Because tubo draws like 17+ amps at a time,battery needs to be able to handle 20A continuos (which gets harder when it is half-way drained) .
Also there is huge difference when you run things to the very edge of their capabilities and when on 70%.
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I remembered to add something else about my usage pattern. I dont drain batteries under 40% cause ,they arent performing as good as fresh ones,when doing back to back sessions with same battery it gets very hot and gets even hotter,so this raises the overall temp of the tubo which leads to device too hot message at times + i get no atomizer found when below 25% at times, so.... i got around by switching batteries. Even when i am not at home. I switch batteries between session,so the used one can cool while the fresh one is in use
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I think the battery weights almost as much as the tubo,so i imagine that it plays a huge role in getting the chip hot. Also a note that crappy batteries are running hotter overall than good ones.