Hi, I have an older GreenForce Tristar light head that I'm looking to replace the LEDs in order to get a little more light from it. The battery pack is 12V 4500mAh
The inner diameter of the head is about 45mm
Does anyone have any good ideas about the LEDs and drivers I can or should be using for best results.
Maybe a driver with 2 modes, 100% and 50%?
It is the first time I modify a lamp so I'm a bit novice
Thanks //Jocke
Hi,
I have upgraded several of these heads, but there are many different variations of this head. Posting a picture of the head might help.
If you search with my username you can probably find some examples of what I've done with them.
It's been a while since I did an upgrade, so I'm not up to date with the latest LEDs, but the upgrade I liked the most (and my fellow divers as well) was a setup using 4 cree XPG (probably the newer variants work too) in combination with a 16mm LLS12N lens from gagionne:
https://www.led-tech.de/en/High-Pow...m--XP-G,-XB-D,-OSLON...--LT-1820_106_122.html
As a driver, I used a simple AMC7135 driver with 1.5A (4*380mA) output where only 1 LED is connected to the output of the driver and the 3 other leds are put in series with the driver so you can drive this driver off a 12V battery pack. probably, the newer LEDs can be driven harder (5x or 6x AMC7135?) but I would add a temperature switch to protect against high temperature when used outside the water.
This driver setup is a bit odd, you can find more about it here:
http://www.candlepowerforums.com/vb/showthread.php?201392-Poorman-Mutli-Lux-setup-method
the setup I used is similar to the 3x P7 (first option), but with only 2 LEDs in series with the driver, the AMC chips overheat when the pack is fully charged.
There are AMC7135 drivers available with 2 modes (or where you can select the available modes by soldering a bridge somewhere), which is also my prefered setup. I hate the strobing/sos modes, really anoying.
This may not be the highest output you get these days (compared to triple cree XML2) , but gives a very nice light distribution with a nice penetrating hotspot but still a reasonable spill around it. The advantage of the XPG is the small chip which is easier to control by the lens.
We have been using this setup in murky Dutch waters and some used it extensively in cave diving as well.
This setup fits in the MR16 halogen version of greenforce, so I'm not sure if this fits in the tristar head from greenforce. Given your inner diameter of 45mm, I guess it should work.
most dificult part is getting the correct heatsink, you will need a lath for this.
I have also found this page to be very usefull to figure out what I can fit inside a certain diameter:
http://hydra.nat.uni-magdeburg.de/packing/cci/d1.html
You can find here that the ratio for 4 circles in a bigger circle is about 2.4 so given the 18.61mm size of the gagionne optic, this should fit: 18.61*2.4142=44.93<45mm.
so if you find a different lens to try out, multiply its diameter with the ratio mentionned for a certain number of circles (3 for example) and you get the minimum inside diameter that you will need for it.
Regards,
Johan
edit: by the way, do you happen to speak Dutch?