Most EVs have standard size 40-50Ah 12V battery. So while it's not a largest one it's still a standard size battery for a small car - it has to be decent capacity to support telematics and other electronics when the HV system is not energized.I don't know anything about the Ioniq, but most EVs have a rather small 12V battery which doesn't last long in parking mode, but since it is not required for engine startup, it can be discharged without issue. I suggest a setting of 12.2V.
It would be nice if it was that simple, but I'm not convinced that it is.EVs will charge the 12V battery even while parked if it gets low so discharging it too low should never be an issue if the battery is healthy.
- Some 12v batteries are simply faulty and can't maintain a charge. Replacing the battery (usually) fixes the issue.
- Many EVs will stop charging a 12v battery that demands to be charged too often to prevent the main traction battery from draining over time. This could be related to item 1, or related to accessories asking for 12v power while the vehicle is turned off (GPS trackers, dash cams, etc).
- Many EVs won't charge the 12v battery when the main traction battery is depleted below a certain level (normally in the 20-30% range).