Holding a ginormous 20,000 mAh, this Anytone portable charger could theoretically charge your cellphone a maximum of twenty times. Most phones have 1000 mAh batteries, and most laptops have around 4000 to 5000 mAh, which means this battery holds twenty times more juice than your phone and four times more than your laptop.
However, thanks to the laws of thermodynamics, you're not going to see a perfect 20x charge. But it is enough to add about 3-6 hours of work time to your laptops. The Anytone APC-20000 is around $200 from Hong Kong, but the sites we saw only took orders of 500.