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12 votes
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Two batteries sharing ground?

Not only can you share the grounds - sharing the grounds is required for there to be any form of meaningful circuit for signals to get around the place. To copy-and-paste a blog post I wrote some time ...
Majenko's user avatar
  • 105k
7 votes
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No power from Breadboard Power Supply Module

I'm not surprised you can smell burning. You have the power supply connected backwards. You see that little + and - symbol next to the ON/OFF jumper? That's the polarity of the two runs of pins. You ...
Majenko's user avatar
  • 105k
7 votes
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Battery solution Nano 33 iOT

You can either use the 3.3V pin to supply power to the board, or use the Vin pin. By using the VIN pin to power goes through a (step down) voltage regulator, that provides a nice stable 3.3V to the ...
Gerben's user avatar
  • 11.3k
6 votes
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Powering from 3V coin cell to VCC, using I/O pin as supply GND

Can I use a I/O as (input/supply) GND? You can use an I/O pin as a supply for another (low power) device, but you should power the Arduino itself from its Vcc and GND pins. I could use the reset ...
Edgar Bonet's user avatar
  • 43.3k
6 votes

How to power an Arduino using automated mains/rechargeable battery switching?

Yes, charging a battery and supplying an Arduino at the same time is possible as long as we manage the caveats (see below) of in-circuit charging. This is what I use: a 3.3V Arduino (a Pro Mini in ...
sekdiy's user avatar
  • 399
5 votes
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NodeMCU power consumption measurement and DeepSleep

An ammeter is basically a small resistor in series over which the voltage drop is measured. That resistance will play a part in the effective output impedance of your power source (battery). This ...
Majenko's user avatar
  • 105k
5 votes
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How to read high voltage (40-65v) from a Solar Battery bank

You need a voltage divider with resistors that have large values. ...but with all values I have tried one resistor almost melts as soon as you connect to battery. This suggests that you have been ...
sa_leinad's user avatar
  • 3,188
4 votes
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ESP8266 Battery Monitor

There are two things you need to measure the battery of the system that is doing the measuring of the battery: An analog-to-digital converter Some form of fixed voltage reference to compare the ...
Majenko's user avatar
  • 105k
4 votes
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Can I power my Arduino Uno with a 9V / 990mAh battery?

While this answer addresses the specific question it should also prove useful as a link to resources relating to current reduction in other microcontroller projects. Short: The "C" rate for a cell ...
Russell McMahon's user avatar
4 votes
Accepted

How do you figure out an efficient battery setup for a project?

Our beloved admin Nick Gammon has made a very neat articile on this subject, I suggest you read it and apply as many of the methods he described. Also, it can be worth to check the requirements of ...
aaa's user avatar
  • 2,695
4 votes

Are any Arduino boards especially suited for low-power operation?

Technically you can use any arduino for that purpose with some modifications. I recommend to go with an arduino Pro Mini and remove the LED and the voltage regulator. But if you don't need so much I/...
Coder_fox's user avatar
  • 688
4 votes

How can I calculate remaining battery life time with arduino

you may use ADC(analogRead) to measure Li-Ion Cell voltage. unlike Ni-Cd or Ni-Mh batteries, a Li-Ion Cell Voltage is a good measure for battery status. the discharge cycle of an usual Li-Ion cell ...
Tirdad Sadri Nejad's user avatar
4 votes

Why does using ESP8266 in deep sleep mode still drain the battery quickly?

The example shows a Sparkfun Thing, which the article notes doesn't have extra peripherals. What you show is something different, like a NodeMCU dev board, which typically has a linear regulator, ...
jose can u c's user avatar
  • 6,974
4 votes
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Powering Uno with 9v battery makes it "freak out"

Not enough current available from the battery, relays take quite a lot. As soon as the relay tries to switch the voltage drops and the Uno resets due to brownout (low voltage)
Bra1n's user avatar
  • 1,008
4 votes

power consumption of esp32

There's a number of things to consider when choosing batteries. First is the capacity. In broad terms, the capacity is, mAh, means "This battery can supply X mA for one hour". So a battery of 1000mAh ...
Majenko's user avatar
  • 105k
4 votes
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Measuring Battery level with ADC already in use

As @dandavis rightly says in the comments, you can't measure the battery voltage from a power bank. This is because the power bank typically includes a step-up converter to turn the batter voltage (3....
Majenko's user avatar
  • 105k
4 votes
Accepted

Can I use LiFe PO4 batteries in a 18650 battery shield?

