Battery issue

[eltsac]

Please excuse ignorance, but really would value advice.
Jan 2016 3.0 Coupe AWD had been running beautifully approx. 30,000 miles.
Went to my local Jaguar garage for MOT and servicing. They kept it couple of days "as they got busy", and I collected it after 72 hrs.
First surprise was that "low battery" was displayed when I collected it although it started first time.
In subsequent week it had drained down to be completely dead as a dodo.
I asked garage if that could be due to anything they'd done and they replied no, as they would have had it plugged into a "conditioner" while in their garage.

AA came and restarted me and thought it charged fine - I ran it for an hour afterwards....it was dead within less than 48hrs.

Questions:
1. Is the garage work a complete coincidence, and the battery failed spontaneously and suddenly whilst there? Seems garage want me to believe that it happened like that and was bad luck.
2. Is changing the battery for a new one simple, and should I get Jaguar garage to do it or not? Should I have a genuine Jag one or a different manufacturer like Bosch/Exide etc and fitted by my local garage instead? Does it take long? (I'm thinking I will as whatever happened to my battery it cant have done it good with being drained repeatedly!)
Thank you for advising me

[eltsac]

presumably 850A start stop battery

[Deleted User 1715]

Sounds like a common issue after use of the OBD port in that the electrics won’t shut down. Solution is to disconnect the battery for a couple of minutes and reconnect, then charge it up again.

You can check by locking the car and then seeing if the hazard warning triangle light goes out after a few minutes or stays on.

[scm]

Second vote for the OBD port issue, follow GusA's advice to check (hopefully) fix. And if that proves to be the case, once sorted out, just give the battery a full charge.

When you say "local Jaguar garage" is that a main dealer or an independent? I'd be surprised if a main dealer's equipment triggered the fault.

[NavigatorNI]

Sounds like a common issue after use of the OBD port in that the electrics won’t shut down. Solution is to disconnect the battery for a couple of minutes and reconnect, then charge it up again.

^ +2

[eltsac]

thank you.
It was the main JAG/lLR dealer so perhaps that makes it less likely?
I shall take a look tomorrow.
Only think I had noted that felt different was that headlights felt that they lingered on for longer after I left/locked the car...

[MikeF]

I had exactly the same issue last year. Took my car to local Jaguar dealer for MOT and service. The battery gradually went flat over the next two days. The AA got me started but it went flat again. As has been mentioned the hazard warning light was on and wouldn’t go off. I didn’t notice this until afterwards. After asking for help on this forum I got the same advice you have been given. Once the battery was completely flat I disconnected it and then recharged it. It has been fine ever since. I called the dealer but they denied it was anything they had done. I couldn’t take it back for them to check because the first Covid lockdown started. If I take it back to the dealer again I will be checking that the hazard warning light is out before I accept the car back. Hope you get yours fixed.

[scm]

Once the battery was completely flat I disconnected it and then recharged it.

Not a good idea to let a battery go completely flat, that can cause internal damage, I believe.

[eltsac]

thank you.
Presume the battery hasn't enjoyed running to flatness a couple of times this week, but hope it recovers to how it was.
Are there any issues for me to be aware of, with disconnecting and then reconnecting the battery? (anything to reset?)

[scm]

Your windows may need resetting, and you'll likely lose your trip values.