So today i went for a walk with my dog, before leaving i checked the status of battery 3buzz, yesterday i use it a few times but still had battery so i went, i immediately noticed a lack of power after the 1st draw, another draw a little longer and hard and still wisp... i raise it up from 4,5 to 5,5 and a bit more but nothing near what im used to, recheck bat status and had 2buzz so i turned it off. After getting back home i change the bat lowered to 4.5 and back to normality 2draws and another at 6 and finish the sesh.
So yes i noticed a little downside to the power from 2buzz down, the bat has around 3.5V according to the external charger.
My normal use is on demand 5/6draws@4.5/5 + 2draws@5.5/6 7m avg. and i can push 5 sesh before i notice this lack of power, it still can be used if i turn from 4.5 to 7 and finish the sesh and need to replace the battery.
With the external charger i kept track of the battery voltage, a fresh sony vtc6 has 4,1V every ~7m sesh is spending 1V and below 3.6V i start to notice the getting weaker.
Cheers