When I was in college in the very early ‘90s (that’s 1990’s wise guys) I was given an old, and I do mean old, UPS that had a bad battery. Back then you didn’t have google shopping, shop.com, or the other plethora of ways to find replacement parts for odd items. So I had a uninterruptible power supply, with no battery. What to do? What to do?
I’ll tell you what I did: I drilled a hole in the case, ran battery cables into it, and wired up a $95 sealed, maintenance free, marine, deep cycle battery. The battery was HUGE. I’m sure it had over 1000 cold cranking amps (which doesn’t mean much talking about this particular application) and I’d guess it had more than a 100 ampere hour rating.
Over the lifetime of the UPS, I had several fully loaded systems running off it: a 486DX with a 14” CRT monitor, a Pentium 60 with a 17” CRT, and an AMD-K2 with a 17” CRT. I build or upgraded my own systems with new guts, so the power draw on these systems just kept increasing as I added crap to them. The UPS worked flawlessly for six years and on occasion supplied power for longer than eight hours at a time.
There’s something inherently funny about being in the middle of a blizzard, no heat, no light, and still being able to mud via modem and phone line on a 486 computer with your internet friends across the country.
Good times… Good times.
Well, the battery died. I worried about the safety of the UPS with it being so old. I knew more modern UPSes would have better circuits for battery maintenance, and safety. So I bought a newer UPS, then a few months later another, and another. I didn’t attempt what I had done in college for fear of burning down my house, gassing my family to death, or causing an explosion and being horribly disfigured by acid.
Well, all three of the UPSes I bought stopped functioning properly between one and two years after purchase; right after the warranties were up. I ran for a while without power protection other than surge and lightning protection of course.
So, what changed my mind about fire, gas and acid, you ask? Well, there are two factors that contributed to my change of heart. The first being more frequent power issues. One week we had two very minor power interruptions that lasted for several hours each. Both times I lost internet connectivity and work. It was very annoying. One was a car accident taking out a pole while the other was a falling tree or branch taking out a line. The second factor is my small problem with hoarding. Yes, in some alternate universe in a previous life I was a Gold Dragon. I can’t throw stuff away. I have a very hard time with it. I hate the idea of my junk being buried in a landfill somewhere. So, I had all three of these UPSes on a shelf in my attic. I started a project of cleaning up and cleaning out. I was going to recycle or reuse what I could and throw away what wasn’t useful or recyclable.
When I came across the UPSes, I went looking for replacement batteries. Two of them were 24V systems. Five tiny little 7 or 9 amp hour batteries were going to cost me a small fortune. It wasn’t near as cost efficient as buying batteries from an auto parts store. So I decided to do some research and do what I had done before, once more.
There are several good resources for reading up on this.
Dan’s Data has an article on how to Upgrade your UPS! And some good video how-to on You Tube: Turn small home UPS into giant UPS, Car battery UPS, and a list of others.
One thing to notice, some of these people are not using SEALED batteries. It’s very important to use a SEALED battery for use inside your home. When a lead acid battery is charged it can produce a poisonous gas and you can suffer harm from it. Don’t be stupid. Don’t use a vented battery in your home. If you’re going to use a battery that isn’t SEALED, use it where there is ample ventilation.
There are several different types of sealed batteries you can use: gel batteries, dry cell, or sealed lead acid (SLA). You can buy an Optima Yellow Top battery, which is a sealed, dry cell, deep cycle, high performance battery. This is the Rolls Royce of batteries. If you can afford it, get it. I went with two 35 amp hour Werker batteries from Batteries Plus. I felt they were cost efficient and safe. Plus they were made in China, and we all know if there’s one thing China does well it is definitely LEAD.
So, two batteries, wired in series, pictured far above — the white wire connects the positive and negative poles of the batteries, then the remaining positive and negative poles get the red and black wires respectively. This wiring produces a 24V battery out of two 12V batteries.
Really, there’s nothing fancy or stupid about that, it’s how batteries work. If you have a remote control that takes two AAA batteries but only one little grove to put them in, you put them in facing the same way right? ( + – + – ) That’s wired in series, and it makes 3V from two 1.5V batteries.
I didn’t like the terminals being exposed, so I added a battery box, and some wiring channel to produce my final product below.The one battery box holds both batteries inside. The UPS is a CyberPower brand; but, if you want to do something similar you can use just about any UPS you have laying around, the brand doesn’t matter.
For my next project, I’m going to wire up four 12V batteries into a 48V system and use a server sized APC Smart UPS I have laying around, surplus, in my garage. But that’s a project and a blog for another day.
If you plan on doing this, do some research. Talk to an electrician. Be smart about it. A 12V battery can deliver non-trivial damage to flesh, either by a spark or by acid burns. Be careful.
And in closing I feel the need to have you agree that you will hold me, my family, heirs, and executors harmless for anything you chose to do after reading this blog. You understand I’m not telling you to do anything or how to do anything. I’m just sharing what I’ve done and what I know. If you try something similar, and lose an eye, or in some other way damage yourself, loved ones, family, friends, etc., you understand it was by your own actions and is, was, and forever will be your own dumb fault. You agree that you will be a grown up and take responsibility for your own actions. And you understand that you are on your own.
How that for a disclaimer? My mom used to just say, “Don’t be stupid.” But I think in todays climate, you have to spell things out for people.