Is the battery drain when not in use substantial enough to flatten the battery completely?

Not used the SD4 for 4 weeks, needed to pick up some bricks and when I went to open the doors... Nothing.

Used the key to get in, absolutely nothing happening when the fob inserted.

New battery put in just before Christmas.

Will put it on charge tomorrow but very strange as it was absolutely fine when in use.

Doesn’t the FL2 literally go to sleep if left for more than a couple of weeks, and you have to use the key in the passenger door handle? So the battery isn’t flat, just the car systems are shut down.
As for the battery, have you ever charged it? New batteries aren’t normally supplied fully charged and run in and normal use doesn’t do much more than maintain a batteries charge unless you are doing very long drives frequently.

Surely it'll have been charged just by driving the car around for 6 months?

Sleep mode in interesting, how do you wake it up again?

Ok, just opened the passenger side door with the key to see if I can wake her up. Fob won't stay in its slot and even hiding it in I can't get anything to happen, no dash lights etc.

Cheers battery first and then try again or is there a sequence I need to follow to wake her up?

Have you checked the 'Blue Wire' for damage? This often give charging problems.

Links on subject ----
https://www.freel2.com/forum/search.php?se...rch_time=0

More Likely ----The FL2 does gradually switch off systems over about 30 days until only the Perimeter Alarm is left working.

Once you have used the manual key (passenger door) to get in it should start once it recognises the key being near the (underside) Steering Wheel Console. A battery Booster may be necessary (or charge)

https://www.freel2.com/forum/search.php?se...rch_time=0 FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Thanks @IanMetro, not sure that link works for me it doesn't take me to a particular thread?

I wasn't getting any fault codes before parking her up. Reason for doing so was the return of another JLR vehicle from the bodyshop, but as it had been laid up it needed a new battery and I did manage to break a tiny wire replacing that which threw up an error.

Nothing in the FL2 tho and the battery has been in 6 months, surely it would have gone flat or thrown an error way before now? And I've had no need to go near any of the wiring. It's just not something I'd even consider doing.

Just double checked both fobs as I typically only use the one without the bike carrier key to prevent scratches.

Neither work.

Will see if the jump leads will reach tomorrow, parked in a rather unfortunate spot for connection, and if the fob is recognised when there is power from another car.

The irony is we were using the FL2 to jump start the Saab before finally coughing for a new battery for that one. But the FL2 battery is only 6 months old.

The links provided were generalised indicators to Forum Posts on similar subjects.

It is hard to be more specific without some clues like error codes.

I can however confirm that it does not take much for the battery to loose enough capacity/charge to not allow you to start. The FL2 is a very power hungry car, although batteries tend to last at least a couple of years, but find it hard to make year 5.

This link explains my troubles with a failing (newish?) battery and how I tried to soldier on by buying 'state of the art' Battery Booster and Charger.
BUT in the end I just bought the biggest 12v Battery that would fit in the tray and that solved my problems.

A failing battery will also give you all kinds of random (phantom) start-up faults due to electronic module power supply variations.

https://www.freel2.com/forum/topic38965.html?highlight=booster FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Thanks for that.

As the saying goes.... tomorrow's another day so I'll see what a jump start or charge does.

I use a bluetooth battery voltage monitor to keep an eye on the FL2's battery when its sitting on the drive for weeks on end between long drives. Jules

4 weeks is enough time for it go into deep sleep mode. When you open it with the key (passeger side only note), the alarm should go off, which you can only stop by inserting the fob. If the alarm didn't go off, the battery is probably completely dead. 
Hung like Einstein, smart as a horse.

Yeah, that's 24 hrs on the optimate now and still no signs of life. Tempted to jump start her but want to be kind to the battery as it is only 6 months old.

Maybe the perfect storm but each of our three cars has needed a battery this year, but this one feels more like a charging issue. I can't believe the alarm can drain a battery in a few weeks.

You'd never dare take your FL2 to an airport car park!

Alternator Charging problems can be caused by damage to the 'Blue Wire'.

See post from 'Refurb Pete in this link
https://www.freel2.com/forum/topic27454.html?highlight=blue+wire

See my post in this thread
https://www.freel2.com/forum/topic36375.ht...tery+light

Also
Your FL2 should start after being left for 4 weeks once you have manually unlocked car and put FOB near Steering Wheel Console.
The Electronic Systems shut down to save the battery from going flat so it can be used

My Heathrow experience is in this link.
https://www.freel2.com/forum/topic35264.html?highlight=heathrow

Also
Is your battery charger not working a Fail-Safe, as it can't detect any voltage in battery..
Some chargers allow you to over-ride this.
Have you lost a battery cell? FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Thanks @IanMetro, if I can get it started either by extended charging or jump starting I'll get it to the garage for a wiring check. We did have some torrential rain here before I parked her up so that might have been the final straw although no warning lights had been showing and everything was running fine.

For a change.

To answer the other question about the charger its an Optimate which gives an initial signal of his bad the state of the battery is and in this case it was heavily discharged. And then after charging does some repeated cycles to check the battery is holding charge and gives a thumbs up or down.

The thumbs up isn't that accurate I've found, it will charge a battery to full which will then start the car but after a few days that battery so have discharged again. Had this problem with the Saab and a new battery has been terrible free do it was definitely the old one that was dead, reverb though it took a charge.

Quick update....

Battery charger failed to get any sort of charge into the battery, not even enough to recognise the key so went for a jump start.

I min of donor charging, key in, system check in progress, press start and .....

Away we go. No warning about low battery, poor charging.

Drove for about 20 minutes with air con off, radio off, even the fan off. Left her for 24 hrs, tried this afternoon and started just fine.

I'm puzzled how a battery which seems quite healthy could have lost charge to go into hibernate and then to have lost ALL charge.

One thing I did notice - the boot light stays on if the doors are unlocked, rather than timing out. This 'option' seems to be of some conjecture but the previous owner did have a dog guard fitted so the random pet light theory may be true.

What I don't understand though is how that drains the battery.

I'm thinking the charging woes may be because I opened the doors with the key, and the drivers side door from inside so the boot light came on and I never noticed/looked for it so any trickel charging was going straight out through the boot light.

Plausible?