20700 was meant to be the next standard driven by Tesla, but Tesla changed their minds and added another 1 mm to the diameter.
A number of 20700 batteries showed up with the old sizing, of which Sanyo ones were good.
Then 21700 started appearing on the market….I thought all major manufacturers will cease to develop 20700 and switch to 21700 but was wrong. Sanyo released 20700C well after others came up with their 21700.
When it comes to 21700, Samsung is not alone - there are LG 21700 on the market as well. Sony is backing the 21700 standard as well, though their cells are not available yet.
Panasonic says they’ll do 21700 for Tesla only, for others they offer 20700 (the same as Sanyo).
So yeah, we’ve got quite some mess on the market.
I would go for 21700. Because of:
- 21700 is closer to the middle between 18650 and 26650
- Sony makes better cells than Sanyo
- The best high-discharge cell on the market is Samsung 21700-30T - and is unlikely to be beaten by 20700 in the predictable future
- when it comes to flashlights, 21700 seems to be winning. Though my view to the market is not wide enough to say this with certainty. Anyway, it’s good if we have 1 standard…