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.

Are you waiting for a phone that can run on a single AA battery? The mobile phone pictured above is the SpareOne which is one such device. But the new device is not meant to function as your regular handset.  The SpareOne has been designed as a back-up phone which can be kept in your emergency kit. Using that one AA battery, the device can deliver up to 10 hours of talk time. But its most amazing feature is that it comes with an isolator that prevents current discharge which allows it to hold charge for up to a whopping 15 years when you are not using it. But that depends on the shelf-life of the battery that is being used.

The device can be used at emergency situations. For example, the phone will be a big help when you are traveling away and you have no way to charge your phone, or when there is no power due to a flood or earthquake. And if you carry a pack of batteries in your bag, you will be able to chat for hours on SpareOne.  As the SpareOne comes unlocked and requires a SIM, in order to use the phone, you will have to swap the SIM card from your regular handset. It’s coming in two GSM versions (850/1900 MHz and 900/1800 MHz) and with an always-on 911 feature (no SIM required) and an LED emergency flashlight. It will ship in March with a price tag of around US$50.

The post SpareOne: The Emergency Mobile Phone Powered By One AA appeared first on Mobile Magazine.