My schedule charging has been come inaccurate

[Dugdale]

My schedule charging has been come inaccurate in the past couple of months. I have a Fremont Model Y LR 2023 with about 17k miles. I have a Gen 3 Wall Charger, last time I checked the software was 22.45.1 and I have it set to charge at 48A. My garage temp lately at night is in the 40's F.

Here is what happens:

• I schedule it to charge to 70% at night, next morning it is 72% (+2%)
• I schedule it to charge to 67% at night, next morning it is 69% (+2%)
• I schedule it to charge to 68% at night, next morning it is 63% (-5%)
• When I supercharge to 70%, it stops at 70%
• When I manually ask it to charge (not scheduled) to 70% at home it stops at 70%

It appears to be related only to Schedule Charging.

This started happening before I recently ran my battery to 0% and charged it to 100%. I thought that might help how it guesses at the percentage.

What else can I try? I could ask my neighbor to charge my car overnight in his garage to see if it's related to my wall charger, but that seems a little excessive. I could try adjusting the amperage. Can I reboot the wall charger by cycling it's breaker? I guess I could see if the charger has the most recent firmware. Ideas?

 

[posity]

Is there a functionality problem with the car when this occurs? Can you not get from point A to point B the next day?

The % charge is an estimate. When any battery charges, you don't really know the final charge amount until it settles out to its final values sometime after the charge completes (hence the overshoot). Consider too that you normally see one charge % the night before and slightly less charge the next morning: the car is performing tasks that consume power that are related to weather, security, sentry, the cameras and so forth so the loss numbers are different every night. There is nothing to be 'fixed' here: the car is simply more complex than our feeble understandings and you need to just ignore it and appreciate the beauty of its design and implementation.

 

[gtae07]

I've found I "lose" a couple percent after charging as the battery cools down and things settle out. But I often gain that couple percent back later in the day as the battery warms up.

These things happen and I wouldn't get too concerned about it.

 

[GtiMart]

If you look at the charge right after it finishes, it will be exactly what you asked or maximum 1% off, just like when you supercharge. If you wait until the next morning, the displayed charge might vary by a few percent in both directions. There are a few reasons for that:
- your car might have consumed a bit of energy.
- The BMS might have readjusted itself one way or the other.
- The battery temperature has changed. The car tries to indicate how much energy it thinks you can get out of it depending on its temperature.

Battery capacity is just an estimate, and thus "current level" as well. It's not a precise measure.

 

[Rocky_H]

What else can I try?

Not worrying about it.

 

[Dugdale]

OK sounds like it is something I shouldn't worry about. I wasn't worried about it, I was mostly curious why it just started to happen.

 

[GtiMart]

The main takeaway is that these values are estimates, not precise values. Total battery capacity, percentage full, energy that can be extracted at this moment... it's all best guesses by the BMS. Once you accept that, you understand that such variations are normal.

 

[Dugdale]

OK, I will try a few things and if it works, I will return and share how I fixed it.