Battery Draining Issue

[Tiernan]

Hi there. 
I have a 2011 Skoda Octavia MK2 Facelift Elegance. Over the past month I’ve noticed when starting the car some mornings it’s a bit chugging to start but it gets there eventually

 

I got the battery tested by a mechanic 2 weeks ago just to be sure and they said it was holding its charge so no problem there

 

However, twice this week the car battery has been dead when trying to start it in the morning. I have nothing plugged into the cigarette port, lights switch is left off, radio never on unless car is on, doors and windows closed and keys never left in the ignition

 

Just a bit confused how the battery could be acting up, any suggestions welcome

[softscoop]

What radio do you have fitted?

[cheshire_cat]

Could try measuring the “resting”  or parasitic drain should be below 40 mAmps preferably less.  Note after locking up +2 hours 

[Guest]

When you start the engine, do so with the headlights on and note if they dim.

 

If they don't dim much it could just be a bad electrical connection from the battery to starter motor or the starter motor could be dying.

 

Your description of chugging however sounds more like a fuel issue than battery.

[Tiernan]

17 hours ago, softscoop said:

What radio do you have fitted?

This is my radio photo attached

11 hours ago, cheshire_cat said:

Could try measuring the “resting”  or parasitic drain should be below 40 mAmps preferably less.  Note after locking up +2 hours 

So I measure this 2+ hours after locking the car?

[J.R.]

20 minutes is all that it will take but opening the bonnet to measure the battery voltage will wake up many of the systems anyway rendering it pointless, ditto leaving the bonnet open beforehand unless you close the latch to fool the vehicle that the bonnet is closed then lock the vehicle normally and do the test after 20 minutes.

 

Also you would have to have put the current meter in series with the battery before locking the car and the central locking will likely blow the multi-meter fuse on the 200ma range and the 10 or 20 amp range is not going to give you the accuracy you need for an expected sub 30ma current.

[cheshire_cat]

To measure the drain you can either use a DC clamp meter( on the battery earth lead)  or disconnect the battery and measure amps between negative and earth point.   To do this it will be necessary to 1 switch off the interior sensor ( door pillar switch to OFF ) 2- leaving the drivers door open lock the latch with ascrew driver ( 2 clicks). 3 - do the same with the bonnet whilst leaving it open. Fit the meter whichever, then using the fob lock the car. Leave for nominally 40 minuted but VAG say 2 hours . Measuring with the fuses in place seems to be the “ modern method” this is measuring the mild lot reading across each fuse.  A reading ***mV should after a few seconds go to Zero .that’s good. Any non zero reading should be noted fuse number - fuse size and its reading, using a chart cross ref the reading and fuse size to give a real value. With the internal fuse box it may be a good idea to get a photo before touching anything as there are a lot of empty spaces - easy to make a mistake🙀.  I’m guessing the radio is prob’ly the main culprit but check them all.  Keep us posted- good luck   It’s worth noting that VW say if the problem persists and all readings are good leave sleeping for 24 hours 😖

 

[cheshire_cat]

Did you get sorted ? 🤔

[Tiernan]

On 23/06/2023 at 16:58, cheshire_cat said:

Did you get sorted ? 🤔

Yes all I had to do was charge the battery overnight using a battery charger and it’s gave no problems since thankfully