The Dark Energy Poseidon XL is built for the situations where a dead battery isn't an inconvenience; it's a problem. At 27,000mAh with 100W output, it keeps laptops and satellite internet devices running through multi-day stretches off-grid. The built-in voltage regulator and surge protection keep sensitive electronics safe even when the power source is a solar panel in variable conditions. What Our Gearhead(R) Experts Are Saying:"I bring this on extended basecamp trips where the satellite communicator, camera, and laptop all need power. The water-resistant rating ensures that a dunking in the creek or a day in the rain doesn't end the trip."