rogerco
Established Member
MG5 SR late 2020. Just got back from 5 days away having left car standing on drive as usual. Car was turned off and locked.
Keys (both) wouldn't unlock the car. Appeared completely dead. Unlocked manually and car would not turn on. Opened bonnet and removed cover. Disconnected 12 volt battery - it measures 2.5 volts open circuit...?
Ok so something has caused the battery to go flat. I have it on charge now which may or may not recover it.
The question is how will it be safe to reconnect it and how much current should be drawn from the 12V with the car off?
What can have caused the battery go flat? Has anyone else experienced this? When I left it last week the state of charge on the HV was about 50% - of course I have no way of telling what it is now, I can't unlock the front flap to plug in the charger (which is what I was going to do as I need it fully charged in the morning.
I'm fingers crossed it will at least wake up when the 12V has had a couple of hours charge - but it is very worrying that simply leaving the car for 5 days it will go dead - we have left it for much longer before so something must have gone wrong. Any ideas what. Anyone else had similar?
Just to add that the car as left unattended for 2.5 weeks late June-early July with no problem. The 12V battery state normally shows 14+ volts - and was doing so last week. Never seen it lower than 13.5v. All seemed normal week ago. Seems unlikely that the battery simply fell off a cliff in 5 days.
Keys (both) wouldn't unlock the car. Appeared completely dead. Unlocked manually and car would not turn on. Opened bonnet and removed cover. Disconnected 12 volt battery - it measures 2.5 volts open circuit...?
Ok so something has caused the battery to go flat. I have it on charge now which may or may not recover it.
The question is how will it be safe to reconnect it and how much current should be drawn from the 12V with the car off?
What can have caused the battery go flat? Has anyone else experienced this? When I left it last week the state of charge on the HV was about 50% - of course I have no way of telling what it is now, I can't unlock the front flap to plug in the charger (which is what I was going to do as I need it fully charged in the morning.
I'm fingers crossed it will at least wake up when the 12V has had a couple of hours charge - but it is very worrying that simply leaving the car for 5 days it will go dead - we have left it for much longer before so something must have gone wrong. Any ideas what. Anyone else had similar?
Just to add that the car as left unattended for 2.5 weeks late June-early July with no problem. The 12V battery state normally shows 14+ volts - and was doing so last week. Never seen it lower than 13.5v. All seemed normal week ago. Seems unlikely that the battery simply fell off a cliff in 5 days.
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