Battery Charge and mileage.

rplinpa

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This is my first electric car, so please excuse my ignorance on this issue. I am getting the AWD FE, which has a range of 270 miles. I keep reading from most people that the car should only be charged to 80%. Does that mean the actual range is 216 miles? (80% of 270).

I have read from one person that charging to 90% or 100% on the car will not be a problem. I'm kind of confused by why the majority of people are saying 80% then. Insight anyone?





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macchiaz-o

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I plan to charge to 100% unless the owner's manual suggests otherwise. Ford's told us they've walled off a fairly large percentage of the rated capacity, so I suspect charging to 100% isn't any big deal.
 

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This is my first electric car, so please excuse my ignorance on this issue. I am getting the AWD FE, which has a range of 270 miles. I keep reading from most people that the car should only be charged to 80%. Does that mean the actual range is 216 miles? (80% of 270).

I have read from one person that charging to 90% or 100% on the car will not be a problem. I'm kind of confused by why the majority of people are saying 80% then. Insight anyone?
Check out this thread below it’s been discussed quite a bit. Basically, Lithium Ion batteries like to be around 50% charge. Any higher or lower puts stress on them. People are saying to only daily charge for the range you need for the day up to about 80%, that should not put too much stress on the battery. High or low states of charge can degrade the battery faster.

https://www.macheforum.com/site/threads/best-practice-for-battery-preservation.549/

https://www.macheforum.com/site/threads/best-practice-for-battery-preservation.549/post-9925
 

JCHLi

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From the little I know about Lithium batteries and the current battery management systems in use, you should have no concern about fully charging your MME.

At the same time there is no need to try to keep it at 100% all the time. If you drive short distances every day, let the charge drift down a bit before "topping off".

The battery management system does a little of this for you if you let it know your driving patterns. Before a long trip, let it fully charge, otherwise, no need.
 

MattG

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That’s true for most EVs, but Ford has already walled off around that %...the rated mileage should be based on the usable capacity, and we should be able to truly use ALL of that rated capacity.
 

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From the studies I've seen online (takes a little googling), the most stress on Li-ion batteries is when the charge is below 20% and above 80%; in between the "stress curve" is flat, although for long term storage you're supposed to keep it at around 50%. Like most BEV manufacturers, Ford keeps a "reserve" in the battery to prevent you from truly draining it to 0 or going all the way to 100%. In the MME case the reserve is about 10%. That is, when the car reports 0% there is probably 5% actually left, and when the car reports 100% it is probably more like 95% charged.

As mentioned, often the recommended practice is to stress your battery as little as possible to keep it healthy, so on a regular basis you shouldn't charge over 80% or drain it below 20%. However, for occasional long trips when you want the most range charging to 100% and draining down to 10% is OK. You could drain it below 10% on those occasions, but just like you don't want an ICE car to run out of gas and leave you stranded on the road, you don't want your BEV to run out of juice and leave you stranded either.
 

Ciero

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I'm sure these batteries and the controllers around them are more advanced than what I use in RC cars, but if you store the lithium batteries at full for too long they have a much higher tendency to swell, and it's clearly visible in the packs when this happens. It is usually time to toss them when this happens so they don't start a fire. I've also had some drain too low and sometimes you can't get them back up to their previous performance levels after that. Some of these chargers have a storage setting that puts them around 50-70% of the battery capacity.
 

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I'm sure these batteries and the controllers around them are more advanced than what I use in RC cars, but if you store the lithium batteries at full for too long they have a much higher tendency to swell, and it's clearly visible in the packs when this happens. It is usually time to toss them when this happens so they don't start a fire. I've also had some drain too low and sometimes you can't get them back up to their previous performance levels after that. Some of these chargers have a storage setting that puts them around 50-70% of the battery capacity.
EV batteries aren't nearly as abused as RC batteries (or cellphone batteries for that matter, not saying you do it but in general).

In addition there is a buffer to the Mach-E's battery: 100% full isn't 100% full.

On top of that its a different chemistry as well.
 
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rplinpa

rplinpa

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EV batteries aren't nearly as abused as RC batteries (or cellphone batteries for that matter, not saying you do it but in general).

In addition there is a buffer to the Mach-E's battery: 100% full isn't 100% full.

On top of that its a different chemistry as well.

There seems to be a LOT of conflicting information on this out there. No wonder I am confused. I sure hope that the "100% full isn't 100% full" is correct. Otherwise, they are selling a bill of goods that is not really factual. The 4th of the seminars is about the battery and charging, so I'm going to be ready for that webinar for sure.
 

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Otherwise, they are selling a bill of goods that is not really factual.
I understand the sentiment, but that is NOT the case at all. Firstly, I doubt you have ever driven an ICE car down to an empty tank where it couldn't go anymore - does that mean the manufacturer lied about the range of a tank of gas? No.

The batteries have a given number of cells that specify an absolute MAX capacity: either 99kwh on the extended range, or 75.7 kwh on the standard range. Unlike some manufacturers they also list the USABLE capacity, which is 88kwh (ER) or 68kwh (SR). With that usable 88kwh, the ER is projected to have 300 miles of range in the EPA driving model, which uses a combination of speeds and behaviors to get an "average" use case. Just like with an ICE, when you use every last drop of available electricity (88kwh), the car would come to a stop. To prevent permanent damage, the battery will actually have a little charge left, but Ford "hides" it from you to protect the battery. SO, the 88kwh usable power of the ER battery would get you 300 miles IF the current prediction models are correct - I say that because the numbers are targets and not confirmed yet by the EPA. All indications are that Ford's estimate are a little low, so when the EPA numbers are published things should be a little better.

