looking for a UPS for raspberry pi 4

[Hubertas]

I am working on a raspberry pi 4 free NAS server, and I thought just for extra safety I should install a UPS. I have a 2.5" 2tb hard disk and a raspberry pi 4 of course. A person suggested a 12v 3~5A UPS for the build, but I'm having a hard time finding one. Could I get a suggestion for the UPS.

[skywatch]

Well, I guess that more details are required here.....

Mainly - How long does the device need to be powered for in the event of a power failure and what power does it draw?

If you just need 30s for it to detect a power failure and then shut down then it's pretty simple......But if you need it to carry on working for hours or days without mains power then it's a little more involved.....

[alowhum]

Without knowing enough about what you need, I would always recommend to get a UPS such as the APC Back-UPS ES 550VA. It will allow 4 devices to stay powered, and provides surge protection for another 4. It is controllable by your NAS. It's about $80.

[zboblamont]

@hubertas Perhaps DIY may interest, built one about a month ago, post is in "What did you build today.."

[skywatch]

I would agree with diy route - I wouldn't use a AC mains UPS like you would use with a normal pc as it looses most of it's power in doing what it does (AC in, converted to DC to charge lead acid or lithium batteries and usually then the batteries power an oscillator that feeds a transformer to get back to AC - Then your pi power supply will convert it back down to DC - There is a lot of losses in that way of doing it).

I did a google search a while back for dc-dc ups and found a lot of interesting designs. Bu maybe DIY is not how you wish to do it, and that's fine.

So in that case find some good dc-dc or ac-dc ups made specifically for the pi or other 5V 3A devices.

[jlaraujo]

Hi, you can try these power supplies:
https://www.aliexpress.com/store/group/UPS-Charge-Function-switch-power-supply/1242857_501520362.html?spm=a2g0o.detail.100008.25.56f87402HSB2Og

The are for 12V, but also support an external battery.

I have two that work very well.