The photo of the Varta battery posted above is from my Macintosh SE. Although the battery was still working fine, I removed it, just to avoid any chance of leakage. The best solution I've found is to solder a CR2032 battery holder in it's place, allowing for easy future battery replacement, and pretty much eliminate any chance of leakage. So far (it's been about 3 or 4 months), the CR2032 3V battery has proven to work fine in my Macintosh SE. Not sure if it's a suitable replacement for later Macs that use removable 3.6V batteries, but I'd say it would be worth a try.