Some crude convoy driver runtimes using ceilingbounce

LED Flashlights – General Info
1

I had the realization recently that the grow tents we use here in Canada for certain indoor plants are kind of a perfect integrating sphere-
No light can enter or escape, every surface is highly highly reflective mylar, the whole thing can be climate controlled, any temperature and wind speed you want, and it’s fireproof. It’s like it was made for this.

And I have an empty one so I started messing around with the ceilingbounce app and put together some very crude graphs of some convoy drivers. I haven’t calibrated lumens yet so it’s all just relative only meant to show regulation and runtime.

The reason the graphs don’t start at 100 is because the ceilingbounce app uses the output at the 30 second mark as 100.

All tests were at 100% mode with a fully charged Molicel p28a

Screenshot_20231117_031904_All Documents Reader~2
Screenshot_20231117_031904_All Documents Reader~21024×804 29.8 KB

Screenshot_20231117_032015_All Documents Reader~3
Screenshot_20231117_032015_All Documents Reader~31023×801 31 KB

3.12V ending voltage for both

Screenshot_20231117_235954_Photos~4
Screenshot_20231117_235954_Photos~4650×789 28.8 KB

3.41V ending voltage

Screenshot_20231117_032154_All Documents Reader~2
Screenshot_20231117_032154_All Documents Reader~21080×803 40.2 KB

Light was approaching 60°C so fan was turned on
Screenshot_20231117_032240_All Documents Reader~3
Screenshot_20231117_032240_All Documents Reader~31072×801 43.1 KB

2.7V ending voltage for both

That last one is a 5A linear driver with a swapped, not stacked, 10mohm sense resistor mod. In theory this is supposed to be ~10A but I get around 8A in this light at the most. Thought it could be a good comparison against the buck. Mostly they were thrown in as an afterthought. I might try doing one where they’re cooled enough to have no thermal stepdown at all.

All tests were done with the same 2 Molicel p28a 18650’s, charged in the same way to 4.205V and left to rest for an hour, settling to around 4.18V. I used an adapter for the m21b just to be consistent with the same battery. Cooling was done with a little 2W fan and ambient temperature maintained at 70°F. The c8+ buck has a bypassed tail spring.

I’ll get better graphs in the future just posting what I have now cuz…why not?

Added:

Screenshot_20231122_013017_Files by Google~5
Screenshot_20231122_013017_Files by Google~51054×814 32.5 KB

10°C ambient with fan
3.2V ending voltage

7 Thanks
2

That’s a great use of what you have on hand! I used a medium sized, rectangular cooler and went as far as to buy a lux meter but always recorded the runs with a smart phone application. This was my setup: Budget Lumen Measuring Rig

I can never find Zack’s ceiling bounce app. on the Play store. Where is it available?

3
1 Thank
4

Ya I’m looking at lux meters. I want the graphing function that ceilingbounce has though. You have to spend a decent amount just to get something that’s better than the ceilingbounce app it seems. But it would be really nice to have accurate calibrated lumens.

If nobody has used these tents for this before I’m surprised. It seems kind of ideal. Especially for high powered lights. If you need a big space to measure big lights well this is 8 feet tall. The walls are as reflective as anything.

And you can potentially set it up in a way that no light would have a thermal stepdown. Up to 1200CFM air circulation at whatever temperature it is outside in Canada in the winter. It would be interesting to see driver regulation with the thermal ceiling eliminated from the equation. Would have to just find a balance so it doesn’t get too cold. Would be an expensive setup if you didn’t already have it but I think everyone in Canada has a few of these lol