What's the truth about charging to 100%?

[Sinclair63]

I have a 2023 GTPE and charge to 100% two to three times a week. I use 90% of that energy everytime commuting to and from work on the interstate. I use a level 2 Juice box and don't give a rats ass about a little battery degradation. The car is a tool to get me to work. I've put 27k miles on the car in two years and have seen a small reduction in battery capacity. The cold weather is much more of a factor.
Don't worry about total capacity, drive your car, enjoy the acceleration when needed. In a few years technology will improve and this issue won't be a factor anymore.

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[Oldlawman]

I hear dire warnings about charging to 100%. They say the batteries will lose range if that's done. I'm not sure it's the real story.

Why do I say that? In the nearly 4 years I've owned my MME I've charged it to 100% at least once per week, sometimes more often. Over 200 times in total. The times that I didn't charge to 100% I charged it to 90%. Yet I haven't seen a lick of range reduction. Not even the expected wear-and-tear range reduction. In fact, the range is exactly the same now as its always been. Well, there was that bump in range that Ford gave us a couple of years ago. But when I charge it to 100% I've seen no side effects or reduction in range.

I believe the warnings were for people that do DC fast charging, something I've only done a couple of times in 4 years.

I'd say don't worry about charging to 100% if you're only using a level 2 charger based upon my experience. I'd like to hear others' experiences who have owned an MME more than 3 years.

I leave my MME plugged in to my Level 2 home charger permanently when not driving set to 90% and 100% occasionally when needed for ether a longer journey or exceptionally cold weather when I turn on the heater etc.

 

[spirilis]

I've no doubt the big batteries on these cars help, but let me tell you my story.

Two Ford electrified vehicles: 2017 Ford Focus Electric, 2017 Ford C-Max Energi.

Focus Electric had a 33.5kWh battery (28 usable per OBD2) and the C-Max had a 7.6kWh plug-in-hybrid battery. Focus liquid-cooled with A/C chiller involved and C-Max air cooled.

Both use Lithium NMC chemistry (like the Mach-E Extended battery and pre-2023.5 standard) albeit the construction has probably improved a lot since 2017.

Both vehicles' batteries were crap by 100K miles. Both were charged to 100% every time I took it home; they did not have a feature to limit the charge %, Ford clearly learned from that since.

The Focus range dropped from 120 miles range to 90 or so after a few years and in the last 18 months it dropped to 50 and then 36 miles on a full charge. Examining the cell voltage report using FORScan (I noticed the Mach-E doesn't have that available in forscan btw) showed most cells were well balanced, but cell#25 would drop in voltage much faster than the rest and 6 months before it died it started throwing wrench/check engine codes. This one cell seems to be the limiting factor. If I plugged in the car it would seem to gain a LOT more range than you'd expect; I think this was the rebalancing effect, the other cells offering some juice to the impaired cell. Eventually it had a bad contactor, I replaced it myself but took like 3 months to complete that repair and cell#25 dropped to 0V, bricking the whole car. (That was a massive disappointment)

C-Max similar story. 21 miles Electric range when new, it was down to 6 miles before I got rid of it last month. Cell#48 was the bad apple here, throwing P0B25 (Hybrid/Electric Battery 'A' Voltage Instability) when it dipped more than 0.5V below the average cell voltage for 15 seconds. Ford was not very helpful and since the car had just passed 100K, they wanted me to spend $2500 to replace BECM and TCU (??why) before continuing so I said NO and got the Mach-E. (Strong question in my head why I stuck with Ford here, but bigger battery and LFP chemistry should alleviate my concerns)

In any case, between this past experience (come on who junks their car at 100K miles!?!?!?) and reading more about LFP and NCM chemistry I run my LFP between 50% and 90% almost all the time, charging to 100% every other week, and I hope to get more than 200K miles out of this one.

There is a small lesson here most people might not understand- Degradation is not a linear thing. 5% maybe no big deal, but by the time you've lost 30% chances are it's 1 REALLY sick cell that is well on its way to bricking the whole huge battery pack. The BMS cannot allow 1 cell to discharge past the point of no return or else it can catch fire when it recharges. If that one cell can be swapped then the whole system is more valuable IMO. Not sure that is the case for the Mach-E, the whole skateboard battery has to be dropped either way.

 

[spirilis]

Note that with my Focus I was ABC - Always Be Charging - because the car would not run its A/C when parked to chill the battery in hot weather. High temp can degrade the battery but my experience here has demonstrated that keeping the battery cool isn't enough; High % charge may in fact be more damaging to the cells' longevity.

