Reduce Power Consumption- first time project

Projects General Guidance
1

First time poster- first project of this type.
Goal of my project is to have a PIR Sensor trigger a buzzer when ducks climb on my boat. Yes- I can buy commercial but wanted to get into this realm of making.
I have everything wired up and working as expected including figuring out the sketch for the arduino - but- it is killing the battery in mere hours. My goal is to have this sit on the back of the boat and be replenished by solar.

order;
Solar Panel → MPPT Controller →7.4v Lithium battery→RF Fob for remote on/ off →Arduino Uno Board→ 2 ea PIR Sensors→ 2 ea Piezo buzzers wired in series.

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Leaving this "on" but without more than 1-2 triggers it killed the 7.4v battery in 2.5 hours and a test 9v in less than 4 hours.
I have been reading in the forum other posts on this but most refer to periodically putting the system to sleep- This may be an option and I mostly need this on dusk to dawn but thus saving power there, but best case is having this run 24/7.

I see the Arduino board has 5v working- but- is it consuming this all the time? Also understood this is probably overkill for what I need it to but it is a one off ( at this point) .

Looking for some kind folk to offer suggestion on how to trim consumption or help point out efficiencies that can be implemented so this can be self sustaining. I get that solar will have it's down days with weather etc, but I was thinking that the sensors should not be drawing much and keeping the other components going was going to be minimal.

Below is the list of the components-
Solar Panel- ASHATA 9V 3W Solar Panel-
https://www.amazon.com/dp/B07N4NTNFM?psc=1&ref=ppx_yo2ov_dt_b_product_details

Battery- EBL 7.4V 2200mAh Li-ion
https://www.amazon.com/dp/B087BYJ51T?psc=1&ref=ppx_yo2ov_dt_b_product_details

MPPT= DAOKI 12V Solar Charge Controller Board CN3791 Solar Charge Controller Board MPPT 1 LiPo Battery Panel Regulator Module JST PH2.0 A
https://www.amazon.com/dp/B091TRHT9M?psc=1&ref=ppx_yo2ov_dt_b_product_details

Remote- QIACHIP 433M Universal Wireless RF Remote Control Switch DC 6V 12V 24V 1CH Channel Relay Wireless Secure RF Remote Control Switches Transmitter and Receiver kit- Static current 3.6 mA ~ 5.5mA
https://www.amazon.com/dp/B083GRC5P7?psc=1&ref=ppx_yo2ov_dt_b_product_details

Board- Arduino UNO REV3-https://www.amazon.com/dp/B008GRTSV6?psc=1&ref=ppx_yo2ov_dt_b_product_details
Microcontroller Microchip ATmega328P
Operating Voltage 5V
USB Standard Type B
Digital I/O Pins 14
PWM Digital I/O Pins 6
Analog Input Pins 6
Flash Memory 32 KB
SRAM 2 KB
EEPROM 1 KB
Clock Speed 16 MHz

PIR Sensor- HiLetgo 3pcs AM312 Mini Pyroelectric PIR
https://www.amazon.com/dp/B07RT7MK7C?psc=1&ref=ppx_yo2ov_dt_b_product_details
Working voltage: DC 2.7-12V;
.Static power consumption: <0.1mA;

Buzzer - uxcell a12081600ux0477 12 mm Diameter 5 Piece DC 5V 2 Terminals Electronic Continuous Sound Buzzer- https://www.amazon.com/dp/B00B0Q4KKO?psc=1&ref=ppx_yo2ov_dt_b_product_details

Thanks for your attention and help.

2

That's not easy. Several controllers have sleep functions but that's not enough when peripheral devices still consume power.

You need to seriously sum up the need of current, the solar charge etc.

Why leave that current consuming build "on"? You obviously can't.
Can You draw an logic block drawing of the build for us to get an overview?
What current consumption do the datasheets tell?
I know You posted links but the work mentioned, You do it.

3

There are many power saving techniques... some simple ones.

  • don't power via the jack... the on board regulator is linear, so the higher the input voltage the move power you are wasting.
  • consider a barebones Arduino. The Uno board has a bunch of things you don't need when the project is running... like LEDs, the UART chip, the voltage regulator, etc.
  • explore the various sleep modes. If you only need to check your sensors every 10 seconds, then you may as well be asleep the rest of the time.
  • using sensors that can trigger an interrupt to wake the Arduino ... that way it can pretty much always be asleep until something happens.

Check out this link which is an excellent source of information
https://www.gammon.com.au/power

4

Those are mechanical buzzers, not piezo.
I doubt that putting two of them in series will work reliably.

The charger seems to be for a single cell 3.7volt LiPo battery.
The two battery terminals seem to be connected in parallel.
Leo..

5

Looking at your overall concept, are you sure this is going to work all that well outside. PIR sensors are frequently "fooled" by changes in the sun during the day. Think of the sun shining down on your boat cover during the day. As soon as the sun goes down, it's going to start to cool right? A PIR sensor is likely to pick that up as movement.

You might want to power off of an extension cord to give it a try for a day before investing in all the trouble to make it battery friendly.

Also, why not simply power off of your 12v marine battery on the boat? Presumably it's deep-cycle, right? As long as you don't let the boat sit for really extended period of time and you get the power consumption down using the sleep method (as posted earlier) you should get much longer run times using the on-board battery.

