When I bought it, my FF showed the low battery warning.

That’s since gone. But even a 330 mile round trip hasn’t got the start / stop working.

My guess is the main battery needs replacing and all will work again.

Am I right? What do I put here then?

I thought it was the auxiliary battery thar was responsible for Stop/Start.

Willing to be corrected

My car has just had its 6th birthday, the stop start has not worked for a few years and I decided it was time for a bit of pro-active work so had both batteries replaced at the service. Stop start working again, so now I start the car and turn off the stop start straight away. letters not necessarily in the right order

It’s the small auxiliary battery behind the rear right boot panel that needs replacing - or it’s been disconnected 2021 L405 Vogue SE 4.4 V8 DIESEL ~ #17

Thank you all.

Had both batteries tested last week.

The aux battery showed as "good". The main one "good but low".

Logic suggests if it can be tested, the aux battery is connected. However, this is a FF so logic may not apply

I'm actually wondering if I have stop / start ...

... every other car I've driven with it has a button to switch stop / start off. Mine doesn't.

Is it possible I don't have it and the aux battery is for something else? What do I put here then?

Entirely possible.

Mine doesn't have stop/start but does have dual batteries.

I’ve got a 2015 SDV8 and pretty sure mine hasn’t got stop/start

Came in on MY16 models through 2015 (generally 65 plate onwards) will have a stop/start off button on centre tunnel if it’s fitted

Both batteries on my 15 plate tested as good, but stop start worked once every now and again. Replaced both and it works all the time now Not sure if thats a good or bad thing... MY17 Santorini Black L494 Autobiography 5.0 SC - Sorry!
Previously Bell a 2015 MY16 Loire Blue Autobiography 4.4 SDV8
Previously George a 2007 MY07 Java Black VSE 3.6 TDV8
Previously a 04 MY04 Defender 90

Mine was first registered 1.3.15 and I've not seen a stop / start button - will have to double check now.

If it doesn't have it, what's the aux battery for? What do I put here then?

Stop/Start was a£460 option on MY2015 and not a standard fit on any model including the AB and SVAB 2015 Range Rover L405 SDV8 AB Corris grey
2010 Range Rover TDV6 HSE Narra Bronze sold
2006 Discovery 3 SE green sold
Defender 90 td5 sold
Defender 90 soft top sold

So all cars had the aux battery. But you only got stop / start - and the button for it - by paying the £460 extra? What do I put here then?

Yes, but think of all of the money you save when stuck in traffic.

Pretty sure it was standard on all MY16 models onwards, happy to be corrected.

The second battery is there because why not ?

It provides extra power for all the other electronic bits & pieces and an extra bit of starting boost if required. Other than cost to replace & a bit of weight, no down side.....