 

[NJ Steve]

I hear dire warnings about charging to 100%. They say the batteries will lose range if that's done. I'm not sure it's the real story.

Why do I say that? In the nearly 4 years I've owned my MME I've charged it to 100% at least once per week, sometimes more often. Over 200 times in total. The times that I didn't charge to 100% I charged it to 90%. Yet I haven't seen a lick of range reduction. Not even the expected wear-and-tear range reduction. In fact, the range is exactly the same now as its always been. Well, there was that bump in range that Ford gave us a couple of years ago. But when I charge it to 100% I've seen no side effects or reduction in range.

I believe the warnings were for people that do DC fast charging, something I've only done a couple of times in 4 years.

I'd say don't worry about charging to 100% if you're only using a level 2 charger based upon my experience. I'd like to hear others' experiences who have owned an MME more than 3 years.

I charge at home on a 220 v/50 amp line and always to 100%. In 3 years I've never seen a range decrease.

 

[Mach1E]

I charge at home on a 220 v/50 amp line and always to 100%. In 3 years I've never seen a range decrease.

To be fair, how would you notice a couple percent degradation?

The GOM changes up to 50% with weather and driving habits. Hard to tell what did what without scanning for state of health of the battery.

And even scanning state of health it’s just 1 data point. Who knows what would be your SOH if you charged differently?

 

[mccdeuce]

DCFC to 100% only if you can’t make it to another DCFC at 90%. Time! 90-100% is 15kW vs 70-80% at 75kW.

AC to 100% whenever you need it (for us every 2 weeks for a med distant trip) energy usage to go from 90-100 is more than from 70-80, so if you do not need the extra why pay for it? (Although my measurements have shown it’s not a huge difference but it’s still $)

 

[4sallypat]

I've no doubt the big batteries on these cars help, but let me tell you my story.

Two Ford electrified vehicles: 2017 Ford Focus Electric, 2017 Ford C-Max Energi.

Focus Electric had a 33.5kWh battery (28 usable per OBD2) and the C-Max had a 7.6kWh plug-in-hybrid battery. Focus liquid-cooled with A/C chiller involved and C-Max air cooled.

Both use Lithium NMC chemistry (like the Mach-E Extended battery and pre-2023.5 standard) albeit the construction has probably improved a lot since 2017.

Both vehicles' batteries were crap by 100K miles. Both were charged to 100% every time I took it home; they did not have a feature to limit the charge %, Ford clearly learned from that since.

The Focus range dropped from 120 miles range to 90 or so after a few years and in the last 18 months it dropped to 50 and then 36 miles on a full charge. Examining the cell voltage report using FORScan (I noticed the Mach-E doesn't have that available in forscan btw) showed most cells were well balanced, but cell#25 would drop in voltage much faster than the rest and 6 months before it died it started throwing wrench/check engine codes. This one cell seems to be the limiting factor. If I plugged in the car it would seem to gain a LOT more range than you'd expect; I think this was the rebalancing effect, the other cells offering some juice to the impaired cell. Eventually it had a bad contactor, I replaced it myself but took like 3 months to complete that repair and cell#25 dropped to 0V, bricking the whole car. (That was a massive disappointment)

C-Max similar story. 21 miles Electric range when new, it was down to 6 miles before I got rid of it last month. Cell#48 was the bad apple here, throwing P0B25 (Hybrid/Electric Battery 'A' Voltage Instability) when it dipped more than 0.5V below the average cell voltage for 15 seconds. Ford was not very helpful and since the car had just passed 100K, they wanted me to spend $2500 to replace BECM and TCU (??why) before continuing so I said NO and got the Mach-E. (Strong question in my head why I stuck with Ford here, but bigger battery and LFP chemistry should alleviate my concerns)

In any case, between this past experience (come on who junks their car at 100K miles!?!?!?) and reading more about LFP and NCM chemistry I run my LFP between 50% and 90% almost all the time, charging to 100% every other week, and I hope to get more than 200K miles out of this one.

There is a small lesson here most people might not understand- Degradation is not a linear thing. 5% maybe no big deal, but by the time you've lost 30% chances are it's 1 REALLY sick cell that is well on its way to bricking the whole huge battery pack. The BMS cannot allow 1 cell to discharge past the point of no return or else it can catch fire when it recharges. If that one cell can be swapped then the whole system is more valuable IMO. Not sure that is the case for the Mach-E, the whole skateboard battery has to be dropped either way.

I have a PHEV (Honda) and charge it to 100% every day for the past 7 years.

EV driving about 90% of the time.
Very little fuel used in a year.

Range reduction after 7 years is about 15% loss.

Plus tire change to RFT adds another 10%.

