My V6S is kept always on the CTEK maintainer when not actually being driven. The other morning, after unplugging the CTEK (which showed, as always, full charge, as I opened the driver's door I saw for the first time the polite warning on the dash display " Battery Low - Please Start Engine" (on German cars does the order start or end with "Bitte"?). Hmmmm... But the battery is fully charged! Through that day and the start and stop that several errands entailed the message was there every time the door was opened. I have not used, nor has anyone except my dealer used an OBDII reader on this car - and not in the last 6 months - and nothing else has been altered in the recent history.
The tell-tale symptom of a battery draining because modules are not shut down , that is the light for the flashers remaining on, was NOT the case here. The light for the flashers extinguished ,as always, a few minutes after locking the car - so that symptom was not present and every function of the car operated correctly while driving. My conclusion after thinking about this for a long time was that the battery was due for replacement (it is almost 5 years old) - despite the fully charged reading that the CTEK unit gave it.
This morning I was prepared to order a new battery, especially when the tailgate would not open automatically - the button unlatched the tailgate but it was not powered to open. I could and did raise it manually. hmmmm....well, that confirms the bad battery.

Not so fast....the final test: disconnecting the battery for a hard reboot. I removed the negative lead connection on the boot floor (the negative terminal of the battery is very difficult to access), and then the positive lead; waited about 30 seconds, reconnected the battery, then touched the button to lower the tailgate - and it powered down and locked. I then locked the car. Done. Unlocked it and opened the door - and guess what? NO LOW BATTERY message!. Through the day and several stops and starts, no message. The disappearance of that message relates strictly to the reboot of the system - nothing else was done. The battery was in the same condition before the reboot and after - that is, fully charged.
Even better news: despite the battery being disconnected for at least 30 seconds, absolutely NOTHING in the systems was altered. The windows worked as they should, the trip km reading was the same as it was before the reboot, the EBP worked properly, everything had been saved...but other threads on the reboot process warn that at the very least the windows would have to be reset. This car has had every update to the software so I wonder if this happy result (the saving of settings) was part of an update? I have no explanation for why the battery management module decided to go on vacation - but my dealer told me today that it just happens sometimes and that a reboot is the answer - unless in fact the battery is bad.
In any case, no need for a new battery (yet).

 

My advice to everyone is to carry a small adjustable spanner in their itiniary.

You only need pop the positive off the battery for 30 seconds to have the reboot effect.

This usually cures all ills!

 

Great idea Tel, that was just about the only tool I didn't already have in the hatch cubby, now rectified!

 

Do you have the second battery? If so, that might explain the saving of those settings.

On a related note, I had the Low Battery warning a while back and despite charging the battery fully, in 1.5 days of non-use the car told Jaguar its battery was flat. I called Jag Assist who boost-started the car and after taking it for an hour long run and then recharging overnight everything was back to normal and it hasn't failed since (about a month now). Early symptoms of the problem were an SOS System not available message on startup and my journeys were no longer logged.

Letting the battery run down seems an easier fix than spannering the leads, assuming you have a means of jump-starting the car, and can let the car sit for a couple of days.

 

Running a battery down kills the reserve capacity each time you would do that, so dont. Just do a hard reset and or to clear the cached message out of the touch screen once battery is at a full charge. lock the car and set the alarm and leave for 20 minutes

 

Yes, my car has the second battery - which was disconnected the day I took delivery! The annoying start/stop system is therefore (happily) not functional, and the small battery that powers it remains disconnected - so that is not the source of the saved settings.
Letting a battery run down is a very bad idea (and I know that you know that) because it can irreparably damage the battery if repeated. Disconnecting the main battery for a reboot is literally a 5 minute job. This is the first time I have had to do it - but I completely agree that carrying a tool to remove the two 13 mm nuts is a really good idea - and using a CTEK maintainer is the best idea.
My car, contentedly plugged in (now more neatly than this photo shows):

 

It really takes less than 2 minutes. It’s even easier with the Lithium battery since it has an on/off button.

 

My 2017 F-Type sat for 10 days in my garage at 65-70F. then would not start without a heavy duty jump start(AAA truck jumper). After driving the car around the area for 20-30 minutes it would take a charge from my home trickle charger over night. Then it began to display the "Please start car, Battery low" lite, or similar notification on start up in the morning. I called local JLR service, took it in and had them check the battery. They found a bad cell in my 1 1/2yr old battery. Removed and replaced quickly.

