Battery loses power overnight

[Voltman]

I came home last night and parked my Model 3 in the driveway. I didn't plug it in for various reasons but it had 8% charge when I drove it in. This morning it had a 2% that went to 1% when I backed it out of the driveway. What would cause this? I don't have sentry mode on so I can't figure out why

 

[jjrandorin]

I came home last night and parked my Model 3 in the driveway. I didn't plug it in for various reasons but it had 8% charge when I drove it in. This morning it had a 2% that went to 1% when I backed it out of the driveway. What would cause this? I don't have sentry mode on so I can't figure out why

The battery will keep itself warm, and if you parked outside it may have used energy to warm the battery.

 

[ewoodrick]

At 8%, the car has already turned a lot of things off. You are probably seeing the temperature changes impacting the apparent range.
Pulling out early in the morning is going to kill you, colder temps, car waking up, not a great combination.

Moral of Story, don't park overnight with a really low battery. You probably won't be able to make it to the charger.

 

[N54TT]

I came home last night and parked my Model 3 in the driveway. I didn't plug it in for various reasons but it had 8% charge when I drove it in. This morning it had a 2% that went to 1% when I backed it out of the driveway. What would cause this? I don't have sentry mode on so I can't figure out why

.

The car uses the HV battery for system checks and to charge the 12v battery. As mentioned colder temps can also result in a lower displayed SOC. It’s not healthy for the battery to keep it at such a low SOC for an extended period of time...ie overnight without charging. For whatever the various reasons you didn’t plug it in...I would avoid making that a routine. Also read the manual and familiarize yourself with the battery system....particularly pg 145

https://www.tesla.com/sites/default/files/model_3_owners_manual_north_america_en.pdf

 

[cassiopeia]

In addition to the other comments, you should check any applications that you are running. Sometimes apps such as Teslafi, Stats and others conspire to keep your Tesla from going into the power saving sleep mode. I recently had a problem with power loss over night and decided to change my Tesla password so that my apps would all be logged out and I could add them back one by one. It has significantly improved my power loss from several percent to 1% overnight.

 

[postersw]

It's normal to use 1% - 2% overnight in summer. in cold weather other things can kick in, like battery warming. When you backed the car out in the morning, it started to warm up the battery and heat the cabin, which can suck electricity quickly. I'm not sure how Tesla determines apparent range, but if it's based on voltage, a cold battery will appear to have less power, hence your range drop overnight.

This forum overflowing with posts from folks who are coming from an ICE car and assume that when the car is off, it is really really off, and no power is being used. But actually the Tesla is never really off, and is always using power, sometimes in mysterious way. And measuring remaining 'power' in the battery can be affected by temperature.

 

[jjrandorin]

The battery will keep itself warm, and if you parked outside it may have used energy to warm the battery.

@Gasaraki

Regarding your disagree with my statement. Here is Teslas official statement that you can find directly on the tesla website: Range
==============================
Does outside temperature impact range?
Yes. Range can be impacted by extreme cold or hot temperatures; however, the impact will seem far more noticeable in cold weather. Tesla high voltage batteries are regulated to keep the battery temperature within optimal boundaries. Even if the vehicle is not being operated, the high voltage battery temperature is monitored and regulated to prolong its lifespan and performance – this is why you may notice the compressor running even while parked. See our Winter Driving Tips for more information.
==============================

So what part of my statement are you clicking the "disagree" button on?

 

[ucmndd]

Did you read and heed the warning that came up when you parked your car that the battery was very low and would have substantially less energy available when it cools?

Turns out that’s not just an empty threat. This is normal behavior.

FWIW, you really should never let your car sit at less than 10% SoC. When I arrive home with a very low battery I’ll charge immediately to ~20%.

 

[ucmndd]

@Gasaraki

Regarding your disagree with my statement. Here is Teslas official statement that you can find directly on the tesla website: Range
==============================
Does outside temperature impact range?
Yes. Range can be impacted by extreme cold or hot temperatures; however, the impact will seem far more noticeable in cold weather. Tesla high voltage batteries are regulated to keep the battery temperature within optimal boundaries. Even if the vehicle is not being operated, the high voltage battery temperature is monitored and regulated to prolong its lifespan and performance – this is why you may notice the compressor running even while parked. See our Winter Driving Tips for more information.
==============================

So what part of my statement are you clicking the "disagree" button on?

While what you’re saying is correct, it’s very unlikely that’s what happened in this case. When the SoC is that low, the car will not further discharge the battery to try and keep it warm unless it’s critically cold.

Rather, as the battery cools with a low SoC, the BMS limits the energy available for propulsion to prevent damage to the cells (thus the SoC drops). As I mentioned above, the car will explicitly warn you about this when you park it with a very low battery.