Hi all,

I have Octavia Mk IV MY21 I got the factory battery replaced in it back in May2024 with an AGM battery when the last one died when we were on a trip.

Friday last week i got a start / stop warning normally indicating a low battery and when this happened last time i was able to use the car for about 2 months before it totally died. Seeing that this might be the case soon i ensured i had the start stop disabled and ran the car for a good 2 + hours on Saturday as well as set the car in sports mode hoping that the extra revs etc would help charge the battery faster.

However this morning when i went to get something from the car the car was totally dead. unable to unlock with the FOB. I called the same roadside that originally replaced the battery just over a year ago as it has 24 months warranty. they came out checked the battery it was at 10V and said the battery is ok and just need to be run more. jump started the car and said to leave it running / go for a 1 hour drive and I should be ok. I have run it today for 1 hour after this and once back hope power cycled the car and it appeared to start back up but i feel tomorrow evening it is going to be the same issue again.

While i dont use the car much on weekdays but the odd local shopping trip. On the weekends i regularly drive a good 1-2 hours a day. My dad who has a VW with the same type of battery has a similar drive pattern and his battery has been going sold for the past 2+ years

It is normal for the battery to drain so fast? could there be some electrical leak that keep draining the battery even when the car is off. I expected the AGM battery to have better life and hold it charge better. or could the car have been re program wrong so it not keeping the battery at the correct levels ?

as a stop gap measure would it be advisable to get something like this to charge the battery overnight ?

https://www.supercheapauto.com.au/p/sca-sca-12v-1.6-amp-battery-charger/611219.html?cgid=SCA01060203

27 minutes ago, molesy94 said:

could there be some electrical leak that keep draining the battery even when the car is off

Yes, there were service campaigns addressing that, as well as some firmware updates available on demand. Authorized workshop should get it sorted.

Just now, Edela said:

Yes, there were service campaigns addressing that, as well as some firmware updates available on demand. Authorized workshop should get it sorted.

by any chance do you have a link to this? or the TPi i can get my local dealer to look into this

When you got the replacement battery did you code it ?

Just now, RADIOTWO said:

When you got the replacement battery did you code it ?

I took it to the dealer and they did the coding. I can only assume they did the correct job.

3 minutes ago, molesy94 said:

I took it to the dealer and they did the coding. I can only assume they did the correct job.

Yes you assume so, but have you checked for parasitic current draw ?

1 minute ago, RADIOTWO said:

Yes you assume so, but have you checked for parasitic current draw ?

no. I have no idea how to do that to be honest. I have already emailed the dealer to see if they can have a once over of the car.

28 minutes ago, molesy94 said:

no. I have no idea how to do that to be honest. I have already emailed the dealer to see if they can have a once over of the car.

Have you got a Multimeter ?

4 minutes ago, RADIOTWO said:

Have you got a Multimeter ?

I have to check i might have one at the parents place

58 minutes ago, molesy94 said:

by any chance do you have a link to this? or the TPi i can get my local dealer to look into this

Service campaign my car had was 90V7, specifically for parasitic drain. For the firmware, unfortunately I don't know the details. Tech told me he flashed three gateways with new FW at the time, but that's all I know. Had no 12V issues since then.

12 minutes ago, Edela said:

Service campaign my car had was 90V7, specifically for parasitic drain. For the firmware, unfortunately I don't know the details. Tech told me he flashed three gateways with new FW at the time, but that's all I know. Had no 12V issues since then.

Was that for a petrol car or the plugin hybrid? I have a petrol only car?

2 minutes ago, molesy94 said:

Was that for a petrol car or the plugin hybrid?

Mine is PHEV. Though all cars regardless the engine have the same issues with 12V system, you'll see many topics on this forum about that.

I’m aware some folk have had 12V battery issues but thought it was only mHEV (e-Tec) and PHEV versions. Could be wrong though.

Mine is a 1.5tsi, 2020 model, registered Sept ‘20. Currently on 65,000 miles and the battery has not shown any issues to date. I do tend to drive long journeys though - already done 1500 miles this month.

Edited 15 September, 202515 Sep by SteveTheElder
Added engine detail

9 hours ago, Edela said:

Service campaign my car had was 90V7, specifically for parasitic drain. For the firmware, unfortunately I don't know the details. Tech told me he flashed three gateways with new FW at the time, but that's all I know. Had no 12V issues since then.

Thanks. Will ask the dealer to have a look of any tpi for it

8 hours ago, Edela said:

Mine is PHEV. Though all cars regardless the engine have the same issues with 12V system, you'll see many topics on this forum about that.

Fair will get that checked out

3 hours ago, SteveTheElder said:

I’m aware some folk have had 12V battery issues but thought it was only mHEV (e-Tec) and PHEV versions. Could be wrong though.

Mine is a 1.5tsi, 2020 model, registered Sept ‘20. Currently on 65,000 miles and the battery has not shown any issues to date. I do tend to drive long journeys though - already done 1500 miles this month.

Yea it could be with the ev versions of the car but will have the dealer check it out.

I have the 1.8l limited edition here in aus. Currently done 27K km overall

They are heavy on the battery, a lot of systems pulling on it continuously. It's not exclusively a Skoda thing as I've had the issue on a previous late model car full of electronics. There are periods when my car isn't used for a couple of weeks or more, or is doing only short runs, so I keep the battery trickle charged with a CTEK smart charger. I did this with my previous car and never had a problem.

