Effect of High Current Switching on 12V Battery Supplies

Hi All and Welcome to MythBusters! There's been considerable argument about whether or not it's safe to run multiple different pieces of telescope equipment from the same battery power supply. Some argue that a battery is a battery and can never put out more than its rated voltage. However, others have claimed that you can see 40V spikes on the lines that can damage sensitive electronics in your computerized mounts. Here's a simple experiment proving the latter camp right.