About disconnecting the battery, the easiest way by far (and I would say the best) is to undo the ground/earth lead from where it bolts to the floor of the boot/trunk. That is, the thick black cable that runs from the battery negative terminal to the floor of the boot/trunk.
One easy to get at 13 mm (IIRC) nut which secures the end of the cable to a bolt.
Just make sure that once disconnected that end is held clear of any possible earthing point.

 

Sorry - excuse my vernacular. Mine is a Schumaker 1.5 Amp 'battery charger/maintainer"; good quality. I trust it's indication of full charge.

 

Only thing about using the body grounding post is it's easier than you'd think to shear it off and the nut is made of aluminum, easy to cross thread.
Only time I've had to do a master reset on the car is after emissions test.
I've done the automatic window up/down reset with the car running, never had an issue with it not taking.

 

I've only needed to reset the windows once after an inspection station disconnect their reader too quick. <--one of three times for having the car inspected

ISTR that it took me a couple or three tries.

 

Another data point for others. As stated by BritCars in a post where I enquired failure modes of AGM batteries - mine has exhibited the slow decline. It started with a more frequent notice of a low battery if sitting for days at a time. I started using my Schumacher maintainer periodically. Of late, I had a couple of instances of low battery, and the car would not open the rear hatch. Of course, starting the car (or charging again) and all fine. Never once did I have any issues cranking the car - each time it cranked like a new battery. I like their cascading levels of function as the battery level drops, giving you enough head's up that at least in my case I could always start it.

Of course, the last instances were when I trailered the car up to the Tail of the Dragon with my nephew and his buds. Couldn't have started the more significant decline at home! In any case, I ordered a replacement. We got home Friday; I just now got around to changing it. It took me about 20 minutes (I went and did some irrigation repairs before hooking up to have at least 30 minutes disconnected). It started right up with the new battery, no issues. I did not have to reprogram my windows. It even defaulted to my USB source of music which was last used.

I'll update later if I notice anything odd.

 

I have a Jaguar AGM, replaced by the dealer about 5 years ago. 5 years has generally been my setpoint for battery replacement, but that was with Lead Acids. I'm in Wisconsin, but the F resides in a heated garage and gets driven fairly regularly. No indications that the battery is on its way out as yet.

How long did your AGM last? Whose AGM did you replace it with?

 

My OEM battery was replaced by the dealer at the 5 year mark under warranty. I had taken it there for the tacky/sticky lacquer/whatever coating on the interior surfaces. I think they may have been revenue driven, or perhaps Jaguar encourages them to do significant checks and replacement under warranty but that was one of several things they did that I had not noted as potentially problematic (like evacuating and recharging the AC refrigerant!).

Here we're right at another 5 years and a few months from that point (symptom of low battery warnings started right around 5 years). I agree with you - that's a good time to replace. Here in South Florida 3 years seems to be a good run for a battery under the hood. These being AGM and being in the trunk help extend life IMHO.

Summarily stated - the OEM battery and this one both lasted 5 years.

 

I replaced mine at 7 years as a preventative measure, it never showed signs of weakness. Some here have gotten 10 years out of theirs. My impression is these Varta batteries that Jag used are quite good. I put a Duralast in, at less than half the price, I don’t expect it to last as long.

 

So who sells VARTA? probably Amazon, but I checked on the store finder, entered my ZIP, clicked 'retailer' and nothing came up. could be the browser, but I also went out on Chrome with the same result. zip 54986

 

I believe Varta is British, and shipping to the US would be prohibitively expensive.

 

Here’s the spec for the Varta from a while ago…
https://www.dropbox.com/scl/fi/8z43w...=z4w0meba&dl=0

 

My life my experience was that batteries never fail when you're in a desired location (like near your home). As such, forever I bought die-hard batteries because a) they were great quality with a great warranty and b) they were sold and warranted by Sears with a Sears store in every medium to large size town. When the Sears stores started disappearing, I also learned that you only rent a car battery - and as such the best price per month ($$$ divided by warranty period) became my purchase metric. That evolved to Advanced Auto since they were everywhere in my travel circles. Then, their warranties went down the poopy shoot - so I evolved to Walmart (there is a shop not far from our North Carolina shared family home). This last battery was $179.95 (AGM H8) shipped to the house, with a $12 core charge they don't know how to give back . This one has an unconditional non-prorated 4 year warranty. It works for me.

