Right to the point - I like

Question. I have a Fenix LD20. Recently I used Litium intead of alkaline AA. There seems to be no distinguishable between different lumen level. Not as when I was using alkaline. Comments?

I assume your Lithium is Energizer AA Lithium , right? which will measure about 1.7-1.8V, while Alkaline AA is 1.5V++, but all LED needs around 3.5V-3.7V Vf to fire it up, so both Lithium 1.8x2=3.6V and AA 1.5x2=3.0V need to boost up to meet the minimum Vf of the LED, so if the LD20 is a boost only light, they will be not much different for both batteries in terms of brightness, but Lithium run time should be longer.

Do not use 2 14500 Lithium ion in the LD20, it will fried unless it has buck driver too.

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Ok. Thanks a lot. Now understand better.

yeah... coz I'm running out of non-flashaholic friends to gift to...
this E05 is really useful with its floody beam and has proven to be very practical for keychain duty...

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I'm a friend, aren't i?