Why does my car only start when jumped using a battery pack?

Posted by No_Refrigerator_1632@reddit | askcarguys | View on Reddit | 12 comments

Anyone know the cause?

I tried to jump via another car, no luck.

Replaced the battery, still dead.

Cleaned the terminals, still dead.

Called a tow truck to tow to a mechanic, he uses a battery pack to jump the car and it works like a charm.

Why couldn't I jumpstart it using another car? And what is causing this issue?

Bad alternator?