Charge Limit Problem

[tbenitez12]

Hello everyone,

I have had my LR M3 for over a year now and lately, I don’t know why, it does not charge to the limit I set for it.

For example, I don’t drive a ton day to day so I have been seating my limit to 60%

In the morning when I get ready to leave it will say charge to 56, 57, 58% but very rarely the actual 60 I set.

Does anyone know why this is happening? And should I do a full draw down to say 5% and then charge to 95 to see if that fixes it?

Thank you!
TB

 

[LoudMusic]

Mine is often 1 or 2 % lower than the set limit but never off by as much as you are reporting. I usually use 80%, but occasionally 90%. What happens if you use a higher % set limit?

There might be some value in charging to full (go for a long drive as soon as it claims to be done) in order to help calibrate it. But from everything I've read the calibration actually happens when the car is in sleep mode for several hours. I know that with most battery systems they need to be fully charged periodically so the battery management system knows what "full" equals and can reset its counters. Though I've never seen that for Tesla cars.

 

[GtiMart]

Battery temperature is probably the reason. SOC is not a precise measure. The car evaluates the total battery capacity and the current "fullness" of that caapcity using voltages. Those are imperfect estimates. When charging, heat is generated in the battery. Once charging stops, the battery might cool down depending on outside temperatures. I very often charge to 75% and I might come back to 72% or 78% depending on the conditions.
Apart from temperature, the car takes its voltage readings when the car sleeps to estimate total battery capacity. A readjustment of that capacity will change your current SOC. That energy was not lost, and the charger didn't "stop before it reaches the set SOC". These things are normal, nothing to worry about.

 

[PaulSu]

I've noticed in my 2022 Model 3 Long Range, I have set my screen chraging setting to the "line" which I believe is 90% and it's always been 90%.

The app shows 90% but the car will only hit 89%. I drive my OCD crazy.... If I charge to 100% everything reads 100%, but for a daily drive I charge to 90% / 89%

Anyone else?

 

[BMWM3Man]

Meh it fluctuates...I wouldn't worry about it. Plus "it" knows what its doing...

 

[GtiMart]

You are seeing this as a precise value but it's not. The BMS estimates the total battery capacity, and estimates the current change using voltages. This is not precise, and the voltages fluctuate depending on multiple factors, one of which is battery temperature. All of this is estimated, based on previous readings when the battery is disconnected (car is sleeping) over months. None of this is precise.
I typically charge to 75% and I come back to my car at 78%, sometimes 73% etc. It doesn't matter. The car charged to what you asked (within margin of error), and is still at that level (pretty much).

I typically have OCD too and I learned to forget about this. Once you understand how it works, it's easier.

Just for fun, you wouldn't expect an ICE car to show you the tank contents in milliliters right? Liquid volumes expand/contract with temperature, you would have stressed over that too