Stop start c3 warning-car won't start- eco = off ?

[charentejohn]

Had a new one today. This is a 'what happens if' question really as I managed to resolve the immediate problem. - C3 petrol 2006 stop start sensodrive

Coming back from recycling centre with a trailer, naturally had to stop on a downward corner and the engine stopped (via stop start system) as normal but wouldn't restart.
All I got was the Stop Start problem message when I turned the key to start it but it wouldn't start. The message appeared randomly a while ago but the car always started. Garage checked it out and all ok.
One question is would the battery under the seat do that (main battery is new) as it would be the original. No idea what that battery controls.

My Eco = off bit in the title relates to a possible way to start it if this happens again ?
This time someone helped me push the car to the side of the road. Then I wondered if the stop start position was now wrong, that is the bit where it stops just before it is about to fire so a nudge and it starts again (or not). I put the car in gear and rocked it, as you would to free a stuck starter motor, and it worked.....

I then wondered if I could have just pressed Eco Off so bypassing stop start and would that have worked. Would be good to know if it ever happens again.
A rare thing I am sure but basically does, insert key, switch on, Eco Off then disable the entire stop start system so it acts from that moment as a normal car ?
Any thoughts appreciated as I hope not to have to find out the hard way

[wheeler]

One question is would the battery under the seat do that (main battery is new) as it would be the original. No idea what that battery controls.

During stop phases, both batteries supply the on-board network
During starting and restarting operations, the additional battery alone supplies:
• The radio
• The multifunction display
• The air conditioning panel
• The control panel
The additional battery prevents any variations in the lighting on the control panel, air con panel and multifunction display and prevents the radio resetting by maintaining a constant voltage during starting or restarting phases.
Not sure what, if any a failed auxiliary battery could have on the actual functioning of the S/S system. I personally would turn of the S/S system every time i got in the car, its just unnecessary wear on the reversible alternator and they aint cheap, some of them are also no longer available from the dealers now anyway.

[charentejohn]

Thanks wheeler, especially for the aux battery info as I can now ignore that.

Makes sense that if the stop start is off then it can't complain I don't do many journeys where I have to stop and the engine does, 4-5 per journey every few days.
It is tedious when stopping a lot as it has to wake up and then move off and can cause a thump (sensodrive) as it sorts itself out.
For the few times it stops I may as well turn it off as not really saving anything.