Dead 12v battery

[DaveH]

Was out yesterday on an 80 mile drive. Left with battery fully charged and returned with about 80 miles left.
Powered off and locked doors. Don’t believe I left anything switched on.
This morning neither fob or door button worked, so opened door with key. (key is inside fob)
Checked 12v battery, which only had 3v. After charging 12v for an hour all was back to ‘normal’.
Only extra to add is I had the software Comfort update put on last week.
Any ideas on what could have drained the battery?

 

[Mark Holmes]

I wouldn’t like to speculate, I’ve heard of people with drained batteries, but it’s never happened to me.
I would simply double check that everything is turning off when you switch off next.

 

[Kithmo]

Was/is the rear hatch shut properly, boot light on ?

 

[DaveH]

Just checked that light only goes out when boot fully closed. If open the warning when stop/start pressed isn’t obvious. It’s just a glowing boot on the dash. Should be similar to leaving lights on. Can’t tell if that was the problem as it’s been opened/closed since last night. Boot not closed properly is a good call though.

 

[Kithmo]

It could do with a switch on it so it can be turned off altogether.
I might put an LED bulb in mine, less power draw if it stays on then.

 

[Septian]

It could do with a switch on it so it can be turned off altogether.
I might put an LED bulb in mine, less power draw if it stays on then.

That's my job for Friday, replacing the "drivers" lights and the boot light with LED

 

[Phil Hayward]

I bought a volt meter that plugs into the 12v socket, I have had the low 12v come up a few times.
I noticed the voltage drops when the aux is used, charges when the green ready is on

 

[Iain]

As I expect to be doing shorter journeys with more demand on the 12v battery (lights, heater etc.) I have trickle charged my battery. I also put a smear of Vaseline on the terminals. Also worth checking all connections are tight.

 

[Chrispydoc]

Funnily enough, I did a similar trip yesterday. 80+70 left......but I plugged in as soon as I got home, as I usually do. So I wouldn't know if I'd left something on..?

I got in the habit of always plugging in as soon as I got home, during my years of driving my PHEV.

I will replace the interior bulbs though as a precaution......anyone got a link?

 

[Phil Hayward]

The boot and interior lights go out after a while, so you don't flatten the battery

 

[Srp111]

Did you turn the radio on after ignition off , don't know if you can.
Or leave the main headlights on

 

[Srp111]

The interior lights are very easy to change lots of led bulbs on ebay for pence, makes it a lot crisper and brighter too