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Power supply for Wind sensor Rev P

Posted: Fri Aug 28, 2020 8:46 am
by MendipMac
Hi Paul, I have ordered another Wind sensor Rev P from Jeelabs.

I would appreciate your advice on why I should not use a step up voltage to power the wind sensor? I am trying to develop a logger to leave in a cave for a week or so to monitor the draught (wind) from various locations, the speed and direction will depend on both outside temperature and atmospheric pressure. I obviously wanted to keep the unit small and didn't want to take a large 12V battery into the cave. I had originally thought I would use 4 x 1.5 (AA) batteries (6V) and then use the POLOLU-2117-UW Converter step up to 12V. The idea was to set the logger to record wind speed using the Rev P and temperature and atmospheric pressure using a BME280 every hour or so. What are the issues with using this setup? You were certain that the step up voltage unit was one of the reasons I was getting an elevated temperature (temp pin) on the previous Wind sensor.

Re: Power supply for Wind sensor Rev P

Posted: Fri Aug 28, 2020 9:21 am
by paul
MendipMac ,

I would advise using a meter to measure the current on the whole setup, then calculating whether your battery is going to be able to support the application for a week. For example if the total current draw is 50 mAH then
50 x 7 x 24 = 8400 mAH AA batteries capacity is in the 2200 mah range so that isn't going to work.

Hook up your whole setup and break the circuit somewhere, then insert the multimeter (set on current) to measure the current.

Another possibility would be to sample intermittently then shut down the wind sensor in between samples. This could greatly extend your battery life. Don't do this too quickly though, the wind sensor is going to need 15 seconds to stabilize.

You would need the boost circuit to have an enable input, or you could use a mosfet to switch the power. This could be a little tricky requiring a P channel mosfet and an N channel mosfet or transistor to switch the gate.

In any case - those are things to consider. Do a dry run for a day or two and check the voltages on the battery.

Re: Power supply for Wind sensor Rev P

Posted: Fri Aug 28, 2020 2:41 pm
by MendipMac
Hi Paul, yes I was intending to sample intermittently, using a RTC clock to0 wake up the Arduino every hour, run sensor for 30 secs / 1 minute, sample and then shut-down. I have done this for my CO2 logger using a 3.7v 2000mAh Li battery which lasted for over a month in the cave.

Sorry Paul but what was your thoughts on my POLOLU-2117-UW Converter step up to 12V for powering the Wind sensor rev P?

I was concerned you were questioning whether this voltage step up unit was a good idea as it might be dragging down the voltage on the AD causing issues with the ambient temp value?