RETRO
XP i3 - Technical Details
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 +100 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 160 lumens! This is 3
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 or 4 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), power in Watts
(W):
|
RETRO
XP RunTimes In Hours |
Battery |
Mode 1
- 0.33W (50 lm) |
Mode 2
- 1.1W (160 lm) |
|
Mode 4
- 2.4W (325 lm) |
|
|
|
|
Oldham
Lead Acid 4V 16Ahr |
147 |
46 |
21 |
FX2
7Ahr |
37 |
11 |
4.5 |
FX3
7Ahr |
58 |
18 |
7.8 |
FX5
7Ahr |
91 |
31 |
13.7 |
Li-Ion
3.7V, 2.6Ahr |
21 |
6.8 |
3 |
Li-Ion
3.7V, 5.2Ahr |
44 |
13.7 |
6 |
Li-Ion
3.7V, 10.4Ahr |
87.5 |
27.5 |
12 |
3 x AA
3.6V, 2.8Ahr |
23 |
7.1 |
3.1 |
4 x AA
4.8V, 2.8Ahr |
31.5 |
9.7 |
4.3 |
3 x C
3.6V, 5Ahr |
41.3 |
12.8 |
5.6 |
4 x C
4.8V, 5Ahr |
56 |
17.3 |
7.7 |
3 x D
3.6V, 9.5Ahr |
78 |
24.2 |
10.7 |
4 x D
4.8V, 9.5Ahr |
107 |
33 |
14.6 |
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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 0.802A at 2.4W, 0.351A at 1.1W and 0.109A at
0.33W, 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 - 2.4W = (6.5 / 0.802) x 0.9 = 7.3 hours run time, 1.1W = (6.5 / 0.351)
x 0.9 = 16.7 hours run time and 0.33W = (6.5 / 0.109) x 0.9 = 53.7
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 (0.4 - 2.4W) for different cell combinations are: 2 cell battery
pack (2.4V) 73 - 82% efficiency, 3 cell battery (3.6V) pack 83 - 86%
efficiency, Li-Ion battery (3.7V) pack 83 - 86% efficiency, 4 cell battery
(4.8V) pack 85 - 88% and a 5 cell battery (6.0V) pack 90 - 92%
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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