If possible, get an AGM battery. Costco has them for $200. AGM seems to work better than conventional flooded battery in our cars. I put an AGM in my XK8 two years ago and haven't used a charger since.

 

As absurd as it may sound, ... yeh - double check those terminal connections. I had all sorts a weird hiccups after a mechanic didn't tighten one of the clamps. Transmission safe modes, weird windows, lights, locking, .... Also - whenever you change your battery, you should temporarily place the car on a trickle charger, or spare battery while removing the old one. This way the car never sees "Zero Volts". Nothing needs to be reset. Remove the aux power source after the new battery is onboard.

As for your dealership woes: I've found Jaguar to be the worst when it comes to maintenance of our older cars. They charge us exorbitant prices for everything. Their message was very clear to me: "We don't want to fix your used car; we just want you to buy a new car, ... and go away." Even Ferrari treats older car owners with respect and appreciation. I have no complaints when taking either my '01 or '17 Spiders to the dealer. But taking my '03 XKR in? Did it twice (early on, and to two different dealers), and never again in the 9 years I owned her.

 

Many dealers have no problem servicing the older cars. In fact my Jaguar dealer a couple of months ago did a complete servicing, including replacing timing chains and tensioners, water pump, gaskets, all fluids, etc on my 2001 XJR with no complaints, no objections, no questions asked, no issues. But then, I am a regular customer. Perhaps that makes a difference. There are benefits to fostering a relationship with the dealer.

 

I’ve been a client at the same main dealer for over 20 years, makes no difference how long. They got rid of all of the veteran Jaguar and Land Rover technicians. They got all New technicians and management and no longer service older vehicles.

 

It sat at the shop for four days unattended, no charger, no maintainer. Technician got in it Friday morning, started right up no problem, no warning lights. Checked the battery, 12.7 let it sit for a few hours, 12.7 again. No issues. Top up and down quickly, windows perfect.

I went and picked it up, drove it home, gave it a wash, and sold it (with full disclosure) on Saturday morning. These cars are, and will always be, a lovely mystery. Easily The most beautiful exterior design of any car. Best to the group and thank you for all the help over the years. Moving on to a restored 1972 Bronco. Cheers.