RETRO
XP i3 400lm - 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 +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).
|
RETRO
XP RunTimes In Hours |
Battery |
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 |
13.8 |
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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.
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