It doesn't add any to the batteries, it powers a system to keep the car cooler when parked outside. When the temperature is above 78 degrees it will run the HVAC fan in the non-recirculate mode. So when it's 98 degrees outside the interior of the car is maybe 105 instead of maybe 145 like a car without the option. It also adds a button to the fob that allows turning on the A/C from maybe 20-25 yards away. It will run the A/C for 3 minutes, provide there's enough juice in the traction batteries to combine with the solar to do so. It makes a HUGE difference in the hot and humid Texas Gulf Coast.
Big yup, here! In the North American media, the focus is solely on VW's cheat device and "dirty diesels". Real-world tailpipe emissions are not discussed, just the in-lab-only numbers, as though they reflected reality. Even the UK Government's reports that virtually all vehicles tested, both diesel and gasoline (petrol), regardless of make or model, emitted many times lab-legal levels in the real world, legally, but this quickly disappears from the media and is lost on most forum jockeys.
It's a weird world out there :-/
Petrol cars can exceed regulation limits outside the lab, but the European diesel models tested emitted magnitudes more than them. The engine design and combustion conditions means a petrol engine is going to make a fraction of the NOx a diesel one does, but it produces more carbon monoxide.
The VWs pass the lab tests, but emit much more on the road. The BMW diesel tested along side them only exceeded the NOx limit by a tiny to small amount on the road.
Most Americans only knew of diesel's reputation from the Eighties, when they majority were unreliable GM's with gas engines converted to diesel, the fuel stunk more, and their was no particle filters.
That was starting to change, leaving the higher than gasoline price of diesel in many areas of the country as the last big hurdle. Then VW gets caught cheating for 10 years on the emissions of their diesel cars. In the long view of the big picture, the extra NOx their cheater cars emitted won't add to much. The reputation to diesels in general is the bigger crime.
So if you are wondering why Americans won't drive diesels in the future, you thank a European company for defrauding them with their cheating.