Losing a few percentage after charging?

[DarkStang]

This has been happening on a fairly regular basis. I have a charge schedule set to a number like 85% overnight. I get a FordPass notification that it is charged to 85%, but when I go out and start the car it’s at like 84 or 83%. Anyone else experience this?

the car is still plugged in, so it shouldn’t be losing anything, even with remote start or departure preconditioning, right? Why would the battery be losing charge while plugged in over a short period of time?

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[mkhuffman]

Yes, I have noticed the same thing recently. I didn't notice it before, but it might be normal.

My guess is the battery temperature is warmer from when the charge completed, which would mean the max SoCD is lower relative to total battery capacity. That's my guess but it doesn't seem to make sense considering the car sits overnight and really the battery temp should be lower in the morning, not higher. But it is the only thing that makes sense to me.

I bet @Mach-Lee has a theory.

 

[Logal727]

Yes, I have noticed the same thing recently. I didn't notice it before, but it might be normal.

My guess is the battery temperature is warmer from when the charge completed, which would mean the max SoCD is lower relative to total battery capacity. That's my guess but it doesn't seem to make sense considering the car sits overnight and really the battery temp should be lower in the morning, not higher. But it is the only thing that makes sense to me.

I bet @Mach-Lee has a theory.

The battery can reach target charge at 84.9% and it rounds up so any slight change will make it say 84 percent, it’s normal, it’s just how it’s being displayed after very very small temperature changes

 

[DarkStang]

Thanks. That makes sense. I have recently started to delay my charging to like 4am since I usually only need about 10% to get to my target. Thinking was that if I delay to charge till early morning, the charging will warm up the battery and not need as much preconditioning.

But what doesn’t make sense is that if the battery cooled off and now the percentage is a tad lower, seems like the charger should recognize that and top it off since I’m still well within my charging time window.

 

[hawkeye3point1]

Why would the battery be losing charge while plugged in over a short period of time?

Yes, I have noticed the same thing recently. I didn't notice it before, but it might be normal.

Have your cars received the GOM OTA?

I track my GOM closely and have never seem SOC% change from PM to AM, even if EV range has decreased as much as 15-20 mi..

Wondering out loud if this is a new post 3.6.2 normal. There are recent observations in the "Winter Range" thread where SOC% goes down, but range goes up after a short drive, that I also find surprising.

 

[MellowJohnny]

Happens to me occasionally as well, I’m still on 3.5.4, so I’ll keep an eye out when the update finally comes. I also assumed it was related to the HVB temp delta between the time charging finished (usually that’s early am for me) and the time I drive, which could be 5+ hours later

 

[AKgrampy]

Have your cars received the GOM OTA?

I track my GOM closely and have never seem SOC% change from PM to AM, even if EV range has decreased as much as 15-20 mi..

Wondering out loud if this is a new post 3.6.2 normal. There are recent observations in the "Winter Range" thread where SOC% goes down, but range goes up after a short drive, that I also find surprising.

I have seen both range and SOC rise 3 - 4% during my initial morning drive from heated garage in right around 0F temps.

 

[hawkeye3point1]

I have seen both range and SOC rise 3 - 4% during my initial morning drive from heated garage in right around 0F temps.

Do you have 3.6.2?

If yes, the Intelligent Range beta resulted in significant cold weather algorithm changes or HVB thermal management while driving. Hopefully for the better.

BTW, your post in the Winter Range thread was one I was referring to.

 

[Mach-Lee]

Thanks. That makes sense. I have recently started to delay my charging to like 4am since I usually only need about 10% to get to my target. Thinking was that if I delay to charge till early morning, the charging will warm up the battery and not need as much preconditioning.

But what doesn’t make sense is that if the battery cooled off and now the percentage is a tad lower, seems like the charger should recognize that and top it off since I’m still well within my charging time window.

Yes, differences are likely due to temp changes or possibly balancing. If you use remote start on 120V charging that will also drop the battery a % or two. Either way I wouldn’t worry about it and just charge daily, delaying charging is a good strategy so it’s still warm.

Once the charge finishes the car will go to sleep. The BECM will not wake the car up to charge the battery if the SoC dips, it won’t look until the next time the car is turned on. It’s just not necessary for the car to worry about a couple % difference in charge since that’s within the margin of error for the BMS. Remember the % is just a guess.

 

[JSW]

Routinely happens to me while attached to a charging station. Interestingly, I do not lose charge% when I’m not plugged into a charging station.

 

[phil]

Never noticed this happening. But I do sometimes get an extra percent showing - I regularly charge to 90%, the car always reports successfully charging to that level, and maybe 1 of every five charges, FordPass and the car will show 91%.

I figure it's not really gaining or losing any charge after completion, it's just that the measurements are slightly imprecise. I don't imagine it's worth worrying about.

 

[mkhuffman]

Have your cars received the GOM OTA?

I track my GOM closely and have never seem SOC% change from PM to AM, even if EV range has decreased as much as 15-20 mi..

Wondering out loud if this is a new post 3.6.2 normal. There are recent observations in the "Winter Range" thread where SOC% goes down, but range goes up after a short drive, that I also find surprising.

No, I don't have 3.6.2 yet.

 

[timbop]

As mentioned, it is a function of the car determining the warm battery is "at 85%". The 85% mark is determined by attempting to make precise electrical measurements - the battery has exactly the same number of electrons in it whether empty or full. What changes is the "electrical potential" of the battery, and measuring that is never going to be exact. As the battery cools off, the characteristics change and it computes that the battery has less electrical potential than it did when it was warmer. I suspect that the software doesn't want to constantly be cycling the charging, so if it is close to the target charge it won't bother adding more because if it warms up again then it would be over the target level.

Don't worry about it

 

[phil]

the battery has exactly the same number of electrons in it whether empty or full.

Approximately, not exactly. The exact number of electrons in the battery changes from moment to moment. As does the exact number of protons...

 

[timbop]

Approximately, not exactly. The exact number of electrons in the battery changes from moment to moment. As does the exact number of protons...

Thank you for being unnecessarily pedantic. The operative point is correct.

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