Could LiPo laptop batteries and the shift to mobile devices spell doom for the 18650?

[StorminMatt]

Whenever the question is asked as to why the capacity of a 26650 is relatively small compared to an 18650, the answer is so often that, due to its use in laptops, the 18650 receives the most R&D. Whether or not this is really true or whether there are other constraints on the 26650 (such as safety) is unknown. However, this does bring something up. My brother recently got a new laptop. And gone was the traditional 18650 based battery pack. In its place was a slim LiPo pack, similar to a phone or tablet. It seems like MANY laptops are ditching battery packs based on round cells in favor of LiPos, which allow for a slimmer laptop. And, even those laptops that stick with 18650-based battery packs are selling less as people make the shift from using laptops to using tablets and smartphones (which also use LiPo batteries). Could this mean that, if development of 18650s really IS driven by laptop use, this could be coming to an end?

 

[Mr Floppy]

Maybe it'll be saved by the eCig industry.

I've taken apart quite a lot of battery packs but I don't think I've seen one of the higher (3000mAh+) capacity cells being used in any of them. Something is driving the production of those cells but whether it is the laptop industry, I don't know either.

I think hybrid cars are starting to use 18650 cells now too.

 

[mojo-chan]

Doesn't Tesla use 18650 cells for it's Model S? They are building a massive new factory with Panasonic (Sanyo) to produce them, which should also drive down prices.

 

[PCC]

Aren't 18650s nothing more than LiPo batteries that are rolled into cylindrical form with a different chemistry? I know that's an oversimplification, but, that's pretty much what I've seen.

 

[bshanahan14rulz]

PCC: more or less. the can is to hold the juices. In LiPo, the "juices" are replaced with a layer of special polymer.

Tesla use 18650.

Factory for manufacturing batteries may be state-side, and wouldn't be surprised to see that factory receiving hugeantic shipments of cells from panasonic.

18650 is also very common in lithium power tools.

I don't know what the market is for the panasonic 3400mAh cells is...

 

[degarb]

I don't know what the market is for the panasonic 3400mAh cells is...

Based on the money I have been putting into them, I guess I deluded myself that I was the one driving R&D of them.

 

[Mr Floppy]

Tesla use 18650.

So does the Prius hybrid, and I think there are many more of them being sold than Teslas

Based on the money I have been putting into them, I guess I deluded myself that I was the one driving R&D of them.

:laughing:

 

[idleprocess]

The 18650 doesn't seem to be going anywhere. It's my understanding that the 18650 is a standard platform of sorts in the battery industry since everyone uses them. As such, it has the lowest cost per watt-hour, the broadest selection of chemistries, and everyone sells the latest chemistry in the format.

 

[Colonel Sanders]

Keepower 3600mAh 18650 V=18694mm3 E=10272Wh@5a=.549
EnerPower 4500 mAh 26650 V=37726mm3 E=15725Wh@5a=.417

The 18650 has 31.65% higher energy density by volume than the 26650 when under a 5a load. Perhaps not as big of a difference as one might expect from looking solely at the capacity of the cells. The 26650 can deliver 53% more energy at a 5a load than the 18650 despite having an advertised capacity only 25% higher than the 18650.

The advantages that 26650s offer are usually underestimated, IMO.

 

[degarb]

The 18650 has 31.65% higher energy density by volume than the 26650 when under a 5a load.

The advantages that 26650s offer are usually underestimated, IMO.

Well, the 26650 is, what, twice the weight of an 18650? So, wouldn't you assume two 18650s would go up against one 26650? Then, where are we at?

 

[HighlanderNorth]

Based on the money I have been putting into them, I guess I deluded myself that I was the one driving R&D of them.

How many have you bought?

 

[StorminMatt]

Keepower 3600mAh 18650 V=18694mm3 E=10272Wh@5a=.549
EnerPower 4500 mAh 26650 V=37726mm3 E=15725Wh@5a=.417

The 18650 has 31.65% higher energy density by volume than the 26650 when under a 5a load. Perhaps not as big of a difference as one might expect from looking solely at the capacity of the cells. The 26650 can deliver 53% more energy at a 5a load than the 18650 despite having an advertised capacity only 25% higher than the 18650.

