Summary of Flexipower – A portable, Controllable, Dual Channel Power Supply
Flexipower is a portable, dual-channel power supply designed for hobbyists and makers. It features remote control via a mobile app over Wi-Fi, operates on rechargeable Li-Ion/Li-Poly batteries, and provides up to 20V at 1A per channel. The device uses voltage step-up and linear regulator circuits for output adjustment, along with specific resistor networks and an INA219 IC for precise current monitoring. Status indicators include RGB and channel-specific LEDs.
Parts used in Flexipower:
- Two cell Li-Ion or Li-Poly batteries
- Voltage step-up circuit
- High current linear voltage regulator
- Voltage divider
- 10-bit ADC
- Shunt resistor network (ten 10 Ohm resistors in parallel)
- INA219 integrated circuit
- Barrel jack for charging
- RGB LED
- Green and red LEDs per channel
Hobbyists, makers, students and pretty much everyone who works with electronics has encountered the same issue, not having a handy power supply to test their projects. Usually, controllable power supplies are big, expensive and for some people difficult to access, and most small power supplies are not controllable. As a result, Roberto Lo Giacco created Flexipower, a small, portable, flexible, and remotely controllable dual channel power supply.
Flexipower is controlled via a mobile application and its battery operated. It can work up to a voltage of 20 V and a current of 1 A (per channel). Power supply is powered by two cell Li-Ion or Li-Poly batteries which provide 8.4 v when fully charged, to reach higher voltages the battery is fed into a voltage step up circuit, and to get lower voltages the battery is fed into a high current linear voltage regulator. Also, a simple voltage divider along with the 10-bit ADC is used to measure the produced voltage, and adjust accordingly.
Current measuring is done through a 1 Ohm shunt resistor network made by ten 10 Ohm resistors in parallel which results in 1 mV voltage drop per mA. In the case of currents lower than 320mA, the integrated circuit INA219 is used to obtain a very precise reading. When the supplied current goes above the capacity of the INA219 the shunt resistor voltage drop is measured using the 10 bit ADC.
As mentioned before, Flexipower uses 2 rechargeable batteries that are charged via a barrel jack connecting a 12 V source capable of around 1 A. An RGB LED is used to inform the user about the status of the device (power on, battery warning, connection status etc.). The LED is also used to indicate the battery status. Additionally, each channel has a green/red LED to indicate if it is enabled (green), or over current (yellow).
Furthermore, the device can create “Flexipower SSID”, an access point for people to connect and control the power supply. The app was created to avoid using a big LCD screen with limited data logging capabilities. The app allows control, unlimited data logging and visualization just with the use of a smartphone.
Read more: Flexipower – A portable, Controllable, Dual Channel Power Supply
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What is the maximum voltage output of Flexipower?
The device can work up to a voltage of 20 V per channel. -
How does Flexipower measure current for values lower than 320mA?
The integrated circuit INA219 is used to obtain a very precise reading. -
What components make up the shunt resistor network?
The network consists of ten 10 Ohm resistors connected in parallel. -
How is the device charged?
Batteries are charged via a barrel jack connecting a 12 V source capable of around 1 A. -
What color indicates that a channel is enabled?
A green LED indicates if a channel is enabled. -
Can Flexipower operate without being plugged into a wall outlet?
Yes, it is battery operated using two rechargeable Li-Ion or Li-Poly batteries.
