I just disconnected the BMS and will give it a try. On a quick test drive, the @ on the dash with a slash through it came on mult times at stop signs/lights so the auto stop didn't engage. Still trying to find all that the BMS does to see what else it controls.

 

The BMS is part of the vehicles ability to monitor current flow and consumption. It is an integral part of the vehicle to keep the battery charged correctly and extend the life of the battery. It allows for consumer cutout to deactivate electrical loads to help make sure you can at least still start the vehicle if you leave a door open or lights on. When manufacturers started using Battery management in vehicles, the lifespan of vehicle batteries increased dramatically. We have seen vehicles come in a 9 year old battery! It adjusts charging paramaters as the battery ages.

Putting this system into a failsafe operation just to make auto start stop not work (another thing the bms system disables if there are battery charge concerns) seems like the juice is not worth the squeeze. Yeah, short term you may not notice a drawback, but this system working in the background is an incredible benefit. The amount of current these modern vehicles use is very excessive. Remember the folks complaining about when they camp and opening and closing the doors kills the battery eventually. Imagine how fast this will happen without BMS.
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Thus my “unpopular solution” post qualifier. Works for my situation. Might not work for all. That’s the beauty of choice.

 

Thank you all , I will try this over the weekend. I hope it works. Every new car has this unwanted feature.

 

Just short of a week and so far no problems.

 

Guess I’m the only one who never touches the button. I enjoy saving gas, and have never had a mechanical problem.

 

The thread that never dies. But does provide entertainment. While some agonize over it, the remainder have simply accepted its existence and use that 3/10 of a second to press the button 6 inches to the right of the button they press to start the vehicle. Debated at length, Auto Start/Stop is in every car I’ve been in and doesn’t appear to be going away anytime soon. But hey, whatever floats your boat. Use the GAP tool, disconnect the BECM, press the button, or use the feature. Your Defender, choose your solution. Doesn’t take away the pleasure to own and drive a fabulous vehicle.

 

Reporting back - I disconnected the BMS as noted previously when I was in Forida. I didn't notice any negative effects down there other than the voltage. By way off background, I use a 12v monitor plugged in the cig lighter.
it seems like when the BMS is noted plugged in, the voltage is consistently 13.8v when the car is running. When I plugged it back in, I saw volts in the range of low 12s to 14.7 when running. So I assume the computer is telling the alternator what is needed based on conditions.

We drove back to Western NY over the weekend, and I had no problems. Today it was quite chilly, and I turned on my heated steering wheel and heated seats and i realized neither was working. I turned off the car and plugged the BMS back in and fired up the car - both the steering wheel and the seats heated up nicely. Based on other stuff that needs re-boot from time to time to turn on (like the PIVI), maybe it needed a reboot or maybe the heated seats and heated steering wheel are impacted by disconnecting the BMS.

BTW, the car was great on the road trip down from Western NY to SW Florida and back to WNY 6 weeks later. My only complaint is the front seats - I did miss the seats in my Porsche Macan. Other than that, it was a great road trip vehicle and that was with Cooper Discoverer Road+Trail AT tires.

 

In general 13.8 is not enough for AGM battery, charging is supposed to be done at 14.8.

 

Interesting, I often see the volts down in the low 12s when driving - must be fully charged?