 

Found my car dead in the garage this morning and had to access it by using the emergency key. Put the car on the battery manager and took another car to work so hopefully it will be fully charged tonight when I get home.

Once the battery manager indicates a full charge and following the instructions of this thread, I plan on removing the positive battery cable for 30 seconds, replace and start the car (measure the voltage at the battery at idle and at 3,000 rpm for my own piece of mind) then turn the engine off and lock/set the alarm for 20 minutes. Anything else?

I had been getting the "low battery, start engine" display recently, and additionally had noticed that the red, triangular light for the flashers was remaining lit after exiting the car and locking it (so I was glad you mentioned that in this post sov211, thanks). My other question is "When that red triangular light for the flashers starts remaining lit is that the tell-tale sign that it's time for one of these system reboots every time?"

 

Yes, if that button light remains lit for more than15-20 minutes after the ignition is turned off.

 

happened to me as well after my friend played around with my settings, reboot made it go away

 

The battery re-boot worked like a charm. I did have to do it before the my battery manager would charge the battery correctly, prior to disconnecting the positive cable to the battery for 30 seconds the battery manager was charging erratically. After driving the car for 40 minutes the light on the red flashers triangle by the stick shift went out in about 5 minutes.

Can't help but wonder if the knowledge of this battery re-boot technique was not available to the JLR dealership that worked on the car for the original owner before he returned it under the California lemon law. From the paper work I was supplied with about the history of service on the car, JLR replaced the battery 5 times while he owned it and he finally through in the towel.

 

It is indeed surprising that 6 years after the F-Type was introduced, the collective F-Type knowledge on this forum still far exceeds that of most dealerships. As a result, you probably got a great deal on a lemon-lawed car that never had anything wrong with it.

 

+1 - And I just want to say thanks to everyone participating on this forum, the knowledge base is truly incredible and regularly keeps a large number of us from experiencing a great deal of frustration.

 

I'm not mechanically minded so when you say 'pop the positive off' do you not need to remove the negative first? Reading other threads removing the negative is not that easy but can be done via the boot floor - how does that work?

My car recently went to a non-Jaguar dealership to have the coolant pump removed so could this in any way be the cause of the Low Battery Warning light? Thanks in advance.

 

The dealership probably plugged into the OBD and that seems to be the triggering event. I took my car to get emissions tested for the first time yesterday (they plug into the OBD) and was curious to see if that would trigger the need for the reboot. Sure enough, I got the red triangular haz light stayed on and I got the charge battery message. This time I unplugged the positive terminal because it was easier. Left it off for about 10 minutes and didn't even get a spark when I put it back on. You will need to reprogram the window auto function again though. Just search the this forum for --> window, auto, battery and discussion for that reprogramming will come up.

 

Thanks rbsj - what I didn't mention is that the battery died about 2 weeks after the light started to come on so I guess that means that the battery either has a drain on it, the alternator isn't re-charging or the battery is nearing its end anyway? Is that correct?

 

Just disconnect the battery (either positive or ground connector) and leave disconnected for 15+ seconds. Then fully recharge the batterY and everything should be good as new.

 

Thanks Unhingd: Worked a treat..... so far!

 

My OBD/battery problem started in January, 2016, when the car was only 1 month old. I have put up with having to disconnect the battery (thank you Forum) after an OBD check since then, but forgot to disconnect after the latest State Inspection, and got the low battery warning a few days later. Because of the information in the 5/1/17 letter from Jaguar, I took the car into the shop on 7/16, and came out a week later with a new battery. I had the State Inspection guys plug into the OBD the next day, and a day later, I got the low battery warning again. The emergency flasher warning triangle was lit, and the push button starter was also lit. I brought the 5/1/17 letter from Jaguar concerning the Jaguar Vehicle Enhancement Program to the dealer when it was serviced, but the mechanic said that no updates were due.
So, today, I called Jaguar US, and initiated a case for the OBD/battery issue for my car. We'll see how that goes.
Very nice lady with Jaguar. She said that starting in 2018, software updates can be done over the air, but my 2016 needs to go in for updates. She could not find a copy of the 5/1/17 letter from Jaguar, but thinks it was just a reminder to all '16 and '17 owners to go into the dealer to have their software updated.
I think I read on the Forum, that the OBD problem might be related to how the OBD is accessed. The dealership never seems to be able to duplicate the problem. So, is it likely that the State Inspection and local auto store guys just unplug, rather than shutdown their program, so maybe that is like a computer being unplugged instead of shutdown. Updates to follow.