Trenneck

New battery, will jump start but engine dies upon removing jumper cables from battery. Alternator? Other thoughts?

carguy07

New battery is charged up an topped off?

Trenneck

Yes new battery is fully charged

salimshah

Monitor Battery voltage, before staring, during jump and once the jump is removed.

Battery may be fully charged, but it can have low capacity to provide current at 12v (expected). Proper testing is under load ... you can have it checked out at a car parts store.

Think of the jump situation as additional capacity to provide current.

Salim

fastnoypi

how are the condition of your terminal clamps? are they reasonably clean and tightened down? A worn out clamp can cause intermittent draw problems.

Puttster

Agree w Fastnoypi, probably a loose terminal clamp, when you put the jumpers on the clamps you make a good +/- connection, when you take them off you lose the connection (loose terrminal)

aznlapin

Voltage should measure ~14..7 volts when the engine is running. If you're not getting that (less than 13v), the alternator is shot.

If it's an issue with the terminals, clean the cable with baking soda + water before you change to the new clamps. Mine were so corroded I had to cut off the cable ends and clamp onto some "fresher" cable.
Doesn't hurt to add some dielectric grease on battery terminals & posts.

Drcoffee

Alternator

Bill Dowd

It sounds like your alternator because when you disconnect the battery your battery is not taking over to run the car. I would check out the alternator because even if you do have a bad battery the alternator will still run the car all a battery is really used for is to start the car and the alternator takes over from there.If you have a battery charger I would charge the battery first because when you charge a dead battery with an alternator it looks like a dead short to the alternator until a base charge gets going. It also takes about 1 1/2 hours to fully charge a battery while driving.Charging a completely dead battery with your alternator does stress it out this is what I've been told by several shops who will rebuild alternators.

maxSteel

I would usually agree it's likely the alternator but the poster said he had a "new battery fully charged".
Which makes no sense to me.

Why would you need a jump start when you have a fully charged battery?
And why would it die immediately (even with a bad alternator) if you have a fully charged battery?