12V battery charging is forbidden for the user/owner

[TheSwede]

Not what I know of.
With OBDeleven I monitored the volt with engine running after changing battery:

Module 01 Engine - live data.
Terminal 30 = permanent supply

 

[andylong]

I have a lil plug in volt meter I use. Charges the phone too.

 

[Seriously?]

Perhaps Mercedes and BMW think it unlikely Thier customers would dirty Thier hands lifting a bonnet.

I'm convinced that's the reason they don't fit engine oil dipsticks

 

[EVangelist]

Did you know, that user manual forbids car owner to charge vehicle 12V battery? This was new to me and what direction we are going. When my car battery voltage low or battery is flat I need to tow the car to dealer and use tow trucks for that... what?

I was amazed to read this in the manual too, it's ridiculous.

what direction we are going - BEVs! charging a 12V battery will be just a memory in 10 years for most of us

But in the e-Hybrid system, does the 48V battery keep the 12V battery topped up to prevent discharge? So charging the 12V battery should not be necessary?

Also, SEAT/Cupra (probably all VAG?) went to the expense of fitting a pressurised fuel tank in the e-Hybrid system, because of the danger of petrol vapours around the 12V battery. Maybe the fear of petrol vapour is the reason they don't want owners charging the 12V battery (but the warning is for all models, not just e-Hybrid...)?

For years, I charged the AGM battery in a Mk3 Octavia diesel with a CTEK MXS5 and MXS7 regularly without disconnecting, and never had problems, so I assume the car's wiring is designed to stand up to charging voltages from a charger (and the smart alternator on AGM-equipped cars would output similar voltage to a smart charger).

 

[Karbonfaiba]

I have never used RECOND mode so I can’t say anything about what happens then.
If I will do it in the future I will remove the battery from the engine bay, a couple of meters from the car .

I've used recondition mode on an unhealthy battery while connected to the car, out of the sun. Positive to positive, negative to any grounding point on the vehicle (so the current passes through the BMS sensor).

CTEK gives it a max of 15.8V at a low 1.8A for about 2 hours, you will hear the liquid boiling inside the battery.

Unfortunately in my scenario, it didn't do anything to improve the unhealthy state of the battery, besides giving it a really good charge that lasted for a few days.


Sidenote; The CTEK MXS 5 is a really great piece of kit to have that meets the minimum requirement to confidently charge any modern car with a BMS.

CTEK MXS 10 is the minimum you'll need if you need a charger / power supply while you perform any software updates, reason being, MXS 5 does not deliver enough amps to sustain battery voltage with the ignition on. So purchase according to your needs.

 

[spezwend]

Actually for coding you need more amps than 10. I have MXS 7 and the voltage keeps dropping.

 

[Wyld Stallyn]

Please forgive the question but for those of us who only have petrol engines and no plug in tech.

Are we allowed to charge our batteries?

 

[spezwend]

This topic is about old school cars, not hybrid cars.

 

[Karbonfaiba]

Actually for coding you need more amps than 10. I have MXS 7 and the voltage keeps dropping.

View attachment 37812

Damn 13.56A !? I didn't expect such a draw on the Formentor. At least with a fully charged battery a 10A supply should sustain it for a few hours to do some work at least.

Otherwise it's going to have to be CTEK Pro25SE which is uncomfortably expensive for a hobbyist. I wouldn't risk it with cheaper non-smart but high amp output chargers out there.

 

[spezwend]

Actually this is pretty good compared to my previos car 20-25A. And yes with Formentor you can code things 1-2 hours with previosly* fully charged battery and connected 10A charger.

