Question Have all new cars migrated to AGM batteries rather than Flooded?

[Joe Hogan]

Been having battery issues of late.

The 12v battery in the 2017 Passat just quit. No warning , no sluggish starting, no indication of a weak battery. Just one day, turn the key and Click-nothing.
Electronics went nuts, warning lights all over the place!

Jumped the vehicle and the warning lights slowly recovered. Left the engine running while I completed the trip. Back home no start.

Called for a replacement and found that the OEM battery is AGM. No objection but interesting that the AGM acted so differently than from what I expected with a low battery.
The battery voltage indicated 12.2V. Low but not DEAD it appeared.
Is it the ECM determining what is a no start condition? Or do AGM indicate Voltage but have no Amps?

Looks like a Jump Box in the trunk is in the future to avoid being stuck somewhere you don't want to be stuck. One more PIA of the digital world.

Update: The OEM battery is in fact a Maintenance Free battery

 

[Neal]

I can tell you my Porsche acted oddly as the battery was going bad. I replaced the battery and all worked fine again. So it can definitely cause issues. I don't know the answer on what cars use today but I don't hear or see people adding distilled water to them like 100 years ago.

 

[Joe Hogan]

Or is it a maintenance free battery Fact About Maintenance Free (MF) Battery | Car RC

 

[Joe Hogan]

After some research and speaking with some techs, the new OEM battery choice is typically Maintenance Free, see above, not AGM. In hot climates like Florida the Maintenance Free battery life is shorter than regular flooded batteries, due to higher ambient heat, but more "convenient" for users. Fluid still boils off in Maintenance Free, just more slowly due to a chemistry change.

 

["EZ"]

Low voltage causes all sorts of issues with the new diesel commercial trucks that I sell. They start doing all sorts of weird electronic things. I'm sure new cars are no different.

 

[Joe Hogan]

Low voltage causes all sorts of issues with the new diesel commercial trucks that I sell. They start doing all sorts of weird electronic things. I'm sure new cars are no different.

Our 2005 Passat acts as expected with a low battery; sluggish starts, dimmer bulbs, etc.
Our newer 2017 Passat apparently has a lower voltage limit for the battery; a low battery at this limit, the ECM just turns off the ability to crank the engine or pull high amps from the battery.

An 8amp trickle charger was enough to start the 2017 vehicle, when hooked up to the battery, to get it to the shop.

 

["EZ"]

I tell you something else that these new cars and trucks don't like.................that's a loose ground!!! OMG!!! If you have a loose ground wire it will cause all sorts of problems all over the vehicle!!

 

[Voyageurs]

The 12 volt battery in our Tesla is maintenance free but not AGM. It’s also a deep cycle and fairly small.