https://www.cnet.com/news/give-dad-a-portable-jump-starter-and-mobile-charger-for-29-99/

A dead battery can ruin your whole day. No, not your phone battery -- though that's true as well -- I'm talking about your car battery, without which you're going nowhere fast.

Thankfully, portable jump starters are inexpensive and plentiful. Amazon is lousy with them. Prices vary depending on peak current and other features, but start at around $40.