I just did another battery test with my new backend, wich doesn't get warm at all.
This time I got about 27 x 12 second draws vs last time 20 x 15 sec draws.
I started at 1 and did 3 x 12 sec inhales.
(well, I timed each of them, from click on to click off it was 12 sec, so including heat up time, I did however always kept going after the click.)
then I did the same on 2 and so on and repeated after 5 with a fresh bowl.
The first time I did this, I had a backend that got really hot on high temps.
This time I got a new backend and I got a total of about 0.4 minutes extra use time out
of the battery.
Note that I haven't been treating the battery like it should have been treated, I charge it multiple times
a day and have not used any of the other batteries it came with, so maybe it already lost a draw in capacity or more? Also last time I did this, I didn't start at level 1 and I did 15 sec draws so this will also be a reason I got more draws out of the battery the second time.
All in all it seems the hot back end doesn't drain the battery that much at all.