Here is an object to take to a desert island: the Telwin Drive Mini 12V.
Restart, recharge, it's efficient, light, you can take it anywhere. In short, it can solve various problems and has a low cost for its technology and performance.
It can start up to a current of 1000 Ampere, the brightness is intense: steady, flashing or S.O.S.
Use LiPo lithium polymers.
Complete with cable with pliers and cable with eyelets