450h+ Battery

[NickMA]

I've experienced a flat Battery on several occasions (450h+), the circumstances are the car is on the drive uncovered, the temperature is cold usually below or close to zero centigrade and after starting the car, so it's ready drive away, and on the dashboard it says, "READY". The car is in EV mode all the time. I then go into the house for 5-10 minutes while allowing the car to warm up and on four occasions I have come out to find  the car 12v Battery flat. I don't understand why, when the car has been started, "READY" why the 12v Battery drains and closes the car down.  Unfortunately I've been going around in circles with my Lexus dealer so wonderd if anyone knows why this might be happening?

[Herbie]

The 450+ is the plug-in variant isn't it? If so, I know nothing about them so I may or may not, be talking rubbish.

To me, EV mode suggests that the car is drawing from the batteries but nothing is going back in to keep them topped up. Try again but just not in EV mode this time.

[RONNIE W HODGEKINSON]

23 minutes ago, NickMA said:

I've experienced a flat battery on several occasions (450h+), the circumstances are the car is on the drive uncovered, the temperature is cold usually below or close to zero centigrade and after starting the car, so it's ready drive away, and on the dashboard it says, "READY". The car is in EV mode all the time. I then go into the house for 5-10 minutes while allowing the car to warm up and on four occasions I have come out to find  the car 12v battery flat. I don't understand why, when the car has been started, "READY" why the 12v battery drains and closes the car down.  Unfortunately I've been going around in circles with my Lexus dealer so wonderd if anyone knows why this might be happening?

Thinking Cognitively Mick Something is Definately Draining Your battery  But I suppose you Know That..Do you have any Accessories connected to your Car Like dashcam Etc...Which possibly Could be the Cause...I,m just Guessing here But Something is Responsible.. I Would switch of Interior lights and any other auxillery Equipment / Wireless Dongle And see if that Highlights and Drainage...I Have a DB2 Unit From Rewire Security which Monitors My 12v and Hybrid Battery on a Daily Basis So I get forewarned if there could be a Possible Problem with the Battery/s..To date this has been a Great little Gadget..Failing all else Mick you Could get an Auto Electrician to check the Wiring Looms for Possible shorts....Can't think of anything else at the moment But know how Frustrating this Scenario Can be...Cheers..!!!!

[NemesisUK]

1 hour ago, NickMA said:

I have come out to find  the car 12v battery flat.

How does this manifest itself? What leads you to think it's the 12v Battery?

When you leave the car to warm up do you have the transmission in Park or Neutral?

P.S. you have your location as London, when has the temperature been at or below freezing?