* I found out that the 12V battery is charged only when the car is in gliding (eco) mode or when braking. When driving the battery is almost not charged. When accelerating the charging is stopped immediately. This is a new standard so 12V battery is never fully charged. In my car the battery voltage has never been over 12V in past couple of weeks in the morning. Someone recommended to disconnect the ammeter plug from the negative pole of the battery and now the battery is fully charged (12,6V) in the morning and the S/S is history also. So the greenwashing has been taken to the next level with this crap. (New battery in every couple of years for example)

I have had none infotainment crash since disconnecting the ammeter plug, previosly had 3 times:

Formentor System Errors

Hey guys! I'm due to pick up my VZ2 310 tomorrow from my local Cupra dealership. Its a late 2020 build. Clearly there have been substantial issues with the system/interface since launch, but I don't see any comments over the past six months. Would any veterans be able to let me know whether...

www.seatcupra.net

 

[Wyld Stallyn]

This topic is about old school cars, not hybrid cars.

Old Skool I understand

All these TLAs are difficult to keep up with IMO.

 

[spezwend]

* I found out that the 12V battery is charged only when the car is in gliding (eco) mode or when braking. When driving the battery is almost not charged. When accelerating the charging is stopped immediately. This is a new standard so 12V battery is never fully charged. In my car the battery voltage has never been over 12V in past couple of weeks in the morning. Someone recommended to disconnect the ammeter plug from the negative pole of the battery and now the battery is fully charged (12,6V) in the morning and the S/S is history also.

I have to correct myself. This is not that simple. When the battery is fully charged (from the wall charger) then it will not be charged. If the voltage is too low, <12V for example, it will charge normally. I do not know exact voltages, maybe some VAG electrician can explain it better.

 

[elzo]

The 12V battery in hybrid Formentors is charged only when driving on a gasoline engine.
And I don't understand why they did it that way. Why can't a 12V battery be charged from a 48V battery when needed?
Or, for example, to charge even when I drive only on electricity from a 48V battery. Thus, even if I have enough to drive only on the electric motor all week, I have to turn on the gasoline engine in order to sometimes charge my battery.

I asked the dealer and they can install a 12V battery charger so I can always keep the right charge. And for this I will need to connect my car to another outlet

 

[andylong]

Perhaps the battery is unused when the ice is off so the two systems are seperate.
However enough people are having issues that this still creates an issue. Is the hybrid battery only 48v?
If so there seems no need for a 12v battery at all as a DC to DC converter could easily do the job of the 2nd battery.
Even higher voltage batteries could create the 12v needed in fairness

 

[andylong]

The mild hybrid has a 48v battery the phev has a 352v battery.
The former sees little use, it assists, can do a little electric only and gets charged from braking it seems.
The latter is more electric and I can see why with that battery you might want a seperate 12v one

 

[oldgitdave]

Now, I know this is not about Hybrid cars but I had a big issue with my phev's 12v battery so I asked Cupra UK about charging. As the 12v battery is in the boot on the phev I hoped to be able to open the bonnet (hood) and connect a charger. I couldn't get the bonnet open due to the passenger door being locked which blocked the bonnet pull handle! Anyway, I digress, there's a post here if you're interested.
This was Cupra's reply:


Dear Dave

Thank you for contacting CUPRA UK regarding your vehicle's12v battery issues. It can be frustrating when such problems arise and I apologise for the delay in my response.

To address your question, yes, you can use a battery maintenance charger to trickle charge the 12v battery in your car. Connecting it to the terminals in the engine bay is a viable option. This can help ensure the 12v battery remains charged and operational, as it's crucial for various systems in your vehicle.

However, I recommend checking your vehicle's manual or reaching out to a CUPRA Retailer for specific guidance on where to connect the charger and any precautions you should take to avoid damaging the vehicle's electrical system. Different vehicle models may have variations in their recommended procedures.

I hope this information helps, and your vehicle remains trouble-free moving forward.

If you have any more questions or need further assistance, please feel free to ask.

Thank you for contacting CUPRA UK.

Kind regards
K
Customer Relations Advisor

 

[spezwend]

Dealer in Estonia also said that you can charge the 12V battery with a smart charger.