Today, while debugging a new 10/10Mbit broadband connection my trusty old Cisco PIX 515E decided it’d had enough or rather the lithium battery did. Bit of Googling didn’t yield any results on replacing it but I remembered that last time I had it open the battery did look quite plain, so I took it apart and found what appeared to be a standard “button cell” battery codenamed BR2032 3V. After scrambling around a bit in a drawer I found a CR2025 which is a bit thinner, .5mm to be exact, but it should fit just fine, the specs are the exact same except for the height but that’s not an issue as .5mm really isn’t much and it’s a real squeeze to fit it in the socket.. Guess what, it works beautifully.