Second Life UPS

You might be interested to know that a second version of the UPS has been built and described - https://hackaday.io/project/192297-secondlife-ups-mark-ii 

Enjoy!

I did another round of design refinements. This time I replaced the LM2596 converter supplying the 5V outputs to another XL4015 which has more current capacity.

This way I can reliably power the raspberry Pi as well as a fan colling the entire rack. I have added some stickers on the front panel as well:

All changes were as usually reflected in the project details.

Today I have performed a number of design refinements:

- I rewired the output board to provide 6 x 12V output and 2 x 5V output as the 12V is much more versatile

- I improved the way that the AC 230V power cable attachment to the device, I have an electrical tube fitting instead of the cable just dangling out

- I added a 7812 V regulator to power the AC PSU Fan, powering it from the DC rail directly was working but the high-pitched sound was annoying

All of these have been reflected in the project details.

It looks like I can't add SVG to the project details page.

I have added a PDF version of the schematics as well as uploaded the Kicad project.

I did some back of the envelope calculations on the energy density of my setup compared to lead-acid AGM batteries often used in UPS applications.

My setup

a 4S10P battery made from junk cells each having around 800 mAh gives me 14.8 V x 8.315 Ah nominal capacity of 123.062 Wh (calculated by https://www.repackr.com/ battery pack builder). As the battery size is 27 cm x 10 cm x 4 cm this gives a volume of 1080 cm^3 and a volumetric energy density of 0.11 Wh/cm^3.

Lead-acid

A random "flat" AGM battery (CSB HRL 634W F2) used in a 1U rack UPS I found laying around in the hackerspace has a nominal capacity of 6 V x 9Ah = 54 Wh with the size of 15.1 cm x 3.4 cm x 9.4 cm without leads. This means that the volume is 482.596 cm^3 and the volumetric energy density of also 0.11 Wh/cm^3.

Not bad considering my lithium cells are essentially on the level of junk not reusable for anything else.