If you're trying to keep the ducks off your boat, I would try something like this

My parents used two of them on their pontoon boat and they worked fairly well. In reality, nothing is going to keep them away completely. Once they learn that the buzzer is just noise, they'll start to ignore it.

6

Hi, @offline30
Can you please post some images of your project so we can see your component layout?

Can we please have a circuit diagram?
An image of a hand drawn schematic will be fine, include ALL power supplies, component names and pin labels.
A cut and paste diagram does not show much about your connections.

Do you have a DMM?( Digital MultiMeter )

Thanks.. Tom... :smiley: :+1: :coffee: :australia:

7

Read this
How to Reduce Arduino Uno Power Usage by 95% _ DefProc.pdf (3.1 MB)

8

wrong board.
Just don't use an UNO Board when power consumption is of any importance.
Check the Pro Mini in a 3.3V Version and desolder the power LED.
As an alternative, create your own "ATmega328p" Board without LEDs

3 Likes
9

Great guidance, thanks for the post.

10

Thanks for the post;

  • why not tie into 12v system of boat? certainly can be done- but it is more holes in the boat and wires to mess with. I have a lot of solar already on the boat and like the idea of an autonomous system if I can do it. This is winter, I need a project , activity so in the end may go that way
  • Ducks getting used the noise- that could well happen- one of the reasons that I was aiming for higher voltage system is to have a really annoying buzzer to help them not get used to it. My original concept was a motorized sweep are that would be triggered by the sensors. This could be v2 if needed.
  • Can I buy something for this commercially- yep- -but again it is winter and I am having fun learning about this realm that I have not touched before.
  • As far as the environmentals- that will be part of the testing, the sensors I bought are the smaller lense types that documentation does not have the same warnings as the larger lense versions. early thoughts was a timer that would periodically sweep the arm - that too may come back into play as well.

Cheers

11

If a standard alkaline 9V battery lasts longer than lithium, I would question whether the lithium battery was fully charged. Have you been using the solar charge controller you listed? I'm not sure it will work with a 7.4V lithium, which is actually two lithiums in series. The CN3791 is for single cells (3.7V).

If the PIR sensors work when the boat is pitching and tossing, how do they work when it's raining? It seems they would be constantly triggered.

12

If the PIR sensors work when the boat is pitching and tossing, how do they work when it's raining? It seems they would be constantly triggered.----------

My understanding without a means to test during winter is that the PIR is looking for a upward change in temp of an object. Other sensors that I have seen seem to work on measuring distances- this was ruled out as you state for waves and boat movement. Not sure about rain- it would be ambient temp or cooler in my mind. But - again have not been able to test.

Have you been using the solar charge controller you listed? I'm not sure it will work with a 7.4V lithium, which is actually two lithiums in series. The CN3791 is for single cells (3.7V).----

I have tried is just a couple of time and it added charge to the battery. Ran out of daylight to see if it would get to full charge. There are three versions of the board, mine is 12v. Thinking ( likely flawed) that the solar panel is putting out 9v +/- in good so it should be able to get the 7.4v battery charged

13

Not if the maximum charging voltage of the CN3791 is 4.2V.

1 Like
14

That board is designed for a 12volt solar panel and a single 3.7volt LiPo battery.
It will kill a 7.2volt battery.
Leo..

1 Like
15

new MPPT board will be coming- thanks

16

Which one...

17

So far I am looking at
Sparkfun PRT- 12885- https://www.digikey.com/en/products/detail/sparkfun-electronics/PRT-12885/5762441?utm_adgroup=Evaluation%20and%20Demonstration%20Boards%20and%20Kits&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Development%20Boards%2C%20Kits%2C%20Programmers&utm_term=&utm_content=Evaluation%20and%20Demonstration%20Boards%20and%20Kits&gclid=Cj0KCQiAutyfBhCMARIsAMgcRJTiD4uUj2y45kDmv4pHWCtru-XWVx8reBFkOHVt_rURxI3Vg6Qo8XcaAvUYEALw_wcB

or

MPPT Solar Panel Controller, Universe 5A Solar Charge Controller Battery Charging Module 9V 12V 18V 24V---Amazon.com : MPPT Solar Panel Controller, Universe 5A Solar Charge Controller Battery Charging Module 9V 12V 18V 24V : Patio, Lawn & Garden

Thanks to feedback so far I am getting better and understanding more of the finer details.

Certainly open to suggestions on another controller as well

18

The first one has this in the specs:
"The output of the Sunny Buddy is intended to charge a single polymer lithium ion cell."
So like your first board, not suitable for a dual cell 7.2volt pack.

The second link seems not safe for lithium batteries (think fire/explosion).
Leo..

19

This is good thanks-

Understood on first controller -
but the second one from Amazon has this text-

  • Can adjust the output voltage arbitrarily, CC-CW automatic control (can support single or multi-cell lithium battery or lithium iron phosphate or lead acid battery, high power LED, etc.). Battery for complete charge management

Is there someplace deeper to that I have not looked to warn me away?

20

There is more to it when charging a LiPo pack that just applying a voltage to it.
There is a max pack charge current, and when the 7.2volt pack is less than 6.6volt or more that 8volt, current should be lowered. And a 2-cell pack might need a balance charger.
Up to you if you think it's safe.
Leo..