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Tweet-A-Watt is a DIY project that adds wireless reporting to a plug-in Kill-a-Watt electricity meter. A transmitter inside the modified meter sends readings to an XBee receiver connected to a computer, where software can log or graph the data. The original design is built around a classic P3 Kill-a-Watt P4400 and XBee Series 1 radios—not a ready-to-use monitor or a currently stocked kit.
What Tweet-A-Watt does
The original project turns readings from a Kill-a-Watt into wireless data. It samples voltage and current signals inside the meter and sends measurements by radio to a receiver attached to a computer. The computer-side software can collect readings, save them to a CSV file, and support graphing or further processing. Adafruit’s overview also describes storing or publishing the data, but that describes the original workflow; it does not establish that the legacy software is maintained or compatible with current operating systems. See Adafruit’s project overview.
Which Kill-a-Watt and XBee models are compatible?
The transmitter guide specifies the classic P3 Kill-a-Watt P4400 and XBee Series 1 point-to-multipoint 802.15.4 radios. Adafruit warns that other XBee versions may not work, particularly high-power Pro models. It mentions that some users had tried an EZ-type meter, but does not recommend it. Check the exact meter and radio versions against the transmitter parts list before sourcing components.
The Tool Desk
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This is not simply a wireless plug-in monitor: the project modifies the meter and adds electronics to power and interface with the radio. The transmitter guide explains that the meter’s internal supply is current-limited, so a 10,000 μF capacitor supplies the XBee’s transmit burst. A regulator adapts the supply to the XBee’s 3.3 V requirement, while voltage dividers condition the meter’s 5 V sensor signals. The design details are in Adafruit’s transmitter instructions.
#1 Best Overall
- Various Monitoring Parameters: The power meter plug can monitor the power (W), energy (kWh), volts, amps, hertz, power factor, cost, minimum and maximum power (W), cumulative days and time of your appliances. By switching 7 display modes, you can easily know the various parameters while the appliance is working. The home energy monitor can also calculate and display how much power your appliance uses and how much electricity bill it cost in cumulative time
- Upgraded LCD Display: With large screen size 2.36 inch x 1.85 inch, clearer monitor backlit, our electrical usage monitor can display the data clearer and more visible no matter day or night. 180°full wide viewing angles is great for reading and recording the data in any angles. No need to stand on the front of the display and bend over to read the numbers
- Adjustable Backlight Time: Our upgraded watt meter has 5 options of backlight time. The default backlight time duration is 10 minutes(bL-0). If you want to change the backlight time, you can press and hold "UP" and "DOWN" button at the same time to enter backlight time setting, then press "UP" and "DOWN" to select the backlight time (bL-0 =10 minutes, bL-1=1 hour, bL-2=4 hours, bL-3=8 hours, bL-4=always on), finally press the "COST" to save the backlight time settings
- Overload protection: When the power of the appliance exceeds the overload power, the LCD will display “OVERLOAD” to warn the user. All the buttons will quit working and can only be workable when you lower or remove the load power. The default overload power is 3680W and is adjustable from 0 to 3680W. In general, you need to set the overload power to 1800W before using. Just press the "function" button for more than 3 seconds to enter the setting
- Data Memory Function: The wattage meter will record your power consumption data when you remove it from socket, or remove appliances from the electricity monitor. You can directly see the last data when you use it next time. This function can also automatically save the data when there is a sudden power failure
Parts, kits, and what is no longer stocked
The historical starter pack listing included two XBee Series 1 modules, two adapter kits, a USB FTDI cable, capacitors, resistors, an LED, ribbon cable, and heat shrink. It excluded the Kill-a-Watt meter and tools. Adafruit marks the starter pack no longer stocked. The separate add-on outlet kit is also marked no longer stocked; an additional outlet requires its own Kill-a-Watt and access to a receiver setup.
The starter-pack page describes one outlet as able to monitor up to 1500 watts. This is a project-page specification, not an independent performance test. If recreating the build, verify availability and compatibility of the legacy Series 1 radio and adapter hardware rather than assuming a modern substitute will work.
Rank #2
- Multi-function power monitor: Our electric usage monitor can monitor the power (W), electricity(kWh), voltage(V), frequency(Hz), current(A), power factor(PF), unit price($/kWh), total cost($) of your appliances. By switching 8 display modes, you can easily know the various parameters while the appliance is working. The “electricity” mode can calculate and display how much power your appliance uses. And the “total cost” mode will show how much electricity bill it cost in cumulative time
- Overload protection: When the loading power of the appliance is over the default overload threshold 1800W, the whole display with backlight and the word “OVERLOAD” will keep flashing to warn the users. Please turn off the appliance for safety concern
- Premium Material: The whole body of our energy meter is made of high-quality ABS material. It makes our home electricity usage monitor more long lasting, fireproof and anti-drop. The standard US socket and plug is suitable for all US standard appliances
- Backlight Display: With white backlight and black words, the LCD display of our home power monitor can display the data clearer and help you to read the data easier no matter day or night. The backlight will only lights up when the device is connected to AC power. If no button is pressed, the backlight turns off automatically after 10 minutes. You can also press the "UP" button to turn off the backlight manually, and press any button to turn on backlight again
- Easy to reset: No reset tool needed, our appliance power usage meter is easy to reset. You can press the “M” button for 5 seconds directly to reset the device. After reset, all cumulative data (electricity quantity, cost) will be cleared, and all settings will be restored to factory settings
Safety and skill requirements
Building Tweet-A-Watt means soldering and opening a mains-powered meter. Adafruit describes the project as moderate to advanced and intended for people experienced with electronics and comfortable around high voltage. Its instructions say: “You should only attempt this project if you are comfortable and competant working with high voltage electricity, electronics and computers.” The spelling is as published in the preparation and safety instructions.
