12V battery always at 80%?

A very helpful earlier post tip said to check the charge state of the 12V battery by holding the trip button with the ignition off until 12V battery showed (the 2d choice) When I do this, it always shows 80%. I don't know if this is a limit set to avoid overcharging. I also don't know how the 12V battery gets charged....by driving the car or by charging the traction battery. I would think if the car isn't used for a week or so, the 12V would lose some of it's charge, but it always shows 80%

Thanks to the poster who discovered the trip button does different things depending on whether the ignition is on or off. How he discovered it I'll never know as the users manual says next to nothing

Ron

I was curious and just tried this. Mine showed 70%.

But I also only had like 7 miles of range left as well before I started charging my car.

Yeah, the user manual isn't very complete.

Hmmm...mine say 0.0%. Wonder what that means?

I just checked again. And with a 50% charge, it now says 90%.

0.0%? Interesting...

I must have been smoking something when I saw the 0.0%. Last night when I had just started charging for the evening, it read 80% SOC and this morning, after I took out the charger, it read 90% SOC.

BTW, anyone know what SOC stands for?

Probably State of Charge. To show how the VW dealers are overwhelmed by this car, I talked to several dealer service people including one I think trained on the egolf. I was concerned that my egolf was not being driven for over a month during the winter season, and I was worried whether the 12V battery would run down making the car unstartable as it's constantly drawing a little power like all ices. I asked about a trickle charger via the 12V outlets in the car.

They did tell me not to use the 12V outlet which I finally confirmed in the users manual. They did say you could trickle charge from inside the hood, but they didn't know if the battery got charged from driving or from charting the traction battery. But they said not to worry as it was a strong battery. However, neither one knew that you can call up the 12V soc from the trip button. If it wasn't for the prior poster discovering this, I still wouldn't know how to get a quantitative no guesswork info about the 12V battery

Ron

Just check the status of my DC 12V car battery, it shows 50%. But actually, the 50% is not accurate. For example, when the real capacity of car battery is 50%, the result that be checked may be 45%~55% or 54%~56%. It is more difficult to measure the realc apacity of car battery precisely like cellphone battery. That is because there are high power discharging when speeding up and low power discharging when cruising at low speed. The car battery pack is more complex than a cellphone battery which is actually battery cell. So, the capacity it shows maynot be precise, but it is still close to real capacity. So, recharge the battery in time when you check the capacity is too low.

It's odd to me that the car even has a 12v battery. It's not rocket science to just convert the traction battery voltage to 12vdc to power the body electrics. Must be a good reason that the engineers decided to keep a piece of 19th century, 75-lb chunk of lead on the car.

dustboy said:

It's odd to me that the car even has a 12v battery. It's not rocket science to just convert the traction battery voltage to 12vdc to power the body electrics. Must be a good reason that the engineers decided to keep a piece of 19th century, 75-lb chunk of lead on the car.

Click to expand...

Yes, it's a necessary safety measure. The high voltage from the traction battery is not released from the battery pack until the car passes some safety checks. The same mechanism also allows first responders to ensure that the high voltage is contained after an accident when the integrity of the high voltage cables in the car could be compromised.

Eventually, EVs will reach a level of integration where the DC-DC converter is fully integrated in the battery pack and the battery can be done away with while still providing all the safety mechanisms I mentioned. The Tesla Model 3 has started this kind of integration, but they still use a 12V battery.