Stu
Active member
Long standing project now finished.
Front end
Front end minus bezel and plastic (cable running left-right ignore - phone cable)
Without reflectors
Innards
Innards 2
Heat sink external
Switch
The shopping list:
Petzl Duo
Cree XML
Driver
Lens 10?
Lens 60?
100mm * 8mm Aluminium
Sheet of 2mm thick Aluminium (ebay)
Switch Type B
Switch cover
Peripherals: wire, solder, thermal paste, nuts & bolts
The reflectors are loose fitting and held in place by a very small amount of pressure from the plastic front. The LED are mechanically fixed with nuts & bolts. Both these adaptations allow for ease of changing stuff around.
The drivers are potted and mounted with epoxy resin. If these blow they're so cheap I'm willing for them to be scrapped if/when they get faulty.
I've retained the Duo battery box and fitted three in parallel 18650 Li-Ion (protected) tagged cells connected with Deans connector. A snug fit but it can be done. The cells are (supposedly) Panasonic 3100mAh. Apart from what they register when I charge them or doing a light on and timed discharge test and crunching some numbers, I have no idea how accurate the figure is.
Obviously the battery box and Duo innards were heavily cleaned out... with a modellers chisel.
One driver is stock 1 Amp (i.e. three of the AMC 7135s). The other has an additional AMC 7135 chip added. Fiddly but not difficult.
This gives nominal output at 3.7V (as you look at it):
Left side LED with 60?: 70mA/28Lumen 430mA/182Lumen 1380mA/504Lumen
Right side LED with 10?: 50mA/14Lumen 320mA/140Lumen 1020mA/392Lumen
The drivers are sold as 10%/35%/100% which they aren't (more like 5%/30%/100%). I knew they wouldn't be as sold as I've given up looking for 10% low setting drivers. What I do like about these drivers is there ability to switch modes without the faff of soldering stars. The silly strobes can be by-passed or brought on line whilst in-situ... neat. I've run the -ve cable through the switch. The +ve cable is run from driver to driver. A solution which on the face of it has no drawback (though I guess they aren't truly independent should the cable detach/corrode/break) but means there is one less run of wire to have to find space for.
The reflectors are clear, fit XML brilliantly and bring out the best of the LED (especially at low setting of 5% - this is still a very usable light output). The output figures mentioned above are interpreted from the XML datasheet and measuring from my multi-meter. There will be anything up to 10% loss from actual because of the reflectors/plastic fascia. With the tight spot running at a lower "level" than the 60? reflected side it still appears brighter. This doesn't surprise me. Running an LED bare and then with a reflector shows how important reflectors are. This instinct/insight means I can have lower battery consumption from one side but not really notice the difference in what I perceive as actual light output (apart from how the light is concentrated).
The external heat sink works well. This is mounted through what would have been the focus switch for the main bulb. Might not be obvious from the pictures but the face plate (what the LED and driver are mounted on - which are three separate pieces of the 2mm Alu mounted one on top of each other) is mounted onto a RAM cooling block which itself is mounted to the round bar (this has been filed flat at the interface between bar and RAM block). With nothing more than my fingers to gauge, this arrangement is working... heat is being lost to the outside of the shell.
After 20 mins of flat out on top setting (again with nothing more than my fingers to gauge!) the LED, the faceplate nor the external heatsink are getting what I would say is too hot. Certainly I can keep my fingers on any bit without needing to take my fingers away. There is a notable difference between the driver running at 1000mA and the other running at 1380mA. I only mention this because a) it's what you'd expect and b) my fingers must be quite good at picking up temperature!! Method to measure the temperature accurately anyone? Would a bog standard thermometer work (I don't own one)?
Anything that is likely to leak is either potted with epoxy and bathroom mastic/sealant.
I'd have liked a less vulnerable to knocks switch but I think this is actually more likely to be a problem when transporting rather than caving.
The faceplate was cut using nothing other than a pencil, a ruler, a junior hacksaw, a modellers file.... and a lot of patience and time.
This was my fourth project. Two were converted Zooms for my night time fell running. Very simple, very easy. I am not an expert and all knowledge was from Google or the very helpful people here and Mine Explorer plus Candle Power Forum and then heavy doses of trial and error. The third was an Oldham monster with four LED. A very good light but quite heavy. I had modified the Oldham so I could actually get it to tilt. The Duo will be my stock light and I will keep the Oldham for nostalgia.
I opted for 3.7V solutions as some of the really big boys on the light scene were to my mind inefficient. There comes a point where illuminating is just illuminating. With 7.4V systems they may be super bright, but they aren't twice as bright as 3.7V systems. LED when very hot (as they would be at 7.4V) are inefficient. To get twice as bright you need four times the input (so a 1000m Lumen light isn't twice as bright as a 500 Lumen light - it's twice as bright as a 250 Lumen light) - seems a waste of energy to me. I carry a three AA battery box with Deans connector with three AA batteries in my kit bag. I'd need six AA with a 7.4V system. The whole point of LED for me anyway, was to make best use of what battery power (capacity and useful output) is out there rather than going for the brightest light output. Happy to be corrected on any or all of this.
Was it worth it? No...
It's very satisfying. It became a hobby in itself, which is no bad thing. Financially it would have been cheaper to by one of Roy Fellows' off the shelf lights (though I wanted a tilt function) or shelled out for a Rude Nora. Biff's new Duo inserts (v.3?) are the best off the shelf I'd say.
