The process of debugging my remote oil level sensor continues. This is
based on a PICO W plus a nano timer to wake it up every couple of hours
to send a message via the home wifi.

After an issue in which it stayed woke, and flattened its battery and
never sent any data, the code has been modified and its back on the tank
after extensive testing, with three *lithium* batteries.

I was unaware of lithium primary cells in an AA format till now. But
three of these start out at 5,2V and stick around 5V for a long time.
Perfect for the unit.

In addition they are reckoned to be more tolerant of the cold and to
last twice as long.

Early days, but if anyone is thinking of battery powering a PICO outside
for intermittent use, a nano timer and lithium primary cells looks to
be the best technology.


--
Any fool can believe in principles - and most of them do!



--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 14/06/2026 18:48, rbowman wrote:

On Sun, 14 Jun 2026 12:17:25 +0100, The Natural Philosopher wrote:

Early days, but if anyone is thinking of battery powering a PICO outside
for intermittent use, a nano timer and lithium primary cells looks to
be the best technology.

Why not 18650s? 2 would give you a little over 7V

"The maximum recommended input voltage for a Raspberry Pi Pico or Pico W
is 5.5V. Powering the board above 6.0V will permanently damage the
onboard voltage regulator"

and battery holders
similar to the AA types are available. The TP4056 charging modules are inexpensive if you want to incorporate USB charging.

--
"When one man dies it's a tragedy. When thousands die it's statistics."

Josef Stalin



--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 15/06/2026 14:58, Peter Heitzer wrote:

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

On 15/06/2026 13:06, Peter Heitzer wrote:

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

On 14/06/2026 18:48, rbowman wrote:

On Sun, 14 Jun 2026 12:17:25 +0100, The Natural Philosopher wrote:

Early days, but if anyone is thinking of battery powering a PICO outside >>>>>> for intermittent use, a nano timer and lithium primary cells looks to >>>>>> be the best technology.

Why not 18650s? 2 would give you a little over 7V

"The maximum recommended input voltage for a Raspberry Pi Pico or Pico W >>>> is 5.5V. Powering the board above 6.0V will permanently damage the
onboard voltage regulator"

One cell should be sufficient for powering the Pico. The regulator
lower limit is 2.3 V so there is a need for deep discharge protection
on the cell.

I bench tested the device., Its not just a pico W. There is an
ultrasonic device in there as well.

It stared to fail around 4V.

Then two 18650 in serial and a 5V switching regulator should do the
job.

Sigh,

The nano power switch will not handle that voltage
Putting a regulator in front negates the point of having a nano power
switch,

Perhaps a small USB powerbank may also work if you find one
that does not shut off if the consumed current it to low.

Or drain the power in a month...

Sheesh. Why do some people always think they know better?

"I have examined, X,Y,Z,A ,B and C I found Q to be optimal"
"Why didn't you use A B or C?"
"
--
Climate is what you expect but weather is what you get.
Mark Twain


--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

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

On 15/06/2026 19:49, Brian Gregory wrote:

On 14/06/2026 12:17, The Natural Philosopher wrote:

The process of debugging my remote oil level sensor continues. This is
based on a PICO W plus a nano timer to wake it up every couple of
hours to send a message via the home wifi.

nano timer ??

What's that then?

TPL5100

https://www.ti.com/product/TPL5110

It's disappointing that it's not available in a higher voltage version
since, as you say, it needs to be directly connected to the battery.

I suppose one workaround would be to use a single lithium ion cell to give
you down to 3V and then a boost converter which you only run when the
CPU is operating. Timer goes off, boost converter spins up to power your
CPU at a stable 5V (or whatever), then CPU tells it shut off again once
done.

That's likely going to take more power than just running directly off
battery, but the flipside is you can install several 18650 cells in parallel
if you want to get more capacity.

The primary lithium AAs aren't a terrible option though, especially if you
are more likely to be killed by self-discharge of the battery than by your
own load.

Theo

--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 14/06/2026 18:48, rbowman wrote:

Why not 18650s?

I've been using Li-Ion rechargeables from disposed vapes to power many
battery devices. Although the supply has dried up now, I managed to
collect over 100 3.7V 500mAh, 550mAh, 1400mAh and 1800mAhr cells when
out walking the dog.

You still find such vapes but rare now. You do find rechargeable vapes
now and then and can recover the USB rechargers from them to use with previously recovered batteries. Rechargeables are normally disposed
because the battery is dead. All the chargers have been fine.