The advantages that 26650s offer are usually underestimated, IMO.

The advantages of a 26650 are definitely underestimated. You hear it all the time about how 26650s are worthless and obsolete because we have 3400mAH and 3600mAH Panasonic 18650s, but only 4000mAH King Kongs. But if you look beneath the surface, those Panasonics don't hit their numbers. For instance, a Panasonic 3400mAH 18650 will get you only 3071mAH at 3A. The 3600 is only a little better at 3177mAH at the same current. Neither cell produces 3400mAH - even at .2A (the Panasonic 3600 almost gets you there, with 3386mAH at .2A). On the other hand, the King Kong 4000 gives you 4224mAH at 3A. A King Kong 4200mAH (which is less overrated) still gets you 4314mAH at 3A. This is not only ABOVE rated capacity for both. But even the 4000mAH has 1000mAH MORE capacity than the Panasonic 3600! How this is considered insignificant is beyond me. And, of course, when you get into safer chemistries (ie IMR and IFR), the difference between 18650s and 26650s flat out soars.

By the way, where do you get this Enerpower 26650? Almost 4600mAH at 3A sounds REALLY good to me!

 

[degarb]

The advantages of a 26650 are definitely underestimated. You hear it all the time about how 26650s are worthless and obsolete because we have 3400mAH and 3600mAH Panasonic 18650s, but only 4000mAH King Kongs. But if you look beneath the surface, those Panasonics don't hit their numbers. For instance, a Panasonic 3400mAH 18650 will get you only 3071mAH at 3A. The 3600 is only a little better at 3177mAH at the same current. Neither cell produces 3400mAH - even at .2A (the Panasonic 3600 almost gets you there, with 3386mAH at .2A). On the other hand, the King Kong 4000 gives you 4224mAH at 3A. A King Kong 4200mAH (which is less overrated) still gets you 4314mAH at 3A. This is not only ABOVE rated capacity for both. But even the 4000mAH has 1000mAH MORE capacity than the Panasonic 3600! How this is considered insignificant is beyond me. And, of course, when you get into safer chemistries (ie IMR and IFR), the difference between 18650s and 26650s flat out soars.

By the way, where do you get this Enerpower 26650? Almost 4600mAH at 3A sounds REALLY good to me!

Again, what you are saying makes absolutely no sense to me. Reason: weight!
see: http://lygte-info.dk/review/batteries2012/TrustFire TF26650 5000mAh (Flame) UK.html
and : http://www.orbtronic.com/3600mah-18650-li-ion-orbtronic-panasonic-rechargeable-battery

You are looking at 47 grams (18650) v. 93 grams (26650). Is this far off?

So, you really need to compare a 6400 mah 14 A 18650 setup against the Kong or 26650, for apples to apples.

For me a single 18650 doesn't cut it for working, so a two PROTECTED/MATCHED 18650 setup seems a no-brainer -- whether headlamp/wristlight/flashlight. Single 18650 makes sense for edc/reading. Also, the fewer battery formats, the better. AAAs don't make sense to me; 123's don't make sense to me;D or C cells are just heavier, pricier, scacer versions of same old NiMH technology. AA and 18650 are about as many formats as I can tolerate, still one too many formats. I personally wish my smart phone and androids used swappable 18650 format, which would add an infinite runtime and save us a ton of cords and money (on proprietary cells), at the cost of only a little in form factor. A standard (video format/audio format/auto-fuel/battery) format is always superior in the real world to a competing format. Even if the competition is marginally better (which I do not see 26650 being as good as 2 x 18650), it remains inferior in real world. How frustrating is it when your music or video just has no player that supports the format. Worse, at large, is no standard. How much nicer it is to have the micro usb in every device now, thanks to EU.

I can see 26650 making sense if machining a light is an issue. Or is you think a 2 bay charger is the way to go, and cannot envision 4/6/8 bay 18650 chargers. Maybe you have a cheap source.