Cheers
Stuart
Front end
Front end minus bezel and plastic (cable running left-right ignore - phone cable)
Without reflectors
Innards
Innards 2
Heat sink external
Switch
The shopping list:
Petzl Duo
Cree XML
Driver
Lens 10?
Lens 60?
100mm * 8mm Aluminium
Sheet of 2mm thick Aluminium (ebay)
Switch Type B
Switch cover
Peripherals: wire, solder, thermal paste, nuts & bolts
The reflectors are loose fitting and held in place by a very small amount of pressure from the plastic front. The LED are mechanically fixed with nuts & bolts. Both these adaptations allow for ease of changing stuff around.
The drivers are potted and mounted with epoxy resin. If these blow they're so cheap I'm willing for them to be scrapped if/when they get faulty.
I've retained the Duo battery box and fitted three in parallel 18650 Li-Ion (protected) tagged cells connected with Deans connector. A snug fit but it can be done. The cells are (supposedly) Panasonic 3100mAh. Apart from what they register when I charge them or doing a light on and timed discharge test and crunching some numbers, I have no idea how accurate the figure is.
Obviously the battery box and Duo innards were heavily cleaned out... with a modellers chisel.
One driver is stock 1 Amp (i.e. three of the AMC 7135s). The other has an additional AMC 7135 chip added. Fiddly but not difficult.
This gives nominal output at 3.7V (as you look at it):
Left side LED with 60?: 70mA/28Lumen 430mA/182Lumen 1380mA/504Lumen
Right side LED with 10?: 50mA/14Lumen 320mA/140Lumen 1020mA/392Lumen
The drivers are sold as 10%/35%/100% which they aren't (more like 5%/30%/100%). I knew they wouldn't be as sold as I've given up looking for 10% low setting drivers. What I do like about these drivers is there ability to switch modes without the faff of soldering stars. The silly strobes can be by-passed or brought on line whilst in-situ... neat. I've run the -ve cable through the switch. The +ve cable is run from driver to driver. A solution which on the face of it has no drawback (though I guess they aren't truly independent should the cable detach/corrode/break) but means there is one less run of wire to have to find space for.
The reflectors are clear, fit XML brilliantly and bring out the best of the LED (especially at low setting of 5% - this is still a very usable light output). The output figures mentioned above are interpreted from the XML datasheet and measuring from my multi-meter. There will be anything up to 10% loss from actual because of the reflectors/plastic fascia. With the tight spot running at a lower "level" than the 60? reflected side it still appears brighter. This doesn't surprise me. Running an LED bare and then with a reflector shows how important reflectors are. This instinct/insight means I can have lower battery consumption from one side but not really notice the difference in what I perceive as actual light output (apart from how the light is concentrated).
The external heat sink works well. This is mounted through what would have been the focus switch for the main bulb. Might not be obvious from the pictures but the face plate (what the LED and driver are mounted on - which are three separate pieces of the 2mm Alu mounted one on top of each other) is mounted onto a RAM cooling block which itself is mounted to the round bar (this has been filed flat at the interface between bar and RAM block). With nothing more than my fingers to gauge, this arrangement is working... heat is being lost to the outside of the shell.
After 20 mins of flat out on top setting (again with nothing more than my fingers to gauge!) the LED, the faceplate nor the external heatsink are getting what I would say is too hot. Certainly I can keep my fingers on any bit without needing to take my fingers away. There is a notable difference between the driver running at 1000mA and the other running at 1380mA. I only mention this because a) it's what you'd expect and b) my fingers must be quite good at picking up temperature!! Method to measure the temperature accurately anyone? Would a bog standard thermometer work (I don't own one)?
Anything that is likely to leak is either potted with epoxy and bathroom mastic/sealant.
I'd have liked a less vulnerable to knocks switch but I think this is actually more likely to be a problem when transporting rather than caving.
The faceplate was cut using nothing other than a pencil, a ruler, a junior hacksaw, a modellers file.... and a lot of patience and time.
This was my fourth project. Two were converted Zooms for my night time fell running. Very simple, very easy. I am not an expert and all knowledge was from Google or the very helpful people here and Mine Explorer plus Candle Power Forum and then heavy doses of trial and error. The third was an Oldham monster with four LED. A very good light but quite heavy. I had modified the Oldham so I could actually get it to tilt. The Duo will be my stock light and I will keep the Oldham for nostalgia.
I opted for 3.7V solutions as some of the really big boys on the light scene were to my mind inefficient. There comes a point where illuminating is just illuminating. With 7.4V systems they may be super bright, but they aren't twice as bright as 3.7V systems. LED when very hot (as they would be at 7.4V) are inefficient. To get twice as bright you need four times the input (so a 1000m Lumen light isn't twice as bright as a 500 Lumen light - it's twice as bright as a 250 Lumen light) - seems a waste of energy to me. I carry a three AA battery box with Deans connector with three AA batteries in my kit bag. I'd need six AA with a 7.4V system. The whole point of LED for me anyway, was to make best use of what battery power (capacity and useful output) is out there rather than going for the brightest light output. Happy to be corrected on any or all of this.
Was it worth it? No...
It's very satisfying. It became a hobby in itself, which is no bad thing. Financially it would have been cheaper to by one of Roy Fellows' off the shelf lights (though I wanted a tilt function) or shelled out for a Rude Nora. Biff's new Duo inserts (v.3?) are the best off the shelf I'd say.
Cheers
Stuart
