Overcharging to 101% Possible??

[Jferrari427]

I fully charged the Mach-E recently and noticed the display in car say it was at 101%. Is it possible to overcharge, or is this an error/bug?! I’ve never seen this before.

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[generaltso]

I fully charged the Mach-E recently and noticed the display in car say it was at 101%. Is it possible to overcharge, or is this an error/bug?! I’ve never seen this before.

Did you get a pic?

 

[dmastro]

It's possible, I believe this theorem proved it.

 

[A-A-Ron]

There are so many things going on with batteries and software, it’s hard to say unless you have access to Ford’s source code.

First of all, there is reserve capacity so 100% isn’t actually 100%. Then there are issues with battery capacity changing with temperature and load. Charging at one temp and measuring at another can give different results. There’s some inaccuracy and inconsistency in measuring battery levels based on output voltage. Extra complexity with multi-cell batteries. And all of it is rolled into software with its own rounding and calculation issues. And I have no idea how their code handles a higher reading than it thinks it should have for 100%.

So is it possible the car reads 101%? Probably. Do you actually have more than 100% charge - not really.

 

[OH2AZ2OH]

I believe it. I charge to 85%, and I regularly see it bump to 86% after I start driving. I haven't seen 101, but I only charge to 100% once every few months or so. My theory is that the battery voltage measurement -and therefore charge percentage - is affected by temperature, so what it reads while it is nice and warm from charging is different from what it reads later. Ford is leaving a fairly large buffer on the battery, so I don't think it is detrimental, other than the usual caveats about not storing the battery for long periods when highly charged/discharged.

 

[AZBill]

It is called “tolerance”, no sensors or voltage measurements are perfect. It is a non-issue. In fact 1% off is really good.

 

[AliRafiee]

I believe it. I charge to 85%, and I regularly see it bump to 86% after I start driving. I haven't seen 101, but I only charge to 100% once every few months or so. My theory is that the battery voltage measurement -and therefore charge percentage - is affected by temperature, so what it reads while it is nice and warm from charging is different from what it reads later. Ford is leaving a fairly large buffer on the battery, so I don't think it is detrimental, other than the usual caveats about not storing the battery for long periods when highly charged/discharged.

Totally normal if you’re going downhill and regen a bit right after charging.

 

[generaltso]

It may be normal for the battery percentage to creep up a percent, but to display over 100%? I’ve never seen that.

 

[KevinS]

I have never seen this myself, but wonder if maybe a temperature change after charging completed could make a 100% car read 101% with enough of a degree swing.

 

[SWO]

My wife said she saw it once. My recollection is that there was a large temp swing between charging to 100% and using the car.

 

[Mach-Lee]

Yeah it’s a temp swing effect.

 

[Larry Paul]

There are so many things going on with batteries and software, it’s hard to say unless you have access to Ford’s source code.

First of all, there is reserve capacity so 100% isn’t actually 100%. Then there are issues with battery capacity changing with temperature and load. Charging at one temp and measuring at another can give different results. There’s some inaccuracy and inconsistency in measuring battery levels based on output voltage. Extra complexity with multi-cell batteries. And all of it is rolled into software with its own rounding and calculation issues. And I have no idea how their code handles a higher reading than it thinks it should have for 100%.

So is it possible the car reads 101%? Probably. Do you actually have more than 100% charge - not really.

Does the firs part of your drive typically start by driving down hill?

 

[josephyancey]

I've never seen mine display over 100% but I've definitely started a trip at 100% and 10 miles later still been at 100%. By my math after 10 miles it should be at 97% or so. I'm not sure I trust the calculations at the far top end and the far bottom end. A percent or two off would make sense because battery chemistry and temperatures can change things. I'm sure a bit of top balancing comes into play as well. Remember, this isn't one large battery. It's thousands of small batteries that each have their own slightly different variances that come in with manufacturing tolerances. The exact percentage displayed is a bit of guess work that the car is doing based on pack voltages.

 

[GERChris]

I've never seen mine display over 100% but I've definitely started a trip at 100% and 10 miles later still been at 100%. By my math after 10 miles it should be at 97% or so. I'm not sure I trust the calculations at the far top end and the far bottom end. A percent or two off would make sense because battery chemistry and temperatures can change things. I'm sure a bit of top balancing comes into play as well. Remember, this isn't one large battery. It's thousands of small batteries that each have their own slightly different variances that come in with manufacturing tolerances. The exact percentage displayed is a bit of guess work that the car is doing based on pack voltages.

I have to say I'm quite amazed how accurate the 'range' is... Ford figured out the range quite well... in the first two weeks of ownership I kept look at the battery level ALL THE TIME!

by now I'm quite relaxed.... about range and battery level

 

[JeffGo]

I saw it once. Rounding error in the software.

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