Extending the Run-time of your UPS

So, you've got your snazzy UPS, and it does a dandy job of keeping your equipment running during brief power outages. The problem is, it is only good for about 5 minutes or so of run-time. What this means is that pretty much as soon as the power goes out you have to start shutting down your system. You'd like to have a UPS with more run-time, but the problem with that is that there seems to be a direct correlation between the size of the UPS and the run-time. You only need a 850VA UPS, or maybe 1000VA, but the only thing that you can buy which offers a run-time of say, 30 minutes, comes in the 1500VA or 2000VA variety, and costs a whole lot more money than you want to spend.

What do you do?  If you bought a UPS that has the capability to extend the run-time, you can just buy an extra battery pack for it, and you are in business. Problem is, even those extra battery packs can be expensive. And if your UPS doesn't allow for extra battery packs, you're pretty much done as far as options are concerned, right?

Well, that all depends on whether or not you want to invalidatethe warranty on your UPS. The fact is, today's UPSes are very reliable units, rarely suffering from any failure other than bad batteries. While it is true that any modification of the UPS (including plugging in battery packs not approved by the manufacturer) will void the warranty of the UPS manufacturer, it is also true that in the vast majority of situations, you won't ever need that warranty (after all, these manufacturers wouldn't be offering $50,000 equipment replacement policies on a $100 UPS if they had a habit of failing in any fashion that would cause the manufacturer to have to honor that policy).

In this guide, I will take you through the process of extending the run-time (commonly known as adding batteries) of the APC Smart-Ups 1400NET unit from American Power Conversion Corporation. While this guide is written specifically with regard to the SU1400NET, the principles should apply to virtually any UPS currently on the market. As always though, your mileage may vary, so try to research things before undertaking any such project.

Tools Required

This project will require some modifications to be made to the UPS. You will need a #2 Phillips screw driver, a high-power (250W or so) soldering iron and solder, wire cutters/strippers, and a small to medium pliers.

Parts Required

• 2 – 12V storage batteries rated at 18 AH each. You should be able to obtain these from a battery wholesaler.

• Roughly 1 ft. of 6 ga. wire, red.

• Roughly 1 ft. of 6 ga. wire, black

• Roughly 1 ft. of double-sided foam tape.

• Either a roll of electrical tape (also called vinyl insulating tape) or heat-shrink tubing, depending on how you choose to do the wiring.

The following items are not required, but are recommended.

• 1 – 100A car fuse

• 2 – Anderson-style electrical connectors, with terminals, gray, rated for 50 amps. You should be able to obtain these from your battery wholesaler.