UPS HAT for Raspberry Pi - Kickstarter (pre-launch)

[AlirezaN]

We are working on a Raspberry Pi UPS HAT that originally came out of a real industrial data-logging project.

In that project, we needed a system that could keep logging reliably even during power interruptions. We chose a Raspberry Pi because it gave us flexibility for the graphical interface, data handling, storage, networking, and custom software. The actual data logger hardware was designed as an industrial board, with proper isolation and protection for the measurement side.

The weak point ended up being the power backup stage.

We tested several existing Raspberry Pi UPS HATs. A couple of them worked quite well for general use, and I don’t want to dismiss them. But when we tried to use them in a more critical industrial logging application, we found that they did not fully cover what we needed.

Some of the things we wanted were:
- More reliable recovery after power loss and deep battery discharge
- Proper prevention of low-battery reboot loops
- Better visibility of each individual 18650 cell, not just the whole battery pack
- Safer handling if the user installs unprotected 18650 cells
- A more serious watchdog approach to help the Raspberry Pi recover from software or boot issues
- More predictable behaviour during adapter plug/unplug events
- A controlled shutdown and restart sequence, rather than just keeping the Pi alive for a while

This made us start thinking that a Raspberry Pi UPS HAT should not only be treated as a hobby backup power board. For some applications, it needs to behave more like a reliable power-management platform.

So we decided to design our own version from scratch, with a stronger focus on real-world reliability rather than only backup runtime.
The features we are currently considering include:
- Modular 18650 battery support
- Individual battery monitoring
- Low-battery loop prevention
- Safe shutdown signalling to the Raspberry Pi
- Watchdog-based recovery
- Controlled power-off management
- Automatic restart after power recovery
- More stable power-path control during adapter/battery transitions
- RTC support
- High-accuracy fuel-gauge feedback
- Protection and safety handling for the battery system

We are still in the early PCB design stage, so I thought this would be a good time to ask for feedback before the design becomes too fixed.
For people who have used Raspberry Pi systems in real applications, especially where power reliability matters, what problems have you seen with existing UPS HATs?

Are there any features, behaviours, or failure modes you think should be considered in a more reliable Raspberry Pi UPS design?

We have also created a Kickstarter pre-launch page for the project, but at this stage I am mainly interested in technical feedback and real-world requirements from people who have used Raspberry Pi systems outside simple hobby setups.

Pre-launch page:
https://www.kickstarter.com/projects/noora-solutions/ups-hat

Any criticism, feature suggestions, or design concerns would be appreciated.

[partycrashercasey]

What pricepoint are you considering targeting?
I have used WaveShare UPS Hat with good results for a few different projects. For their price, I felt a got a lot of bang for my buck there.

What method are you considering to detect and handle the unprotected cells?

[AlirezaN]

Thanks for the feedback.

We are still in the early design stage, so I don’t want to give a firm price yet. My current estimate is that it probably will not be under USD 45. If price is the main priority, then this may not be the right direction compared with some existing low-cost UPS HATs.

The photo I shared is actually from a Waveshare UPS HAT. I agree that they can offer good value for many projects, and we tested a few similar boards as well. In our specific case, though, when we tried to use them in a more critical industrial data-logging application, they did not fully meet our requirements. That was one of the reasons we started looking at a different architecture.

Regarding unprotected 18650 cells, the idea is not to rely only on the cell’s own protection circuit. Each battery module/cell position is intended to have its own protection and monitoring. This includes temperature protection, over-voltage protection, over-current protection, over-discharge protection, and protection against imbalance when cells are connected in parallel.

So even if the user installs an unprotected 18650 cell, the UPS HAT should still manage protection at the system level. If a protected cell is used, then that protection becomes an additional layer, but the design should not depend on it.

For each cell, we are planning individual monitoring of cell voltage, charge current, and temperature during both charging and discharging. The goal is also to allow charge-current settings for each cell through software.

Another feature we are considering is the ability to add or remove battery modules while the system is running, instead of requiring the whole Raspberry Pi system to be shut down first.