why aren't there 14500's with higher capacity?

[brightasday]

Seems like recent 18650's, e.g. Panasonic, have legitimate 3400mAh capacities. A good 14500 has a capacity of 840mAh (Sanyo), less than 1/4 the capacity of the new 18650s. Why is it that there aren't 14500s with considerably higher capacity?

Just doing basic volume calculations, an 18650 only has a bit over twice the volume of a 14500. Based on volume, I'd think a good 14500 would hold close to 1500mAh.

Is a lot of space lost to the packaging of the batteries, so that the actual material that holds charge is significantly less than the exterior dimensions? Even if I assume, for example, that the packaging takes 2mm of the diameter, and 3mm of the length, the volume of an 18650 is still only ~3x the volume of the 14500. With those assumptions, I'd still expect to see 14500s with legitimate capacities over 1100mAh.

Is it that 18650s are used much more extensively, so they get the latest and greatest technology years ahead of the 14500s?

 

[Th232]

Is it that 18650s are used much more extensively, so they get the latest and greatest technology years ahead of the 14500s?

Yep. Demand for most other sizes outside of 18650s is relatively tiny, so it's not worth it for a lot of manufacturers.

 

[reppans]

Is a lot of space lost to the packaging of the batteries, so that the actual material that holds charge is significantly less than the exterior dimensions? Even if I assume, for example, that the packaging takes 2mm of the diameter, and 3mm of the length, the volume of an 18650 is still only ~3x the volume of the 14500. With those assumptions, I'd still expect to see 14500s with legitimate capacities over 1100mAh.

That's what I would have guessed, although the non-charge holding volume seems greater than you estimate.. click on the image on this link:

http://support.radioshack.com/support_tutorials/batteries/bt-liion-main.htm

 

[glockboy]

There are lot more laptops than flashlights.

 

[Shadowww]

There are lot more laptops than flashlights.

Then again, 14500's are used not just in flashlights (if they were used only in flashlights, Sanyo wouldn't bother making them..), they also are used in camera battery packs, and some other small electronic devices.

 

[jasonck08]

14500 capacity hasn't changed in 5+ years. All the R&D goes into 18650's, and we see new capacities about every year lately.

 

[mccririck]

Seems like recent 18650's, e.g. Panasonic, have legitimate 3400mAh capacities. A good 14500 has a capacity of 840mAh (Sanyo), less than 1/4 the capacity of the new 18650s. Why is it that there aren't 14500s with considerably higher capacity?

Just doing basic volume calculations, an 18650 only has a bit over twice the volume of a 14500. Based on volume, I'd think a good 14500 would hold close to 1500mAh.

I'm not so sure about that. Did you consider the thickness of the casings in your volume calculations? That will affect the smaller battery's volume more than the larger one. Also, most 18650 are about 2600mAh really, and half that minus a bit would be 1200mAh, then as I said I think with volume of casing considerations it may well drop to 900mAh.

 

[ShineOnYouCrazyDiamond]

There are the new Sanyo AA cells that are 840mAh. Zebralight is selling them as well as a few others.

HKJ reviewed the EnerPower version here: http://www.candlepowerforums.com/vb...est-Review-of-EnerPower-14500-840mAh-(Yellow)

 

[brightasday]

I'm not so sure about that. Did you consider the thickness of the casings in your volume calculations? That will affect the smaller battery's volume more than the larger one. Also, most 18650 are about 2600mAh really, and half that minus a bit would be 1200mAh, then as I said I think with volume of casing considerations it may well drop to 900mAh.

I did try to account for the casings. In the paragraph that starts with "Is a lot of space lost to the packaging of the batteries", I was writing about space lost to the casings. In pretty much a pure guess, I suggested the casings take 2mm from the diameter and 3mm from the the length. As reppans noted, possibly the casings take more space than I think.

Regarding "most 18650 are about 2600mAh": That might be true, but I'm really asking about the current state of the art: 18650: 3400mAh, 14500: 840mAh.

Thanks for all the replies. Probably the real answer is some combination of space lost to casings and the fact that low volumes for 14500s mean less incentive to put the latest technology in them.