The Thrunite TH20 "Pro"

I got it to replace a Fenix HL22. The HL22 was a single AA headlamp that was light and ideal for backpacking -- but it just stopped working.

The Thrunite TH20 surprised me, because it came with a rechargeable AA size Li-ion battery. The battery has a built in charging circuit and a USB-C port on the side of the battery! It even has an LED on top that is red when charging, and green when fully charged. The battery is labeled a 14500 with 920 mAh capacity and 3.7 volts. They even include a USB-C cable.

I was somewhat worried that I could only use this battery, but the light works fine with AA alkaline batteries, as well as a 1.2 volt Eneloop Ni-MH battery. So I can carry as many of those as I might consider necessary.

A comparison to make is Watt-hours, not mAh.

The 14500  920 * 3.7 = 3400 mWh
An Eneloop 2000 * 1.2 = 2400 mWh

Plenty of 14500 batteries are available if you want a second battery. Many of these (like the Fenix ARB-L14U) give a 1.5 volt output, so they must have some kind of internal voltage conversion circuit. It would be better to avoid this for the sake of efficiency, Yet the TH20 is probably not safe with an unprotected Li-ion battery given that it works with 1.5 and 1.2 volt cells. My choice would be the Nitecore Nitecore NL1410 1000mAh. I see this for sale for $9

I'll probably carry one or two Eneloop NiMH if I feel the need.

Modes

Click the button to turn the light on, then hold the button down to cycle lo, med, hi

Double click to get to turbo.

Triple click to get to SOS.

Here are the times with the Thrunite 920 mAh battery.

firefly -- 0.6 lumens -- 18 days
Low     -- 39  lumens -- 18.5 hours
Medium  -- 100 lumens -- 7.8 hours
High    -- 350 lumens -- 6.3 hours (? more like 2)
Turbo   -- 760 lumens -- 2 minutes

I don't believe the time cited for High if it has 350 lumens. I think 2 hours is a more reasonable estimate (why should you get 2 hours at 285 lumens after the turbo drop down, and 6 at 350 lumens?)