So according to the calculation of Voltage x Amperage = watts that means that the 12v 500w power supply only puts out 42 amps and the 18v 500w power supply only puts out 28 amps does that make a difference in the performance of your charger? Does amperage make any difference on how a charger will perform? What is the lowest recommended amperage you should ever go down to on a 12v power supply? Just wondering seeing as my computer converted power supply is d.c. rated for 160w output but at 12v it has a maximum of 11a max, accoring to the formula I get 12v x 11a = 132w so what does that mean that the manufacturer doesn't know what the actual watts rating is or am I missing something? Is that enough to run a 50watt 5amp charger? With this power supply what is the biggest baddest charger I could use on it? Could I use it with a mutiple battery charger? or would I have to get a more powerful power supply?