[OptionOfT]

To be more specific, that is why the battery needs to be in a place that can vent.

When I replaced the AGM battery on my German car, I learned that, even though they don't vent under normal conditions, still have a vent hole. But that's paired with a pressure regulator and not for normal conditions.

Which makes me wonder: did BMW start to use AGM so they can move the heavy battery to the trunk, which helps with weight balance? Or was it an emissions thing that enabled them to move it to the trunk.

[iancmceachern]

I've always wondered why they put it there too.