I plan to start using my Toshiba Portege again. It is nice and light and has a built-in optical drive. The computer, unfortunately, will only last for about three hours, which might be serviceable if I'm not away from a plug for too long. I would like to find the lightest, reliable power supply for a reasonable price. When I look online, many of the offerings, at least according to the reviews, either break very quickly, set things on fire or tend to explode. Can I get some recommendations for devices that will work and not be dangerous? I would also like to know if I can get around this time limitation using an external battery such as the Ravpower lithium-ion devices (I have some 10,000 mA hour models available to me). Thanks. Any help appreciated and appropriate points awarded for useful advice.