By: Zuzana Prochazka
Which consumes more power: a 12v four-cup coffeemaker or the same 120v model using a converter?
Normally, the straight 12v DC unit will be more efficient, because an inverter has a certain power loss to convert from DC to AC. The bigger question is the watts used by one or the other version. A four-cup AC coffeemaker requires approximately 650 watts. (For a 10-cup version or for a cappuccino maker, that wattage doubles.) Check your individual appliance label for exact requirements, and if it doesn’t tell you the watts, remember this formula: volts x amps = watts. So a device whose label says 120 VAC and 7.5 amps will draw 900 watts. You’ll need to make sure your inverter has enough power plus a 10 to 20 percent reserve. If the watts are about the same, a difference of no more than 10 to 20, the DC will be more efficient. The other question is: How long does it have to run to make a pot of java? If the DC version is slower and will have to run longer, your savings by not converting are erased. If you have an inverter that is at least 1,000 to 1,500 watts, you might consider getting a good 120 VAC four-cup coffeemaker and enjoying your morning.