Dear all,
I've been reading the various threads about disabling start-stop.
I rather like the approach of disconnecting the small battery in the boot.
Does this affect any other functions of the car? or is its sole purpose only for the start-stop operation.
Thank you for any answers.

 

There was only a 2nd battery on I think the first 2-3 model years. After that they went with an ultra-capacitor, I believe. The 2nd battery (if you have it) is easy to disconnect, but it took me quite a while to figure out how to remove it.

It does nothing other than support start/stop. On my car, the ECO button lights up when I start the car, then turns off after 5-10 seconds, as start/stop isn’t available. No messages or codes.

 

Thank you for your answer,
my car is a 2016 model year and I haven't looked to find the 2nd battery assuming there is one.

 

It’s under the trunk liner, near the right taillight.

 

Took a while to find these, from when I removed the battery in 2021…


From the front of the trunk, looking towards the back left corner of the car from this perspective

Looking down at the battery

 

Thank you for the pictures, they do help.

 

Also, if you have a convertible, you can get a SmartTop module that will allow you to systematically turn off start/stop, along with several other functions, including setting the exhaust and enabling the fob to lock/unlock the doors, open/close windows and top)

 

Thank you, my car is a coupe.

 

My 2016 didn’t have a second battery.

 

Thank you, won't that affect anything else?

 

The Start/Stop disable light on the instrument panel stays on. Otherwise, no ill effects.

 

Thank you, I'll go and do it. You have solved a big problem for me,

 

The module is in the trunk space under all the trim and compartment covers. Sitting right on the bottom of the trunk floor. I think this covers post dual battery cars up to the facelift cars.

 

I've done it, I switched on the ignition without starting the engine but the start-stop disable light didn't come on, also the disable button was lit all the time.

 

Need to complete the cycle. Start/Stop wasn't available for a couple minutes after startup anyways. After the motor is running it determines if the car has enough volts available to enable Start/Stop. It will decide it doesn't because you've unplugged the module and it doesn't "see" the voltage. Same as having a car with an older battery with less capacity.

 

Thank you, now I have 1 less thing to worry about.

 

I unplugged mine in the first week of ownership. I've never seen a light unless I've actually pushed the button as a 'what if' test.

In the US, 2016 and up did not have the second battery.

 

Problem solved, thank you all. This is the greatest forum ever.

 

There is one use for auto start/stop that has some value: it only activates with sufficient battery charge. I kept mine active for this reason. If auto start/stop is active, then I know I don't need to put the battery on my maintainer. I do a bit of short trips around town, and occasionally have to top-up the battery. Auto start/stop is a very nice way to determine when the battery needs to be charged.

 

As I don't use the car regularly, It's always connected to the Noco maintainer. when garaged. I'm under the impression the Noco maintains the battery to last longer.