Hi
car not used for 2 days and then pre-heated and then failed to start.
I read somewhere else in the 'parish' that after ignition, the only battery use is the fan or perhaps other other control units come alive.
The battery was new LR one in July and has been drained once since.
Bit of a bummer really! I do find it odd that there is not a means of internally monitoring battery state and always protecting a reserve for at least one assured start. It is the biggest cause of breakdown.
Kind regards,
Ed '96 Volkswagen Polo 1.4CL - SOLD
'00 Audi A3 1.8T - SOLD
'97 Lotus Esprit V8 - SOLD
'03 BMW M3 - SOLD
'93 Range Rover 3.9 Vogue SE - SOLD
'92 Peugeot 205 GRD - DIED
'99 BMW 540i Touring - SOLD
'94 Peugeot 405 GDRT - SOLD
'00 Peugeot 406 HDI estate - 63mpg! - SOLD
'08 Range Rover TDV8 Vogue SE - SOLD
'11 Skoda Fabia Greenline II - 94.2mpg!- SOLD
'07 E61 BMW 530d msport touring - SOLD
‘20 Tesla Model 3 SR+
‘20 Tesla Model 3 Performance

The biggest favour you can do yourself is buy a CTEK charger. I have a 7000 unit which I have used to good effect when a lot of load is placed on the battery.

FBH uses power as do all the other bits in cold weather. Short journeys never put back the full charge. Give it a recondition cycle initially and then leave it on overnight one day a week. When FBH is on the vehicle 'wakes up' and the overall current draw (measured with an ammeter) is about 9 amps.

Summer months will see normal service resumed. D3's have the same issues but the battery can't get much bigger really so extra charges are needed in some circumstances. C7000 kit comes with a plug which can be left connected so it's plug and play. I connected mine using a 13 pin towing plug which is another easy option (saves lifting the bonnet). the 3600 kit is also good, cheaper and half the power output but works fine.

LINK

I have it on very good authority from a Land Rover Assist guy that so far this winter the most popular reason for him being called out is FFRRs with a flat battery caused by the pre-heater. Apparently even dealers are now telling customers not to use it as more often than not it flattens the battery

Andy. 2015 L405 SDV8 Autobiography, Indus Silver with Black Pack.
SWMBO: 22MY Defender 110 HSE X Dynamic, Gondwana Stone.
Gone: 2014 Discovery 4 HSE Luxury Firenze Red
Gone: 2006MY Java Black TD6 Autobiography
Gone: 2013 Jaguar XKR Convertible, Italian Racing Red with Ivory Seats
Gone: 2010MY Stornoway Grey TDV8 Vogue SE with RSE
Gone: 2008 Disco 3 HSE, Hybrid Tv + Retro-fit RSE System & DVD
Gone: 2003 Epsom Green 4.4i Vogue, LPG, Mk4 Nav, BMW Bluetooth Phone, Hybrid Tv Tuner,

I drive 8 miles to and from work a day and use the pre-heater in the morning and afternoon.

I have the heated seat and heated screen and heated wheel on every journey.

You should be fine - Pre-Heaters are nothing new on Range Rovers and are certainly nothing new on cars/trucks in general. The draw is minimal and should give plenty left to start the car. As long as the battery/charging system is in good condition and there are no non-factory drains from car kits or the like. 

Fortunately Dan we benefit from BMW technology and not Jag! Apparently the newer cars are the problem but I'm only repeating what I was told in person last week by a Land Rover assist man with 15 years on the job when he turned up to sort my wifes D3 in his nice new Silver 2010 D4. I guess he could be wrong though  2015 L405 SDV8 Autobiography, Indus Silver with Black Pack.
SWMBO: 22MY Defender 110 HSE X Dynamic, Gondwana Stone.
Gone: 2014 Discovery 4 HSE Luxury Firenze Red
Gone: 2006MY Java Black TD6 Autobiography
Gone: 2013 Jaguar XKR Convertible, Italian Racing Red with Ivory Seats
Gone: 2010MY Stornoway Grey TDV8 Vogue SE with RSE
Gone: 2008 Disco 3 HSE, Hybrid Tv + Retro-fit RSE System & DVD
Gone: 2003 Epsom Green 4.4i Vogue, LPG, Mk4 Nav, BMW Bluetooth Phone, Hybrid Tv Tuner,

