What are Lithium Ion Batteries? - 21700 vs 18650 Cells

21700, 18650, 20700 and others simply refer to the physical size of the lithium-ion cell. For 18650, it’s an 18 mm diameter x 65 mm length. 21700 is 21 mm x 70 mm. While the explanation is simple, the difference is profound.

NOTE: Correction on the math in the video—the volume differences should be π x r^2 x h NOT π x d^2 x h

Apologies for not catching that before publishing.

Current 18650 Cell Battery Pack Values
- Compact 1P Battery: 2.0Ah–3.0Ah (36 Wh–54 Wh)
- General Purpose 2P Battery: 4.0Ah–6.0Ah (72 Wh to 108 Wh)
- High Capacity 3P Battery: 9.0Ah (162Wh)

Current 21700 Cell Battery Pack Values
- Compact 1P Battery: 3.0Ah–4.0Ah (54 Wh–72Wh)
- General Purpose 2P Battery: 6.0Ah–8.0Ah (108 Wh–144 Wh)
- High Capacity 3P Battery: 9Ah–12Ah (162 Wh–216 Wh)

[railmastercnr]

The guy at the end cutting concrete with no mask is classic! Can’t fit a smoke under a mask

[MrBjorntsc]

By mass some 18650 cells have better output.
Sony:
Vtc6 18650 30A 3.0AH 47.6g
Vtc6A 21700 40A 4.1AH 72.9g
21700 are still behind 18650.

Form factor is the reason for the change. A 21700 makes a larger footprint and decreased height.

[Bob_Adkins]

What I like most about 21700 is you can make a pack with only 4 cells with a once, low profile.

[Proer]

That guy at the end breathing the silica dust while smoking a cigarette is not long for this world.

[IMPACT-NATION]

Congratulations on the 100k guys. Well deserved 👊

[frankd]

For Pro Tool Reviews:

Since the battery comparison shown pits the smaller cell battery against the larger cell battery, the batteries are rated about 108 watt hours and 113 watt hours since watts is a measure of power output and is the simple product of amps times volts. Since it is DC there is no power factor involved as in AC power. To get 800 watts from the 18650 cell battery at rated 108 watt hours, it would have to provide 6 amps at 18 volts for 7.4 hours. The larger 21700 cell unit would have to produce 6.3 amps at 18 volts for 12.8 hours to get 1440 watts delivered. Do these batteries last that long or are the manufacturers inflating the total power output like they do the horsepower on power tool motors where they use inrush current instead of rated current?

[Taylormade]

Why do concrete guys always have a cigarette in their mouth when cutting concrete.

[trevornelmes]

And now we see a 5A 21700 from Liitokala (model Lii-50E), on Aliexpress for as little as $4 each, and some vloggers have tested and confirmed that they are at least 5A, and some more than that.

[Fee.]

Excellent video. The 6.3 Bosch was 20700 iirc, so I bet the newer 21700 Bosch's are about 1600w

[satanisawa]

Great video, . lots of info, no fluff. Thank you!

[MrTmax]

And knowing is half the battle, thank you

[jjjjjj]

Volumen =π x Radio is not = π x D.
π x 9²= y π x 10.5²R

[e-bikerbulgaria]

Brand of battery would be useful data. Great video very good data for us battery builders.

[onlyintellectuals]

18 and 21 are diameters. divide by 2 : pi* 9*9*65

[-MacCat-]

How things change!
Both in batteries AND in how we react to guy with a cigarette in his mouth, regardless of the fact that he is cutting concrete with a dry blade.

[taunteratwill]

Thanks for explaining the bloody obvious!! :-))

[nathangreen]

Could o build a ebike battery with these

[theyootlegacy]

Thank you very much, this is very informative.

[Inkling]

You argument is a good one for power tools, but for pocket flashlights the smaller size of the 18650 can be a plus.

[muhammadhumayun]

How can we know we r buying 18650 flexvolt battery or 21700 flexvolt battery online