R2 Cree arrived today, vast improvement on the standard Oldham on a short test. 🙂

I have also changed my avatar, the old one made me look elderly; the new one could signal a brighter future.

I have to say Roy, I'm sad to see your old avatar disappear.
I think it summed up the very nature and also the comic ethos we ME's share about our interest and the inherent dangers associated with it. ...Can't you put two up or put your new light bomb on the old skeleton? :thumbsup:

Besides the old avatar looks a lot younger if you ask me (but after all I'm just a dodgy penguin so what do I know?)
😉

---

I think we need Cornish Pixie's feedback on the RF avatar subject.
Sorry! ....wandering slightly off the topic of the original post here......but then....being old and all that....... ::) :offtopic:

---

I will think about this one.

I have some results on testing etc.
The 2 parallel Li Ion power packs will not support 4 Crees, I now have them on direct drive and they only run at half power. My solution to the light bomb is a simple one, I will use 3 core cable and adapt a cut down Oldham MF battery case to take 2 power packs.

The current situation is a difficult one as most of the components on the Hong Kong suppliers website are either "Sold Out", "Out of Stock" or "Back Ordered"
I would have thought that in a recession when customers have money waiting manufacturers would at least attempt to fulfil their orders.

---

I have found where my avatar was hiding, he was in a back up disk hoping that he would not be noticed. My new lamp had frightened him away.
I shall try to coax him into wearing this and coming back to the website.

---

<<<< He's back!!!

---

<<<< He's back!!!

Much more distinguished looking gentleman. 😉

Anyway to business, what would be the max operating temparature for a Cree R2 unit, any ideas?

Hi Mr Morlock, nice to hear from you again.

I would say that its basically the same as for any other high power LED such as Q5, and in that, its rather arbitrary as nothing appears to be engraved in stone.

My own lamp building projects are very successful in getting rid of the heat, in that they use a copper thermal conductor system and 2 Cree Q5s can be run at full power and the internal temperature does not exceed 32 degrees centigrade, and this is an Oldham conversion. The final product however, bears very little or any resemblance to an Oldham as we know it. This is successful to the point where I am also going ahead with a 5 Q5 lamp with an SW2 position that will put 4 of the Crees on full power. However this will require a higher voltage than my current system.

I have been working in collusion to a certain degree with a BA technician whose opinion I greatly respect and he now ventures to suggest that temperatures of slightly over 100 degrees centigrade could have no detrimental effect on the LEDs, although he personally takes a conservative approach to his own lamps. I take a similar view as I am developing products that I will eventually offer for sale.

I believe that the R2 is similar to the Q5 and I will be testing a lamp with no external heat sinking but running a Q5 at full power. My current view is that is that I would not be comfortable with the results, and will attempt to develop something similar to the thermal conductor system already posted about but on a small scale.

To answer your question. Don’t forget that as well as the emitter you will be having some form of driver circuit, with associated wiring etc. At this point in time and my opinion on this is somewhat fluid if you catch the drift, I would be uncomfortable with an internal lamp temperature exceeding 85 degrees cent.
Maybe Mr Mike will so kind as to post on this, such as at what temperature does his excellent Retro 2 conversion start to power down?

---

To answer your question. Don’t forget that as well as the emitter you will be having some form of driver circuit, with associated wiring etc. At this point in time and my opinion on this is somewhat fluid if you catch the drift, I would be uncomfortable with an internal lamp temperature exceeding 85 degrees cent.
Maybe Mr Mike will so kind as to post on this, such as at what temperature does his excellent Retro 2 conversion start to power down?

Thank you Mr Fellows, I did a bit of research prior to the the info request, not a lot of useful info about (maybe not looking in the right place).
When I finish the machining for the "Redwinch" conversion I'll try a thermometer inside the headlamp or on the alloy heatsink.

<<<< He's back!!!

That's quite a diet! :lol: :thumbsup:

Second-best avatar on the forum 😉

---

Good to see him back Roy ;)

Also great reading with the lamp builds and conversions.

---

Nice to see him back Roy.... Like finding an old friend.
Does he have a name.......?

---

[.....temperatures of slightly over 100 degrees centigrade could have no detrimental effect on the LEDs..]