In my opinion it is NOT SAFE, if your 18650 Battery Shield also charges the battery. Anyhow some pages state that it is possible to charge LiFePo4 batteries with 4.2V instead of the recommended 3.65V. ...
Kwasmich's user avatar
  • 1,513
4 votes
Accepted

Slow WiFi reconnection after deep sleep (6 to 10 seconds)

It is in general take around 6s for the ESP to scan all the 2.4GHz Wi-Fi channels to find the SSID and the associated BSSID (i.e. Mac Address), you can eliminate the scanning time by connecting using ...
hcheung's user avatar
  • 1,406
3 votes
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How do I power my Arduino Micro directly?

According to this schematic, VIN goes to the on arduino-micro's 5 and 3 volt regulators. So you should not need a resistor. The 5 volt regulator needs a bit more than 5 volts at it's input to do a ...
st2000's user avatar
  • 7,338
3 votes
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Barebones 328p, 2xAA vs 3xAA, which will last longer?

Yes, running at a higher voltage will consume more current. In the datasheet you have this nice graph: I have highlighted the two voltages at 8MHz for you. At 4.5V you would typically be using about ...
Majenko's user avatar
  • 105k
3 votes

can homemade arduino be powered up with battery?

First, of course, you'll need a battery with enough capacity, and voltage enough greater than 5v (assuming you want to run your home-built at 5v - typical, but you could run it lower, say 3.3v) to ...
JRobert's user avatar
  • 15.3k
3 votes

Power Arduino from 230v with battery fallback

This kind of setup lasts around 2-3 days off a single battery. I measured 15.8 mA consumption on my Pro Mini, running from 9V. A typical 9V battery may have a capacity of 500 mAh, so that is 500 / ...
Nick Gammon's user avatar
  • 38.3k
3 votes

How to power an Arduino using automated mains/rechargeable battery switching?

There are many ways you can do this, as you mention there are ready made shields that do this. You need to take a few thing into consideration: Power - how much power will your cirquit be drawing, ...
Hans Neve's user avatar
  • 466
3 votes
Accepted

Is it possible to charge a battery using a water flow sensor?

Is it possible to charge a battery using a water flow sensor? No, it is basically a hall-effect sensor that requires power and generates a low effect pulse. Look for a generator. Something like this;...
Mikael Patel's user avatar
  • 7,969
3 votes

Get Battery voltage on raw

No. Not directly. You can use voltage divider and measure the result with using internal reference. But it's another current consumption and you can't reduce it by (for example) entering one of the ...
KIIV's user avatar
  • 4,752
3 votes

How do you figure out an efficient battery setup for a project?

Agreed, the DC motors would drain the 9V in no time. Consider the other way around. The 9V powers the Arduino and the 4 AA batteries power the motor. Then again, you probably don't need the 9V at ...
sa_leinad's user avatar
  • 3,188
3 votes

How to make battery last for months?

The Arduino UNO always consumes current mainly because: it has 2 MCU, the ATmega328 which you can power down, and an ATmega16u2 for USB communication which is never powered down. in addition, the ...
jfpoilpret's user avatar
  • 9,132
3 votes

Connect 9 V battery to Arduino Mega 2560 directly?

Yes. On this page, you can see that you can safely connect 7-12V to the VIN pin. Furthermore, you can simultaneously connect the USB; your Arduino will automatically draw power from the appropriate ...
Sanchises's user avatar
  • 149
3 votes

Low Power Pin Change Detection (ATtiny)

The additional 80uA drain is almost certainly coming from the pull-up resistor being shunted to ground though the reed switch. https://www.wolframalpha.com/input/?i=(3+volts)+%2F(50k+ohm)+in+uA As ...
bigjosh's user avatar
  • 1,553
3 votes
Accepted

Servo motor with 9V battery

A 9v "transistor" battery is unsuited to powering servos - at best it might work very briefly. Use 4 alkaline (or depending on the servo ratings, perhaps 5 rechargeable) AA or AAA cells to power the ...
Chris Stratton's user avatar

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