I have had a few TDV8's and they all work fine with 30 minute remote warm up without battery drain. Jag cars are great too you know

Please don't shoot the messenger I'm just reporting what I was told. Besides which I cannot wait to get my hands on a TDV8 Vogue SE in the Spring, trying to hold out for 2010 model

Andy. 2015 L405 SDV8 Autobiography, Indus Silver with Black Pack.
SWMBO: 22MY Defender 110 HSE X Dynamic, Gondwana Stone.
Gone: 2014 Discovery 4 HSE Luxury Firenze Red
Gone: 2006MY Java Black TD6 Autobiography
Gone: 2013 Jaguar XKR Convertible, Italian Racing Red with Ivory Seats
Gone: 2010MY Stornoway Grey TDV8 Vogue SE with RSE
Gone: 2008 Disco 3 HSE, Hybrid Tv + Retro-fit RSE System & DVD
Gone: 2003 Epsom Green 4.4i Vogue, LPG, Mk4 Nav, BMW Bluetooth Phone, Hybrid Tv Tuner,

Hi,
Have been looking at the CTEK gizmos - seem very good.
The XS 3600 model looks as though it will do the trick. Has anyone any experience of the cigarette lighter input to charge the battery?
Seems better option for the driver (wife) than lifting the bonnet all the time.
Kind regards,
Ed
P.S.any cheaper places than £42.00 delivered? '96 Volkswagen Polo 1.4CL - SOLD
'00 Audi A3 1.8T - SOLD
'97 Lotus Esprit V8 - SOLD
'03 BMW M3 - SOLD
'93 Range Rover 3.9 Vogue SE - SOLD
'92 Peugeot 205 GRD - DIED
'99 BMW 540i Touring - SOLD
'94 Peugeot 405 GDRT - SOLD
'00 Peugeot 406 HDI estate - 63mpg! - SOLD
'08 Range Rover TDV8 Vogue SE - SOLD
'11 Skoda Fabia Greenline II - 94.2mpg!- SOLD
'07 E61 BMW 530d msport touring - SOLD
‘20 Tesla Model 3 SR+
‘20 Tesla Model 3 Performance

been using pre heat recently obviously, only do short journies and last weekend car totally died. Not sure there is a connection always been ok before cold spell, no hint of failure but new battery sorted it, and had old one checked, totally fuk'd No body told me there would be days like these

L Reg dark purple/burgundy sort of Disco
R Reg very red disco
Bright Silver disco TD5
Sort of bright girly powder blue disco TD5
Gone (a while back) 1999 P38 4ltre Autobiography. 13 miles to the gallon, 10,000 miles to the engine
Gone MY06 RRS HSE Rimini Red
Gone MY10 RRS HSE Purple
Gone 2007 TDV8 Vogue OF Stornoway Grey (In Love again)
2011 4.4 TDV8 Vogue Baltic Blue
MY66 VOGUE TDV6 3.0 Red

£42 is about right for the CTEk 3600.

CL option for plugging in is fine - not sure if the sockets on the FFRR are live when there's no key in the ignition though. That needs to be checked. If it's not connected to the battery then it can't charge it.

Failing that, the kit comes with a pre-made lead for connecting permanently to the battery. This could be connected to one of the permanently live fuses behind the glovebox with the plug tie wrapped to the panel below. Easy to get to but out of sight.

Personally I use a 13 pin towing plug which has the perm live feed for the fridge.

The FBH should not draw enough to kill your battery after 1/2 hour. The Thermotop draws around 32w IIRC + you also have the heater blower running on low speed. So (roughly) the FBH draws around 2.5A and the blower... let's say 10A (high IMO). That equates to approx 6.25AH - less than 10% of your battery's capacity.

Get your battery checked or, if this only happens when the car has been sitting for several days, get your RR checked for a current drain.

Unless the Jag based RR's have some sort of programming or other error (FBH burns too long, blowers come on too soon and too high), the dealers telling customers not to use the FBH is typical. Chronically underinformed service personnel eliminate problem by eliminating the use of the feature. 
RRC 2Dr, RRC 4Dr,
P38, and 2 L322s
(wife thinks I'm nuts - prob right, too)