PiRA is a universal solution for solar powered IoT devices implementing all commonly required features, enabling you to finally fully focus on the development of your core application.

PiRa - Power in Responsive Applications

A universal solution for solar powered IoT devices handling:

1. charging
2. battery monitoring
3. voltage regulation
4. power scheduling
5. battery protection
6. standard LiPo cell usage
7. optional on board processor
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Why PiRA?

Designing power supplies, solar charging circuits and other standard function for every application is an effort being constantly repeated and requiring time and money. PiRA has been developed as a response to the lack of IoT suitable battery pack or powerbank systems that can easily and rapidly integrated into target applications.

At Institute IRNAS we work with a range of leading experts in various field and are constantly challenged to develop customized solutions in short periods of time. PiRA has been designed as a solution for ourselves, but has since grown into a more widely useful system that is by following best open hardware practices enhanced and expanded with every project.

Development time and costs are significantly reduced by using this tested and constantly improved open hardware design, allowing for idea to prototype batch time to be under a month. PiRA thus enables everyone to be very responsive to the needs and quickly implement an optimized and verified solution.


For whom?

PiRA enables almost anyone to build a robust standalone battery powered IoT system. We envision its usage in a number of ways:

1. Prototype development and test batch construction (0-10 units): Combine existing modules on one of the existing motherboard designs to best suit the required application and complete the design in minimal time.
2. Application specific mainboard (20-100 units): Use existing modules on a custom developed motherboard for the particular situation to best integrate a proven solution for your application.
3. Fully integrated solution (100+ units): Use the existing open hardware design to create an unified circuit board with the features combined in application specific setup.

At Institute IRNAS and Fabrikor we provide development of all these types of solutions and their manufacturing.


PiRA Modules

PiRA is typically used with multiple LiPo battery cells in parallel in 1SxP configuration, generally with 1-12 battery cells. Such configuration simplifies the battery management and charging and enables the installed capacity to vary from device to device. Multiple Charging modules can be used in parallel to charge the battery, creating anything from solar-only solution to solar-backed uninterruptible power supply for most critical applications.

The current PiRA version 2 consists of the following range of modules that can be combined on the motherboard in a number of ways.


Charging modules

Provides the interface between a power source and the single cell battery.

USB charger: Designed to charge via a standard microUSB.

  • 5V/2A charging
  • auto-disconnect to prevent leakage thor ughconnected and un-powered charger
  • configuration and monitoring via I2C
  • thermal protection

Solar charger: Designed to charge from a solar cell with MPPT .

  • 4.95-32V input voltage range, fits most cells
  • 2A charging current
  • reverse protection for panel
  • adjustable MPPT point
  • adjustable charging voltage for prolonged battery life

Output modules

Useful output for various applications:

Fixed regulator: 3.3V/2A

  • low-quiescent consumption, designed for always-on configuration
  • self or external enable
  • for: sensors, processor

Fixed regulator: 5V/1.5A

  • low-quiescent consumption, designed for always-on configuration
  • self or external enable
  • for: Raspberry Pi, sensors, USB devices

Adjustable regulator: 3-5V/1.5A

  • low-quiescent consumption, designed for always-on configuration
  • self or external enable
  • for: various devices, 3G modules requiring 4.2V

High-side switched battery output: 10A+

  • external enable
  • for: various outputs, 3G modules and other devices

Higher voltage regulator: 24V/300mA

  • self or external enable
  • adjustable voltage
  • for: WiFi routers with PoE, networking equipment

Battery modules

Battery protection module:

  • Over-voltage
  • Under-voltage
  • Shipping-disable mode
  • Push-button activation
  • Master power switch

Battery charge controller

  • battery voltage, current, health and other monitoring
  • I2C interface

Motherboard modules

General purpose or application specific, simple motehrboard board that can be easily developed and soldered.

General purpose motherboard

  • Up to 2 charging modules
  • Up to 4 output modules
  • One battery protection module
  • One battery monitoring module
  • 6x 18650 socket
  • Nodemcu V2 socket
  • expansion connectors

PiRA Prototyping kit is a suitable starting point for everyone and is the full-featured setup with all functions implemented on the general purpose motherboard.


Low-power system with high-current intermittent loads

Many IoT devices operate in very low power regimes for majority of the time, while intermittently requiring significant amounts of power, such when using 2G or 3G module modems, power hungry sensors or actuators. This requires a low standby power consumption, which is under 100uA of total battery drain with active 3.3V output in PiRA and up to 10A current delivery to the load through MOSFET controlled output module.

Use case: Solarcast

PiRA v1 is used in Safecast Solarcast devices as a standalone module that is dropped in with batteries included. Solarcast main board has been significantly simplified as only the application specific features were implemented, regulated voltage outputs and power switching is provided by PiRA.


Scheduling power hungry devices

Using RaspberryPi microcomputer and WiFi router is due to their cost-effective and widely supported range of features becoming more significant in industrial sensing applications. Due to the power constraints in off-grid deployments however powering these devices can represent a challenge. PiRA with a processor installed enables smart scheduling of these loads based on voltage levels, external sensors or other inputs and can significantly prolong the battery life.

Use case: AAMP

PiRA v2 is used in AAMP camera devices for off-grid solar operation in the jungle. Based on ambient light, PIR sensor and other inputs it calculates when Raspberry Pi with a camera should be turned on and then in regular intervals powers up a 5GHz long-range WiFi router to upload the captured information. PiRA processor used in this application is ESP8266 with built-in WiFi and using ESPEasy firmware one can simply configure the scheduling through a web interface in a matter of minutes and deploy the application as well as optimize it on-site or remotely.

The modular design of the system is very crucial for this particular deployment, because every feature is a standalone module, one can in a matter of seconds replace them and service any potential problems in the field, recombine modules for a new application or re-use them if new motherboards are developed for a different application.