GS450h 12V battery 'feature'

[hazelnut]

Today I lent my partner my 2009 GS450h. 100 miles or so journey, parked it, did some stuff, came home. Then went for the school run and the car was dead, some 2 hours later.  It seems when arriving home, she forgot to put the wing mirrors in, and 'quickly' pressed the start button, folded the mirrors and pressed 'Start' again. This we believe left the car on, but not in 'READY' mode. I put a spare 12V Battery in for the school run, and then checked this scenario with a clamp meter. It seems to draw 18Amps in this 'suicide' mode. With a perfect 12V Battery of 60A this would be a little over three hours until the 12V is deep cycled.  So is this just my car or do all the GS450h do this?

PS. picture shows my 'spare' Battery the proper one is on charge...

Edited July 3, 2023 by hazelnut
picture note.

[Kijan]

Hello Hazel,

From my own experience with MK4 if I leave with keys and car is on it starts beeping like crazy, not sure of it auto shuts off after a while as never tested that out.

All the best,

Bart

[ColinBarber]

2 hours ago, hazelnut said:

So is this just my car or do all the GS450h do this?

Pressing the power button without a foot on the brake would turn on ACC mode, then pressing again would turn on full ignition. I'd say 18 A is probably correct in that mode given all the ECUs would be powered up.

I would expect a warning beep if you try and exit with the car still on, and again if you try and lock it.

[Steven Lockey]

Sadly, I've done this more than once 😉

Car basically have 4 modes:

Ready
Off
12V only - This is what you left it in.
Air-con/Dog mode - Ready light off, won't shift out of park, but is using hybrid Battery to power air-con etc and will run engine to recharge it as needed.
 

[hazelnut]

I've just finished the charge cycle of the old Battery, 7hrs x 5A = 35Ah (label says 60Ah). So around 2hours of charge if the car is left in ACC mode (18A). New Bosch Battery S4026 ordered from Parts In Motion. This is a 70Ah Battery, so would last 4 hours in ACC. Modes I found so far with currents are:

OFF locked (-0.7A)

OFF unlocked (-2A) no dash lights

ACC (-18A) all dash on, but no READY

READY (+9A) float Battery to 14.0 V (less when hot battery)

I have not been able to find camping/dog mode.

[Steven Lockey]

I found it by sheer accident. 

Turn car into ready mode. Press power button then put car into park. 

Ready light went off, fairly sure the wheel retracted as well, but it was happy to run the engine to keep the Battery charged and the air-con running.

I was really confused when I came back to my car and the engine was running but the dash was saying nothing 🙂