if you were to build a battery pack say the same size and weight as a 36v 10ah ping you could build a 10s 7p 18650 pack.

If did this using sanyo cells that i have tested to be capable of discharging at 5amps to 2.3ah then i would have a 16.1AH pack capable of 35amps current output.

I have a source for these cells that works out at ₤1.66 per a cell which means that pack would cost me about ₤116 to build.

A 10AH ping would cost me £278.88 delivered so to me personally its definitively a no brainier but if you just want a plug and play solution then pings battery's are great just too heavy for my liking.

 

[SamTexas]

i would have a 16.1AH pack capable of 35amps current output.

That's 2.17C on 18650 LiCo cells! How long (time) do you run "your battery" at that rate?

 

[chilledoutuk]

Erm until its empty or 3.0v lvc from full i have tested my cells at that rate.

In fact on one of my sanyo cells i was trying to reduce its capacity so that i could use it with a couple of other cells that had a lower capacity i cycled it 50 times with a 5A discharge to 3.0v per cell and only managed to reduce its capacity by about 40mah.

The only lipo cells i have ever seen as durable as these 18650 japanese cells are the Korean made ones generally.

 

[SamTexas]

Erm until its empty or 3.0v lvc from full i have tested my cells at that rate.

How many minutes did it take before hitting 3.0V lvc from full? What is the cell temperature at the end of the test? What is the ambient temperature?

 

[neptronix]

Read the spec sheets, assume the C rate is greatly exaggerated, and the path will become clear

The 1-2C laptop cells are really great for building a super long range pack. The high end stuff ( like panasonic 3400mAH 18650's for example ) will approach or exceed the 200wHr/KG mark, which is great.

For short range, you will want to forget them entirely unless you have a super putzy setup.

No lithium battery cell runs good at or near it's maximum C rating, just look at some spec sheets and that will be obvious. Battery cycle life is often calculated at 1C or lower. The maximum C rate is basically what it can tolerate without blowing up, but will perform like crap at!

If you're drooling over a super light 1C cell, you need to run it at 0.5C or less in reality. So if your controller has a maximum draw of 30A, you want a 60AH pack at the absolute minimum.


Other end of the spectrum is the RC Lipo stuff. The lowest it generally gets is 15-20C. 5AH x 20C = 100A, so even a little 5AH brick can put out 50A fairly well. Nobody worries about intentionally oversizing their batteries with RC Lipo.

But the chemistries with the highest wHr/KG have really weak output.. so if you're going to go with laptop 1C ( or less ) 18650's.. i really hope you are going for an ultra range pack.

 

[chilledoutuk]

Here are a couple of pics of the results of my discharge tests of my 18650 cells. I don't have a temperature gauge anymore but suspect the cells are about 50 celcius after discharge as they feel similar temp to my RC motors when i used to use an infrared temp gauge.

 

[SamTexas]

Thanks for the data (pictures).

FWIW here's my experience at 2C continuous discharge until 2.50V from 4.20V:
Ambient temp = cell temp at beginning of test = 77F (25C)
Cell temp at end of test (22 mins later) = 160F (71C, too hot for me to hold more than 5 sec).
And that was one single cell in the open so it had plenty of surrounding air for cooling. In actual use cells would be grouped together and stuffed into certain enclosure. At continuous 2C discharge, reaching or exceeding 212F (100C) would not surprise me at all.

 

[chilledoutuk]

It probably does vary greatly depending on the actual cells you have.

When i was researching 18650 cells it was generally considered that the sanyo 2600 cells were the best at high current output whilst still having good capacity.

I have some sony 18650 cells and at 5A they were comparatively hotter than the sanyo cell.

The sanyo cells are definitively not to hot to handle after being discharged to 3.0v maybe the higher lvc helps with the cell temperature.

I do notice with the sanyo cells that i have that the cells only get hot towards the end of the discharge and at midway are only slightly warm.

In my experience if the cells are ventilated somewhat they do have good the ability to dissipate heat.

Being in texas i am sure keeping the cells cooler would be considerably more difficult than it is in the UK during use but not impossible.
The cell temperature could be managed quite well using a temperature controlled fan.

There is however an upside to the the cells getting warm during use is thats when its so cold that other batterys will start loosing performance during a ride whereas these will more easily keep themselves warm and perform as expected.

 

[SamTexas]

When i was researching 18650 cells it was generally considered that the sanyo 2600 cells were the best at high current output whilst still having good capacity.

Not from my personal experience. I have hundreds of Sanyo red cells as well as Panasonic pink cells. The Sanyo cell are good, but the Panasonic cells are better.

 

[migueralliart]

What I did to determine the LVC of these cells was to obtain first the current my setup was drawing while CRUISING. Again this is the best use for these cells. Then I built a brick of 6P 2.6Ah samsungs that were matched for IR and capacity. Joined them and did a discharge test with my icharger @ that amp. I wanted to be before the "cliff" so I have my LVC at 3.4V. Even if you discharge these cells at .5C you will notice there is no benefit of running them lower than more or less 3.5V.

Again I get GREAT range from the packs I built and a good cruising speed. I tend to pedal each and every start to help the pack. I'm sure it can do 30+ amps but I want it to last longer.

 

[Kin]

Something to point out is that even "sanyo" or "sony" or "panasonic" doesn't necessarily say too much about the cell. There are panasonics designed for 0.5C max and there are panasonics (substantially lower mAh) designed for 5C theoretically.


I like seeing all these responses here. Encourages me to think maybe my plan to put together a pack sometime is more reasonable than I think.

 

[parabellum]

I wanted to be before the "cliff" so I have my LVC at 3.4V.

In case of those low C-rate (high IR) cells LVC can be set to 3.00V since sag will be severe and after loaded condition LVC they will jump up to somewhere 3.6V. Now, for high C rate LiPo 3.4-3.6V LVC in bulk is mandatory.

 

[SamTexas]

There are panasonics designed for 0.5C max

No such thing. All Panasonic 18650 LiCo can handle 2C max. Panasonic always provide a datasheet with discharge graph at 2C. What they don't provide is a temperature chart at that rate.

there are panasonics (substantially lower mAh) designed for 5C theoretically.

No such thing either. We're talking about 18650 LiCo cells specifically designed for use in laptops.

 

[migueralliart]

I wanted to be before the "cliff" so I have my LVC at 3.4V.

In case of those low C-rate (high IR) cells LVC can be set to 3.00V since sag will be severe and after loaded condition LVC they will jump up to somewhere 3.6V. Now, for high C rate LiPo 3.4-3.6V LVC in bulk is mandatory.

At cruising speed and low amps being pulled from the controller I rather have LVC at 3.4V than 3.0V if I want to prolong cycle life. IF you see a discharge graph at CRUISING speed like I do you will notice there is so little left in the pack after that 3.4-3.5V level at a low discharge.

 

[SamTexas]

In case of those low C-rate (high IR) cells LVC can be set to 3.00V since sag will be severe and after loaded condition LVC they will jump up to somewhere 3.6V.

Agreed. Actually some Panasonic cells can be run down to 2.5V under load. However, there isn't much juice left below 3.0V under load. So it's just an academic question whether the LVC is set 2.5, 3.0, 3.2 or 3.3. The difference is probably less than 5%.