Battery charge level on 1.5 eTSI - alarm going off on its own

[Major]

I drive a 2025 Leon ST 1.5eTSI, I didn't do a lot of kilometers yet but I already faced some issues, like when I have front windows opened just a bit and I want to open them fully, when I press both buttons fully down, the passenger window goes does and the driver windows goes up ...

Today my wife drove home and around 60 sec after locking the car, the alarm went off on it's own - thought that a door or window was left open, but no all closed so I disabled interior monitoring as I had bad memories from my MK3 when a wasp was in the car and the alarm went off several times in the night, but it didn't help.
I disabled keyless entry, easy open, took the 2nd key to close the car, but it kept turning on the alarm.

Unfortunately I didn't check the battery level when the issue was present but I did a 37km drive and the issue went away on it's own, I connected a OBD11 diagnostic tool to see that the bater was at 12.4V after the drive and when the engine was on idling, it was at 13.1V - I was expecting higher figures but as this is a mild hybrid, most likely it has it's own charging algorithm.

Can other 1.5eTSI owners share their battery voltage when the engine is turned off?

P.S.
I'm starting to get worried as I'm finding a lot of articles that the 1.5eTSI engines have frequent issues where the engine doesn't start due to battery drain

 

[BoomerBoom]

I've not had the battery or alarm issue but one of the rear windows on my '24 eTSI goes the wrong way when you try to close it.

 

[FormentorGranny]

I drive a 2025 Leon ST 1.5eTSI, I didn't do a lot of kilometers yet but I already faced some issues, like when I have front windows opened just a bit and I want to open them fully, when I press both buttons fully down, the passenger window goes does and the driver windows goes up ...

Today my wife drove home and around 60 sec after locking the car, the alarm went off on it's own - thought that a door or window was left open, but no all closed so I disabled interior monitoring as I had bad memories from my MK3 when a wasp was in the car and the alarm went off several times in the night, but it didn't help.
I disabled keyless entry, easy open, took the 2nd key to close the car, but it kept turning on the alarm.

Unfortunately I didn't check the battery level when the issue was present but I did a 37km drive and the issue went away on it's own, I connected a OBD11 diagnostic tool to see that the bater was at 12.4V after the drive and when the engine was on idling, it was at 13.1V - I was expecting higher figures but as this is a mild hybrid, most likely it has it's own charging algorithm.

Can other 1.5eTSI owners share their battery voltage when the engine is turned off?

P.S.
I'm starting to get worried as I'm finding a lot of articles that the 1.5eTSI engines have frequent issues where the engine doesn't start due to battery drain

I have a new Formentor PHEV (252 reg - with same 1.5 TSI engine) Last night while the car was charging via granny charger ( White box was under cover in pump house so not exposed to elements) the car alarmed twice during the night & then this morning on my run to school while in electric mode, it kicked into hybrid (I wasn’t accelerating hard) I stopped up the car and tried putting into electric mode but a dialog box came up on screen which said "battery not charged enough to run on electric mode" - there was 80% in battery. Very strange.
I’ve been driving a lot in electric mode, do I need to drive more in hybrid to charge 12volt battery or something? (Although I did drive about 40klm Sunday evening using petrol-only as had ran out of electric battery)
Did you get your 12 volt battery checked out again?
Any advice welcome- should I go to garage Thanks

 

[Deimokas]

Hi, I drive 2020, Leon Sportstourer 1.5 eTSI and the issue i'm having is dead 12v battery, from time to time I find the car just dead. Not even unlocking itself and I don't know why, it was under warranty but official dealer didn't find any issues with it and just returned the car to me.

Battery voltage is from 12.1 to 12.4v

 

[Major]

Hi,

I took the car to the dealers and I when the car was being taken I've asked if they get many cars with battery issues, the guy sad that I'm the first one , after a few min of me asking questions, he said that usually the cars are sold with a faulty battery and the dealer replaces the battery ...

I was was fortunate enough to talk to a technician who knew what he was talking about, he said that majority of these battery issues are due to emissions, the manufacturers wanted to avoid paying penalties for CO2 emissions, hence they modified how the battery is being charged, you get full battery charge only when engine breaking. So before the "eco" madness times, your alternator has charged the battery around 14V and with higher revs the values went up to around 14.4V. Now you get even over 15V but only when engine breaking, if you are on idle or rev the car it's between 12.2V and 13.4V - don't quite me on these values, I heard them a few weeks ago
The technician also said that by the book, if the battery goes below 12.55V, you should charge the battery, so I asked, is the charging system in the 1.5etsi capable of charging the battery to a satisfactory state, he said no. I'm glad that he was honest.

So my car stayed 3 nights at the dealer and when picking it up, I was told that the car needs a software update, which doesn't yet exist ...
No information what was done, etc.

So as far as my own investigation goes, these battery issues originate from the charging algorithm, cars after around 2012 have a Battery Management System (BMS), it's connected to the negative battery terminal under the bonnet. I had a 1.8TSI Leon previously, I have never had a battery issue on that car though out 7 years of owning that car - I admit, I have turned off start/stop in the 1.8TSI Leon by using this method. I heard also positive feedback on disconnecting the BMS connector from the negative terminal of the battery - I'm not doing that at least not while the car is under warranty ...

I did not have the issue with the alarm since that visit to the dealers, I have been monitoring the battery charge level - it never went above 12.43V. When it comes to checking the battery, you need to open the car (unlock + open the driver's door and bonnet) and wait a few minutes to get a reliable reading - if you measure it straight away, the value will be around 0.3V lower than if you would wait. This is because of the central locking and fuel pump being activated when you open the driver's door.

 

[James_R]

The 1.5etsi with or without the 48v system is more than capable of charging and maintaining the battery.

You'll be suffering with the same issue that 1000s of other users are having, and it's software related.

The update (PV4RC) was released a couple of weeks ago now and addresses battery drain faults.

I have also replaced lots of batteries on Seat and Cupra Leon's that have been defective very early on.

Send me your VIN and I'll confirm the availability of the update.

 

[Major]

Hey James_R,

thanks a lot for taking the interest! I've sent you my VIN number via a private message. When I wrote not capable, I meant software wise it's crippled - this is what I understood from the technician.
Can you please share some details on what does this PV4RC update change?