@HDJ Any updates on this? I'm having a battery problem that sounds similar - fully charged battery will last a week or two before going flat and shows 12.3 to 12.4 on dash when normal driving. Cheers
TLDR; get your battery load tested and check for a high parasitic load when the car is parked.
Long story…
A fully charged battery will generally be sitting at an open circuit 12.8V or more. One that’s placed on a shelf in storage should last 6 month before a maintenance charge is needed.
Holden recommends an in vehicle battery be maintenance charged every 6 weeks if the vehicle isn’t being used.
Maintenance charge should be done at 12.3V (open circuit voltage) else battery sulfation will begin.
Charging lead acid batteries is a complex task because battery chemistry is complex.. Todays vehicle smart chargers aren’t the be all and end probably because of compromises in the charge logic because of patent issues. VE & VF use smart charger logic but unlike some makes doesn’t require programming when a new battery is added (the system learns that by itself if the drive habits are appropriate)…
If your battery is needing a maintenance charge after one week or two, presumably with the car being garaged during that time, I’d suggest that the battery either has some internal self discharge (due to sulfation) or the vehicle has some parasitic loss (where some rogue circuit is sucking the juice out of your battery).
If your car is being driven during the week or two it takes to drain the battery, then it can still be similar causes as above or it could be the alternator isn’t being commanded to charge at an appropriate rate (in which case check the battery current sensor and other parts of the charge logic as something may be amiss, check for any charge related DTC’s).
Below is some battery charge info
BU meta description needed...
batteryuniversity.com
What’s missing from the equation is detail about the algorithm that the BCM uses which Holden doesn’t disclose within the workshop manual (which makes it harder to fault find that smart charger function).
PS: welcome to the forum.