It's not the battery. It's all the electronics that keep the voltage at 120V. A power surge strip usually just has a small capacitor (they call it something else) between the lines. It only kicks in when voltage goes way up for a certain amount of time. A UPS will protect anything over 122V no matter how quick. We have a bad wire going to our house. We have 220V service, one line is 118 - 119 V and the one that goes to my wife's PC is 114 to 116. I tried a extension cord to a circuit on the better side. But it ran across the rug. This new UPS adjusts voltage by taking the 114 and kicking it up to 119. The old UPS I had would use the battery to kick it to 119V. So during the summer, when everyone on the street has their air on, the old UPS would drain the battery, and after 9 hours of 114 V, kick off. The new UPS (Ultra brand) is bigger and has a digital readout. Got it for $99 at
www.tigerdirect.com last year or so with free shipping. Shipping is a cost you have to look at as these are very heavy and can cost $30+ for shipping.
My UPS was a used one, it's now 13 years old. At that time the batteries cost just as much as a new one. At $45 per car battery, assuming you need two for a 24V input. You can pick up a used BIG UPS for dirt cheap on E-bay. Without batteries the things weight 15+ lbs. So shipping is dirt cheap. If you don't want to add water, get the $140 gel car batteries.
UPDATE.. just check the water level (after 4 months) and that was not bad. BUT the metal push together connectors that join the battery wire and fuse, are corroded to the point that they split when I tugged on them. Will have to solder them, wire to wire. No bi-metal connections anymore.
With 17 years with no replacement fans or board... what else can I say. It goes on 24/7 in Nov. and off in March. I just had to adjust the feed screw again. When it was on low, it was pumping too many pellets, then over flowing and not burning right and smoking up the glass every day. Must be that contact going.
Interesting story. Last week the local paper reported a tree falling and taking out a transformer. Not quite. A power surge went through several houses. How bad, an outdoor meter exploded and was setting the side of the house on fire. All kinds of things in other houses caught fire, not smoked but went on fire. People reported hearing their outlets sizzling. If the 400V upper wires crossed the 120V. That would toast anything what was on or kicked on.