Portable Jump Start Battery

TARDCORE

LONG STORY AHEAD:
About a month ago my friend's car battery died and he does not have another car nor a room mate and none of his neighbors were around to help him. Luckily I was getting off work a little early and I saw his text message and went to help him and he wasn't too late for work but still late and still a stressful situation to deal with. A few days later he bought this portable jump start battery that charges using AC or DC current. It looked like a great idea but when he had to use it... about 3 days after, it did not work! . So same situation he was in again only this time we were working our normal 10 hour shift. So he had to call in sick because where we work if you don't show up its considered AWOL (no not military). Best part was that he paid $99.99 for it and they charged him a 20% restocking fee for returning it.

Point of this: Is there a portable jump start battery that any of you have used that actually works? If my car battery died, I would be in a much worse situation than him because all my neighbors hate me.

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