Do you remember the episode of Seinfeld where George Costanza wants to immortalize his high score at Frogger for posterity? He buys the old arcade machine from a pizzeria that is going out of business and then has to find a way to transport the machine while keeping it plugged in so it doesn't lose the high score list with his initials (GLC) displayed prominently at the top. The episode culminates in a re-enactment of Frogger as George tries to cross a busy New York street while pushing the arcade machine before its power supply runs out (Retroblast has the video clip at the bottom if you've never seen it before).
Over at Everything2 someone by the name of TheBooBooKitty has basically debunked the Frogger plot by explaining all of the technical inaccuracies behind the premise.
They powered the machine with a car battery. That is a big problem as well. The Frogger gameboard is a Konami Standard board, it requires +12 volts, +5 volts, and -5 volts power, which they apparently supplied with a standard car battery. They somehow managed to provide the needed AC power for the monitor as well. They could have possibly used some sort of power inverter to power the whole thing, except that that none of the standard ones that you buy at the store can put out enough juice to power an arcade game (Autozone sells these things, I tried, it doesn't work), and a higher rated one would have drained the battery in seconds, if it even worked at all.
"The Frogger" is one of my favorite episodes of Seinfeld and while the explanation offered here does make a lot of sense, I choose to suspend disbelief and just go with the episode. There's something special about trying to keep one's high score alive indefinitely. I can't begin to count all of the games I have that feature MAG listed proudly in the high score table.