Runtime test on turbo?

I ask myself how i can do a runtime test on "turbo" mode because many lights have step downs after a certain time, there are lights with step downs after 3 minutes already. There are two possibilities, you have to reset the timer all the time which will take ages and you never know if its a step down cause of the temperature or cause of the battery itself. The other possibility is to not reset the timer but isnt that more or less the same as the runtime in high mode minus the 3 minutes in turbo? What would you do to measure the turbo runtime based on the lux values? I usually measure the runtime from start to the low voltage warning and write down the lux values every 15 minutes. Lights with temperature sensors are less problematic i guess, i would just use a fan to prevent them from stepping down.

Obviously you just shut the light off and notate it on a piece of paper, with the approximate time of the turbo cycle. If you can start the light up again, start it up and count that cycle again. If the light gets too hot, stop and wait 10-20 minutes to let it cool down and rinse and repeat.

I do this on my timed lights, so I get an idea of how many cycles I can go.

Chris

If heat is the only concern you could put the light in a plastic bag and put it under water.

or, when that is no junk light, simply submerge directly,
any better light should be able to ...