Author Topic: Petzl MYO RXP, power consumption and battery box  (Read 1762 times)

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Offline Someone

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Petzl MYO RXP, power consumption and battery box
« on: August 10, 2014, 01:10:18 am »
Just some quick measurements to look at the standby and operating consumption of this headlamp, among some comments on it generally. It has programmable sequencing of the power button which retains its settings without the batteries installed, but uses a soft rubber button without any locking mechanism as when the head is in the closed position it is still possible to press it and turn the headlamp on.

The battery compartment is plastic with a soft rubber slip on cover and gets an IPx4 protection rating. Sadly they have not added any polarisation protection on the battery slots which is a bit dangerous since this lamp specifically supports lithium batteries as mentioned in the instructions, all previous lamps I have used from this manufacturer had plastic shrouds around the positive terminals to ensure correct polarity (and allow loading in the dark for instance).

An Agilent 34461A bench multimeter was added inline with the batteries using some small segments of copper tape with the backing paper still on.

Standby consumption is a base of 7.5uA, waking regularly enough to alias the trend plot of the multimeter even when running at 0.02PLC. Maths reported a peak of 110uA and a mean of 8.2uA which should be below the self discharge of any sensible battery.

Running with the supplied batteries of 4.72V at the lowest regulated intensity setting the current draw was 70mA, and at the highest setting (described as unregulated in the instructions) it consumed 850mA. Knowing all this it would be a good candidate for the lower cost energizer EA91 batteries, or even just normal E91/EN91 alkaline although anything but the lowest power settings would induce extra loss from their internal resistance.

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