- Unplug the meter before opening or inspecting it.
- Never open, test, measure, or probe its circuit boards while it is connected to a wall outlet.
- Do not proceed if you are not confident working safely with mains-powered electronics.
These are essential precautions, not optional troubleshooting steps.
Rank #3
- 【Matter-Certified】Matter-certified devices, regardless of brand, can work together and are compatible with most major smart home platforms like Amazon Alexa, Apple HomeKit, Google Home, and Samsung SmartThings. Enjoy more flexible and unified control.
- 【Insightful Energy Tracking】 Monitor your energy consumption with in-depth statistics and clear visuals, helping you optimize power usage.
- 【Estimate Your Energy Bill】 Enhance energy management by integrating with billing systems for clear cost visualization (both single and periodic readings). Additionally, programmable scheduling allows automatic operation of high-consumption devices during off-peak hours with lower electricity rates, resulting in cost savings.
- 【Overcharge Prevention & Power Management】 Automatically cuts off power based on user-set thresholds and durations to prevent overcharging, conserve energy, and protect connected devices from overcurrents by shutting off when power exceeds set limits.
- 【Voice & Remote Control】 With built-in support for both Alexa and Google Assistant, issue simple voice commands to adjust settings, turn devices on or off, or even access specific functions without lifting a finger. Manage Tapo P110M and its connected devices from anywhere with the user-friendly Tapo app.
What to expect from the readings
The software guide’s calibration example reports an idle reading below 2 W rather than exactly zero. It attributes the residual reading to analog-to-digital noise, the Kill-a-Watt’s own power consumption, and the limited samples available to the XBee. That is an example from the guide, not a guaranteed specification or a current independent accuracy test. Tweet-A-Watt is best understood as a project for logging and observing trends, not as a promise of laboratory-grade measurement. See the dated software and calibration instructions.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Is Tweet-A-Watt a good fit?
It is most appropriate for an electronics hobbyist who wants to build a wireless measurement and data-logging project, has the required skills, and can source the specified legacy hardware. Someone seeking a monitor that works out of the box should compare ready-to-use products instead; Adafruit’s project documentation does not evaluate current alternatives.
Quick Recap
Rank #4
- Various Monitoring Parameters: The power energy meter can monitor the power (W), energy (kWh), volts, amps, hertz, power factor, cost, minimum and maximum power (W), cumulative days and time of your appliances. By switching 7 display modes, you can easily know the various parameters while the appliance is working. The home energy monitor can also calculate and display how much power your appliance uses and how much electricity bill it cost in cumulative time
- Upgraded LCD Display: With large screen size 2.36 inch x 1.85 inch, clearer monitor backlit, our electrical usage monitor can display the data clearer and more visible no matter day or night. 180°full wide viewing angles is great for reading and recording the data in any angles. No need to stand on the front of the display and bend over to read the numbers
- Adjustable Backlight Time: Our upgraded watt meter has 5 options of backlight time. The default backlight time duration is 10 minutes(bL-0). If you want to change the backlight time, you can press and hold "UP" and "DOWN" button at the same time to enter backlight time setting, then press "UP" and "DOWN" to select the backlight time (bL-0 =10 minutes, bL-1=1 hour, bL-2=4 hours, bL-3=8 hours, bL-4=always on), finally press the "COST" to save the backlight time settings
- Overload Protection: When the power of the appliance exceeds the overload power, the LCD will display “OVERLOAD” to warn the user. All the buttons will quit working and can only be workable when you lower or remove the load power. The default overload power is 3680W and is adjustable from 0 to 3680W. In general, you need to set the overload power to 1800W before using. Just press the "function" button for more than 3 seconds to enter the setting
- Data Memory Function: The wattage meter will record your power consumption data when you remove it from socket, or remove appliances from the electricity monitor. You can directly see the last data when you use it next time. This function can also automatically save the data when there is a sudden power failure
- Choose the project if the build, radio link, and local data workflow are part of the goal.
- Check component compatibility and availability before committing to the original design.
- Choose a ready-made monitor if you do not want to solder, modify a mains-powered device, or maintain legacy software.
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