Welcome to Wrong Time Watch—my name is Kevin, and in this video I walk through replacing the battery on a Cartier Tank 3169 (the quartz version). The first thing I cover is figuring out the correct battery, because the case back doesn’t spell it out. I did some digging and saw a couple suggestions online, but the most reliable match ended up being a 315, so I grabbed a five-pack of Energizer batteries (not the Swiss Renata) and got to work. From there, it’s all about taking your time with the tiny hardware. The case back uses four very small screws, so I used a 1.2mm flathead screwdriver and worked over a silicone mat with ledges so nothing goes flying into outer space. Inside, you can see the Cartier 690 movement and a plastic movement holder, and the old battery in mine was already an Energizer 315. Since this Tank doesn’t have a seconds hand, I verified it was running by watching the minute hand move after installation. I also talk about screw tightness—snug enough to seat for water resistance, but not “woodworking torque”—and I remind you this is basically hand-washing-only water resistance anyway.