Battery acting dead when it can be jump started

[Tony_Whenua]

Having issues starting the Ute even after its been running.
I have to jump start it to get it going. The thing is dead once the key is off. Not even the alarm works.
I’ve checked the terminals and the battery is only 6months old.
Faulty alternator not charging batt?

[DJZ]

Sounds like you're on the right track, put a multimeter across the battery terminals when it's running once the jumper battery is removed, you should see about 13.8 volts.

[Tony_Whenua]

I’ve been starting it everyday now. No longer need jump pack but it still struggles to turn over at first. Kinda like the draw to the starter is shit. Vaultage at the batt terminals when running is 14.3.
Maybe it was just a really drained batt? Had been sitting since Feb.

[2 doors]

whats the voltage say, in the morning after its been sitting a while.

[DATSN1200]

Had similar problem
Try trickle charging over night
Check terminal voltage in morning
Should be 12.8 to 13.8 volts approx
If below get replacement battery under warranty
Is it a Lead Acid battery ?
If its a Calcium one your Alternator may be only 35 amps which will not be sufficient to maintain as its output voltage is too low
Good luck