This battery charge issue can also be a source of those little electrical gremlins e.g. false bulb failure warning, random wiper action etc. The systems need a fully charged battery to function properly.

2 hours ago, SouthernComfort said:

They are heavy on the battery, a lot of systems pulling on it continuously. It's not exclusively a Skoda thing as I've had the issue on a previous late model car full of electronics. There are periods when my car isn't used for a couple of weeks or more, or is doing only short runs, so I keep the battery trickle charged with a CTEK smart charger. I did this with my previous car and never had a problem.

This battery charge issue can also be a source of those little electrical gremlins e.g. false bulb failure warning, random wiper action etc. The systems need a fully charged battery to function properly.

I do get that but seems very odd for such a new battery to have this issue. With decent daily driving should not need a trickle charging.

I've had it with new and aged batteries. It depends on what decent daily driving means, if you're doing good freeway km's for example, I'd expect better battery performance.

Interesting. I have a 4.5 and it has progressively used stop/start less and less to the point where it never does it. I’m taking it in to the dealer to check as I suspect low battery voltage on this 6 month old car. We will see what happens.

Update 1: car started this morning took it to the dealer and left for 2 days so they can do a full check. Apparently there is an update for the gearbox control. Unrelated to the battery issue

Generally speaking, I find that if the (a) car is driven even for 2 or 3 miles daily then one should get a reasonable battery life, my Jan 2019 Polo has no problem with the stop/start on the rare occasions that I enable it and will do so after driving the mandatory 500 meters even if parked up in the airport for 8/10 days. It wouldn't do any harm to invest less than a fiver on a DVM (digital volt meter) and leave it permanently plugged in to the cabin power socket, you should find that the battery charges at 14.8/15.0V allways on the overrun and ~ 13.6V while driving or idling.

The batteryhas never indicated more than 85% SOC, even when new, one might think that at its present alleged 71% SOC that it would charge at well over 14.0V to get the SOC back up to 85% but it doesn't, on a 2 hour trip a few weeks ago it just did its usual 14.8V on overrun and 13.5V ish, while driving normally but I will be happy enough if I can knock around 8 years out of this battery, car has only 23,000 miles up but as stated above, driven daily.

If I check the battery current (VCDS) sitting in the car with the doors locked and ignition key out, it reads ~ 2.5A for a few minutes and then falls to zero, presumably means little or no parasitic loss, all my previous cars had a parasitic loss of ~ 40mA when measured with a multimeter in series with the battery, but one, a 2005 Polo, still in the family had/has a parasitic loss of 85mA from new and even with a 10 year old battery would start up after being parked up for a week or more, after a draw down of presumably ~ 16AH from a 44AH rated battery, of course these cars charged properly at a constant 14.4V.

(VCDS readings taken with engine idling) Original, 59AH, EFB Battery, 6.7 years old.

  IDE01834   Battery voltage 13.499 V

  IDE01836   Battery current 2.828 A

  IDE01837   Temperature of battery sensor 34 °C

  IDE01839   Battery charge level 71 %

  IDE01841   Battery internal resistance 7.8 mOhm

  IDE01842   Usable battery charge 26 Ah

  IDE01843   Battery voltage at rest 12.4 V

 

Edited 17 September, 202517 Sep by Johngerard

Interestingly if i put my battery tester on my 17 month old car it keeps telling me to “replace” it. Not sure what to do, works fine including the start stop. Strange.

Update 2: The dealer has done a full battery test and drain test. All looks normal at this stage. Could not see any fault or abnormal battery drain. We currently suspect that the cars alarm might have gone off and since the car was underground by the time i came to use the car again it had gone flat.

On 15/09/2025 at 14:06, molesy94 said:

Hi all,

I have Octavia Mk IV MY21 I got the factory battery replaced in it back in May2024 with an AGM battery when the last one died when we were on a trip.

Friday last week i got a start / stop warning normally indicating a low battery and when this happened last time i was able to use the car for about 2 months before it totally died. Seeing that this might be the case soon i ensured i had the start stop disabled and ran the car for a good 2 + hours on Saturday as well as set the car in sports mode hoping that the extra revs etc would help charge the battery faster.

However this morning when i went to get something from the car the car was totally dead. unable to unlock with the FOB. I called the same roadside that originally replaced the battery just over a year ago as it has 24 months warranty. they came out checked the battery it was at 10V and said the battery is ok and just need to be run more. jump started the car and said to leave it running / go for a 1 hour drive and I should be ok. I have run it today for 1 hour after this and once back hope power cycled the car and it appeared to start back up but i feel tomorrow evening it is going to be the same issue again.

While i dont use the car much on weekdays but the odd local shopping trip. On the weekends i regularly drive a good 1-2 hours a day. My dad who has a VW with the same type of battery has a similar drive pattern and his battery has been going sold for the past 2+ years

It is normal for the battery to drain so fast? could there be some electrical leak that keep draining the battery even when the car is off. I expected the AGM battery to have better life and hold it charge better. or could the car have been re program wrong so it not keeping the battery at the correct levels ?

as a stop gap measure would it be advisable to get something like this to charge the battery overnight ?

https://www.supercheapauto.com.au/p/sca-sca-12v-1.6-amp-battery-charger/611219.html?cgid=SCA01060203

Where is the 12v battery located?

On 27/09/2025 at 06:57, All-Right-Drive said:

Where is the 12v battery located?

? In the engine bay