The Natural Philosopher <tnp@invalid.invalid> wrote:

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?

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?

--
__ __
#_ < |\| |< _#

--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 11/05/2026 15:29, David Taylor wrote:

On 11/05/2026 13:49, The Natural Philosopher wrote:

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


--
If I had all the money I've spent on drink...
..I'd spend it on drink.

Sir Henry (at Rawlinson's End)


--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

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?

--
"When a true genius appears in the world, you may know him by this sign,
that the dunces are all in confederacy against him."

Jonathan Swift.

--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 11/05/2026 13:49, The Natural Philosopher wrote:

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....

--
David
Web: https://www.satsignal.eu

--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Hello

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.

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.

--- GoldED+/LNX 1.1.5-b20250409
* Origin: Éáí«ΓáÑΓ, ¡« ¿ºñá±Γ úαπßΓ¡δÑ ºóπ¬¿. (1:229/616.3818)

On 12/05/2026 17:00, Nikita Nazarenko wrote:

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,

yes

or on batteries itself?

yes, later

One of batteries may be depleted more than others and whole pack may give less current
than usual.

nope..

Best regards, Nikita.

--
There is nothing a fleet of dispatchable nuclear power plants cannot do
that cannot be done worse and more expensively and with higher carbon emissions and more adverse environmental impact by adding intermittent renewable energy.


--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 11/05/2026 23:38, Computer Nerd Kev wrote:

The Natural Philosopher <tnp@invalid.invalid> wrote:

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?

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

--
There is nothing a fleet of dispatchable nuclear power plants cannot do
that cannot be done worse and more expensively and with higher carbon emissions and more adverse environmental impact by adding intermittent renewable energy.


--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 13/05/2026 12:12, druck wrote:

On 12/05/2026 14:04, The Natural Philosopher wrote:

On 11/05/2026 23:38, Computer Nerd Kev wrote:

The Natural Philosopher <tnp@invalid.invalid> wrote:

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?

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

How? Multimeter, USB power measuring dongle, oscilloscope.

Sigh

The Pi PICO W has three ADCs on board and one is connected directly to
VSYS by a voltage divider. I transmit that data every time the device successfully activates.

This is the relevant code frangment
while (TRUE)
{
temperature = read_temperature();
printf("getting distance\n");
distance=get_distance();
voltage=get_battery_voltage();
// check wifi is up and connect/reconnect as necessary..if cant
connect in 10 goes, give up.
for(i=0;i<10 ;i++)
{
printf("Attempting to connect to wifi %s\n",ssid);
cyw43_arch_wifi_connect_timeout_ms(ssid, password,
CYW43_AUTH_WPA2_AES_PSK, 20000);
sleep_ms(1000); // allow DHCP handshake to take place
if ((cyw43_tcpip_link_status(&cyw43_state,CYW43_ITF_STA)) ==
CYW43_LINK_UP)
break;
}
if(i==10)
{
suicide();
sleep_ms(1000);
}

and so on.

The battery voltage is read after wifi initialisation but before a
connection is established.
The log file on the wifi hotpoint reveals no successful connections at
all in the last 30 hours

Not even one that aborts later from low/bad signal.


This is the last transmission

OIL-SENSOR
OIL-TANK
-79dBm
78.47cm
5.9°C
4.5V
11/05/2026 21:52:47

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.

Pico should never gulp more than 200mA and that is well within a dry
cell . There is a 220uF cap as well to handle spikes.

From raspberry Pi forum

"Re: Pico W power consumption

"Sun Aug 07, 2022 1:32 pm
Using a battery pack with 3 AA batteries, reading 4.6V, I measured 52 mA
using wifi and the LED. While starting up it did spike up to ~150 mA
briefly. "


Anyway it's all irrelevant as the new batteries stopped working almost immediately, Last reading was 4.5V

I suspect it us the Triffid like growth of the Russian vine over the oil
tank plus a stiff breeze making the leaves flutter.

I will remove the batteries and check them with a multimeter. I reloaded
with the cheapest possible amazon 'value' cells and it is entirely
possible that they are in fact utter shit

I will actually order energizer lithium AAs from Amazon and try those.
They have a far higher OCV (up to 1.75v) and netter sustained discharge voltages as well

When I tested the unit indoors for a month with an admittedly better
wifi connection it operated down to under 4V measured by the ADC.
Limiting factor was the ultrasonic sensor. Not the wifi.

Ah well, These things are sent to try us.

Let me see what is going on with the unit now...

--
?Puritanism: The haunting fear that someone, somewhere, may be happy.?

H.L. Mencken, A Mencken Chrestomathy


--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 13/05/2026 12:12, druck wrote:

On 12/05/2026 14:04, The Natural Philosopher wrote:

On 11/05/2026 23:38, Computer Nerd Kev wrote:

The Natural Philosopher <tnp@invalid.invalid> wrote:

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?

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

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



--
The lifetime of any political organisation is about three years before
its been subverted by the people it tried to warn you about.

Anon.


--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 14/05/2026 18:08, druck wrote:

On 13/05/2026 14:06, The Natural Philosopher wrote:

On 13/05/2026 12:12, druck wrote:

On 12/05/2026 14:04, The Natural Philosopher wrote:

I measure at the far end of the chain

How? Multimeter, USB power measuring dongle, oscilloscope.

Sigh

The Pi PICO W has three ADCs on board and one is  connected directly
to VSYS by a voltage divider. I transmit that data every time the
device successfully activates.

I'm not sure I trust something to measure it's own voltage, when it
might be experiencing low voltage.

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.

---druck

--
The lifetime of any political organisation is about three years before
its been subverted by the people it tried to warn you about.

Anon.


--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 14/05/2026 22:27, Pancho wrote:

On 5/14/26 22:17, The Natural Philosopher wrote:

On 14/05/2026 18:08, druck wrote:

On 13/05/2026 14:06, The Natural Philosopher wrote:

On 13/05/2026 12:12, druck wrote:

On 12/05/2026 14:04, The Natural Philosopher wrote:

I measure at the far end of the chain

How? Multimeter, USB power measuring dongle, oscilloscope.

Sigh

The Pi PICO W has three ADCs on board and one is  connected directly
to VSYS by a voltage divider. I transmit that data every time the
device successfully activates.

I'm not sure I trust something to measure it's own voltage, when it
might be experiencing low voltage.

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


--
In theory, there is no difference between theory and practice.
In practice, there is.
-- Yogi Berra


--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 5/14/26 22:17, The Natural Philosopher wrote:

On 14/05/2026 18:08, druck wrote:

On 13/05/2026 14:06, The Natural Philosopher wrote:

On 13/05/2026 12:12, druck wrote:

On 12/05/2026 14:04, The Natural Philosopher wrote:

I measure at the far end of the chain

How? Multimeter, USB power measuring dongle, oscilloscope.

Sigh

The Pi PICO W has three ADCs on board and one is  connected directly
to VSYS by a voltage divider. I transmit that data every time the
device successfully activates.

I'm not sure I trust something to measure it's own voltage, when it
might be experiencing low voltage.

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.


--- PyGate Linux v1.5.14
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)