Repurposing an Old UPS With an External Battery

PLEASE read the whole description!

This video helps prove that there is something (some) CFL bulbs are good for. ;-)

In light of the blizzard and the fact that my electricity has been going up and down around the time I made this video, here is a presentation on how to repurpose an old uninterruptible or standby power supply with an external battery. Toward the end of this video, you also get to see a demonstration of how it works.

First: consider your safety. Don't do this if you don't understand what, why and how to do this. Be honest with yourself and your skills. It's not worth being hurt or burned. Disassembling a UPS presents a risk of electrical shock and some of the parts inside can remain energized! A big UPS has its own hazards. Always use fuses and appropriately sized wiring. Never charge a lead acid battery in an enclosed space or in a heavily populated part of your home. Explosive gases can build up and be ignited.

Second: consider that not all UPS units will properly charge or operate from any other battery than the one they were sold with. You will have to experiment to see what works with what you have.

Third: yes, there are other ways of doing this--a large enough charger and inverter can perform the same function if you supply the batteries. It's a "good idea" to use a battery intended for the purpose, such as a deep cycle type, but cheap car or lawn tractor batteries will usually work better than you'd expect and live long enough to be a more economical choice, especially if your electrical service is reliable.

UPS units with dead batteries are available almost anywhere. The plastic box came from a Dollar General store and was drilled and cut appropriately. I bought the toggle switch at Wal-Mart, in the automotive department. You can get a wide variety of panel meters from eBay. There are scores of sellers in Hong Kong, China and Taiwan that carry them. Such meters usually cost less than $20 (US).

Most UPS units have a "modified sinewave" or "stepped approximation to a sinewave" output. This can cause problems with some equipment. Really old and/or cheap UPS units will have a squarewave output. If you get lucky and find a UPS with a true sinewave output circuit (usually marked as such--also try downloading the manual for the unit you have), it will safely operate almost any electrical device you can connect, so long as the output rating of the inverter is not exceeded.

Recycle any dead batteries appropriately and do not put them in the trash.

Category:

Science & Technology

Tags:

• repurpose
• UPS
• dead
• bad
• battery
• external
• rewire
• uxwbill

[Lachlant1984]

I have an Eaton Powerwear 3105 UPS that no longer works, so I'm thinking of getting rid of it, today I was looking at the warnings on the battery cover and it said something about "This device output is not sinusoidal", what does that mean? Does that have something to do with a sine wave output? 

[uxwbill]

@Lachlant1984 Normal AC "line" power looks like a smooth sine wave if you were to observe it with an oscilloscope (or, perhaps more honestly, "it should look that way").

It's more expensive and difficult to do this with the output of a UPS. Since most end up hooked to computers whose power supplies don't really care about the shape of the incoming power waveform, most UPS units either generates a square wave or "stepped approximation to a sinewave". Some motors and transformers don't like that.

[uxwbill]

@uxwbill In those cases, the motor or the transformer could hum loudly, get hot, operate improperly or possibly even fail. There are UPS units--mostly larger ones--that have a true sinewave output. These can operate almost any AC line powered device without incident.

[petegrimsby]

Hi...could you tell me how you wired up the voltage lcd screen as i have one exacly like the one you have

[uxwbill]

@petegrimsby Yes. I've seen some variation depending upon where you get the meter, even if it looks the same as another. There are two wires for voltage input, positive and negative. Then there are two wires for the input from the voltage to be monitored. Here is where things get tricky. Some meters will read the voltage no problem, however you hook the leads up. Others will read the voltage with only one negative connection. Still others will blank out with + and - reversed. (cont'd...)

[uxwbill]

@uxwbill ...on the voltage sensing side. (Reversing them on the power supply connections might prove fatal to the meter, so if you have to get one connection right, it is the power connection.) There are also some meters with five wires--the fifth is ignored.

[Gotye1]

That Sony es component that you have situated atop of the speaker, could you make a video of it please?

[petegrimsby]

@uxwbill my meter only has a positive and negative. these 2 wires read the voltage and also powers the screen and backlite. do i simply connect it on my battery and put a switch in the middle ?

[uxwbill]

@negativeeffect2 Centris 650 - a future project when I get some time to play with it. (Like I've been saying since this video was made.)

[negativeeffect2]

Is that a Macintosh IIvx on the right?