I have a brand-new battery...the big 900CCA one from Walmart, and a battery tender junior wired into the terminal connectors on my 2007 997 Turbo. The car cranks very slowly...so slowly that it actually stopped cranking for an instant before starting today. The light on the battery tender was green.

Could the batter tender be preventing the car from going to "sleep" when locked?
How long do starter motors last on these cars? It has 125000kms on it.

Thanks!

 

More information please. Why did you change your battery? Was a battery test and charge test happen? Was it slow cranking before the battery swap? If the battery was deemed to replaced and verified that the alternator was charging fine. It could be the starter that's is the issue.

 

Check your grounds, plenty of info on the forum about similar issues related to poor grounds.

 

I changed the battery because it wouldn't start one day after sitting out in -20 degrees Celcius all night. I didn't do any testing, so that old battery may have still been ok. The alternator is definitely charging well, because the lights were bright and everything worked well after I jump started it.
It was kind of slow cranking before the battery swap.

I'm out of town for a week, and it's sitting in the very cold garage without the battery tender. I'll check the batter voltage before I try to start it. As 93ls1rxy stated...it would make sense for it to be a connection problem. I've seen a few posts about an engine ground strap and a positive terminal connection under the battery in the front.