Black Diamond Headlamp bulbs.

[Chuen]

Does anyone know the true rating for black diamond bulbs? The ultrabright bulb is rated at 0.7 A. However, when I measured the current draw and voltage of my spaceshot 2, I found that it's pulling 3.7W from the battery. 3.7W / 0.7A = 5.3 V. Given that the same bulb can also be used in other 3 cell bd headlamp, it's unlikely that it's a 5V bulb. So either the 0.7W rating is inaccurate or it's beening overdriven in the spaceshot. Anyone got an idea?

I'm also curious about what kind of bulb they are using in the supernova. Is it an ordinary or multifilament bulb?

 

[Alan]

I was told by Black Diamond that it's 3.6v bulb. Spaceshot is a regulated light thus current feed to the bulb is different from current drawn from the battery. By the way, how did you measure wattage from the battery?

Alan

 

[Chuen]

Thanks for the answer Alan. I measure the voltage the current draw from the battery under load. Multiply the 2 would give the power draw from the battery. That's around 3.7W. Since the regulator is claimed to be over 99% efficient, I would assume all 3.7W is feeded to the bulb.
Another thing puzzling me is that it's drawing 100ma from the battery in the LED mode, yet the LED is dimmer then an ARC-aaa. 100ma at 8V is an awful lot of power for an LED. Could the pulsing current draw screw the current reading?

 

[hairydogs]

Alan will tell u that all regulation tend to be extremely inefficient. I would be surprised if the efficiency reach 65%.

Added to this is the dimmer circuitry which will introduce further efficiency loss.

This is why the lamp is not all that bright. So at least next time, opt for a lamp with regulation but forget about the diming circuits.

 

[papasan]

a step-down type PWM circuit (like the willie hunt LVR) can get in the upper 90s for effeciencey. i do believe that willie's web page claims 98% eff. with a dimmer.

if the eff. claims are correct then measure the wattage comming off the battery and it would be almost the same going into the lamp.

 

[hairydogs]

papasan

thanks for the info. - my oversight that we are talking about a step down regulating circuits - from 9 V to 3.6 V. but what is the effect or efficiency loss when coupled this circuit with a dimmer?

On the other hand, why black diamond spaceshot 2 needs to step down to 3.6V from 9V rather than from 4.5 V or 6V as in the case of supervona? There must be a reason.

I always think the spaceshot 2 is too dim and probably the supernova would be dimmer still.

 

[Chuen]

The spaceshot is using Willie Hunt LVR3j regulator/ dimmer (it's stamped on the PCB). Willie Hunt claim an efficiency of over 99% in their webpage although I don't know how accurate that claim is.

As for the bulb in the supernova, I just find out that it's not a multi-filament bulb. The 3 output levels are achieved by a dimmer. The fact that the supernova needs a different bulb from other 3 cell bd headlamp leads me to believe that the bulb is of different voltage, perhaps 2.4V? That would explains why it requires only 4 cell to operate.

While the spaceshot is dim comparing to other flashlights such as the surge or scropion, I find the output quite respectable as far as headlamp goes. It's more then twice as bright as the halogen beam in a Petzl duo. And yes, the supernova is dimmer then the spaceshot. I tried both in a store.

 

[papasan]

the step-down circuit that willie uses, i suspect, is a PWM that simply modifies the duty cycle. meaning that if you have a 9V source and want 4.5V output then you turn the batteries on for .5 seconds and leave them off for .5 seconds, giving you an average of 4.5V output. simply turning the batteries on and off like this is a highly efficient way to do things assuming you have a good low-R transistor. to dim a circuit like this it's a simple matter, just change the duty cycle. say .2 seconds on and .8 seconds off for a 1.8V average output from a 9V source.

unfortunatly, unlike LEDs, filiminet bulb efficiencey goes _way_ down when it's under-driven so alot of the run-time gains from dimming the bulb go away, but it's still better than nothing.

 

[hairydogs]

papasan and chuen

Again, thanks for the info.

From what I get, in order to operate a 3.6V bulbs with a power regulating circuit in spaceshot 2 and a 2.4 V bulb in the supernova, black diamond needs to draw the power from a 9V power source and 6V source respectively.

Whereas, when no power regulation is required, a power soruce of 6V (spaceshot 2) and 4.5 V (supernova) may serve the purpose.

If this is the case, I do not see the design is efficient at all. Have I misunderstood the picture?