I have my2015 Range rover Sport which isn't used much, about once a week (6000miles) but is regularly hooked up to a ctek charger. Last week it sat for about 3-4 days not on the charger. When I took it out of the garage & switched it off it said battery low, start car. I stuck it on ctek which immediately lit up 4 lights which meant it was good to start. I left it for a couple of hours & it showed full charge with the green light on which makes me think the battery was ok as when the battery is low it takes about 12 hrs to get up to the green light. It did the same again this week. Does anyone have any thoughts on this, is the battery finished or ?. Suggestions welcome

That warning is usually for the auto stop/start battery not the main car engine battery - take the car for a 15-20 mile run to recharge the stop/start system battery and then try operating the auto stop/start system and it should work fine whereas if you tried to use it with the warning showing it wouldn’t auto stop/start. 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

I did just that this afternoon, about a 30mile fast run & noticed the stop/start did not happen when I returned home which made me think there was a battery problem. I did not realise there were 2 batteries. Do you know where the stop/start one is situated, then I could check the voltage. Thanks for that.

I don’t know where it is but Disco_Mikey will! If your aircon was running a lot it is possible that it was putting too much load on the systems for stop/start to work - i’ve Noticed that in my car the stop/stat will restart the engine within a few seconds of stopping if the aircon is blasting out cold air in traffic, also if it was really hot (I cannot remembervthe uppervtemperature limit) outside then it won’t work anyway like in cold weather stop start won’t work below a set temperature because thenload is too high for the reserve battery. 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

The stop start battery is located behind a trim panel on the right hand side in the luggage compartment. I had a dash cam fitted & the numpty used it as the main power supply - hence within a week it was totally flat. I removed it & recharged it with the CTEK - its been spot on since - be careful the battery lugs are not that strong & over tightening the connectors will split them

Peachy. 16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

Not sure if this may be of some use as well.

OVERVIEW - DUAL BATTERY SYSTEM VEHICLES WITH STOP/START SYSTEM.
Two batteries are fitted to accommodate the dual battery system used for the all markets vehicles with stop/start
system.
A primary battery is located in the luggage compartment floor in a plastic molded tray and clamped in position by the
air suspension air supply unit.
On stop/start system vehicles, the secondary battery is located in the right side of the luggage compartment on a
battery support tray and secured with a strap bolted to the tray.
The primary battery is a 90Ahr, 850CCA Absorbed Glass Mat (AGM) Valve Regulated Lead-Acid (VRLA) battery
on all vehicles.
The secondary battery is a 14Ahr, 200CCA AGM battery on all vehicles with stop/start (except TDV6 3.0L cold
climate vehicles).
The auxiliary battery is a 70Ah, 760CCA, AGM battery, in TDV6 3.0L cold climate vehicles with stop/start
system ONLY.
A BMS control module is mounted on the primary battery negative terminal. The BMS control module is integral with
the battery negative cable and is controlled by the GWM.
The secondary battery is not fitted with a BMS control module.
CAUTION: To avoid damaging the BMS control module, always use the ground (negative (-)) terminal stud point
on the right side top mount in the engine compartment. Never connect directly to the primary battery negative
terminal when connecting a slave power supply to the vehicle, the BMS control module can be damaged.

Cheers
Col

Thanks everyone, will try to have a look at it later today

Peachy
There is a piece of trim which forms a cavity on the right hand side. Its about 9.5" wide, near the tailgate. Is the battery behind this. I gave it a bit of a tug but it did not want to come off. Dont want to force it if its not the correct part

It's the full piece about 18in long - 15in high will add a pic in about an hour if needed  16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

Pic would be good if its not too much trouble

 16MY Estoril Blue SVR.............
17MY Autobiography Dynamic - Corris Grey - WOW.
14MY Autobiography Dynamic - SDV6 - Fuji White
12MY Autobiography - SDV6 - Santorini Black - Dual View - Rear Entertainment - Sunroof.
12MY Autobiography - SDV6 - Orkney Grey - awesome ;(
2005 Java Black - 4.2 V8 Supercharged First Edition- will never be forgotten ;(

Thanks for that, I was just pulling the recessed piece

Finally got round to checking the secondary battery after a struggle pulling down the trim. The car had been sitting for about 6 days. When started it came up with low battery, start car, so after opening up the trim, I checked the voltage which read
13.02 volts, which seems ok to me. Stuck Ctek on & 4 lights lit up. Its been on for an hour approx. & all lights plus green light are on. Will be using it this afternoon so will see if start/stop works. Any more suggestions welcome

Is that 13.02V with the engine running? If so, might that suggest the alternator isn't pulling its weight? 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

No that's with the engine off. I have just disconnected Ctek as it says fully charged, jumped in, nothing on & it says low battery, start engine