There are no 18650 batteries that are 40 amps. You can't trust the numbers on the battery wrap. The highest true amp rating you'll find in an 18650 is only 30 amps, and, of the few ones that are 30 amps, the best performing one (both in terms of the run time and in terms of how hard it hits) is this:
https://www.e-cigarette-forum.com/t...bit-overrated-but-incredible-performer.834167
It is currently in stock at liionwholesame.com:
https://liionwholesale.com/collecti...-38a-wholesale-discount?variant=4226347073564
For reasons that are obvious, the run time you'll get with this battery will suck big ones compared to other, lower amp battery choices.
That said, if you are looking for the best performing 18650 battery that is still suitable for use in a mech mod, but that, at the same time also, maximizes on the run time, get this:
https://www.e-cigarette-forum.com/t...s-a-20a-vtc6a-rewrap-better-than-vtc5a.860613
For more info on how that one compares to other batteries, visit here:
https://www.e-cigarette-forum.com/t...ts-vtc5a-estimated-2900-3000mah-20-25a.849291
It is currently sold out at liionwholesale.com:
https://liionwholesale.com/products/vapcell-18650-3000mah?variant=6132957577248
...but are still currently in stock at eggcity.com:
https://eciggity.com/vapcell-inr-18650-3000mah-25a-battery
Second best choice for maximizing on the run time would be the VTC6, which is older than the VTC6A, and obviously a lot cheaper. The problem with both the VTC6 and the VTC6A, though, is that their amp rating sucks big ones compared to other, lower run time battery choices... so that's why you might want to consider something that sits comfortably in between all of the stuff I mentioned above. I.e., consider going for the VTC5D (or a
rewrap thereof), or, if you can't find that, stick to the VTC5A.
