I stumbled across a semi-forgotten cat toy last week. It’s one of their favorites — it’s a motion-sensitive ball that lights up in a variety of colors when kicked. It also eats up batteries. It takes three watch batteries, but I only had two left in the package in my desk drawer. They were super-cheap on amazon ($5 for 30 including shipping, whereas Radio Shack will typically sell you a single battery for $2 or $3). I ordered 30! Good news!
The batteries arrived the other day. I popped open the cat toy, went to insert three batteries, and discovered they’re too thick. I got the wrong kind of battery. Watch batteries of this kind are all the same voltage, but in a vast array of physical dimensions. These had the right diameter, but were just too thick. I’d accidentally ordered batteries for the kitchen timers — the only other things in the house that take watch batteries. Bad news!
I looked closely at the design of the cat toy circuit board and battery holders. If the batteries were too thin, I could have bent the tension tabs more for a tighter fit, but the batteries were too thick, so there was not much I could do that didn’t require surgery. The battery holder design was pretty simple, though, so surgery was not completely out of the question. I grabbed my trust Weller soldering iron and assorted other tools and hacked the battery holders. Good news!
Additionally, now everything in the house that takes a watch battery (the kitchen timers and the cat toy) all take the same battery! There’s no need to stock two different kinds. Good news!