i have a habit of sleeping in a power recliner... which is great except when the power goes out. The built in (2) 9v transistor radio batteries really don't cut it... so I sliced in (2) 6 in series AA battery holders which is better. The motor is rated 30 volts so I decided to up the power by swappng the 6 series for 8 series AA battery holders (24vdc). I needed 2, so I ordered 3. I swapped my nearly new AA cells in & added new to make my 8 cells in each. Glad I was working on my desk. One of the holders shorted ONE AA cell. The coil spring on the negative was off center & somehow got in contact with the cell case which is positive. Dead short! So the cell quickly became too hot to touch... just that one cell. The battery holder wasn't connected to anything... no other shorts. Somehow I pried the smoking little battery out before anything melted. Yeah, that was fun.