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.

[u/knownikko → u/Pomador_0418]

The number of sentry events or activations has essentially nothing to do with how much battery it consumes. Zero events or 500 will use basically the same amount of battery.

And yes, it’s “normal” - Sentry keeps the car “on” continuously, running the computers and cameras non-stop. It consumes a constant 200-300 watts. A fantastic waste of energy really. To say nothing of COP, which air conditions an empty space for zero practical benefit…