The current/voltage/wattage displayed numbers of TOMO, of USB doctor, or omnicharge are not precise because the numbers fluctuate (nature of any fan, hello?). Current draw looks around ~0.5A, so wattage should be ~2.5W, but omnicharge displays 3.0W. So maybe a more relevant practical measure for comparison is device runtime!!
- TOMO V8-4 w/ 4xNCR18650B (old cells with few cycles, charge-tested avg. 4x3160mAh totalling 49.312Wh): USB fan runtime is a whopping 16h31m30s, i stopped it to the second yay. The four cells recovered after 24h to 4x3.264V offline.
- omnicharge 4xNCR18650B (old cells with few cycles, nominal 49.500Wh): USB fan runtime is only 15h31m57s, i stopped it to the second. It is unclear to which voltage level the four cells recover after the fan has turned off.
I like this simple clear result. The tomo has a longer runtime than omnicharge, at least for this low current application (0.5-0.6A current draw). I don't think that the tomo has a better energy conversion efficiency. I believe that in the omnicharge the cells don't get discharged as much/deep as in the tomo (did @HKJ measure how deep the cells get discharged in the tomo?); this alone could explain why the tomo runtime is that much longer.
Oh for watt do i need the portable USB fan? — I thought of building a diy mosquito trap hehe. But in the end i solved the mosquitoes-in-tiny-room problem with some spray and a handheld vacuum. Lol!