Originally Posted by rivers

A decent powerbank will do the job. A 20,000mah powerbank charged all my devices (phone, wahoo, lights) for 4 days without needing a top-up. If I were on a longer trip, I would probably take multiple powerbanks. They're not that heavy and don't take up loads of space. 2 x 20000 and 1 x 10000 would do 9-10 days of charging. And in a real emergency, my front light can act as a powerbank if needed (I carry other sources of light, inc a head lamp).