Not too shabby for a 7 year old PHEV....

 

[evfinder]

I used to charge my Prius Plug-in to 100% on a regular basis and over the 10 years I owned the car I estimate that battery capacity dropped about 10%. For the Mach-e, I typically charge it to between 80% and 90% once per week. I don't drive that much so it is usually at between 60 - 70% when I charge the car. Once it a while, when I need to drive it for longer distances, I will charge it to 100%. It usually gets charged at 110V. Over the two and a half years I have owned the car it has been DC fast charged just 5 times.

 

[ChehRob]

Many of us want to have the car in good shape when we replace it - if we know it is good there is usually a relative or friend who will want it.

 

[RickMachE]

I charge at home on a 220 v/50 amp line and always to 100%. In 3 years I've never seen a range decrease.

A range decrease is not a measure of battery health.

 

[RickMachE]

47 people respond with 63 different strategies. 2 out of 63 say "follow manufacturer guidelines"... ?

Ah, the value of social media...

 

[Bilyjck]

My newer Samsung tablet is factory set to stop charging at 80 percent.

 

[astrorob]

I used to charge my Prius Plug-in to 100% on a regular basis and over the 10 years I owned the car I estimate that battery capacity dropped about 10%. For the Mach-e, I typically charge it to between 80% and 90% once per week. I don't drive that much so it is usually at between 60 - 70% when I charge the car. Once it a while, when I need to drive it for longer distances, I will charge it to 100%. It usually gets charged at 110V. Over the two and a half years I have owned the car it has been DC fast charged just 5 times.

dunno which generation you are talking about but the original PiP has a huge guard band, i think overall like 40% of battery capacity is invisible to the user. i think this in part is to avoid customer complaints and also to preserve the battery. i think these are also NiMH batteries which are quite different from the lithium batteries in newer cars.

 

[Snakebitten]

I've no doubt the big batteries on these cars help, but let me tell you my story.

Two Ford electrified vehicles: 2017 Ford Focus Electric, 2017 Ford C-Max Energi.

Focus Electric had a 33.5kWh battery (28 usable per OBD2) and the C-Max had a 7.6kWh plug-in-hybrid battery. Focus liquid-cooled with A/C chiller involved and C-Max air cooled.

Both use Lithium NMC chemistry (like the Mach-E Extended battery and pre-2023.5 standard) albeit the construction has probably improved a lot since 2017.

Both vehicles' batteries were crap by 100K miles. Both were charged to 100% every time I took it home; they did not have a feature to limit the charge %, Ford clearly learned from that since.

The Focus range dropped from 120 miles range to 90 or so after a few years and in the last 18 months it dropped to 50 and then 36 miles on a full charge. Examining the cell voltage report using FORScan (I noticed the Mach-E doesn't have that available in forscan btw) showed most cells were well balanced, but cell#25 would drop in voltage much faster than the rest and 6 months before it died it started throwing wrench/check engine codes. This one cell seems to be the limiting factor. If I plugged in the car it would seem to gain a LOT more range than you'd expect; I think this was the rebalancing effect, the other cells offering some juice to the impaired cell. Eventually it had a bad contactor, I replaced it myself but took like 3 months to complete that repair and cell#25 dropped to 0V, bricking the whole car. (That was a massive disappointment)

C-Max similar story. 21 miles Electric range when new, it was down to 6 miles before I got rid of it last month. Cell#48 was the bad apple here, throwing P0B25 (Hybrid/Electric Battery 'A' Voltage Instability) when it dipped more than 0.5V below the average cell voltage for 15 seconds. Ford was not very helpful and since the car had just passed 100K, they wanted me to spend $2500 to replace BECM and TCU (??why) before continuing so I said NO and got the Mach-E. (Strong question in my head why I stuck with Ford here, but bigger battery and LFP chemistry should alleviate my concerns)

In any case, between this past experience (come on who junks their car at 100K miles!?!?!?) and reading more about LFP and NCM chemistry I run my LFP between 50% and 90% almost all the time, charging to 100% every other week, and I hope to get more than 200K miles out of this one.

There is a small lesson here most people might not understand- Degradation is not a linear thing. 5% maybe no big deal, but by the time you've lost 30% chances are it's 1 REALLY sick cell that is well on its way to bricking the whole huge battery pack. The BMS cannot allow 1 cell to discharge past the point of no return or else it can catch fire when it recharges. If that one cell can be swapped then the whole system is more valuable IMO. Not sure that is the case for the Mach-E, the whole skateboard battery has to be dropped either way.

This is why I am far more concerned with the health of the weakest cell, than I am with the natural degradation due to age or charging.

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