26650’s are a fair bit fatter than 18650’s. If I understand correctly, the first two digits refer to the diameter of the cell in millimeters, while the next two digits refer to the length. For example, a 18650 is roughly 18mm in diameter and 65mm in length, and likewise a 26650 is roughly 26mm in diameter and 65mm in length
As many has explained the 18650/26650 is a size difference.
The 3.2V / 3.7V volt is a chemistry difference.
Anything marked as 3 or 3.2 volt need a charger with a maximum charge voltage of 3.6 volt (LiFePo4 chemistry).
Anything marked as 3.6 or 3.7 volt need a charger with a maximum charge voltage of 4.2 volt (LiCoO2 or LiMn chemistry), this is the most common LiIon charger.
In my option the 26650 is very disappointing. only 30% more real capacity but 100% more volume. what a waist. I wish some of the 18650 manufacture will wake up and start to use the same technology in the 26650.
Just about every laptop out there uses 18650s - as does the Chevy Volt (8192 of them AFAIR). There is a lot of competitive pressure to make higher capacity 18650s. Just about nobody uses 25650s. And they don’t fit properly in C cell lights. For every 25650 sold I’d guess a few tens of thousands of 18650s get sold.
are actually made up of a different chemistry than 18650’s? I kinda find that hard to believe. But I’m flexible.
Maybe volume doesn’t equate to a one for one linear increase in capacity due to battery physics? I’ll let the batt experts chime in here. In any case, given my druthers I’ll take a 30% increase over 0% increase any day. In a one-hour runtime torch that’s about 20 extra minutes. Nothing to sneeze at IMO especially if it can save yer skin someday.
The details of manufacture are what really makes a difference. You can get 1600 or 3400mAh 18650s. Which one is harder to make?
What market is there for $5000 26650s? I’d guess approximately none.
That’s the sort of money that gets amortised over billions of 18650s.
An 18650 has pi*r*r*h volume - or 3.14159x9x9x65 cubic millimetres. Or 16540 cubic millimetres. For a 25650 - 312,686 cubic millimetres. Or 19x the volume of an 18650. So the best cells ought to be able to do 3400x19mAh - or 64Ah. Want, want, want quite a lot of those.
Even if they cost 19x as much as 3400mAh 18650s - so say $200 each.
How many of those would you buy?
Given that they are unlikely to last more than three years?
Look at it this way. I can buy a King Kong 26650 4000mAh for around $9; An XTAR 18650 2600mAh costs about the same. The KK has tested capacity of 4400mAh, The XTAR, 2600mAH on a good day. If I use the XTAR on a 2 hour ride, I'm going to have to switch cells a little over 1/2 way through the ride. The King Kong gives me close to 2 hours run time with a brighter flashlight. 26650's are great for cycling - I wish I had more choices in lights.
Does anyone know what the highest capacity 26650 is out there? I know most of the higher capacity claims are false, with both 18650 & 26650. Are those 4400 king Kongs the top of the real capacity mark? I’d like to buy 3 or 4 of them but not sure where to find them? Any ideas thanks
Well, i have to object:
My preferred A123 systems 18650 (APR18650M1A) has a capacity of 1100 mAh.
The corresponding A123 systems 26650 (ANR26650M1B) has a capacity of 2500 mAh, that’s more than twice!
…but maybe, other producers didn’t do their homework? :~