This isn't an engineering question, but I don't know which forum is better suited to ask. I pulled two AA batteries out of my daughter's toy this morning after it had been left running all night. One of the batteries read 0.80 volts, and the other read -0.24 volts! That's right, one was reading negative voltage and the leads were on right (as evidenced by the positive voltage on the other battery). The negative-voltage battery had some powder (sulfur?) on the negative terminal and a small stain (leaking acid?) on the sleeve. They were both Energizer batteries, new just a few months ago, though they may have been subject to trauma in the toy. What gives for the reverse polarity? This just seems weird to me.