So, I've been pretty successful with Battery Tender car charger with my BMW;
http://batterytender.com/product_info.php?products_id=2

Since we don't drive our Cayenne daily, thought it would be worth to charge the battery while parked in the garage.
Typically the light indicator turns into "Green = maintenance" mode once it thinks the battery is fully charged after over night charge w/ my BMW; but with my Cayenne, I begun charging around 9am and checked throughout the day and decided to pull the plug around 9pm, that's 12hrs of charging! and afraid that it might over charge the battery. (who knows.... )
Or did my battery really need to be charged that long? I just didn't feel comfortable leaving it plugged while I'm on the bed waking up with fire in the garage, I don' know.

Does anyone here have an experience with battery tender brand car battery charger on Cayenne? I know Porsche has their own version of battery maintenance tool that you plug in via cigarette socket, but I think they are all same thing as long as charging 12V batteries...

Please advise, thanks in advance!

 

What year? Two batteries?

 

could be different chargers depending on the capacity of the batteries, one might charge it in 3 hours, the other one might charge the same battery in 30 hours, you never know (numbers are exaggerated yes)

 

2006, single battery (since I have the Bose bass box under the spare tire)