The RedReactor Battery Power Supply

I have developed a robust, powerful and feature rich battery power supply board for the Raspberry Pi which I believe will work equally well with the Banana Pi family of boards (e.g. M3/M4), therefore I hope you don’t mind if I provide some information about it.

We are in the pre-launch phase for our Kickstarter campaign at . We designed this board as part of creating a portable internet radio and found that existing boards did not provide all the features we needed, or could not reliably supply enough current and steady voltage for the whole system when dealing with peaky demands from the Pi, display, amplifier etc.

Whilst a simple power bank might seem like the obvious solution, they typically fail to either deliver enough power (so you have under-voltage issues causing crashes), can’t provide power whilst being charged (or if they do, causing the battery charging to be permanently on thus reducing battery life), don’t give you access to battery voltage for a safe shutdown, don’t have adequate voltage regulation (which will cause crashes when heavily loaded - as they’re designed for charging batteries, not match peaky power demands), won’t restart unless the load is removed first, and don’t have a way of connecting your own external power button nor read the charging status in software.

The Red Reactor board delivers a very stable 5.1v, with an I2C interface for battery voltage and current for safe shutdown on low battery or when you detect that the external supply has failed (uses 3v3 from the Pi for this), and drives a GPIO to provide the ON button state information with a separate open drain pull down interface for a long-press RESET function. We will be providing one version with pogo-pins to sit directly underneath the Pi, and a version of the board where you can easily wire these connections, and use your own ON button which can also be used for other functions in your software (short press, long press etc) and/or drive it from an RTC alarm.

The circuit design ensures that the 18650 batteries are not under load whilst being charged, allowing the charging cycle to complete accurately, whilst the board only consumes 10uA when off (compared to some designs with CPU’s that consume many mA’s monitoring the ON button!), ensuring maximum battery life. But at the same time, our extreme testing shows a super steady 5.1v output when delivering over 4 Amps, where we used 1 board driving a Pi4, display, USB hub with keyboard, mouse, webcam, and at the same time it was charging the battery of another board connected to a Pi3, also with a display and both running a heavy graphics test case.

If you would like more information and register to be notified when the campaign goes live, please check out for details, including pictures and a video of the extreme testing. We’d love to get your support to achieve our goal and also benefit the Banana Pi community! Of course, feel free to ask questions too. Thank you!

if you want to do your project with banana pi , we will full support you.

Thank you! Your support will be much appreciated.

Based on the information I have seen, our ‘headerless’ version can work with all your BPI boards, whilst the pogo-pin version can mount directly underneath the following models, retaining full access to their buttons and interfaces:

  • BPI-M5
  • BPI-M4
  • BPI-M2-Berry
  • BPI-EAI 80
  • BPI-M2 Zero

It would seem the BPI boards have lower power consumption which can easily be supported by the Red Reactor board, with enough power for many accessories that can be attached to the USB, SATA, camera and 40-pin header interfaces.

Please send me a private message to discuss how we can support each other.

There are some use cases where the system is remote or up-time is critical, yet consume too much power to run for long periods on batteries. So whilst a high performance battery back-up power supply is essential to ensure an orderly shutdown when there is an external power outage, you may also want to restart everything as soon as the external power is restored.

Whilst the Red Reactor can easily support a BPI-M5 with accessories and cleanly switch to battery power, you can also use the Vin port and ON button interface to easily integrate additional functionality into your project. In a previous video we showed how to add an RTC alarm to manage timed power-on and power-off requirements, you can see that at

We’ve now also created a short video at on how to add a simple circuit to detect when external power is restored, which connects to the Vin port and operates alongside an ON button to create a trigger (even if you’re using USB as the power input). A simple script will detect a power outage over I2C and perform a safe shutdown, whilst the system is automatically rebooted when external power returns!

I hope you’ll find these videos useful. Please don’t forget to register at our site for more information. Thank you!

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Just wanted to give you a quick update on our progress. We were expecting our Kickstarter campaign to go live this week but unfortunately the world’s shortage of ICs (as you’ve no doubt read about in the news) has affected one of the components on our board. We obviously don’t want to present a delivery schedule that we cannot commit to, so we’ll look at alternative suppliers and solutions first.

We’d be happy to hear if you know of suppliers’ stock for this particular component (INA219AIDCNR/INA219AIDCNT) or had good results with comparable, alternative parts. We’ll let you know how we get on!

These days, everything is controlled by software. In fact, even my DVD player’s ON/OFF button is no longer hard wired into the power supply, and needs its software to decide that I really wanted to turn the thing off. Well, many a time that software gets completely stuck, refuses to obey my command, and the only option is to pull the power plug at the back. Not a pretty sight with all the dust and cobwebs, I can tell you!

Now imagine this happening with your Banana Pi project, but when the mains is backed up by battery power you can no longer just ‘pull the plug’. And when your Pi is inside a nice case design, getting those batteries out is not going to be a quick and easy task.

