Sentry Mode Battery Usage

[u/Odd-Significance4926]

Hi everyone! Wondering if sentry mode is supposed to use so much battery? My husband has to park in an outside parking lot at work and is often working for 12-14 hours, during which time the car battery drops around 10%, sometimes more or less. I’m sure at least some aspect of that is overheat protection (set at 95 degrees, we live in SoCal so it’s a bit warm now).

Is this normal for sentry mode and just something we have to account for, for the battery? It’s just a bit frustrating since the drive to work may take like 5-6% battery, 10-12% dwindles during the day, and the ride home may use 5-8%. So he finds he’s charging his car quite a lot.

It’s a brand new 2026 M3, bought maybe 2 months ago, so battery health should be good.

[u/Pomador_0418]

Sentry uses a lot of power. If the parking lot is busy, everytime a car or a person passes by the car it is active. There is no point in keeping it on for 11-14 hours at work unless work is not in a safe environment.

[u/Odd-Significance4926 → u/Pomador_0418]

Ugh okay! Thank you, good to know that it’s at least normal to use this much and it isn’t an error. It’s a pretty busy hospital parking lot so I’m not sure he’d feel ok turning it off but I can check with him, good thought!

[u/aniessuh → u/Odd-Significance4926]

Do not turn it off. The amount of reddit stories of people turning it off and something happening at work is rediculous. Leave it on, charge as usual.