PRO and CON to use 4,35v batteries? better lifespan if charged at 4,2v?

this is a noob question, but i don’t understand the meaning to produce or use a 4,35v battery.
The most impostant part of a flashlight is the driver….it’s the principal part involved to transform the voltage from the battery to a SPECIFIC/USEFUL voltage. right?

so, why should exist a “similar” lithium battery with nearly identical max cut off voltage? is it so important to have 0,15v more ? the most important thing in a battery is also the total WATTAGE. and i see that these 4,35v batteries do have similar W, even lower!

the only one PRO that i can find, is that i buy for example a 3000mah battery but i charge at 4,2v it would only keep about 2800/2700mah but the GENERAL LIFESPAN would be greater than normal 4,2v batteries, because you could “store” a fully charged battery at 4,2v ( but 4,35v battery) without to worry about battery usury and health. ( a 4,2v can not be stored at 4,2v, but max at 4,1 or 4v for 2/3 months , preferably at 3,6v if stored YEARS)

i hope to receive good expanations from skilled members here :slight_smile:

in a single cell configuration a 4.35v battery will hold a higher brightness for longer when driving an XML2 vs a regular 4.2 volt battery. Will it be noticeable to your eyes? probably not.

and yes, charging them to 4.2v will increase their lifespan (speaking of 4.35v cells)

so, for example normal LiCo are rated 500 cycles , but a 4,35v charged always at 4,2 could have 700,800 cycles……however always more respecting a 4,2v battery. And this seems a nice PRO imho