--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 15/06/2026 12:31, The Natural Philosopher wrote:

On 14/06/2026 18:48, rbowman wrote:

On Sun, 14 Jun 2026 12:17:25 +0100, The Natural Philosopher wrote:

Early days, but if anyone is thinking of battery powering a PICO outside >>> for intermittent use,ÿ a nano timer and lithium primary cells looks to
be the best technology.

Why not 18650s? 2 would give you a little over 7V

"The maximum recommended input voltage for a Raspberry Pi Pico or Pico W
is 5.5V. Powering the board above 6.0V will permanently damage the
onboard voltage regulator"

and battery holders
similar to the AA types are available. The TP4056 charging modules are
inexpensive if you want to incorporate USB charging.

The Energizer lithium primary cells are a lithium iron sulphide
technology. I have measured the cell voltages of about 20 new
cells and found them all to be between 1.800V and 1.805V open
circuit. This would make them completely safe for this usage.
They maintain a voltage above 1.5V for much of the discharge
curve and most importantly they are unlikely to leak.
John


--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

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

On 15/06/2026 13:06, Peter Heitzer wrote:

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

On 14/06/2026 18:48, rbowman wrote:

On Sun, 14 Jun 2026 12:17:25 +0100, The Natural Philosopher wrote:

Early days, but if anyone is thinking of battery powering a PICO outside >>>>> for intermittent use, a nano timer and lithium primary cells looks to >>>>> be the best technology.

Why not 18650s? 2 would give you a little over 7V

"The maximum recommended input voltage for a Raspberry Pi Pico or Pico W >>> is 5.5V. Powering the board above 6.0V will permanently damage the
onboard voltage regulator"

One cell should be sufficient for powering the Pico. The regulator
lower limit is 2.3 V so there is a need for deep discharge protection
on the cell.

I bench tested the device., Its not just a pico W. There is an
ultrasonic device in there as well.

It stared to fail around 4V.

Then two 18650 in serial and a 5V switching regulator should do the
job. Perhaps a small USB powerbank may also work if you find one
that does not shut off if the consumed current it to low.


--
Dipl.-Inform(FH) Peter Heitzer, peter.heitzer@rz.uni-regensburg.de

--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 15/06/2026 13:04, John R Walliker wrote:

On 15/06/2026 12:31, The Natural Philosopher wrote:

On 14/06/2026 18:48, rbowman wrote:

On Sun, 14 Jun 2026 12:17:25 +0100, The Natural Philosopher wrote:

Early days, but if anyone is thinking of battery powering a PICO
outside
for intermittent use,ÿ a nano timer and lithium primary cells looks to >>>> be the best technology.

Why not 18650s? 2 would give you a little over 7V

"The maximum recommended input voltage for a Raspberry Pi Pico or Pico
W is 5.5V. Powering the board above 6.0V will permanently damage the
onboard voltage regulator"

and battery holders
similar to the AA types are available. The TP4056 charging modules are
inexpensive if you want to incorporate USB charging.

The Energizer lithium primary cells are a lithium iron sulphide
technology.ÿ I have measured the cell voltages of about 20 new
cells and found them all to be between 1.800V and 1.805V open
circuit.ÿ This would make them completely safe for this usage.
They maintain a voltage above 1.5V for much of the discharge
curve and most importantly they are unlikely to leak.
John

Exactly. I have lithium ion polymer cells coming out of my ears, but one
cell is too low and two cells are too high.

This technology is higher voltage, greater capacity, and better
performance over the discharge curve and in heat and cold than alkaline
cells.
I estimate over a years life.

Which is good because its a ladder climb to access the unit.

--
"If you don?t read the news paper, you are un-informed. If you read the
news paper, you are mis-informed."

Mark Twain


--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 15/06/2026 19:49, Brian Gregory wrote:

On 14/06/2026 12:17, The Natural Philosopher wrote:

The process of debugging my remote oil level sensor continues. This is
based on a PICO W plus a nano timer to wake it up every couple of
hours to send a message via the home wifi.

nano timer ??

What's that then?

TPL5100

https://www.ti.com/product/TPL5110


--
Future generations will wonder in bemused amazement that the early twenty-first century?s developed world went into hysterical panic over a globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to contemplate a rollback of the industrial age.

Richard Lindzen


--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 15/06/2026 13:06, Peter Heitzer wrote:

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

On 14/06/2026 18:48, rbowman wrote:

On Sun, 14 Jun 2026 12:17:25 +0100, The Natural Philosopher wrote:

Early days, but if anyone is thinking of battery powering a PICO outside >>>> for intermittent use, a nano timer and lithium primary cells looks to >>>> be the best technology.

