Powering My Pollutants Sensor

Dear Arduino Community,

Recently I have been working on a project to detect pollutant concentrations in the air and report them live. I am using an Arduino Nano to process data from the DHT11, MQ-135, Figaro 2600, and Figaro 2602 sensors which I have integrated onto a PCB. The processed data is sent to a NodeMCU module which uses its WIFI capabilities to send the values in PPM to a ThingSpeak channel. Attached below is an image of the current circuit I am working with. I need help powering the circuit. I prototyped the project using 6V AA battery packs which only lasted for about 8 hours in earnest. Now, I need a method to provide a stable output of 5V to each sensor and meeting the minimum requirements of the Nano and NodeMCU. I cannot really consider intermittent data collection since the whole idea is to record data continuously. I need a relatively inexpensive and small method of powering the circuit since I building 20 of these units and placing them outside near highway tunnels, chemical waste dumps, and factory units. I was considering solar power, but I am inexperienced with how to implement a reliable system. If you could please provide some guidance I would greatly appreciate it!

Thank you in advance.

**P.S. I understand the way I made the circuit is not the best. I could have just use 5V and GND markers instead of drawing the wire.

You told us what you tried, but you never told us what the actual voltage and current requirements are for your entire project.
Paul

I see 267mA for the gas sensor heaters, add power for the Nano and NodeMCU + NodeMCU's radio transmitter, I would figure a constant 320mA.

A 10 or 20 watt 12V solar cell into a PWM Charge Controller to a lead acid or LiFePo4 12 V battery to a 5V switching regulator to power the rest of the circuit.

The use of solar might depend on where you live, and what the weather is. If you are in a climate with substantial overcast weather, you'll have to size your array and battery for perhaps multiple days of reliance on battery. As a rule of thumb, solar cells, in good climates, can deliver on average about 1/3 of their rated capacity. if you are not in mostly sunny conditions, you might only get about 20% of rated capacity. Don't invest in a caboodle of parts here until you've done a good analysis of that. There may be some solar installers in your area who would have a good rule of thumb on the sybject.

Idahowalker:
A 10 or 20 watt 12V solar cell into a PWM Charge Controller to a lead acid or LiFePo4 12 V battery to a 5V switching regulator to power the rest of the circuit.

Woulda a 12V 5Ah Lead Acid Battery offer enough current?

Hi,
From datasheets.
2600 uses 42mA
2602 uses 56mA
MQ135 heater is 33R, which at 5V == 5 / 33 = 151mA

Can you post a jpg, exported, image of your PCB please.
From what I can see from your circuit, you are lacking bypass capacitors too.

Thanks.. Tom... :slight_smile:

akarshaurora:
Woulda a 12V 5Ah Lead Acid Battery offer enough current?

Perhaps.

TomGeorge:
Hi,
From datasheets.
2600 uses 42mA
2602 uses 56mA
MQ135 heater is 33R, which at 5V == 5 / 33 = 151mA

Can you post a jpg, exported, image of your PCB please.
From what I can see from your circuit, you are lacking bypass capacitors too.

Thanks.. Tom... :slight_smile:

Dear Tom,
Thank you so much for your help. Here is the image of the PCB I have designed so far. It is currently shown with the battery pack connections I was using. I have yet to integrate a 5V switching regulator and the bypass capacitors to filter a clean voltage. I am thinking to combine the Arduino and NodeMCU power routes meaning I will most likely need a greater amperage on my output. Would a 12V 5Ah Lead Acid Battery suffice?

Considder a better quality sensor.

You can find gas sensors that use a lot lesss power.
Or find a way to power them from nearby grid power

HI,
Nice clean PCB, but for the sensor currents you are having to use your tracks could be much wider.
Especially your gnd tracks.

My philosophy on PCB design.
[soapbox]
You have purchased a blank PCB, loaded with copper.
You are paying someone to remove that copper, which you purchased.
They are not giving you a discount for the copper they reclaim.
You have plenty of room so keep YOUR copper and use it to help provide strong solder points and good current carrying capacity.
[/soapbox]

Where is your 4K7 pullup resistor for the DHT11 signal line?

Tom... :slight_smile:

You should add pull up resistor in your circuit.

It appears that you are using at least 250 ma continuous. If you go to solar, it would be smart to have two days back up. So 1/4 amp x 48 hours is 12 AH for the battery. Solar panels are pretty much at best 33% efficient, so you need yo size the solar panels large enough to put 12 AH in the battery on a good day, while also supporting the load.

TomGeorge:
HI,
Nice clean PCB, but for the sensor currents you are having to use your tracks could be much wider.
Especially your gnd tracks.

My philosophy on PCB design.
[soapbox]
You have purchased a blank PCB, loaded with copper.
You are paying someone to remove that copper, which you purchased.
They are not giving you a discount for the copper they reclaim.
You have plenty of room so keep YOUR copper and use it to help provide strong solder points and good current carrying capacity.
[/soapbox]

Where is your 4K7 pullup resistor for the DHT11 signal line?

Tom... :slight_smile:

Thank you for the insight. I will definitely look into widening the tracks for my VCC, GND, and sensor output connections. As for the DHT11, I am using the version with integrated housing so I omitted the resistor.

akarshaurora:
Woulda a 12V 5Ah Lead Acid Battery offer enough current?

No doubt it can deliver enough current.
Now ask yourself the question (and do the math): does it have the ability to deliver this current for a long enough period of time to make sense for my project?
For reference: an alkaline AA battery has about 2 Ah capacity.
And don't use lead acid. Those batteries are dirt cheap for a reason: it's old, and very soon will be obsolete, technology.

This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.