Eaton 5P 1500RT UPS Battery Backup

My favorite method of server power reserve is a flywheel. It’s also the best way to have completely air-gapped protection from lightning strikes and surges.

NASA flywheel UPS

I was about to get one but realized I don’t have the space for it in the garage. When you have limited space, a Battery UPS will do in a pinch.

We have a light load. A firewall, three switches, a wireless AP, and a few servers. Those are running Xeon-D, and AMD EPYC processors, so they are highly efficient. I don’t usually see a load above 300W.

I considered APC, CyberPower, and Tripp Lite. I almost purchased the Tripp-Lite SMART1500LCD since it was affordable. It would have worked fine, but reading through forums, many SysAdmins recommend the Eaton brand for quality and longevity. By providence, a brand new Eaton 5P1500RT was listed minutes earlier on eBay for $330 shipped. Sold!

Rack Installation

The product includes rails. Installation was simple. It took 10 minutes to rack it and power it on.

Sine Wave Output

The best benefit of the Eaton is it outputs a pure sine-wave. Cheaper UPS units produce something approximate to a sine wave. It works but can cause excessive heat and strain on your devices. Imagine trying to ride a bike on a simulated sine-wave, and you’ll see why a pure sine-wave is better for electronics.

Bike riding on sine waves - simulated vs pure sine wave

Priority Outlet Groups

One feature I love is the three distinct groupings of outlets: Primary (four outlets), Group 1 (two outlets), and Group 2 (two outlets). This allows you to shed less critical systems during an extended outage. E.g., If you have high availability clusters, you could power down less critical backup systems and secondary nodes and divert all power to the primary nodes.

Back of Eaton UPS unit

Noise Levels

It makes the noise of a quiet 2U server. The noise level is ~52db standing a few feet away. The fan constantly runs. It’s not bad in the garage, but I wouldn’t put it in the house.


The unit claims 35 minutes runtime on my 300W load. This is a huge step up from my older APCs that were down to 2 minutes.

Network Module

My unit included a network ethernet card module (I do not think this is standard, but something extra the seller included). It looks straightforward to configure auto-shutdown for servers and integrate it into TrueNAS.

Alarm Silencing

Red Alert Alarm

I do not like power outage alarms on UPS units. If I’m awake and the power goes out, I’ll know. If I’m asleep and the power goes out, I don’t want to wake up. I mean, what am I going to do about it? Call the power company and make the power come back on faster? I trust the Eaton UPS to make the best decision on when to power down.

You don’t need a special cable and software to silence the alarm. You can do it directly from the control panel.

Can you send forth lightnings, that they may go and say to you, ‘Here we are’? – Job 38:35 ESV

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