Why not 18650s? 2 would give you a little over 7V

"The maximum recommended input voltage for a Raspberry Pi Pico or Pico W
is 5.5V. Powering the board above 6.0V will permanently damage the
onboard voltage regulator"

One cell should be sufficient for powering the Pico. The regulator
lower limit is 2.3 V so there is a need for deep discharge protection
on the cell.

I bench tested the device., Its not just a pico W. There is an
ultrasonic device in there as well.

It stared to fail around 4V.



--
"And if the blind lead the blind, both shall fall into the ditch".

Gospel of St. Mathew 15:14



--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

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

On 14/06/2026 18:48, rbowman wrote:

On Sun, 14 Jun 2026 12:17:25 +0100, The Natural Philosopher wrote:

Early days, but if anyone is thinking of battery powering a PICO outside >>> for intermittent use, a nano timer and lithium primary cells looks to
be the best technology.

Why not 18650s? 2 would give you a little over 7V

"The maximum recommended input voltage for a Raspberry Pi Pico or Pico W
is 5.5V. Powering the board above 6.0V will permanently damage the
onboard voltage regulator"

One cell should be sufficient for powering the Pico. The regulator
lower limit is 2.3 V so there is a need for deep discharge protection
on the cell.


--
Dipl.-Inform(FH) Peter Heitzer, peter.heitzer@rz.uni-regensburg.de

--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 14/06/2026 12:17, The Natural Philosopher wrote:

The process of debugging my remote oil level sensor continues. This is
based on a PICO W plus a nano timer to wake it up every couple of hours
to send a message via the home wifi.

nano timer ??

What's that then?

--
Brian Gregory (in England).

--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 15/06/2026 20:54, Theo wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

On 14/06/2026 12:17, The Natural Philosopher wrote:

The process of debugging my remote oil level sensor continues. This is >>>> based on a PICO W plus a nano timer to wake it up every couple of
hours to send a message via the home wifi.

nano timer ??

What's that then?

TPL5100

https://www.ti.com/product/TPL5110

It's disappointing that it's not available in a higher voltage version
since, as you say, it needs to be directly connected to the battery.

I suppose one workaround would be to use a single lithium ion cell to give you down to 3V and then a boost converter which you only run when the
CPU is operating. Timer goes off, boost converter spins up to power your
CPU at a stable 5V (or whatever), then CPU tells it shut off again once
done.

One workaround is to use 3 lithium primary batteries,.

That's likely going to take more power than just running directly off battery, but the flipside is you can install several 18650 cells in parallel if you want to get more capacity.

The primary lithium cells have more capacity. Better temperature
response. Better discharge curve.

The primary lithium AAs aren't a terrible option though, especially if you are more likely to be killed by self-discharge of the battery than by your own load.

They are, having exhausted all other alternatives, by far and away the
best option.
This design took nearly 3 years from idea to completion, and this is the optimal solution

The ultrasonics have no voltage regulation. Just very high voltages to
drive them Over 20V. They fail if they don't get at least 3.9V input

Theo

--
?A leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
?We did this ourselves.?

? Lao Tzu, Tao Te Ching


--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 24/06/2026 07:33, Anssi Saari wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

Yes.

Plus there is the advantage that you get a complete reboot every time
things fire up.

And its very very simple. Drive pico pin high. get power cut.


--
Canada is all right really, though not for the whole weekend.

"Saki"


--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

That does sound surprisingly bad for the Pico. Seems that the RP2040 is
0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a bit better. So must be something else on the Pico that's not so good in sleep mode.

If you've got other stuff hung off the MCU that isn't super low power,
you're going to have to power-gate it anyway, in which case the nano timer
will do that at the same time.

Theo

--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 24/06/2026 13:41, Theo wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

That does sound surprisingly bad for the Pico. Seems that the RP2040 is 0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a bit better. So must be something else on the Pico that's not so good in sleep mode.

The broadcomm wifi chip.

If you've got other stuff hung off the MCU that isn't super low power,
you're going to have to power-gate it anyway, in which case the nano timer will do that at the same time.

Indeed. I have an ultrasonic unit.

I looked at every combination I could think of, and ended up with the
nano timer after trying to construct my own in analogue.

