Non-boaty car battery question.

[gordmac]

Google may well tell you what current drain your particular car should have, easy enough to check with a multimeter. To find the cause of a drain use the meter to monitor current draw and pull fuses individually to narrow down the cause.

 

[Alex_Blackwood]

Just a though, probably doesn't apply, but a friend of mine has an Audi which will not charge the battery unless the car is moving forward.
So he tells me!

 

[lw395]

Google may well tell you what current drain your particular car should have, easy enough to check with a multimeter. To find the cause of a drain use the meter to monitor current draw and pull fuses individually to narrow down the cause.

A lot of modern vehicles, the drain when the vehicle is 'switched off' varies a lot over time.
For instance my bike has an immobiliser which goes into a low power mode 24 hours after it last gets a stimulus.
Some BMWs take a similar time before fully putting the ECU into sleep mode.
So you need to monitor the current long term, and avoid doing anything that might wake the machine when you measure it.
Allegedly, some cars draw more ( or, bizarrely) less power if theres's a maintenance charger connected.

It's well into Schrodinger's Cat territory, measuring it will change the answer.
Drive it every fortnight.
Get a Ctek
or disconnect the battery and hope.

And make sure you have jump leads.

 

[lw395]

Just a though, probably doesn't apply, but a friend of mine has an Audi which will not charge the battery unless the car is moving forward.
So he tells me!

Some cars will choose not to charge the battery unless you're going forwards, not accelerating and not going uphill.
Seriously!
They will do anything to get into a lower CO2/km rating on the euro tests.
And I mean 'anything'!

 

[Alex_Blackwood]

Some cars will choose not to charge the battery unless you're going forwards, not accelerating and not going uphill.
Seriously!
They will do anything to get into a lower CO2/km rating on the euro tests.
And I mean 'anything'!

So the OP's car in question, a VW part of VAG, could conceivably have that set up. Every time it was started it just drained the battery without sticking any charge back in.