Hi there everyone
I am reaching out to see if anyone else has had a similar issue or can suggest where to from here.
My daughter recently purchased the 2018 Hyundai i30 Active Auto MY18 2.0 from a dealer (86,000 on the clock) in late November 2023.)
All presale checks (was completed due to a lemon that was purchased before this car) and no issues were reported.

Issue
The car will not start intermittently, symptoms are flat battery.

What has been done to correct the issue
Jump-starting the car will get the car however, the above symptom will repeat itself.
Battery charge process (alternator will charge the battery)
I did replace the battery with another (same specs) only for the issue to reoccur.
Ended up calling roadside assistance -
Quite certain it was the battery, the alternator /charging was checked, no issues found
The battery was swapped out with one from the roadside assist company
One week later the issue has appeared again.
My daughter finished work (02:00am) the car would not start, was jump-started by a co-worker)
This morning I started the car, no issue
Checked the state of the battery under load, always over 14V. 12.8 when the car was not started, the alternator appeared to be charging the battery.

radio, cabin lights, AC, and exterior lights are all off when locking the car.

Any suggestions, on where to from here would be great, we cannot use the manufacturer warranty as that has expired.


thanks in advance,
ozbankman
based in Melbourne, Australia