Quad Power Management I2C Board ($22.95)

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The Quad Power Management I2C Board allows you to switch on and off batteries, power supplies and solar panels.  It is like an I2C controlled quad solid-state relay.

features:

• I2C controlled
• 4 Independent Solid State Relays each with LEDs
• Each is able to switch 20V and 2.3A
• 4 Additional GPIOs
• Software drivers for Arduino and Raspberry Pi Included!

The Quad Power Management Board (QPM) is a fabulous addition to our product line. We have needed one of these for a long time. Back when we were building Project Curacao, we were continually needing relays (mostly latching relays) to switch power on and off to computers and devices, to switch from solar to wind and a variety of other chores. What a pain! Now we have developed and designed a Quad Power Management board incorporating I2C controlled 4 Independent Solid State Relays each with LEDs to show what is going on with the board. Each solid state relay is able to switch 20V and 2.3A. You can switch DC signals and analog signals (with proper conditioning – you need to add a DC Offset for analog signals).

Specification

The full specification is available here (updated October 19, 2015).

Software

Arduino Software Drivers are available here at https://github.com/switchdoclabs/SDL_Arduino_QPM.

Raspberry Pi Software Drivers are available here at https://github.com/switchdoclabs/SDL_Pi_QPM.

Description and Applications

This board is magic to us for building power systems. There are 4 Additional GPIOs provided on the board (thanks to the SX1502 as in the above board) that can be used as GPIOs, interrupts or a programmable logic gate as above. Software drivers for Arduino and Raspberry Pi Included!

We are using this board extensively in our new SunRover semi-autonomous robot design. You will be seeing a series of articles on this robot in Raspberry Pi Geek magazine starting in the August 2015 issue. The robot uses a total of 10 Quad Power Management boards to stack/unstack all the batteries and to switch the solar panels from one computer to another.

And they are all controlled by an I2C bus! No more massive use of GPIO pins for latching relays and other devices.

Applications

Applications of the QPM Board

The Quad Power Management board has many applications that come to mind. Any time you want to switch a battery out of the circuit, switch from one battery to another, turn power off to a device, stack and unstack batteries or turn power on or off to a device, this is your board.

The three applications below are from a new SwitchDoc Labs project, SunRover. SunRover is a semi-autonomous tracked robot that is being developed here in Washington state, but will eventually make it down to Curacao to join Project Curacao in the tropics.

SunRover has three computers. The first is the motor controller (TRex I2C controller made by Dagu) and connected to a Dagu set of robot TRex tracks.

The other two computers are an Arduino Mega 2560 (the power management computer – also does weather sensing) and the brains of SunRover, a Raspberry Pi 2 Quad Core computer.

The electronics will be packaged in a BUD enclosure as below. Note the Circuit Board Condo that we designed and 3D printed. It allows us to have three levels of PC boards in the box.

 

Application Examples

The three example applications for the QPM board are:

– Battery Stacker
– Solar Panel Multiplexer
– Robot Compartment Heater

Battery Stacker

To get the ~12V we need to run SunRovers motors, we need to stack 3.7V LiPo rechargeable batteries. It takes 3 batteries to get up to about ~12V.
The problem is that all of our Solar Powered Charging system is designed to charge 3.7V LiPo batteries. Our solution? Use two QPM boards to switch the batteries from a series to parallel connection and then charge the batteries from SunAirPlus. The QPM board even has two inputs per device. One with a protective diode and one without the diode. Perfect for our application.

 

Solar Panel Multiplexer

SunRover has 6 3.5W/6V solar panels. These will be on a “wing” across the top of SunRover. Each of these six solar panels can be switched by a Quad Power Management board and be connected in different ways to provide more power to the subsystem (Motors, Arduino or Raspberry Pi) depending on what needs it at the time and the Sun.

We are using four QPM boards to accomplish this.

SunRover Motors subsystem – up to 6 solar panels

Raspberry Pi subsystem – up to 4 solar panels

Arduino Power Management subsystem – up to 2 solar panels

Robot Compartment Heater

Our third example application of the QPM board is a resistive compartment warmer. The winters are cold up here in the frozen north and LiPo batteries and electronics need to be kept warm to keep working. We are accomplishing this by using the QPM board to switch 10W/20 Ohm resistors, one in each compartment. We have temperature sensors in each compartment that will give us the feedback we need to moderate the heat sent to the resistors. How do we control the heat coming off of each resistor? We pulse the QPM switches to only power the resistor for the amount we need. If we want 3.6W, we turn the QPM switch on 1/2 of the time (7.2W/2). We can make it generate just enough heat to keep the compartment at the right temperature. Very cool. Or hot in this case.

 

QPM – Battery Stacker / Unstacker Applicaton

void unstackBatteryStack(uint8_t i2cmuxchannel)

{

// first turn all off

resetBatteryStack(i2cmuxchannel);

// Turn on grounds first

QuadPower0.setPowerChannel(QuadPower_POWER_CHANNEL_IO1, QuadPower_ON); delay(100);
QuadPower1.setPowerChannel(QuadPower_POWER_CHANNEL_IO0, QuadPower_ON); delay(100);

// Now turn on all the connecting switches to SunAirPlus

QuadPower0.setPowerChannel(QuadPower_POWER_CHANNEL_IO0, QuadPower_ON); delay(100);
QuadPower0.setPowerChannel(QuadPower_POWER_CHANNEL_IO3, QuadPower_ON); delay(100);
QuadPower1.setPowerChannel(QuadPower_POWER_CHANNEL_IO2, QuadPower_ON); delay(100);

}