S.USV advanced UPS HAT
I was sent one of these HATs to get some feedback and a review. I’m free to say what I like.
Introduction
Today, I’m reviewing the S.USV HAT from German company S.Seprotronic GmbH. The HAT comes in two flavours – Basic and Advanced. They sent me the Advanced one but I will point out the differences between the two versions where appropriate.
Functionality
The HAT’s primary use is as a UPS (uninterruptible power supply). It comes with a 300mAh LIPO battery that you plug into the board via a standard connector. The HAT has a charging circuit built-in so when you’re not using the battery, it is being charged. On the Advanced version (but not the basic) there is a connector and some extra circuitry to allow you to provide between 7 volts and 24 volts of power as an alternate power source. This could come in very handy if you had a power source such as solar panels, for example. The HAT comes with an extended GPIO header so you can carry on using the GPIO and the board communicates with the Pi via I2C so it doesn’t take up any GPIO ports. The I2C is even configurable, so if you should find a hardware conflict, you can change the I2C address via software. There are various indicator LEDs on the board that tell you the status of the UPS and the battery. The board is well-designed, well-laid out and clean. There are two buttons: ‘off’ and ‘on/reboot’. These are not labelled on the board, which is a shame as it is difficult to remember which one carries out which function.
Software
For a 40-pin Pi, the HAT automatically configures the ‘overlays’ required for it to work. There are instructions on how to configure the Pi manually if you need to. There is a daemon to be downloaded from their website. It is a small download and the instructions to install the package are clear and simple: easily within the capabilities of anyone who can follow some simple steps. The daemon is configurable and you have control over automatic start-up, automatic shutdown and various other options such as how long to wait to shutdown safely after switching over to battery power. My favourite option here is to switch the automatic on-battery shutdown off entirely. There is a safety feature which means that, even with this option off, if the battery goes below 10% the Pi is shutdown safely. Configuring the daemon is done via the command line, but most people who are going to be using this board should be comfortable enough in that environment. I found the configuration/status facility to be excellent and clear. If you are required to restart the daemon, it clearly tells you that you need to do so. There is a real-time clock on-board too which automatically installs itself when you boot for the first time.
Conclusion
This is one of these things that “just works”. I should say that I experienced a couple of software-based problems:
- The ‘off’ button didn’t work.
- The automatic, scheduled shutdown didn’t work when I tried it out, but I have a feeling that I did something wrong!
Overall, I have to say I’m very impressed with this HAT. A lot of thought has obviously gone into the hardware With the advanced model, the extra power supply flexibility is very welcome and the inclusion of a LIPO battery as standard is great as it saves you having to source one yourself. There is even an option on their website to purchase a 3000mAh battery if you want a bigger margin for safety.
The instructions and manual are very good and I had no trouble following them.
The software, even though it is command-line based, is very good and I liked the amount of configuration options available.
The HATs are currently only available from their website. The basic model costs 30 Euros (£24) and the advanced model costs 55 Euros (£44). Postage is on top of that. I would say that the extra £20 for the additional power circuitry is worth it if that’s what you need to make your project work. There are a lot of components on this HAT, so I think the prices are reasonable for what you get.
Recommended if you need a UPS!
Very interesting 🙂 Does it report the remaining charge level? How does the Pi interface with the RTC?
It DOES report the remaining charge, yes, in ampage and percentage. I can’t remember how it interfaces with the RTC. 🙁
I can’t find a schematic and BoM. Without them, purchase is off the table for me.
Not sure why they would publish that!
I found the S.USV to be very susceptible to stray magnetic fields. If you happen to place the combination of raspberry pi and s.usv on top of a 2,5” HDD in a plastic enclosure to save ‘real estate’ it will severely affect the currents measured by the device. Even if the HDD is not connected and not running.
Needless to say that this will turn the operation of the s.usv to be
erratic at best.
I struggled with this for more than a week. Support from Olmatic was helpful, but didn’t come up with the real cause. In the end I found it myself and have been wondering why the internet has next to nothing on stray magnetic fields and Hall sensor IC’s, because that’s what is used on the board. Two of them to boot. If you take that into account, it works as advertised, but a warning would be more than considerate.