Current draw of eggs?


#1

I’m trying to power eggs using a USB hub that also needs to power some other instruments. Can you let me know what the max current draw of an Egg is? I can’t seem to find in the specs.


#2

@eiliscoleman it depends on the model / sensors in play, and what mode you’re operating in (offline or online), but a conservative ballpark figure is about 250mA @ 5V in Wi-Fi mode.


#3

What about offline mode (writing on sd card) for both PM and NO2/CO eggs? We tried one NO2/CO egg with a biker using mobile power bank as power source and thought readings were lower than expected, so current draw could have been one of the reasons (sorry, bank specs unavailable).


#4

@AbedKhooli Offline mode is about half the power demand of Wi-Fi mode so about 120mA would be a conservative estimate.

As far as we know currently, there should be no significant difference between running the Eggs from a USB battery power source compared to using the AC/DC power supply that comes with the Egg. To be clear, we haven’t extensively studied whether the mode (offline vs wi-fi) and/or the power source (USB battery vs wall transformer) influences the measurements significantly (if at all). When we perform calibration over temperature, the units are powered by wall-transformers and connected to Wi-Fi.

We do know, however, that the gas sensors require some warm up time before their readings are stable. So even when you are operating in offline mode and battery powered, you should turn your Egg on and let it run for, I recommend, an hour before your intended data collection activity. This is obviously less of a concern in continuous monitoring situations.


#5

Great to know. If anyone on this forum tried AQEs in a mobile situation (as opposite to fixed location) and has other operation tips (like warm up period, which we confirm is required as most of our bike test was warming up!) to share, that would be highly appreciated.