Cree MC-E flashlights arrive

[EuphoricGrIn]

It appears the first batch of Cree MC-E flashlights have arrived at DX - I count 5 different models from all the usual suspects (2xMTE, Aurora, Ultrafire, and a no-name brand version); however, they're all based around a single 18650 design. My understanding is that the real potential advantage of the MC-E over the SSC P7 is the fact that the individual emitters aren't hard-wired in parallel. The P7 needs a driver capable of delivering 2.8Amps at around 3.5V-3.7V to run at full design brightness, whereas the MC-E could potentially be driven by a higher voltage, lower current arrangement, that should prove easier to implement (and not as hard on batteries, switches and circuits)? Which means MC-E flashlights with multiple batteries (say, 2 x 18500) could potenially outperform their P7 cousins?

I see DX and Kai are carrying various MC-E accessories (serial and parallel stars, emitters), so I guess it's game on for all the modders out there!

 

[LukeA]

Yep. Series is MUCH easter on the switch.

 

[saabluster]

My understanding is that the real potential advantage of the MC-E over the SSC P7 is the fact that the individual emitters aren't hard-wired in parallel.

That and the MC-E has a higher CRI than the SSC. Oh yeah and they are far smaller.

 

[EuphoricGrIn]

Here are some pics of the various contenders (they look familiar, no?)

MTE 8 mode with "assualt crown"

MTE 8 mode (er, the MTE's look identical to me too!)

Aurora 2 mode

Ultrafire 2 mode

Generic 3 mode

 

[rantanplan]

But you need a special driver for a series setup ... like a Shark, Fatman or Maxflex.

I haven´t seen a similar driver on DX & KD yet, so you´ve to spend at least $22 for such a high quality driver ... a stronger switch for a direct drive setup is much cheaper I guess

 

[LukeA]

But you need a special driver for a series setup ... like a Shark, Fatman or Maxflex.

I haven´t seen a similar driver on DX & KD yet, so you´ve to spend at least $22 for such a high quality driver ... a stronger switch for a direct drive setup is much cheaper I guess

There's no way DX is using a switch rated for 3A DC.

 

[EuphoricGrIn]

I agree with you, LukeA - a reliable 3 Amp switch is not going to be cheap.

How about 2x18650 in series direct driving a MC-E hooked up in a 2 x series, 2 x parallel arrangement? I guess the Vf of each individual series emitter needs to be the same as its "partner" (does Cree ensure this is the case during the manufacturing process?). Other than that, what other complications could arise?

(The obvious advantage is that the switch only needs to handle half the current - i.e 1.4amps max)

 

[ichoderso]

MCE parallel or in serie have different current from driver to the LED, but the current from Batterie (and this is the current through the switch most) are the same!

jens

 

[LukeA]

MCE parallel or in serie have different current from driver to the LED, but the current from Batterie (and this is the current through the switch most) are the same!

jens

With a constant amount of power passing through the switch, the amperage (that's what cause wear on the switch) varies inversely as voltage, up to the switch's voltage limit. So series doesn't reduce wattage at all, but it does reduce current.

I agree with you, LukeA - a reliable 3 Amp switch is not going to be cheap.

How about 2x18500 in series direct driving a MC-E hooked up in a 2 x series, 2 x parallel arrangement? I guess the Vf of each individual series emitter needs to be the same as its "partner" (does Cree ensure this is the case during the manufacturing process?). Other than that, what other complications could arise?

(The obvious advantage is that the switch only needs to handle half the current - i.e 1.4amps max)

That might be kind of high. I keep seeing MC-E Vfs measuring about 3.2/3.3V @ spec around here.

 

[EuphoricGrIn]

Ouch. If the MC-E Vfs are only 3.2V a set of fresh-off-the-charger LiIons may well fry the emitters. Are all these direct driven single 18650 P7 flashlights relying on a high current draw induced rapid voltage drop, or are the P7 Vfs much higher?

I guess if the Vfs are that low, it means there's another advantage for MC-E versus P7's - everything else being equal, a properly configured MC-E flashlight would be able to stay in regulation over more of typical battery's discharge cycle?

 

[LukeA]

Ouch. If the MC-E Vfs are only 3.2V a set of fresh-off-the-charger LiIons may well fry the emitters. Are all these direct driven single 18500 P7 flashlights relying on a high current draw induced rapid voltage drop, or are the P7 Vfs much higher?

