My car won’t start with jump
If you’ve tried jump starting a dead battery and the car still won’t crank or cranks but won’t fire up, this post is for you. If your car won’t start with jump, start here
Most common causes of car won’t start with jump
Mistake #1 The battery is severely discharged
The biggest mistake DIYers make when trying to jump-start a dead battery is thinking that the jump provides enough power to recharge the dead battery and still provide enough power to start the engine.
When you connect jumper cables to a severely discharged battery, the jumping power will first flow into the battery to recharge it before it will flow to the starter. So leave the jumper cables attached and DO NOT TRY STARTING THE DEAD vehicle for at least 10-minutes! Seriously, give it time to recharge the battery
Mistake #2 — Leaving power accessories on while trying to jump-start
Turn off the headlights, blower motor, heated seats, rear defogger in BOTH vehicles while you’re jumping the dead battery. A vehicle alternator can only output about 1/3 of its maximum capacity when idling, so there’s no way it can recharge the dead battery and still power all those electrical accessories at the same time.
If you’ve followed those instructions and the dead vehicle still won’t crank, try cleaning the battery posts and terminals. High resistance in the posts/terminals will prevent power from recharging the dead battery and the starter and probably caused the dead battery condition in the first place.
If you don’t know if the problem is a dead battery or bad alternator, read these articles:
©, 2014 Rick MuscoplatPosted on by Rick Muscoplat