Just cursing the Maplin site and saw this and thought it may be useful. All-in-one Jump Starter with Wind Up Charging Inverter and Torch http://www.maplin.co.uk/all-in-one-jump-starter-with-wind-up-charging-inverter-and-torch-612549 The all-in-one jump-starter, power bank and torch, can be charged by using the crank handle, mains supplied electricity or car adapter. This handy device has a myriad of outdoor uses; in the garden, on holiday, camping, travelling, on a boat - just about anywhere where there's no mains supply. After a few minutes of turning the crank handle you'll have a fully charged power source with which to jump start all kinds of engines, or power a laptop. It has a multifunction display that keeps you informed of the current charge status and a powerful LED light, and red warning light. The cable clamps for the jump-starter function are included and there are outputs for recharging mobile phones, laptops and other devices.
It might be useful, but I'd be a bit sceptical about the claims that you can start a car after a few minutes of cranking. The spec says 2.5A at 80rpm cranking speed, the battery in it is 15Ah so it would take about 6 hours of cranking to full charge, thats assuming 100% efficiency. Best to keep it charged up off the cig lighter
