Hey i got alot of runtime on my blf gt… 8* lg mj1… i havent charged my cell since i first got it… maybe because of buck driver.??
“A lot” is a relative term. If both drivers were running at 2.5A and had the same 4 cells powering it, then run time is going to be kinda close. The efficiency of the driver could be the deciding factor.
The buck driver can maintain a regulated 2.5 amps down to a certain voltage and then output will start to taper off.
A boost driver will maintain 2.5 amps until the voltage gets low enough to trigger the low voltage protection. As voltage drops on the boost driver the amperage being drawn from the batteries will increase to compensate, so you end up with more voltage sag and the driver has to step down or power off abruptly.
So I really don’t know which driver design would maintain 2.5A longer. We would need somebody a lot more familiar with driver designed than myself to come in and maybe explain which will do 2.5A longer.
We have run time charts for the GT. With 30Q cells it will do 2.5A for about 32 minutes, then output will taper off for 40 minutes until lvp kicks in.
2A is much better to run the xhp35 at. The GT will do 2A for about 50 minutes, then taper off for 45 minutes until lvp kicks in.
I was able to find some run time charts from Maukka using the 30Q in the MF02. Unfortunately, it usually steps down from turbo after about 7 to 8 minutes. Even with a cooling fan blowing on it, it only ran on turbo for 16 minutes before stepping down. Here is his chart:
Now in theory, the same driver in the MF04 with its larger mass and increased surface area should be able to maintain 2.5 amp without stepping down. We just don’t have this data yet.
If we look at that chart about we can count up the turbo run time minutes. It looks like about 30 minutes of turbo. I’m guessing that after the third blast of turbo the batteries aren’t powerful enough to go back into turbo for a fourth time. If that’s true, then it looks like both the GT and the MF02 can run 2.5A for right around 30 minutes.
Is it fair to calculate it this way though? I mean, what cells were used? Were they new? Isn’t the GT a 2 carrier design with double the capacity because of it? High discharge cells really aren’t needed, so wouldn’t 3500mAh cells be best for the GT and then with 8 of them present wouldn’t the run time be calculated at 2500mA draw on 7000mAh capacity? It’s one thing to do the paperwork and another thing to do the real world testing, run time is always going to differ regardless how you go about it in the real world, ambient temperatures being one of the many variables.
Plug it in. 
Sample is in my hand now! 
I mean it is complicated… i know from my experience i can get 10 minutes turbo 4 * 18650 and triple xhp 70… ( when the battery reach about 3.7 v )
Single xhp 35 is 2.5 amp… so i say about 20 to 25 minutes turbo… 8 cells is about 50 minutes…
I think it is pretty fair. It’s not super accurate, but close enough for the average person.
Cells were 30Q in both lights.
Assumed new.
Tested with only 4 cells each to keep things even.
The 35E cells tend to have more voltage sag under load, but run longer on the GT once out of regulation. You can see the runtime charts here in post 3 of the GT thread. They used Panasonic 3500 protected cells, but it is pretty close to 35E chemistry. [PART 2] Official BLF GT Group Buy thread. Closed, but Public sales open! - #3 by Team-Giggles
35E or similar high capacity cells are not recommended on the MF02/04 due to it using a boost driver. They recommend high drain cells like 30Q.
I’m sure we will get more accurate turbo runtimes on the MF04 in the near future.
Getting both lights together with the same cells, conditions and test equipment would be ideal, but it hasn’t happened yet.
I think the biggest thing to take away from these run time tests is the big difference between 2.5A and 2A. For anyone that has a GT they can see firsthand the difference in brightness and it is very little. You almost can’t see the difference, yet it extends the run time from 30m to 50m. That’s huge!
Any idea when they will be shipping them?
Interrested
When will they start selling it?
Interested please add me to the list
BG have MF04 on preview …
only 999$ :person_facepalming:
They do that so you can’t order… mf04 is not ready for sale, and they are debating on the final price…
I am have taken first group of measurement about 30mins ago. Will duplicate the test again with different set of battery model.
"The measurement I got is around 1.08 Mcd." Is that what most people got for BLF GT?
There is not many actual measurements out there, my guess on average expect 2.1 km for a stock GT (~1.15 Mcd).
I got 0.9778 Mcd @10m with slightly off-centered emitter for my prototype. Should be all good are some fine-tuning.
Measured around 1.1 Mcd for the BLF GT.
I think 20m is recommended with these big reflectors.
The distance I used to do the measurement was 10 meters also.