The 100 degrees quoted (as you say, rather high), would only be extant where the LED chip is bonded to the substrate it is mounted on. If this temperature existed anywhere else then the temp at the chip would be far in excess of this. Good alloy heat sinks will sink heat away pretty rapidly from cold, but this efficiency drops off as the temperature of the heat sink rises, so it's generally seen as good practice to run devices at no more than 60% of the max recommended temperature on the data sheets.
Apart from a few exotic exceptions, all devices obey the Voltage Current Resistence relationship better known as Ohms Law.
Raise the voltage and the current will rise. Lower the resistence and the current will rise. When current flows heat is generated.
Raising the temperature lowers the resitance allowing more current to flow which raises the temperature and lowers the..etc. A condition known as 'Thermal runaway'
Yes I know there is current limiting circuitry built in on the control board but the overload has to go somewhere and this situation will only serve to load down the poor old control circuit thus forcing it to operate close to it's rated working spec.
Running without a heat sink is pure folly even at low currents. Strip a cree from a Tesco AA torch and see how long it lasts without the alloy surround..I'd give it 15 mins tops.
Yes Roy... your heat sinking is the best way forward without using a fan that is :lol: :thumbsup:

---

I finally managed to manufacture all the bits for the "Redwinch" Odlham, must say it works a treat although only 300 lumens.
Heat sink gets up to 40 degrees C on test at an ambient temp of 25 degrees C. :)
Just need to sort out the pilot lamps(s).

🔗Personal-Album-1695-Image-31478[linkphoto]Personal-Album-1695-Image-31478[/linkphoto][/link]

🔗Personal-Album-1695-Image-31479[linkphoto]Personal-Album-1695-Image-31479[/linkphoto][/link]

🔗Personal-Album-1695-Image-31480[linkphoto]Personal-Album-1695-Image-31480[/linkphoto][/link]

Very neat set up, will be interested to see what light output is like

Hi Mr Morlock
This is an absolutely superb job and does you great credit.
How long did it take you to make?

---

Very neat set up, will be interested to see what light output is like

Some quick shots with the camera on snapshot mode, both lamps are off the same battery so voltage to both equal.
The general light spill is excellent with the Cree unit and is much more useful than the Oldham spot reflector.
I'll have to get some timed pics in a tunnel to really see what the longer range results are but overall I am very happy with it so far.

🔗Personal-Album-1695-Image-31520[linkphoto]Personal-Album-1695-Image-31520[/linkphoto][/link]

About 16 feet lamps to wall.
🔗Personal-Album-1695-Image-31522[linkphoto]Personal-Album-1695-Image-31522[/linkphoto][/link]

I will think about this one.

I have some results on testing etc.
The 2 parallel Li Ion power packs will not support 4 Crees, I now have them on direct drive and they only run at half power. My solution to the light bomb is a simple one, I will use 3 core cable and adapt a cut down Oldham MF battery case to take 2 power packs.

The current situation is a difficult one as most of the components on the Hong Kong suppliers website are either "Sold Out", "Out of Stock" or "Back Ordered"
I would have thought that in a recession when customers have money waiting manufacturers would at least attempt to fulfil their orders.

For those who dont visit the 'other' site, the above is scrapped. I will be using the MF case but with 2 power packs in series to give a maximum of 8.4 volts. The system works, I have tested it, and had 4 Crees running at 90%+ power, and may be able to get 5 on line.

EDIT
As an afterthought I had better add that the 2 Cree model is currently in use and doing well. This uses AMC 7135 drivers that slightly overdrive the Crees at 2.1 amps between the 2. The light output is better than the previous model with 4 on direct drive at 1.9 amps. This is logical.
Single or parallel Li Ion will not drive more than 1 Cree or a P7 at full power. There is a volts drop accross the battery terminals that brings it down to 3.85 V and the cells cannot supply enough current.
NiMH are far worse, series array of 6 gave nearly 9 volts, under load of 4 Crees voltage dropped to 5.9V
Ouch.
See my posts on Miles site.

---

Hi Mr Morlock
This is an absolutely superb job and does you great credit.
How long did it take you to make?

Thank you.
Probably about 4-5 hours machining if you discount the measuring/double checking and setting up time, reduced most of a perfectly good bit of alloy bar to this.
🔗Personal-Album-1695-Image-31523[linkphoto]Personal-Album-1695-Image-31523[/linkphoto][/link]

The 3 inch alloy bar was £10 (4 inches long 😞 ) and the Cree R2 was £8.99.

Really enjoying reading these updates, and very impressed with the engineering. Keep up the good work :thumbsup:

---