At the supermarket, we look at the price/kg or price/l when comparing similar products. But we can’t really do that when it comes to getting an AA battery. For getting those, people usually go for names they are familiar with, such as Duracell or Panasonic, or go after attractive terms such as ‘PLUS’, ‘SUPER’ or ‘MAX’. But Denis Hennessy had other ideas. He bought a pack of every AA battery type he could find to do an experiment to see which brand provides the most bang for the buck.

Hennessy had an Arduino and an LCD panel, and he designed a circuit which allowed him to measure how much energy each battery produced. He also added a temperature sensor and USB logging capability. The circuit measured the voltage across a fixed load every second until the battery reached 0.2V, while the LCD displayed voltage and the amount of energy generated, in Joules and watt-hours. With the data collected, Hennessy compared each of the batteries in terms of the cost per Watt-Hour.

And the result revealed that super charged names such as ‘super’ and ‘max’ don’t really mean much. The best performance was from RS Power Ultra, and the worst from the Panasonic Evolta.

Head here to know more about the experiment and you can recreate Hennessy’s test as he has posted the source code on GitHub along with the design and result files.

The post How To Choose The Best AA Battery appeared first on Mobile Magazine.

Weather reports are useful sometimes, useless others. To make things interesting and switch it up from watching those typical forecasted weather reports, how about feeling the weather tomorrow?  I know that I still have a habit of stepping outside to “see how cold it is” and whether I need a coat or not, even if I happen to have the current conditions displayed on my phone or computer.  And it’s that kind of tactile experience that paved the way for the Cryoscope. It’s a little aluminium cube devised by Robb Godshaw, what it does is gives you the ability to literally feel tomorrow’s temperature instead of trying to wrap your head around a number. The Cryoscope uses a thermoelectric Peltier element, heat sink, and a cooling fan. It is then connected to an Arduino controller and an external power supply which then pulls the weather forecast from the Internet. Heat is pumped in or out of the cube until its surface temperature mirrors the forecast. You lay your fingers on the aluminum surface and get a real feel for what it’ll be like tomorrow. The cube also factors in wind chill, humidity, and the properties of the aluminum surface itself. The Cryoscope has an effective range of 0 to 100F (-18 to 38C) so you may actually be able to fry an egg on it.

Weather reports are useful, to be sure, but there’s nothing quite like feeling the weather to really get a sense of things. I know that I still have a habit of stepping outside to “see how cold it is” and whether I need a coat, even if I happen to have the current conditions displayed on my phone or computer.

[ source via Robb ]

The post Cryoscope Will Let You Feel The Weather Tomorrow, Literally (Video) appeared first on Mobile Magazine.