PT Owner,
Post the dealership question on the "Gulf", Regional Forum near the bottom of the Forums list. That may help getting a Houston answer. Or, post on one of the Texas PT sites.
Big D Cruisers
I do know that I have had a problem with corrosion & drain on one of my 2006 PTs. The dealer ended up replacing the battery connectors.
But, beyond that, I think that the OEM batteries are just pretty "weak", like the OEM ignition parts that are talked about constantly on the tech forum. The GT Vert's battery was replaced this spast fall. And, the NA
soonercruiser's battery has been pretty weak cranking in the cold weather this winter in OKCity. So, I will probably get it replaced before the hot summer weather!
Look for a good replacement, like Interstate Battery. Got ours for around $70 (including install) at Sam's Club!