Hi everyone,

So I’ve spent the last few months on this project - building a completely custom 1.5U UPS for my 6U 10" mini rack. Although technically it only takes the bottom 1U - there’s some extra space at the bottom of most that seems designated for a 25*120mm fan?

You can take a look at it on GitHub, I’ve finished the first version that I’m happy with, but I definitely want to work on a second version that uses some custom power circuitry to charge the battery and provide all the voltage rails.

For those interested, here are the specs:

6s4p EVE-26VA 2650mAh battery pack (~230Wh rated, I only use mine to ~180Wh - 4.0-3.0V)

600W 27V AC->DC power supply

At least 400W power

1*DC 27V output

1*System output (either 27V or batt depending on bypass)

1*Battery output (18-24V 30A)

3*12V 3A XT30

3* 5V 3A XT30

300W/20A buck converter, used to charge the battery CC/CV

2*150W/9A buck converters, providing 12V and 5V rails

3*60A ideal diode modules to prevent back-feeding power and allow a bypass mode

the bypass mode turned out to bypass the low-side current shunt on my charging buck and I accidentally put 30A into the pack very briefly. Fortunately little/no damage appears to have occurred, but I’m keeping a close eye on it.

Bypass diode was subsequently disconnected until I find a proper solution, limits average power to ~120W from battery, but can handle significantly higher peaks.

Lots of 12/14/16/18 gauge wire, depending on the current required

even more XT60/XT30 connectors

In my rack I currently have:

banana-pi r3 acting as my router/firewall/gateway

RPi5 8G with GeekWorm x1009 5 port sata hat

4*Patriot P210 2TB SSDs in RAIDZ1

A framework desktop mainboard in need of a properly fitting mount.

This UPS!

Space for 1U of something else...

Here’s a few photos, including my cardboard prototype (which I actually mounted a lot of things to with screws and zip-ties, very effective if you ask me!) I hope y’all like it. Feel free to provide feedback and ideas for my next iteration.