SOC self-adjusting up?

[abcut973]

Not too sure how is this possible but for 3 nights in a row my SOC in the morning before leaving for work has been bumped by 1% compared to what the GOM reported the previous day when I parked the truck.
Any ideas of what could cause that?
This week temperatures have been cool overnight like 57-60 but in the 75-85 during the day. The truck has not been plugged in since the last time I charged it to 90% last sunday/monday overnight hours.
I'm currently at 40%. Started this morning at 44% but parked it yesterday at 43%! Same thing the previous 2 days but at different SOC.
Have you guys experienced that before?

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[sotek2345]

I have seen it happen, but usually with the battery warming up, not cooling down. Remember the battery % is an estimate based on the voltage coming from it. We see an exact percentage, but it really isn't that accurate.

 

[SpaceEVDriver]

When the SoC is reported immediately after driving, the battery is still in “voltage sag” condition so the voltage read from the modules gives a lower SoC reading. After some time the voltage recovers and the SoC reading goes up.

 

[abcut973]

When the SoC is reported immediately after driving, the battery is still in “voltage sag” condition so the voltage read from the modules gives a lower SoC reading. After some time the voltage recovers and the SoC reading goes up.

How consistent is this? Because it was not doing it before. I've had the car for close to a month now.

 

[RickLightning]

Not too sure how is this possible but for 3 nights in a row my SOC in the morning before leaving for work has been bumped by 1% compared to what the GOM reported the previous day when I parked the truck.
Any ideas of what could cause that?
This week temperatures have been cool overnight like 57-60 but in the 75-85 during the day. The truck has not been plugged in since the last time I charged it to 90% last sunday/monday overnight hours.
I'm currently at 40%. Started this morning at 44% but parked it yesterday at 43%! Same thing the previous 2 days but at different SOC.
Have you guys experienced that before?

Total non-issue. One reason could be warmer battery. But, a 1 or 2 point difference from day to day is a non-issue.

If you park it in the dead of winter, at like 30 degrees, and the next morning come out to say 0 degrees, you'll likely see a tad lower SOC until it warms up.

 

[SpaceEVDriver]

How consistent is this? Because it was not doing it before. I've had the car for close to a month now.

It’s also temperature dependent. How much sag happens is T-dependent; how quickly it recovers is T-dependent. You could also be seeing your battery warming up after you’ve stopped driving. I don’t see it all the time, but do see it regularly.


Another possibility is that the temperature of the battery has increased slightly overnight. This sounds counter-intuitive because you’re talking about leaving it overnight and seeing the SoC higher in the morning, and I’m not sure this is the cause. But…As long as ambient temperature is somewhere within the proper operating temperature of the battery for driving, the battery will typically be a little colder than ambient when you stop driving. This is because the car’s battery thermal management doesn’t want to expend extra energy maintaining the battery temperature and moving air across the bottom of the battery is a great “passive” thermal management technique. When you stop driving, the battery can warm up to ambient.

 

[Athrun88]

My guess-o-meter will probably start adjusting the state of charge up as the weather warms up. Batteries have a temperature window where they're the happiest, meaning it will give you the best charging/discharging rates when compared to being too cold or too hot. When I woke up the other day and it was around 15C, (59F) my 80% charge was showing a range of 340km (211mi) instead of the usual 300km (186mi) when ambient was around 5C (41F). My state of charge will also change slightly during the day depending on the time of day and ambient temperature.

TL;DR: Nothing to worry about

 

[Phineas Magliozzi]

I think this is why Ford didn't give us ready-access to the digital percent-remaining at the instrument cluster originally, just the "analog" gauge. People get fixated by the numbers, understandably, but its called the Guess-O-Meter for a reason.

 

[Maquis]

If you are experiencing this behavior and did not previously under similar conditions, it’s possible that your BMS calibration is off. This is especially likely if you rarely do deep discharge cycles.

Here is a post on the Mach-E forum describing the condition along with a calibration procedure.

 

[Heliian]

One percent is less than the margin of error. Keep on truckening.

 

[abcut973]

One percent is less than the margin of error. Keep on truckening.

I definitely like to trucken

 

[FloridaMan655321]

I saw this happen recently. I'm in FL, so it was probably about 60f or so out in the morning. The thing for me though is I charged up to 85% the day before, disconnected, didn't move the truck, and the following morning it showed 84%. I didn't think anything of it but then as I pulled out the driveway I happened to look and it was at 85%.

 

[RST]

Not too sure how is this possible but for 3 nights in a row my SOC in the morning before leaving for work has been bumped by 1% compared to what the GOM reported the previous day when I parked the truck.
Any ideas of what could cause that?
This week temperatures have been cool overnight like 57-60 but in the 75-85 during the day. The truck has not been plugged in since the last time I charged it to 90% last sunday/monday overnight hours.
I'm currently at 40%. Started this morning at 44% but parked it yesterday at 43%! Same thing the previous 2 days but at different SOC.
Have you guys experienced that before?

I have noticed the exact same thing on my truck for the past month or so. This is something new, bought truck 2 years ago, and would have noticed long before now.
Doesn't seem to be battery temperature, I've parked after a 25 mile drive at 55 degrees, and the next morning at 42 degrees, it will read 1% higher. Maybe some OTA update side effect?

 

[cal]

This is normal for my ev's. I see this happen every year. Summer 80% charge is between 250 and 265 miles. Winter it drops to 225 to 240. Same thing happens on my Teslas.

 

[chl]

The electricity for lead acid batteries is due to chemical reactions inside them - and those chemical reactions are affected by temperature.

Higher internal temperatures generally cause a lower terminal voltage.
Lower internal temperatures the opposite.

Also the internal chemical reactions in the battery are exothermic meaning they produce heat.
So a battery that has rested and cooled down will generally give a higher terminal voltage.

The same holds true for other battery types.

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