I guess if the Vfs are that low, it means there's another advantage for MC-E versus P7's - everything else being equal, a properly configured MC-E flashlight would be able to stay in regulation over more of typical battery's discharge cycle?

The voltage sag under 3A is significant.

You could take an 8xAMC7135 driver and reroute the traces (scratch through the ones you don't want) so that each die gets current from two of the AMC chips. That way you don't risk thermal runaway nor do you need a boost driver.

 

[ichoderso]

With a constant amount of power passing through the switch, the amperage (that's what cause wear on the switch) varies inversely as voltage, up to the switch's voltage limit. So series doesn't reduce wattage at all, but it does reduce current.



That might be kind of high. I keep seeing MC-E Vfs measuring about 3.2/3.3V @ spec around here.

The higher voltage will be generated from the driver, the current from batterie over switch to driver is the same, you can change the current to the switch only through higher voltage from batteries, sa. 2 or 3 cells, but from a singel cell light the currents are the same with parallel or serie design (maybe a bit more in serie because worse efficiency from the boost driver!

 

[LukeA]

The higher voltage will be generated from the driver, the current from batterie over switch to driver is the same, you can change the current to the switch only through higher voltage from batteries, sa. 2 or 3 cells, but from a singel cell light the currents are the same with parallel or serie design (maybe a bit more in serie because worse efficiency from the boost driver!

Boy was I not thinking straight or what!

 

[HKJ]

With a constant amount of power passing through the switch, the amperage (that's what cause wear on the switch) varies inversely as voltage, up to the switch's voltage limit. So series doesn't reduce wattage at all, but it does reduce current.

Because the switch is usual placed between the battery and the driver, led voltage has nothing to do with switch current, only battery voltage will affect switch current.

 

[LukeA]

Because the switch is usual placed between the battery and the driver, led voltage has nothing to do with switch current, only battery voltage will affect switch current.

Six minutes earlier and I would have appreciated this! :wave:

 

[ichoderso]

Boy was I not thinking straight or what!

sorry, my english is very bad, maybe i have not understand you correct...???

 

[EuphoricGrIn]

ichoderso, I think LukeA was referring to my original contention that MC-E's only yield a real advantage when the emitters are setup in a parallel/series arrangement and powered by 2 or more batteries in series - in which case the switch voltage is higher and current is lower to provide equivalent power.

I still don't see much (any?) advantage for these single 18650 direct-drive (I'm assuming) MC-E units over an equivalent P7.

What are the flood / throw differences likely to be for MC-E equipped versus P7 equipped flashlights in otherwise identical units?

 

[ahorton]

You could take an 8xAMC7135 driver and reroute the traces (scratch through the ones you don't want) so that each die gets current from two of the AMC chips. That way you don't risk thermal runaway nor do you need a boost driver.

This is in fact how I am already running my recently arrived MC-E. Except I made my own PCB. All 8 chips share the same ground and Vdd but the Outs are hooked up in 4 pairs (one to each -ve on the MC-E).

It runs very nicely at what I assume is 700mA to each die (I couldn't seem to find a small resistor to check current and my DMM has internal resistance of 0.8 Ohms, so that's no good for testing). The Vf of the dies at 700mA are 3.56, 3.56, 3.58, 3.58. So I figure it will drop out of regulation when the 18650 cell that runs it drops below 3.7V.

I'll be putting 4 cells in parallel to give me a capacity of 10Ah and over 3 hours of run time.

As for switches, I'm using one from **** Smith (Aussie) that is rated to 3A, 12V DC. It's also a double pole, double throw which will have bridges made so that it is a single pole. This will make me feel safer about the thing lasting when I run 2.8A through it for extended periods.

 

[EuphoricGrIn]

ahorton:

• What host are you using?
• Do you have access to any similar P7-based flashlights for comparison purposes?

It would be interesting to hear about differences in "real world" beam characteristics - flood/throw, CRI, tint - which I'm guessing could be due to differences in the emitters physical and optical characteristics, as well as differences in how the pills are able to dump heat?

 

[mrQQ]

there are now a lot of different models of mc-e lights at DX. Anyone knows which are worth looking at?

thanks