 

[idleprocess]

Keepower 3600mAh 18650 V=18694mm3 E=10272Wh@5a=.549
EnerPower 4500 mAh 26650 V=37726mm3 E=15725Wh@5a=.417

The 18650 has 31.65% higher energy density by volume than the 26650 when under a 5a load. Perhaps not as big of a difference as one might expect from looking solely at the capacity of the cells. The 26650 can deliver 53% more energy at a 5a load than the 18650 despite having an advertised capacity only 25% higher than the 18650.

The advantages that 26650s offer are usually underestimated, IMO.

Depends on usage. Looking at faceplate specifications for two cells I have modest familiarity with - Fenix ARB-L2 18650 and 4Sevens 26650 - and two other cells I found on Amazon:

CELL           A-H  V    W-H    cm³    W-H/cm³
4Sevens 26650  3.9  3.7  14.43  34.51  0.42
FENIX 18650    2.6  3.6  9.36   16.54  0.57
Orange 26650   6.3  3.7  23.31  34.51  1.41
Nitcore 18650  3.1  3.7  11.47  16.54  0.69

... the conclusions are mixed. I'm certain that the 4Sevens and Fenix cells have protection circuits and are (relatively) safe. The Nitecore and "Orange" cells also claim to have protection circuits (or "protective: yes" in the case of the no-name orange cell), but I'm not as certain about the claims being made in their spec sheets. Comparing our more known entities, the 18650 has a slight edge in power density; conversely using the other two, the 26650 has double the energy density of the Nitecore.

We know that in general for any given current a higher-capacity cell will give a greater percentage of its faceplate capacity then a lower-capacity cell, but this is really only noticeable at higher rates of discharge. Driving something like a XM-L at 3A, 26650 cells will exceed; driving that same LED at 1A or less, the differences will be smaller.

From the perspective of the end-user, one must consider availability. The 18650 is used far more widely than the 26650 and can often substitute for 2x 123A cells. Price and selection for protected 18650 cells appears to be both better and wider than 26650 cells in terms of the cells themselves and the tools that use them (simply finding protected 26650's is a challenged for the uninitiated). The situation in alkaline land is similar - the AA utterly dominates for reasons of commonality (and perhaps also convenient size) in spite of C/D cells offering much more capacity and power delivery.

 

[idleprocess]

The advantages of a 26650 are definitely underestimated. You hear it all the time about how 26650s are worthless and obsolete because we have 3400mAH and 3600mAH Panasonic 18650s, but only 4000mAH King Kongs. But if you look beneath the surface, those Panasonics don't hit their numbers. For instance, a Panasonic 3400mAH 18650 will get you only 3071mAH at 3A. The 3600 is only a little better at 3177mAH at the same current. Neither cell produces 3400mAH - even at .2A (the Panasonic 3600 almost gets you there, with 3386mAH at .2A). On the other hand, the King Kong 4000 gives you 4224mAH at 3A. A King Kong 4200mAH (which is less overrated) still gets you 4314mAH at 3A. This is not only ABOVE rated capacity for both. But even the 4000mAH has 1000mAH MORE capacity than the Panasonic 3600! How this is considered insignificant is beyond me. And, of course, when you get into safer chemistries (ie IMR and IFR), the difference between 18650s and 26650s flat out soars.

By the way, where do you get this Enerpower 26650? Almost 4600mAH at 3A sounds REALLY good to me!

The conditions for determining capacity really need to be spelled out by the manufacturers - preferably via some standard methodology that's reflective of real-world usage. I know the spotlight guys are often greatly disappointed when they discover that the common 7.2 A-H 12V gel-cell does extremely well to deliver half of that rating under the loads that a 35W HID or 50W+ halogen bulb present... but that's because gel-cells are typically rated under a 30-hour load. Energizer makes this data available for their products - it's depressing to see how poorly alkalines perform once you discharge at any significant fraction of C.

Some manufacturers will spell this out in data sheets with a nice capacity-vs-load graph and voltage curves at given loads, numerous others will label cells with a somewhat meaningful capacity without test data, and a lot of the fleabay garbage slaps the biggest number on the label they think they can get away with secure in the knowledge that they can change names every 6 months when their reputations sink.