Make your own Power Meter/Logger

let's say you have an awesome gadget that uses a USB connection to charge its battery year or simply uses USB power directly to work properly in both cases a so-called USB power meter can be useful tool to measure the voltage of the USB port the current your gadget draws the power it does needs and most importantly it also locks how much energy is transferred this way after converting the value to kilowatt hours you can simply multiply this value with the price per kilowatt hour and therefore for example calculate that wireless charging a smartphone cuz you 0.15 U or more for every 100 charges now of course you can get such a power meter for cheap on eBay but in this video I will show you how to create your own portable upgraded version which has a wider voltage range a higher measuring frequency and even SD card support in order to evaluate your measurements later on let's get started an Arduino Nano will be the brain of the organization for the first prototype measuring voltage bovitz is as simple as connecting the positive terminal of your loads to analog inputs the negative terminal to ground and writing a simple analog read commands but measuring current is definitely a bit more complicated commonly you will need a current shunt which is basically a precise low value resistor that needs to be placed in series to your loads in order to create a voltage drop proportional to the flowing current this voltage drop can then be amplified and fed into a microcontroller in order to calculate the current value but in order to make life easier for us let's simply use the I n a 219 bi-directional current power monitor I see I got mine embedded on a PCB year for only $2 from eBay which also includes a supposedly zero point 1 ohm current and a screw terminal due to the maximum current shunt input voltage of 320 millivolts we can measure a maximum current of 3.2 amps and a maximum voltage of 26 volts hooking up the IC to the Arduino is the same procedure as with any other I squared C device serial data connector a4 and C you a clock connects a5 at this point we could use the wire library of the arduino to write our own ice query codes in order to communicate with the IC but we could also just download the i na 219 library from Adafruit included and write wait fewer lines of codes in order to output the current and load voltage through the serial monitor in order to measure anything useful though we first need to connect the v+ pin to the positive terminal of the supply voltage the me- pin to the positive terminal of the loads and the ground of the loads to the ground of the measuring system now the serial output levels pretty accurate values which means we can continue by using three more variables and the moolies function in order to that the measurement repeat every 100 milliseconds this way I cannot only add a power measurement outputs by multiplying the current and load voltage but also an energy counter which adds the power value multiply it by 100 milliseconds converted into hours to the previous energy value since the serial monitor now presents all the values we care about correctly it was time to add a display to the circuits in this case a 0.9 6 inch OLED LCD which I got from eBay for $4 the wire ring was exactly the same as before since the LCD also uses the I squared C communication protocol after downloading and including the library for it from Adafruit it was simply a job of using the print light function and figuring out where to position the text on the LCD in order to make it look decent and for many people this setup should already fulfill the demands for power meter but not for me that is why I got myself a commonly available SD card PCB which can be found for $2 and also includes the lvc 125 level shift I see this I see is important because the SPI pins of the Arduino 11 to 14 to which the SD cards needs to get connected to have a high voltage level of 5 folds but the SD card can only handle 3.3 volts and don't worry if you miss the step during the wiring of those components because I utilized the EZ EDA free circuit design software to create an appropriate schematic before hands you can find a link to it along with other project information as always in the video description now after formatting the SD card and plugging it in we could use the SD library which is always included in the Arduino IDE in order to write to it but I have to say that had quite a few problems with its while trying to open the files I rather recommend the SD fat library which uses the same commands but does function without a problem with its the SD card create three text files which contain the time voltage and current values by simply importing them into a program like Excel you can then create decent-looking graphs and of course also calculate the power and energy values last but not least I remove the used components from the breadboard replace the Nano with an ultra no pro mini which are programmed within FTDI break ouch added a lipo battery both protection / charging circuit to the system so load everything onto a piece of perf boards and connected the components to one a novel of course you can create a beautifully crafted enclosure for your power meter but mine doesn't really need one for what I have in mind for it and with that being said this project is completes and works like a charm I hope you liked this video as always don't forget to Like share and subscribe stay creative and I will see you next time

Channel: GreatScott!

Views: 918,231

Rating: 4.9426918 out of 5

Keywords: power, meter, logger, energy, volt, current, measure, measurement, log, arduino, nano, pro mini, ina219, monitor, ic, current shunt, shunt, oled, lcd, 0.96', SSD1306, micro, sd, card, SPI, I2C, how to, tutorial, make, project, diy, DIY, electronics, greatscott, lipo, TP4056, portable

Id: lrugreN2K4w

Length: 6min 33sec (393 seconds)

Published: Sun Nov 27 2016