There is a Lamp mode where you can run the headlamp from a USB-C power supply with or without a battery.
You could use a powerbank with an efficient 5V/2A output to keep this headlamp powered while camping long after the 21700 cell has gone flat. You would not need to waste energy charging the 21700 cell if you unscrew the tailcap 1/4 turn to disconnect the battery.
I would recommend testing the turbo performance further. When the Elf C2 Max was released in December, Armytek updated all the other Elf models to “PCB” versions that come with protected cells. The protected 21700 cell included with the Max is totally inadequate for the current draw on turbo. It’s supposed to have a 60 second stepdown, but the cell can barely manage that from cold on the first run. After any real use, the light starts doing a voltage-based stepdown well before it hits the 60 second or thermal limit. It’s easy to confirm the cell is the issue by just doing the same test with a proper unprotected cell. Alarmingly, Armytek appears to be making the same change with the Wizard series based on new availability from China.
I didn’t actually notice the issue myself because I was running it with a 50PL. I modded one for someone and they asked me why turbo was stepping down after only 17 seconds. After some testing, we eventually realized it was because of the protected cell. You can see it gives a red blink very quickly and does a hard stepdown soon after as if the cell is nearly discharged, except it wasn’t.
It is likely some sort of combination of voltage sag and temperature. Mostly temperature unless the battery is not fully charged. There’s no good reason for them to " try" to add any sort of a timer just for turbo.
Do the test again starting with all battery voltages at 3.9 or 4.0 ..
But you have to start each test with a fully cold head.
