I just finished modding my GT using the TA GT driver and an XHP-70.2 P2 Led
I LOVE THIS (expeletive) LIGHT!!!
Here are some pictures I took comparing it to my other throwy flooder, the Acebeam K60 which is using a XHP-70.2 P2 Led, the GT totally Pwns it.
Left Acebeam K60 on turbo, right GT XHP-70.2 on turbo
I did not want to unsolder the brass button of the original driver so I used a belt sander to make a copper button out of a sinkpad MCPCB it is 11 mm in diameter and 1.54mm in width
I used 18ga wire, BTW here is the correct wiring.
The lights works fine but I have this problem, when I turn off the light 2 dies stay on and the switch leds don’t light up. they do work since I see them blinking when turning on or off the light, I think the modified SD75 MCPCB might be bleeding some current to those dies instead of the switch, hopefully TA will offer the proper MCPCB’s
Yes, I was wondering what the lumen sag over time was (ie 9000 lumens @ turn on, 8500 lumens at 1 minute, 8000 lumens at 5 minutes, 7000 lumens at 10 minutes etc.) Like a nice little graph showing how its taper is.
120 watts is a lot of heat, usually you need a fan to dissipate it. I too imagine it’s only 5 or so minutes before it needs to step down.
Well, there’s lumen sag due to emitter temperature, but on turbo I think it gets up to temperature pretty quick then mainly stabilizes in 20 to 30 seconds. It’s the drop in battery voltage that will cause the lumens to continue tapering off. Is that what you meant?
I don’t have a power supply to test with, but I’m sure there are plenty of guys here who do and can tell you the lumen drop off rate purely from temperature.
The lumen drop off rate from batteries probably varies a lot based of which batteries you use and if you have one or two carriers.
Real dumb question as I am a noob among you modding gods: Why was the stock GT not designed to emit 8,000 lumens? Cost and material constrains? Because Lumintop didn’t want to? Other reason?
I had problems like that with a modified mcpcb, There is most likely a short of some kind as only dies lighting up is almost always a case of the 6V short. I had masive issues getting the reflow with the modded mcpcb, took me several reflows to get it to work.
Now the side switch is an odd problem although it is possible that the main LED is sucking all the current and it is not making it to the switch LED.
The reason for the FET over the buck is quite simple. The GT is large enough to handle the power and it wuld drop out of regulation very fast if used at high currents. Plus there is little reason to want the GT at low power levels. It is not exactly a walk the dog light.
A buck driver will drop out of regulation almost instantly if the current is high enough to be a worthwhile amount of power. For example the FET driver only does around ~9-9.5A peak on a 70CRI LED.
Add in the voltage drop of the buck driver and the max current is suddenly less then 9A (possibly closer to 8A peak). Meaning that it will drop out of regulation almost instantly as the cell voltage will drop below the level needed to maintain 8A and then it is just a high resistance , and overly complicated FET driver.
I saw this with the modded stock buck driver, even at 6A it would drop out of regulation before it would even heat up.
So if it is not going to be regulated anyways, then might as well get maximum power out of it.
You can choose your battery and the load and see how it tapers off.
I think TA’s FET driver is 12v, right? So your using 4 cells in series. If we look at one carrier and say the amperage draw is 6A at the emitter we then have to account for driver and spring losses. So just to be conservative, let’s say it’s 7A at the carrier which is 7A per cell. We can compare different cells at 7A.
Some cells immediately sag way down and some smoothly taper down.
I know Kawiboy could probably tell you first hand. He ran a 6v 70.2 in his GT and converted the carriers to 6v. He was pulling about 22A! That’s 12A at 12v.
I don’t think you’ll be able to measure a steady drop in lumens from the battery because you’ll have to turn the brightness down pretty quick.
I forgot what I was talking about, I’m probably rambling. Time to go to bed.
I think you’ve just created the ultimate search light for search and rescue operations VOB. Sounds like a side gig for ya to me. I’ve already shown my light to my emergency manager counterparts and they’re amazed by it’s presence. I have three GTs so might have to have one modded.
