So yeah, came home from work one night and as we walked to the landing I could smell a funky electrical burning smell, hmmm, walked upstairs and it got stronger, went into the little bedroom which I have converted into an office for myself and it was a really potent electrical burning smell I immediately started sniffing about (as you do) I had my fingers crossed it wasn't my beasty watercooled SR2 rig but the smell wasn't very strong near that, I then sniffed my HP Microserver and another machine I had running, nether smelt that bad then I got on my knees and sniffed the APC UPS under my desk and wow I nearly threw up the smell was so strong, I touched the side of it and it was stupidly hot, I mean if you left your hand on it you would get burned!! I quickly shut the HP Microserver down along with a couple of other things running of it and then grabbed a towel and legged it into the garden with it! I left it 2 hours and the dammed thing was still pretty hot when I went to check it, I took the front off to look at the batteries and could see they had majorly expanded and were stuck in there! After another 2 hours the batteries had shrunk enough to get them out, and well, check the pics below and bare in mind these were after they had cooled and contracted! The PCB board in the top of the UPS is bent like a banana now as well so I have decided its getting binned, not even going to try and salvage it, was a good 8-9 years old anyway and I've done 3 battery changes over those 8 years, just had its time I think... R.I.P APC UPS! Any idea what would have caused these batteries to do that, dodgy battery cells or something??