Terminal Melted

[Kate]

The positive terminal on one of my batteries melted. It looked like a candle that had burned from the bottom. Apparently, it was caused by a loose connection or an old/damaged battery. (Battery was about 3 & 1/2 years old.)

Anyone else experience that and identify the cause?

[jhnmdahl]

I've seen it in a car, but not on a boat. It was pretty clearly a corroded and loose connection with high impedance, so when you draw a bunch of current for things like starting the engine the resulting voltage drop across the terminal was significant. Using P=I^2 x R, you can dissipate a lot of power at the terminal and heat it up fast if resistance at the terminal isn't negligible once you start drawing high currents such as for starting the engine (or even charging the battery if the connection is really bad).