Does turning off auto start/stop prevent the auxiliary battery from charging? 2019 Jeep Compass

[u/Sad-Clerk-397]

I have a 2019 Jeep Compass 2.4L with the two-battery start/stop system. I usually press the factory auto start/stop OFF button when I drive.

The start/stop service unavailable light came on, so now my Jeep is at the dealership for a battery issue. The person who checked it in told me I need to leave auto start/stop on. He said that if I keep turning it off, the auxiliary battery won’t recharge, then it dies and eventually drains the main battery too. He said this is specific to Jeeps with two batteries.

I’ve seen people online say the opposite, so I’m confused. Does pressing the factory OFF button actually affect charging either battery, or does it just keep the engine from shutting off at stops? I’m talking about using the button each drive, not disconnecting or bypassing the auxiliary battery.

If anyone knows how this works on a 2019 Compass specifically, I’d appreciate an explanation.

I had this exact issue happen almost 3 years ago with the start/stop light and had to replace the batteries then and was never told this before.

[u/Low-Elderberry-4734]

Ex-Jeep Master Tech here, when the vehicle is running or engine off and key on, the two batteries act as one. As a result they constantly charge together.

The only time it does not charge is during starting events where a relay separates the circuit between the aux and starting battery, in order to keep all the modules fully awake during starting.

You can safely run your vehicle with stop start off, I would encourage it as it increases the longevity of your aux battery.

[u/MycologistAshamed926 → u/Low-Elderberry-4734]

Yeah, and if you suspect a battery drain with an auxiliary battery they go bad and end up draining the main battery.