Re: ArcMania Super MJLED 3-mm upgrade for Mag-Lite Solitaire: any review?
After recently reading the very favourable reviews in the CandlePower Forum threads about the new Arcmania Super MJLED 3-mm for Mag-Lite® Solitaire®, I was sufficiently convinced it was well worth getting and so purchased one
from Lighthound
http://www.lighthound.com
http://www.lighthound.com/index.asp?PageAction=VIEWPROD&ProdID=2217
Their service and postage rates for international customers were great and it arrived a third of the way around the World in just over a week.
I've always run my Solitaire® on a Ni-MH cell because I dislike non-rechargeable cells. However, this had meant having to accept the dimmer, yellowish light that results from the lower cell voltage.
I'm probably in the minority because even despite this I've still liked the torch and found it to be useful, especially for seeing in tight spaces when servicing electronic equipment.
I have to say this new drop-in LED for it is absolutely brilliant.
I'm thrilled with the improvement it has made, transforming the Solitaire® into an exceedingly more useful and desirable torch with a bright beam that remains white despite lower voltage of a Ni-MH cell.
The torch still retains its ability to focus the beam. Maximum focus is not quite as tight as with the original incandescent bulb, but not too far short of it. That's because the LED's die is slightly less of a point source of light than the tungsten filament. Nevertheless, its Lambertian emitting area is still tiny, a little under a millimetre in diameter, radiating over an angle of 180 degrees so that it utilizes the reflector and works well in candle mode too. Even when fully focused, the spill is bright and very useful.
The only slight disadvantage is that the head does not screw down quite as far when the torch is turned off. However, when the head is twisted to turn the torch on the LED is immediately at the focal point of the reflector (maximum focus), so unlike the incandescent bulb, it does not require a turn or so to maximally focus it. This should save wear and tear on the threads. When defocused to make a broader beam there is a welcome absence of a doughnut (again, unlike the incandescent bulb) until the head has been unscrewed so far that it can be removed.
Compared to a white Luxeon® LED it is bluer with an ever so slight lavender tint, especially in the spill, which I don't mind at all. I estimate its colour temperature is somewhere between 6500-8500 Kelvins.
Using a variable-voltage power supply I have measured its current consumption versus input voltage and calculated input power and effective resistance over the voltage range up to 1.6 V. Unfortunately I can't insert the graphs in this posting, but here is the data:
Voltage Current Power Effective Resistance Comments
0.08 0.000 0.000 ∞ Stops conducting
0.09 0.006 0.001 15.0
0.10 0.038 0.004 2.6
0.11 0.085 0.009 1.3 LED extinguishes as input voltage is being decreased
0.15 0.099 0.015 1.5
0.20 0.112 0.022 1.8
0.25 0.121 0.030 2.1
0.30 0.127 0.038 2.4
0.35 0.129 0.045 2.7
0.40 0.125 0.050 3.2
0.45 0.127 0.057 3.5
0.50 0.130 0.065 3.8
0.55 0.133 0.073 4.1 LED starts as input voltage is being increased
0.60 0.136 0.082 4.4
0.65 0.139 0.090 4.7
0.70 0.141 0.099 5.0
0.75 0.143 0.107 5.2
0.80 0.147 0.118 5.4
0.85 0.149 0.127 5.7
0.90 0.152 0.137 5.9
0.95 0.154 0.146 6.2
1.00 0.157 0.157 6.4
1.05 0.161 0.169 6.5
1.10 0.164 0.180 6.7
1.15 0.168 0.193 6.8
1.20 0.172 0.206 7.0
1.25 0.176 0.220 7.1
1.30 0.182 0.237 7.1
1.35 0.188 0.254 7.2
1.40 0.192 0.269 7.3
1.45 0.199 0.289 7.3
1.50 0.205 0.308 7.3
1.55 0.211 0.327 7.3
1.60 0.219 0.350 7.3
Increasing from 0 V, the LED doesn't light until about 0.55 V. Up to 1.20 V the lamp exhibits a rising effective resistance from about 4 to 7 Ohms, though not enough to prevent the current from rising. From 1.20 V to 1.40 V the lamp's effective resistance flattens, becoming a constant 7.3 Ohms from 1.40 V to 1.60 V.
Although I have read that the lamp can tolerate an absolute maximum input of about 1.8-1.9 V, I wasn't game to try this. The data can probably be extrapolated to predict the current draw and power consumption at that voltage.
Decreasing the voltage, the LED extinguishes when it gets down to 0.11 V! However, it is understandably very dim at this stage. Oddly, there is a slight hump in the current as the voltage passes from 0.40 V to 0.35 V.
The conclusion is that the switch-mode power supply in this lamp is not fully regulated: neither current nor power are constant. There is therefore a very slight difference in brightness (which is hardly noticeable) between a new non-rechargeable cell and a Ni-MH cell. The relatively flat discharge profile of a Ni-MH cell means that there is very little dimming as this sort of cell discharges, so light output is pretty constant at a current of about 180 mA (input power 235 mW). This compares with the original incandescent bulb (which had maybe 10 hours of use and the envelope was starting to darken on the inside) drawing 200 mA (260 mW) and a new incandescent bulb drawing 220 mA (285 mW). This LED lamp is producing
far more light with only 82-90% of the power consumption!
With a fully charged 900-mAh (nominal) AAA Ni-MH cell it ran for 4 hours, 10 minutes (the cell is sixteen months old and may have lost come capacity). When it was exhausted the torch went into moonlight mode for about 1 minute then extinguished abruptly. Still, this would give adequate warning to put in a fresh, recharged cell.
Cheers,
John.
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