Out of curiosity, I redo the runtime test using Duracell coppertop and Duracell Ultra...
Using Duracell copper-top
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Using Duracell Ultra
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both type seems to gives approx. the same runtime >> ~12-13 hours on Sun-mode, ~8 hours on moon-mode
During the Duracell Ultra test, the battery vented at the end of the test. When E01 turn off at hour 20+, the head is very stiff when attempted to unscrew. The moment I reach the o-ring, a loud "spark" sound was heard. I quickly tested the light with a new battery, it seems to be working fine. A quick inspection of the vented battery reveal no physical damage, voltage reading 0.934V after rest for 3 hours. :sweat:
Note: These Duracell batteries are made in China.