That is why the Red Reactor has a nifty Hard Reset function built into the ON button interface (and here you are not tied to the location of this button on your board for your case design, nor do you need a separate reset button), so all you have to do is wire the RUN port of the Red Reactor to the RESET button on your Pi board. The RUN signal from the Red Reactor is open drain, so will not affect normal operation, but pulls it to Ground after pressing the ON button 10 seconds until you let go, restarting the board.

So now, a long press of that ON button sorts it all out for you, and no need to pull the plug on that pesky software!

This short video (The Red Reactor - Hard Reset Feature ) shows you how the ON button and RESET functions are integrated together for all your projects, and I hope you’ll find it useful!

Please continue to register your interest at , thank you!

We’re pleased to announce the first release of our Red Reactor Battery Widget, so you can see the battery status right from your desktop screen! Perfect for when you use the Red Reactor to make your Pi project portable, or you just want to make sure all is well in case you loose mains power.

The battery icon will show you the percentage charge, and during charging and discharging you can also see the battery current and voltage in the tool-tip when you hover over the icon, as well as the estimated time to full charge or how long you can keep going till you run out of juice!

The code is designed for use with the Red Reactor battery power supply, and is available from our Github repository. For more information about the battery charging and discharge profiling results head over to our blog at

NEW features: We’ve just updated it to provide a pop-up warning at 10% capacity and a 30 second timer warning to an automatic shutdown when your battery reaches empty. Instructions to install or update are on our github site

Feel free to post comments there or here, we’d love to hear from you, especially to help support the Banana Pi designs.

The Power of Standby

If you are thinking of creating a battery powered Pi project, like remote monitoring with sensors, you might find our new article measuring standby performance useful. If you want to save power by turning your device OFF between readings, battery drain in the power supply itself can have a real impact on total days of battery life.

We created a simple moisture monitoring example and measured the battery voltage each time the Pi was powered up by an RTC alarm, and whereas a competitor battery power supply barely managed to run for 2 weeks, the Red Reactor showed that it would keep working for months. That could save you a lot of hassle with sensors in hard to reach places!

The article and measurement results can be found on our News page at

Let us know what you think!

Thank you for continuing to track our progress (and for reading this far down this thread!). The world chip supply shortage is still causing a problem for us, but we are hopeful that we can launch soon as things are slowly improving.

In the meantime, we have developed a Flask based web application that will enable you to monitor your battery status and usage remotely via a web browser, configure the monitoring process and even perform a remote reboot or shutdown. Perfect for when your Pi is used remotely or running without a display!

(a webpage screenshot can be seen at

For more details please head over to our news update on, and you can download the code with install instructions from our GitHub page at

Just a quick update to tell you about our Power of Standby experiment, which we documented on … f-standby/

We had a Pi Zero powered by the Red Reactor using 2x 3000mAh batteries, set up with an RTC alarm to boot up every 4 hours to take a moisture sensor reading, email it out and turn itself completely off again. With these measurements we could show the benefit of the Red Reactor’s ultra-low standby current (few uA) for sensor applications, and our setup was able to take 481 separate readings (it took 6 readings per day) before finally signing off from duty today.

So, if you just needed 1 reading per day, we’ve shown that it could run for well over 1 year on batteries. It’s funny, I kinda got to like seeing emails from my Pi every day…:smiley:

We’re very pleased to have been accepted by PCBWAY into their Crowdfunding Project Sponsorship Programme, and with their excellent support this has enabled us to proceed with our final prototypes and set our target Kickstarter campaign launch date for September! We’re waiting for our new boards to arrive and all being well with testing we hope to have everything ready for launch!

You can find more details on this in our latest update at

We know it’s been a long wait but thank you all for your continued support! Please continue to register at our site so that we can update you directly.

A quick heads up that we are now counting down to our Kickstarter launch on Tuesday 13th of September!

We’ve been busy testing the final prototypes from PCBWAY and made a short video at with assembly, testing and simple integration for a typical use case with a Pi, touch screen, USB keyboard and mouse.

For more information please visit and hopefully you can catch the early bird discount!

We are now live on Kickstarter, and you can find us at for more details and great purchasing discounts.

As well as exciting options on the Red Reactor board, we are also making our custom, high performance Pogo-pins available for your own projects.

We really hope you will join us on this exciting journey to reach our goal! If you can, please tell all your friends too!

Thank you to all who’ve been following us here on this thread, and a special THANK YOU for helping us to reach our goal in less than a week!

We’re really excited to see so many pledges from all corners of the globe. It is just so great to see so many people with plans for gadgets that will benefit from our robust battery backup! Hence we’d love to hear about your projects and hope our software examples can help you. Based on your feedback we’ve just added a background monitoring app on our GitHub site that can email you any battery status changes and log battery performance. Check it out!

The campaign is still live so catch a great discount to support us, and if you can, please share our campaign link with your friends!