I can say that the three lithium primary cells plus the nano timer (MUST
have a BIG electrolytic on its back end or it goes unstable) is THE very
best way to have a periodic remote sensor 'phone home' if a cable can't
be laid



--
I would rather have questions that cannot be answered...
...than to have answers that cannot be questioned

Richard Feynman




--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

That does sound surprisingly bad for the Pico. Seems that the RP2040 is >0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a bit >better. So must be something else on the Pico that's not so good in sleep >mode.

I think (ultra) low power was not a primary design goal for the Pico.

--
Dipl.-Inform(FH) Peter Heitzer, peter.heitzer@rz.uni-regensburg.de

--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 24/06/2026 15:51, Peter Heitzer wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

That does sound surprisingly bad for the Pico. Seems that the RP2040 is
0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a bit
better. So must be something else on the Pico that's not so good in sleep >> mode.

I think (ultra) low power was not a primary design goal for the Pico.

I think that is very true. What attracted me was the amount of flash,
and ram, the availability of wireless and ADCs and the price. Less than
a pint of beer in a nightclub.
Arduinos were 3 times the price

The ZeroW running debian is a damn sight easier to code for, however.

--
?There are two ways to be fooled. One is to believe what isn?t true; the
other is to refuse to believe what is true.?

?Soren Kierkegaard


--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 25/06/2026 04:35, wmartin wrote:

On 6/24/26 08:41, The Natural Philosopher wrote:

On 24/06/2026 15:51, Peter Heitzer wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built >>>>> in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this >>>>> timer draws 35 nA.

That does sound surprisingly bad for the Pico.ÿ Seems that the
RP2040 is
0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is
a bit
better.ÿ So must be something else on the Pico that's not so good in
sleep
mode.

I think (ultra) low power was not a primary design goal for the Pico.

I think that is very true. What attracted me was the amount of flash,
and ram, the availability of wireless and ADCs and the price. Less
than a pint of beer in a nightclub.
Arduinos were 3 times the price

The ZeroW running debian is a damn sight easier to code for, however.

Be careful about trusting that ADC, it is somewhat notorious for inconsistent lower bits...summing and averaging helps, if you have the inter-sample time to do that.

The errors are very predictable as they are caused by certain
very low value capacitors in the switched capacitor adc having
incorrect values. It seems that the chip design tools did not
model stray or fringing capacitances accurately enough.
There is software around that can post process the adc readings
to make a substantial improvement. https://github.com/kitanokitsune/rp2040adc_correction
John


--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 25/06/2026 04:35, wmartin wrote:

On 6/24/26 08:41, The Natural Philosopher wrote:

On 24/06/2026 15:51, Peter Heitzer wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built >>>>> in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this >>>>> timer draws 35 nA.

That does sound surprisingly bad for the Pico.ÿ Seems that the
RP2040 is
0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is
a bit
better.ÿ So must be something else on the Pico that's not so good in
sleep
mode.

I think (ultra) low power was not a primary design goal for the Pico.

I think that is very true. What attracted me was the amount of flash,
and ram, the availability of wireless and ADCs and the price. Less
than a pint of beer in a nightclub.
Arduinos were 3 times the price

The ZeroW running debian is a damn sight easier to code for, however.

Be careful about trusting that ADC, it is somewhat notorious for inconsistent lower bits...summing and averaging helps, if you have the inter-sample time to do that.

Oh yes. It has noise allright. But feeding sensors from the stabilised
3.3v line helps a lot.

Do I really need 12 bit accuracy to measure temperature? Not really. Nor
is it a microsecond sample that I need, Ring buffers and averages are
easy to implement


Onboard is fine.

--
The difference bweteen a psychopath and a saint is that the psychpoath
takes what he can and gives only what he must, but the saint gives
everything he can and takes only what he needs.




--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 6/24/26 08:41, The Natural Philosopher wrote:

On 24/06/2026 15:51, Peter Heitzer wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

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

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this >>>> timer draws 35 nA.

That does sound surprisingly bad for the Pico.ÿ Seems that the RP2040 is >>> 0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a
bit
better.ÿ So must be something else on the Pico that's not so good in
sleep
mode.

I think (ultra) low power was not a primary design goal for the Pico.

I think that is very true. What attracted me was the amount of flash,
and ram, the availability of wireless and ADCs and the price. Less than
a pint of beer in a nightclub.
Arduinos were 3 times the price

The ZeroW running debian is a damn sight easier to code for, however.

Be careful about trusting that ADC, it is somewhat notorious for
inconsistent lower bits...summing and averaging helps, if you have the inter-sample time to do that.


--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)