Windows Secrets Newsletter • Issue 3 • 2003-04-10 • Circulation: over 400,000

In my last issue, I wrote that I’d found an ad on a Japanese site for a coffee-cup warmer (pictured at left) that plugs into your USB port. Because I can’t read Japanese, I couldn’t say how much the device cost or whether it was available in any countries outside Japan. But it seemed like a very funny idea.

Several readers came to my aid with helpful information. John Weber, who describes himself as “a coffeeholic in Portland,” sent me a link that questioned whether a USB port had sufficient voltage to heat coffee. The forum page, run by HalfBakery.com, received numerous pro and con comments, including supportive ones from a poster named JKew:

• “My back-of-the-envelope calculations suggest that 2.5W is sufficient to raise 300ml of water by ~11 degrees Kelvin an hour – ignoring any cooling losses and ignoring the mass and heat capacity of the mug. Flipping it around, this suggests that a USB port is capable of maintaining the temperature of 300ml of water which would otherwise cool by 11 degrees an hour.”

Fortunately, reader Arent Smit of Lake Cowichan, BC, Canada, provided a translation of the Japanese text, showing that the USB device doesn’t have to heat the coffee, just keep it from losing heat as fast as it normally would:

• “The bottom surface is warmed up by the USB power source and with heat retention by the thermal insulating material from which the sides are made. This prevents hot drinks from cooling down.”

Finally, reader Howard Yamaguchi reports that coffee is sold in heated cans that stay warm with help from the insulated sides of the USB cup holder:

• “In Japan, every street corner, train station, and other public area has a gazillion vending machines selling drinks of every kind. Coffee, both hot and cold, is sold in cans of various sizes. The hot coffee sold in cans is heated in the vending machines.
  
  “What the device being advertised at the Japanese Web site does is keep the already hot cans of coffee (45 degrees C) hot for a longer period of time (around 40 degrees C), for 30 to 60 minutes. It states that it cannot heat a cold can of coffee up to the temperatures stated.”

So there you have it. If you’ve seen something equally wacky on the Web, tell me about it at WindowsSecrets.com/contact