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)