Heres a reviewer using dollar store power bank battery pulls for BLF A6 testing, he even uses turbo
If you dont use the higher modes constantly itll work fine
Here is a BLF member a few days ago having a mode locked s2+ from biscotti. notice how folks are quick to recommend biscotti but dont answer if you get one of the problematic ones?
Its an issue that shows up every now and then
https://www.reddit.com/r/flashlight/comments/c83fsz/convoy_s2_memory_mode_stuck/
If you are one of the unlucky ones then youll need to reflash or replace the driver. Which means soldering or more hardware, and on the 6/8x7135 versions even more soldering
Which might be fine for a DIY flashaholic, but maybe not for an average consummer
If you like the sofirn SP40 or SC31b just go with those
I have both, the SP40 is on my desk right now … its a good value light