5v vs. 3.3v Pro Mini battery powered nodes

[zboblamont]

@mhkid Ok, see what you had in mind now.
If it were me looking at doing it on the cheap, I'd screw down an old pump pressure switch or similar adjustable to simply connect when pressure falls below a set-point. A simple alarm out switch rather than sampling the sensor to decide on an alarm.
For the water consumption, assuming the pump is powered, could your metering be done there, or is it not a dedicated supply?

[mhkid]

@zboblamont - interesting thought on the pump pressure switch. It's not a dedicated water supply. I'm in an irrigation district and the line is pressurized by their pump which is pumping from a canal. It does go down at times and then one of my neighbors or I have to call and alert them to come out and get it going. Yes you would think they would have some sort of alarm on their system but apparently they don't. I use the water for watering lawn, pasture, and just added the filtering so I could water my animals. I may end up with more than one flow meter so I can measure water consumption in each pen. These are show animals and water consumption is important as it relates to nutrition and weight gain.

[zboblamont]

@mhkid Ok, so the pressure monitoring is to alert for pump supply failure, a refurbed single pump pressure controller could easily control a submarine dive klaxon on a big battery, or maybe just trip an Arduino interrupt to radio in, as not sure 3am 130dB klaxon alarms would go down too well with the chickens let alone the family...

For meters, I would seriously reconsider the notion of using a turbine meter, they MUST be powered continuously.
Standard apartment meters with a K10 pulse output (every 10 litres) might cost 30-50 GBP depending on where you buy them, the meter will continue to register even if you lost all power, the turbine will not. A box/cupboard to house the meter and however many others you envisage manifolding off will protect them, insulated if you experience frosts, in a heated room in you get -20s...
If you need to get down to 1 litre pulses, they are less common but not silly money unless going for Class D or Magflow...

So getting back to your OP, you only need one voltage for the Arduino if you ditch the turbine idea...
As the Limerick Man explained to the motorist asking directions to Dublin... "Well I wouldn't start from here..."
https://www.amazon.co.uk/15mm-Water-Meter-Pulse-Output/dp/B0078NMBX6

[tochinet]

@mhkid For battery powered sensors, you should always try to go 3V3. And if necessary change the model of sensor. At 3V3 the consumption is lower as well, so you win twice the energy (very roughly). Your device should also sleep continuously between the sensor captures. It can become tricky. But I used a DHT22+328p+TI CC RF sensor powered by 3V3 on a single AA cell and up-converter for 5 years now, and I only need to recharge it every 4-6 month.

[MaAh]

A video here https://www.youtube.com/watch?v=kEkD4SLMX8Y on some different ways to power the Pro Mini

[alexsh1]

There are no thoughts. Just get 3.3v pro mini.
Generally speaking for any low consumption (battery driven nodes), try to get rid of 5v devices (chips or sensors). I have moved completely to 3.3v almost without regulators with exception of the solar /supercap node.

[mhkid]

@alexsh1 like I said of course it would be preferred to use the 3v sensors but that's not always possible. My question is more about what are people doing when they are using a battery powered node with a 5v sensor.

[mhkid]

@tochinet Do have diagrams, pictures and sketches you've posted?

[mhkid]

@maah This video doesn't show different ways to power an arduino it's talking about power consumption. I'm already removing the regulator, LED and sleeping it. I'm more asking about battery powered nodes with sensors than are more than 3.3v. How are people feeding 5v to these sensors?

[alexsh1]

@mhkid replace the sensor. If you cannot replace the sensor, you have several options:

1. use 5v pro mini + 3xAA batteries + 5v sensor.
   This is going to be a very power hungry setup.

2. use 3.3v pro mini + level shifter + 3xAA batteries + 5v sensor
   Again this setup now ideal - you have to drop voltage from 5v to 3.3v

I still have several old 5v sensors I used with Arduino Uno. I am just not using them any longer with one exceptions when a node is powered from mains.

[mhkid]

@alexsh1 Which sensor should I replace the water pressure sensor with?

https://www.amazon.com/dp/B00RCPDCQU/ref=twister_B00RCPDQOI?_encoding=UTF8&psc=1&tag=wwwmysensorso-20

[zboblamont]

@mhkid IF the objective is only to detect supply pressure failure rather than monitor pressure over time for process reasons, why not use a pressure switch set between max supply pressure and Zero? Your processor sleeps until the switch detects a fall in pressure and wakens the processor to call home ?
https://www.ebay.com/itm/1-8-QPM11-NC-Pressure-Switch-Wire-External-Thread-Nozzle-Adjustable/272843081265?hash=item3f86b70631:g:iJcAAOSwKnVZtrP~ Perhaps ?
There are undoubtedly plenty of other alternatives, on the expensive side there is always RS etc....

[alexsh1]

@mhkid I cannot see the consumption. Do you have the datasheet?

Most likely this is not a battery friendly sensor. In this case you stil can use it via a step up converter and TPL5110, which will switchit off completely while sleeping

[Yveaux]

@alexsh1 it is a mechanical switch, just like a button or reed switch.
https://www.google.nl/url?sa=t&source=web&rct=j&url=http://www.cneni.com/cn/file.asp%3FFilename%3Dupload/products/download/2009_10_29_16_27_30_150570.pdf&ved=2ahUKEwjZgbb605LcAhWG-qQKHXHjC6YQFjAOegQIABAB&usg=AOvVaw2MqIOPIURwEs_sa7VMGGoi

@zboblamont nice find :+1:

[alexsh1]

@yveaux Maximum operating current - 500mA. It depends how often the pressure is going to change, but one can pretty much forget about batteries as the source of power.

[mhkid]

Thanks for all the suggestions and replies. I'll take all the info, weigh the options and then report back on what I end up doing.

[alexsh1]

@mhkid Another option for you is using TPL5110 module:

https://www.adafruit.com/product/3435

I have just received one today and going to tinker with it.
To me it seems like a good idea to have a powerful sensors with Arduino on batteries.

[mhkid]

@alexsh1 - Thanks for the suggestion. I'll be curious to hear what you think of the TPL5110.

[Yveaux]

@alexsh1 look at the schematic; it is just a mechanical switch with 2 wires. It can probably only carry 500ma max.

[zboblamont]

@yveaux Are you sure you are not talking at crossed purposes about different devices? The device @mhkid was originally referring to is the one with the 5v supply requirement, Circuit hopefully below.
The one I suggested as a low pressure alarm actuator was a variable pressure switch, which may be the one you are referring to...