I have developed a first prototype application using the SDS011 sensor. While running it with a LoPy and a PyTrack I assembled a buck/boost converter to create the 5V power supply for the SDS011 due to a fully functional Lipo Backup battery solution.
But the problem seems to lie in the low battery situation that probably killed the fan due to flapping power from the Lipo security circuit detecting under voltage at the load and swithing the battery off. Then the battery get enough voltage to come back and thus the fan draws a higher power up current to start the motor.
This is my assumption that probably killed the electronics in that fan.
How could I mitigate this scenario?
Simply monitoring the lipo voltage within my code and disable the buck/boost converter?
While thinking about power savings, I found two options to reduce power consumption:
Control the SDS011 to go into power saving mode (adding a 3.3V to 5V level shifter required) or
switching off the buck/boost converter completely by a 2N7000 switching mosfet?
I have built a few prototype systems which included this sensor. In fact I have a couple of the on my desk at the moment.
I suspect the fan on the SDS011 is just a dumb motor that does not contain any electronics. I do not believe the flapping of the +5 volt rail would kill the fan. The fan, being an electro-mechanical device, may simply have had a mechanical related failure. Have you removed the connector from the sensor board and tried powering it directly from +5 volts? If the motor is indeed dead I would not immediate look to modify your design. There is one thing to consider, did you realise that the sensor has specific mounting requirements? It turns out I have been using these upside down
My power management is the other way around, I supply my entire system from solar power through +5 volt switching regulator and drop it to 3.3v for the electronics. For the SDS011 I feed the +5 volts via a FET. When it is time to sense, I power up the sensor via the FET. However I also disable the serial interface between the SDS011 and the rest of my system when the +5volt is disables to prevent powering the SDS011 via the sensors Rx input. This is to avoid latch up which could otherwise kill the processor in the sensor.
