This is a bit of a puzzle. My oil sensor stopped transmitting last night. I replaced the batteries just now and its working again. The voltage from is 3 x AA supply had dropped to 4.2V. This is supposed to be enough to work a PICO W off? And IIRC on test it worked down to around 3.8V or so.
Anyone know more?
The WiFi needs more....
Yes. but allegedly not *that* much...On test it was the ultrasonic sensor that gave out before the wifi. At around 3.8V
I don't know the Pico's power specs, but maybe there's resistance on one of the electrical connections, such that the voltage drops more under load than where and when you measured it?
I measure at the far end of the chain
It has since failed again after only a few hours.
Back to the drawing board
yes
or on batteries itself?
yes, later
nope..
Hello
TP> This is a bit of a puzzle. My oil sensor stopped transmitting last TP> night. I replaced the batteries just now and its working again. The TP> voltage from is 3 x AA supply had dropped to 4.2V. This is supposed to TP> be enough to work a PICO W off? And IIRC on test it worked down to TP> around 3.8V or so.
How did you check voltage? On working device, or on batteries itself? One of batteries may be depleted more than others and whole pack may give less current than usual.
Best regards, Nikita.
How? Multimeter, USB power measuring dongle, oscilloscope.
The first two will average the voltage readings over a short period. You really need a scope to spot transient drops, such as when the Pico is transmitting over WiFi.
---druck
Further investigation shows that a brand new set of AAs has discharged more overnight than the last set had in six months...(4,3V)
That is not possible if the nano timer is operating correctly: I suspect there is a constant battery drain from the unit somewhere.
Fortunately it's a socketed unit and I have spares...
I need to 3D print a cover for the oil tank before I can remove it however..it looks like rain
I'm not sure I trust something to measure it's own voltage, when it might be experiencing low voltage.
---druck
That is probably because you have not understood the first thing about how a PI PICO W is constructed.
It has its own onboard buck/boost regulators and the ADC is driven from a stabilised 3V line
The rest of the chip runs on a less well regulated 3.3V.
The chip runs down to 1.8V
The ADC is not set up to 'measure its own voltage' but that of the incoming voltage TO the chip.
FWIW my rpi4 is able to give low voltage warnings, seemingly reliably.
Yes. I have the thing back on the bench and have tested with an ammeter and a scope as well as voltmeter. After several startups it blew a 200mA fuse in the ammeter . So short term peaks are a little over that. Well a good excuse to buy a much better digital meter then. I was already sick of the previous one, Ali express are giving the previous type away for free when part of another order...so that is what THEY were worth...
I did catch it in two fault modes, one was an oscillating low energy switch, which results in the PICO never being switched on, and the other was some kind of network issue that resulted in it never switching off.
Either might cause loss of connection and high battery drain.
Both have not been possible to reproduce reliably.
I've modified the code to hopefully eliminate the 'I am stuck trying to connect to a TCP socket' condition, which should not happen anyway.
The oscillation might be caused by a bad electrolytic, and cold
Its not reoccurred since testing on the bench
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