Hey all,
My battery on my 2005 S-type Base 3.0 needed a new battery. Well below nominal voltage and parking brake was locked up. 5 years on the old one, so I got my use out of it.
Got a deal on a NAPA. A Flash Sale at the end of the year, plus another discount signing up for Rewards, etc. All-in-all, this batt listed for $180 and got it for $107 (tax, core return, rewards, flash sale, etc.). Great deal for me. Same exact size and all venting was done in the trunk. No more acid odor.
I was wary about disconnecting all power and having to go through resets and all that, so I Attached one of those portable lithium battery jumpers on the terminals before taking off the main clamps. Once clamps were off, one of the external alligator clamps fell off, so I was at your basic full disconnect of the battery. Just went ahead and took it off and replaced the battery to deal with what was ahead. Might have been disconnected for around 15-20 minutes.
All secure in the trunk (hold down was not corroded on the bolts,but added anti-seize anyhow) and clicked the fob. All opened doors fine. Started right up. Idled perfect. Trip odometer was at 0 on both A&B, went back to Km (easy reset back to miles), The aftermarket Pioneer radio was like it was just installed so I had to program time, stations, EQ, etc.
Did I get lucky here? All power windows, seat recall and sun roof worked fine. Parking brake worked fine and put it on OFF for my upcoming rear brake job.
Thought it was way more complicated and involved than I read on this forum.

 

I personally never had a problem with disconnecting the batteries in several S Types I have wrenched on.

In my daily, I have replaced a NAPA Gold(?) 3 times in my 11 years of owning. NAPA always respected the warranty which was supposed to be for only the first I purchased. Keep your receipt. I marked mine with date and mileage. The sales reps were always impressed. My latest battery just a month or so was $60.00 OTD.