That range also applies to a particular driving pattern, and will not apply to every situation - drive slower and it will go farther, drive faster and it won't go as far. In my ICE mustang if I drive 65 on the highway, I get 29 MPG. If I go up to 75 MPH, my mileage goes down to 25 MPG - a 13% drop. When I drive in the winter the mileage goes down by roughly another mile or 2 per gallon (5% - 10%). With a BEV, the cold weather and higher speeds affect the "fuel efficiency" more than an ICE, but ICE cars are not immune to the effect. How much they are affected is somewhat car-dependent, but a fair average is that cold weather gives a 20% to 25% hit and higher speed driving a 10%-15% decrease.

It is also an attribute of the battery chemistry that constantly draining too low or charging too high will start to damage the battery, decreasing the amount of charge that they can hold. Therefore one should only go 100% down to almost 0% infrequently. If that is unacceptable to you, then you should not buy any BEV - they all have the same issue to some degree or another. But the amount of the usable capacity you can safely exercise on a daily basis without damaging the battery depends on the amount of reserve/buffer the manufacturer sets.
 
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rplinpa

rplinpa

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I understand the sentiment, but that is NOT the case at all. Firstly, I doubt you have ever driven an ICE car down to an empty tank where it couldn't go anymore - does that mean the manufacturer lied about the range of a tank of gas? No.

The batteries have a given number of cells that specify an absolute MAX capacity: either 99kwh on the extended range, or 75.7 kwh on the standard range. Unlike some manufacturers they also list the USABLE capacity, which is 88kwh (ER) or 68kwh (SR). With that usable 88kwh, the ER is projected to have 300 miles of range in the EPA driving model, which uses a combination of speeds and behaviors to get an "average" use case. Just like with an ICE, when you use every last drop of available electricity (88kwh), the car would come to a stop. To prevent permanent damage, the battery will actually have a little charge left, but Ford "hides" it from you to protect the battery. SO, the 88kwh usable power of the ER battery would get you 300 miles IF the current prediction models are correct - I say that because the numbers are targets and not confirmed yet by the EPA. All indications are that Ford's estimate are a little low, so when the EPA numbers are published things should be a little better.

That range also applies to a particular driving pattern, and will not apply to every situation - drive slower and it will go farther, drive faster and it won't go as far. In my ICE mustang if I drive 65 on the highway, I get 29 MPG. If I go up to 75 MPH, my mileage goes down to 25 MPG - a 13% drop. When I drive in the winter the mileage goes down by roughly another mile or 2 per gallon (5% - 10%). With a BEV, the cold weather and higher speeds affect the "fuel efficiency" more than an ICE, but ICE cars are not immune to the effect. How much they are affected is somewhat car-dependent, but a fair average is that cold weather gives a 20% to 25% hit and higher speed driving a 10%-15% decrease.

It is also an attribute of the battery chemistry that constantly draining too low or charging too high will start to damage the battery, decreasing the amount of charge that they can hold. Therefore one should only go 100% down to almost 0% infrequently. If that is unacceptable to you, then you should not buy any BEV - they all have the same issue to some degree or another. But the amount of the usable capacity you can safely exercise on a daily basis without damaging the battery depends on the amount of reserve/buffer the manufacturer sets.

Thanks. I appreciate the tutorial. My concern was that if we are not to charge past 80% without hurting the battery and the 270 miles per charge is based on 100%, then in truth 270 doesn't even exist if by doing so you will harm the car.
 

JCHLi

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Thanks. I appreciate the tutorial. My concern was that if we are not to charge past 80% without hurting the battery and the 270 miles per charge is based on 100%, then in truth 270 doesn't even exist if by doing so you will harm the car.
It won't hurt your car/battery any worse than normal wear and tear on any other type of car. Certain practices may reduce wear and tear, but by no means will you have to keep your battery only partially charged at all times.
 

hiimisaac

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Thanks. I appreciate the tutorial. My concern was that if we are not to charge past 80% without hurting the battery and the 270 miles per charge is based on 100%, then in truth 270 doesn't even exist if by doing so you will harm the car.
So, yes. On the surface you're correct. 270 miles is the best-case-scenario and is from a 100%-0% charge-to-discharge cycle. However, the idea of running out of charge is mitigated by the fact that 1) you plug in every night (if applicable); or 2) you visit a DCFC and charge for a bit like you would a gas station.

For the few times you'll need to use the 270 miles, you CAN charge to 100. Lithium-ion batteries are rated in charge cycles, with one cycle being from 0%-100%. And most lithium-ion batteries are rated for a certain number of cycles. According to the chart on this page (note: I have no idea how accurate this article is): https://cleantechnica.com/2018/08/26/the-secret-life-of-an-ev-battery/ it says that if you charge from 65%-75% every night, you'll net around 12,000 cycles.

Long story short, however, is that the cars on the road (even early Bolts) have a battery that really isn't effected too much by any degradation (which is natural). So, just charge your car for your needs and drive. That's all. Let the BMS take care of the rest, and if your battery is truly underperforming or has any defects, it'll be replaced under warranty.
 

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Theres already a lot of study on this on Tesla's. The degradation definitely grows exponentially after 80% but honestly 90% looks fine. If you look at the studies, people charging to 90% will lose about <10% at 300k miles.

Tesla's also have a much smaller buffer. I would just follow what Ford recommends. I know VW, Volvo, Polestar is recommending 80%, Tesla recommends 90%, while Bolt, Hyundai, and Kia doesn't say anything so 100% is assumed.
 

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