Start / Stop suddenly started working after 3 years of not working… WHY??? | SwedeSpeed

I have a late MY17 T6 Momentum bought new in 8/2016 and am still running the ORIGINAL OEM main battery. My start/stop stopped working (yay!) around December 2022. After reading the forums, I thought I’d replace the AUX battery to see if it would help. I replaced it Jan 2023 at 83k miles, but it did NOT fix the S/S non working issue. Since that time, I have driven about 35k miles with 14 hour long drives multiple times during the summer. Start/Stop never came back or would come back for 1 or 2 cycles right after the long drive.

This past week, I drove 7 hours to 118k miles and suddenly…voila! I was surprised that the engine stopped at a stop light. I’m like… wth just happened. I thought it was a fluke and that it would stop working after a few S/S cycles. But it has kept on working!!! I am now on my 3rd day of it working. I understand all the scenarios shown from the manual below and none apply to me.

I have done NO ELECTRICAL work on the car whatsoever. The only maintenance I’ve done since 83k miles were:
-change brake pads and rotors
-several oil changes
-transmission fluid flush
-cabin filter
-brake fluid flush

So what the hell happened here? How can it suddenly start working again when I have NOT even replaced the original OEM battery (entering 9th year in service)? What suddenly changed over the past 3 years? Anyone have any thoughts?

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FROM THE MANUAL:
In certain situations or conditions, the engine may not auto-stop when the vehicle comes to a standstill, such as when:

• the vehicle has not reached a speed of approx. 8 mph(12 km/h) after starting.
• after several auto-stops, the speed must again exceed approx. 8 mph (12 km/h) before the next auto-stop.
• the driver’s seat belt is unbuckled.
• the main battery’s charge is below the minimum level.
• the engine has not reached its normal operating temperature.
• the ambient temperature is below approx. 23°F (-5°C) or above approx. 85°F (30°C).
• the windshield’s heating function is activated.
• the climate system cannot keep the desired settings in the passenger compartment.
• the vehicle is backing up.
• the main battery’s temperature is above or below the permitted limits.
• the driver is turning the steering wheel hard.
• the road’s incline is very steep.
• the hood is opened.
• the transmission has not reached its normal operating temperature.
• driving at high altitude and the engine has not reached its normal operating temperature.
• the gear selector is in the manual shifting position.
• the ABS brakes have activated.
• hard braking (even if the ABS brakes have not activated).
• many starts during a short time period have triggered the starter motor’s overheating protection.
• a trailer’s electrical system is connected to the vehicle’s electrical system.