I'm sorry but I posted this in the MkIII section of the Forum in error.

 

Hi, I was wondering what voltage to expect across the battery terminals on idle please?   Last week my rear sensors advised that they needed cleaning and that manoeuvre braking no longer worked.  All sensors were clean.  Reading some comments on this forum I decided to charge the battery overnight.  Upon selecting Reverse for the first time following engine start everything worked as expected.  Subsequent selections of Reverse lead to the 'Clean Sensors' etc. warning.

 

I have measured 13.0v across the battery terminals whilst idling - Is this normal?  I was expecting closer to 14v.  Could there be a cell failing - The battery is the original from 2020.

Any thoughts please?  

Kind regards

Alan

Edited 4 February, 20251 yr by AlanOsborne
Posted in the wrong Forum Section

This is not a battery voltage issue - more a battery capacity problem.  Its odd that when battery voltages start flucuating, you notice that odd things start happening with the reversing sensors.

 

You need to do a CCA battery test on your car battery (engine off).  Anything less than 20% of the CCA capacity and it need replacing.  I had to replace two batterys on our Octavias.  One is a MY19 and the other is a MY15.  Getting 5 years from a battery is about right.

Hi varaderoguy, thank you for your swift response.   The car is going to Mitchells Skoda (Chester) next week under the 'All in service' warranty.  I will 'Point' them in this direction (I appreciate that the battery is not a warranty item)  I was relieved to see that the sensors still worked as expected, albeit one time only following charging!

The battery voltage is dynamically controlled, with the battery only being charged when needed to keep it pretty well charged - so a battery voltage anywhere between 12.5V and 14.5V is normal depending on the situation.

 

Typically 14.5V just after starting and when coasting, when driving as low as 12.5V can be considered normal, and when idling 13V is expected and is not an indication of a failing battery.

+1 for PetrolDaves comment....

As you have a Mk4 you'd be unlucky if the problem was a low/bad battery...

 

Do you have something plugged into the 12V socket like a dashcam that could be draining it?

 

Hi Gabbo,  There are no accessories plugged in anywhere.  I would like to think that the battery should still be ok after 4.5 years, but it was just tested at my local garage, the result was <80% power and 12.1 V after charging.   It should also be noted that there is a lot of Sulphate residue which is slowly dissolving the retaining strap on top.

Sorry, I'm jumping between forums too much 😕 

I was confused between the Octavia MK4 & superb mk4 which had only been available 3 or 4 months. 

 

4.5 years old is not long for a battery but it's feasible it could be the cause especially if you've had it tested...

 

 

Edited 4 February, 20251 yr by Gabbo

Hi again, yes it all started last week following a prolonged wait at a car wash!  I was using the stop-start system (For once) which operated say half a dozen times with smaller 'Stop' intervals as time went on.  That evening I noticed the first rear parking sensor 'Glitch'  Over the next day or so the parking sensors' operation became more intermittent until last Sunday the system began 'Flashing' and telling me to clean the rear sensors! 

 

 

(See video) before finally refusing to work.   The error clears itself when the engine turns off and only returns upon selecting reverse gear.  As stated previously, if I fully charge the battery and then start the car, all sensors work as they should, until I have driven for a mile or so after which the 'Clean the rear sensors' error comes back.

okay - this is the wrong forum for this post.  It needs to go to the MK4 Octavia section.