RETRO XP -
Light Level Usage:
When you are on a multi-day trip Mode 1 - still
provides a perfectly adequate amount of light, so you can now consider dumping
the carbide or spare batteries as you can easily achieve +80 hours (for mixed
power mode usage with predominately Mode 1 output) lamp run time from a
standard Oldham battery.
For normal activities Mode 2 is perfect and
more than enough at 185 lumens! This is almost 4 times the light output of a
standard Oldham 3W bulb, however due to the light output being closer to 'day
light' and having a wider flood angle the perception of brightness is enhanced.
If you require an extra amount of light then Mode 3 gives that extra
illumination.
RETRO XP - Run Times:
If you have a battery pack or
cell combination that is not listed below it is possible to calculate the
estimated battery run time, see: RETRO XP - Input Voltage / Current Curves. The
table below lists estimated lamp run times for various battery packs. Light
output is in Lumens (lm).
Battery |
RETRO
XP RunTimes In Hours |
|
Mode 1
- 70 lm |
Mode 2
- 185 lm |
Mode 3
- 400 lm |
Oldham
Lead Acid 4V 16Ahr |
90.0 |
42.0 |
19.0 |
FX2
7Ahr |
20.0 |
9.0 |
3.8 |
FX3
7Ahr |
35.0 |
16.0 |
7.4 |
Li-Ion
3.7V, 2.6Ahr |
13.5 |
6.3 |
2.8 |
Li-Ion
3.7V, 5.2Ahr |
27.1 |
12.5 |
5.7 |
Li-Ion
3.7V, 10.4Ahr |
54.2 |
25.0 |
11.3 |
3 x AA
3.6V, 2.8Ahr |
14.0 |
6.5 |
3.0 |
4 x AA
4.8V, 2.8Ahr |
19.0 |
8.9 |
4.1 |
3 x C
3.6V, 5Ahr |
25.4 |
11.6 |
5.3 |
4 x C
4.8V, 5Ahr |
33.7 |
15.8 |
7.2 |
3 x D
3.6V, 9.5Ahr |
48.0 |
22.1 |
10.1 |
4 x D
4.8V, 9.5Ahr |
64.0 |
30.1 |
13.9 |
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RETRO XP -
Input Voltage / Current Curves:
The switch mode power supply keeps a
constant power level to the LED's over a varying input voltage. As the input
voltage falls the input current rises. From the curves below it is possible see
the current that will be drawn for a particular input voltage. This can be used
to estimate the lamp run time on a particular battery pack.
If a 3 cell
NiCAD battery pack with a capacity of 6.5Ah is used to power the RETRO XP, then
the total input voltage is 3.6V, this corresponds to a input current of 0.900A
at 400lm, 0.408A at 185lm and 0.187A at 70lm, dividing the battery pack
capacity by the input current and multiplying the result by 0.9 will give an
estimation of the run time for a particular setting - 400lm = (6.5 / 0.900) x
0.9 = 6.5 hours run time, 185lm = (6.5 / 0.408) x 0.9 = 14.3 hours run time and
70lm = (6.5 / 0.187) x 0.9 = 31.3 hours.
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RETRO XP -
Efficiency Curves
Using a switch mode power supply to drive LED's is
more efficient than limiting the current with a resistor especially at higher
powers (a resistor can only be used if the forward voltage of the LED's is
lower than the batteries - in this case with two 1W LED's the forward voltage
is around 6V). Where possible it is better to use a higher number of cells
(higher input voltage) to keep efficiencies high and power loss to the minimum.
Efficiencies over the whole power range (0.46 - 2.6W) for different cell
combinations are: 2 cell battery pack (2.4V) 64 - 70% efficiency, 3 cell
battery (3.6V) pack 69 - 81% efficiency, Li-Ion battery (3.7V) pack 69 - 81%
efficiency, 4 cell battery (4.8V) pack 70 - 84% and a 5 cell battery (6.0V)
pack 82 - 87% efficiency.
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RETRO XP - Light Output:
Due to the power supply light output
remains constant as the battery pack drains. The LED's will still give out
light when a normal bulb would not even glow. The optimal input voltage range
is 1.3 to 6V, however the RETRO XP will also work with input voltages as high
as 7V (absolute maximum), if the input voltage is above 6V then the lower
settings will actually give more output than stated - this is because the
switch mode power supply cannot regulate when the input voltage goes above the
LED forward voltage - this will not damage the unit. If you look at the curves
below this can be seen above 6V.
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