 

Do you have a few more details on the Walmart battery?

I put AGM H8 in their search box and any number of batteries from different companies came up. Thank you!

 

https://www.walmart.com/ip/EverStart...-CCA/380996471

Many of the stores are confused as to how to handle the walmart.com core charge. They are totally broken as a Corporation on this. The Artificial Ignorance voice said to take to any store. I called my local automotive Walmart desk, they said sure - bring it in. When I got there, the other person (who told me his partner never should have said that) refused to process it. I told them to cart it to the inside customer service desk and I'd go around to take care of it. He told me they wouldn't take it either. I left, called Corporate, and insisted they credit my account the $12 core charge. He did - immediately I got a confirmation email to that effect.

It's only a $12 core charge but I'm a person of principal. They are broken and I made them give me money, damnit !

 

I just discovered a new scan tool which did not give my car insomnia. I always used the lowest cost phone app with the cheapest possible BT OBD to read codes and otherwise diagnose all ills.

There were just too many modules and functions unavailable to I took the leap to an ICON T10 scanner. In context for this subject, all systems went to sleep perfectly. If that were the only advantage, I would have paid the price for it. I'd expect many lower cost scanners with R/W access to all the modules are likely to work as well. Lately there's been a plethora of new, much more capable scanners on the market.

I'm not saying the ICON T10 is perfect, it's far from perfect. That's for a different thread.

I have only a single test event so far, but I just couldn't wait to share the good news.

I'm working through a P0420 code now, so it'll be a bit before I can see if it'll take it out of a previous insomnia mode. But I'll test all conditions that I can replicate.

I guessed it would work as I scrubbed through all the operations narratives from Jag. The BCM will not send the sleep code if any signals it sends are still required from other modules. Since my very limited OBD system could only communicate with 2 total modules, very many others were put into OBD comm mode but never released. Just the app guys doing some cut-n-paste from other systems. When they interrogate to find modules, they enable comm but never found the responses, they were looking at the wrong addresses.
I can't even guess why the state OBD inspections cause the same symptoms. Perhaps the data they received from Jag has some obscure errors.

 

....
no, not at all, my V6 F-type recently had a new water pump fitted at 68,000 miles and after 5 days of leaving the car idle it read "low battery, please start engine" so i put a voltage tester on both battery terminals and it read 12.1 volts so that is fine, i did the same to my other car which i use more regularly and that read 12.2 volts so you have nothing to worry about, just buy yourself a decent battery voltage tester and keep an eye out on the voltage if you only use your Jaguar as a weekend car.. most modern cars show this warning i was recently told by a shop that specialises in car / van batteries.

 

AGM battery charts aren’t very consistent, but most show your 12.1V reading as being around 50% state-of-charge. While that should start the car fine, these cars are quite sensitive to battery voltage, and you might start seeing other unrelated errors if it gets any lower.

 

I suspect your shop that specializes in car/van batteries isn't aware of the obdii bug in F-Types. Usually, when you get "low battery, please start engine" message, you don't have maybe a day before your car will be dead. I have experienced the "low battery, please start engine" message two times and each time was after dealer service. The first time I got the error, it was 4-5 days after dealer service and the next day it was dead. The second time was after the next dealer service and fortunately a knew to reset it. Couple that with cocnsisten overfilling of oil and I stopped taking my car to the dealer.

My first ever smog check is due in about a month. Im fairly confident that the smog check will cause the "low battery, please start engine" error.

 

Sorry to hear that your dealer isn't up to snuff. I seem to be one of the lucky ones. That, and I know my service advisor from back in my motorcycle racing days

And yes, you'll almost certainly need to reset after the smog check. I was ready for it, so no problems.

 

The giveaway for the "smog test fault" is that the hazard light switch stays illuminated long after the car has been locked and allegedly shut down. Check after 10 minutes and the light should have gone out.