Parks College Parachute Research Group

Airtec GmbH Cypres AAD Power Consumption


Investigator: Gary Peek


Background:

Much has been said and many questions have been asked related to Airtec's implied policy in advertisements that tell you to "turn it on (the Cypres) and forget it." Most of us are used to turning off electrical devices when they are not being used, so it is hard for us to take the advice of those suggesting that we do otherwise.

Actually, the Cypres manual does not say that, and even mentions several situations where you would definitely want to turn it off and then back on again to re-calibrate it. What the manual does say is that the battery life was taken into consideration when the Cypress was designed and that it can easily accommodate situations like having to power-cycle the Cypres to re-calibrate it.

Many people have speculated as to the desirability of turning off their Cypres AAD after use specifically to save battery power, rather than letting the Cypres turn itself off hours later. I, too, had speculated about this, but without knowing how much battery power was being used by a Cypres in different situations, any conclusion formed by my speculation would be faulty.

Tests Performed:

I was curious enough about how much current the Cypres used that when my Cypres was due for battery replacement and the battery connections were easily accessible, I did a series of current measurements.

I used a small "altitude chamber" combined with a hand operated pump to remove air from the chamber and simulate increased altitudes. Naturally, if I had increased the equivalent altitude in the chamber to the point where the Cypres armed itself, and then something failed on my test setup which caused a rapid re-pressurization of the chamber, the Cypres would have fired and the experiment would have cost me the price of a loop cutter assembly, therefore, I increased the equivalent altitude in the chamber only enough to see the effect of increasing altitude, and did not do a complete test of the Cypres operation.

Disclaimer:
These values are from only one unit, at one particular time, and in one particular test situation, and may not reflect the current consumption of Cypres AAD's in general. Furthermore, these measurements are provided only as general information for the curious, and are not to suggest to anyone how to operate their Cypres AAD or when to turn it on or off.

If in doubt about how to operate your Cypres, read the manual!




Test results:

Special note: When my Cypres was calibrating just before the tests, the display paused at 6280 (meaning 6.28 volts), but with the ammeter connected it paused at 5840. I do not have any explanation of why this occurred other than the voltage drop caused by the wires I used to make the measurements.

Key:
mA = milliampere = 1 thousandth of an amp
uA = microampere = 1 millionth of an amp
(Both are quite small of course, but not insignificant when
talking about a device that operates for 2 years on batteries.)

Battery connected but Cypres off           1.7uA
(Cypres switched off)

Button pushed                              7.6mA
(as when switching on or off)

LED (light) on                            13.5mA
(during the switching on or off process)

During calibration                        6-13mA
(when the display is counting down)

After calibration completed (initially)   0.23mA

Cypres on but at rest                     0.23mA, increasing to 6.5mA
(as in the time between jumps)            for 3 seconds every 30 seconds
                                          (to check for altitude change)

Cypres undergoing an increasing altitude   6.5mA
(as in a climbing aircraft)





For questions or comments about this study contact Gary Peek at peek@pcprg.com

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