Anker 20,000mAh power bank
The dead phone is the festival failure with the highest stakes, because it takes everything else down with it: the tickets, the rendezvous plan, the map of which field your tent is in. A 20,000mAh power bank is the capacity the festival threads keep landing on — enough for four to five full phone charges, which covers a phone-heavy weekend with margin for the friend who brought nothing — and Anker is the brand those threads circle back to when the question is which one. The recurring line in the long reviews is about trust: the capacity is real, the ports don't wobble loose by year two, and it recharges fast enough to top up from a campervan or a paid charging locker in the time it takes to eat lunch. The honest caveat is weight — around 350 grams, a genuine brick — but the consensus is firm that the 10,000mAh version runs out exactly one evening too early. Charge it the night before you leave, not the morning of.