What if you could power your phone on a single AA battery? The SpareOne is a mobile phone that can to do just that. Designed as a back-up that you keep in a glovebox or emergency kit rather than a phone you keep in your pocket everyday, the SpareOne claims to deliver you up to 10 hours of talk time on one AA battery and it has an isolator that prevents current discharge so that (depending on the shelf-life of the battery you're using) it can hold charge while unused for up to a whopping 15 years.
The SpareOne comes unlocked and requires a SIM card in order to make calls, with the idea being that you swap the SIM card from your regular phone when the power is drained and there's no way to recharge it.
The phone could come in handy in situations where you're traveling away from power for long periods of time, or for emergencies like a flood or earthquake. If you stored the handset in a glovebox with a pack of batteries, you could be chatting for weeks in an emergency situation long after your smartphone loses its juice.
The SpareOne will be available in two different GSM versions (850/1900 MHz and 900/1800 MHz), meaning it should work pretty much worldwide (here's a GSM coverage map ) and it also features an always-on 911 feature that works without a SIM and an LED on the top that could pass for an emergency flashlight.
The SpareOne is expected to start shipping in March at a cost of around US$50.