Does your UPS battery backup not run long enough to shut down the computer?
Tired of waking up to the UPS beep due to low battery?
The photo of the UPS to the right sits under the authors desk in a leased building.
This upgraded battery backup system has "BIG TANKS" or deep cycle batteries underneath it to accomodate longer run times. Want to know how? Read on!
Your computer UPS system is just like the rechargeable or disposable battery in a smoke detector; when the amount of power the battery can store eclipses a minimum, it beeps until you change it or charge it. As the battery ages, it's ability to charge diminishes until you are sick of it. You can either buy a new smoke detector, recharge the same battery again putting it up, or just buy a new 9 volt. Many folks don't recognize that their battery backup system for the computer is the SAME! Every two years you should plan to pull, and replace the battery. This is a HIGH USE application, just like your car. If you use it sparingly, you might get 5 years time, but a replacement is immenent, know it.
When it is time to replace the battery, start by unplugging the UPS from the wall, computers, and everything from the back goes next. (I assume you shut it all down nicely, first!) Next locate the battery hatch, and open the UPS up. The battery should slide right out. Be careful to disconnect the wires, and keep everything for the next battery. Often you must turn the thing over, and find the battery door. If you plan to just replace the battery, call your local battery dealer with the specs from the one you removed. Better yet, pull it out and take it to the battery store.
If we are tinkering, I suggest you leave the system alone for 15 minutes to an hour to let things dissipate. While you wait, we inspect the batteries that came out of your system. Look at that battery to determine these 5 things:
Battery Voltage - MOST IMPORTANT- WE SIMPLY MATCH IT!
Battery weight - Second Most Important, determines power storage capacity
At this point we look at the UPS itself. We want to know what we are dealing with.
Do you want to upgrade the system? Batteries are power tanks to electrical circuits. Technically, a battery is the ONLY electrical device that can store power for use at a later time. This storage feature allows your UPS battery backup to store power, and give it to your computer, on an as needed basis. This battery is the HEART of everything. So if our power supply here is rated for 540 watts, at a power factor of .9, we can use (540 * .9) 486 watts safely, in a sustained manner. Therefore, we do the equations with this number to determine the power of our little unit.
Since replacing the battery on a UPS system is a basic, fundamental, and mandatory maintenance on a bi-annual basis, you might as well upgrade while you are at it. Here is what this stuff means:
The easiest part is to just match the voltage. Like putting "D" cell batteries in an "AA" sized stereo, it runs longer and the batteries hang out.
The weight in lead determines the amount of power the system could store, same or bigger is required. (represented as AH or ampere hours).
The weight in lead divided by size in cubic inches determines space efficiency. Better batteries are built more tightly.
Is the battery UL approved? If not, you can get a better one and increase efficiency too.
The Dimensions determine the battery bay size. You don't have to have the battery in the bay.
The Dimensions determine the battery cube. AH/in cubed = space efficiency. Is your battery a piece of junk?
Once you have determined the voltage, any AGM battery that has the same voltage, that you can hook up, and is heavier; will run better and longer.
So let's look at mine again. We have 2 PVX-420Ts sitting under there :) those hold 42 ah each, at 12 volts. I don't ever want to use more than half of the power, once per day, so they last for 5 years. How long can I run with the power out?
The math for the amount of power those hold looks like this.
496 watts running * X hours * 1.2 = 12v * 42ah * 2 batteries * 50% limit
Roughly 1, which equates to 1 hour power outage I can sustain, per day!
If I had to, I could work for 2 hours before the batteries totally gave out.