Electrify America charge rate for --- is up to 20 miles per minute

[eastern refugee]

Ummm I am a novice. I am BEV enthusiast but have never owned one until the Mach E. You all sound like engineers which is impressive. I know the basic math but you all getting extremely technical. Can one of you please explain in simple English this means. I admit I LOVE to learn but I am basically in elemtsry school trying to comprehend a thread of professors speaking. HELP.

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[dbsb3233]

Ummm I am a novice. I am BEV enthusiast but have never owned one until the Mach E. You all sound like engineers which is impressive. I know the basic math but you all getting extremely technical. Can one of you please explain in simple English this means. I admit I LOVE to learn but I am basically in elemtsry school trying to comprehend a thread of professors speaking. HELP.

Charging curve talk can get rather geeky. And deeper into the weeds than most people really need to worry about.

Batteries usually do not charge at an even rate. While it's more complicated than this, you can think of it as "pouring electrons back into the battery". As a general rule, the more "empty" the battery is, the faster the battery will accept electrons, and vise versa (has to do with the chemical aspects of how batteries actually store energy).

The rate at which electrons are moved is measured in kilowatts (kW). A 150 kW charger can move electrons 3x faster than a 50 kW charger, for example. But that's only the rate at which the charger can DELIVER electrons. The rate at which the battery can ACCEPT electrons is determined by how full the battery already is, and further controlled by the car's computer (battery management system, or BMS). Manufacturers fine tune the BMS to try and protect the battery and keep it from degrading too fast, as can happen if you try to pour in too many electrons too fast. The rate at which a car's BMS allows it to charge at each point of "fullness" (state of charge, or SOC) is referred to as the CHARGING CURVE. Here's a sample charging curve graph for a Tesla Model 3:

The Mach-e's charging curve will probably be similar to this profile. The Tesla accepts up to a 250 kW charge rate but the Mach-e will only go up to 150 (on the ER model, or 115 on the SR). It'll probably only accept the max rate for something like the first 20-25% of the SOC curve (i.e. when the battery is mostly empty). But that's only a guesstimate at this point. After buyers get their hands on them, some will track it and graph the charging rate. You see the data points on the car's screen. When the car is nearly empty, we'll probably see it filling at almost 150 kW. But when it gets to maybe 30% or 40% full, it'll start slowing down. How much we're not sure. That's what everyone is curious to find out.

 

[dbsb3233]

So from a driver standpoint, why does that all matter? Well, it determines how long you'll be sitting at that EA charger. If you want to spend less time sitting at those EA chargers, then you want to charge mostly in the lower end of the curve where it charges faster. In other words, do most of your driving when the battery is less than half full. Also, since EA prices by the minute in most states rather than by the kWh, charging faster will save you money at the pump.

Remember though that this really only matters when you're fast charging (L3), like at an EA charger. If you're plugging into a 240v (L2) outlet at home overnight, the charging curve is pretty irrelevant because you're likely charging for more than enough time to fill the vehicle anyway. No one really cares that it starts slowing down at 2am, as long as it's full by 8am.

 

[dbsb3233]

Here's a sample video you can use to see what it really looks like in the vehicle. This one happens to be a Kona. It appears to max out at ~70 kW charging rate. Looks like the Kona stays at the max charge rate for the first 57% of the battery before it starts to taper off. You can see it drop from 71 kW to 56 kW when it reaches the 57% full point.

It drops again when 72% full, and again at 77% full. And so on. It's why people often talk of filling the vehicle no more than to maybe the 80% mark on road trips (using retail L3 chargers), because trying to squeeze in that last 20% can take as long as the first 80%. (And cost a lot more when being charged at a per-minute rate.)

 

[eastern refugee]

THSNK YOU ALL!!!! So now I understand it far better. I thought the charging to say 80% was strictly to protect the battery from degradation. Sure it does that but for me it says also that when I stop and fill up to 80% I will be there a much shorter time then say topping of the tank like I do with an ICE car. Is this right?

also I am getting the drift from all of you that we are hoping ford can solve the fast charging aspect to make is fill like at home charging where it acts more like going to the gas station and getting a steady stream of gas.

 

[dbsb3233]

THSNK YOU ALL!!!! So now I understand it far better. I thought the charging to say 80% was strictly to protect the battery from degradation. Sure it does that but for me it says also that when I stop and fill up to 80% I will be there a much shorter time then say topping of the tank like I do with an ICE car. Is this right?

Correct. Even without knowing the precise Mach-e charging curve yet, it's a sure bet that the far right end of the curve will charge far slower. And not just the last 20%. It'll probably start slowing much sooner than the 80% mark. I'm guessing it'll look fairly similar to the Model 3 curve above, based on the clues we already have.

Some BMS's produce a gradual decline (like the Model 3 above), while some ratchet down in plateaus (like the Kona video). No idea yet which the Mach-e will be. That really only matters if you want to stop charging at a specific taper point. And even then, it's kinda nitpicky.

If you really want to minimize time (and expense) when using EA chargers, you just live (roughly) in that 10-40% range. But that's also risky, and annoying. It's really hard to envision only charging when you get down to 10% and only filling up to maybe 40%. That requires recharging every 80 miles or so, and doesn't leave much safety buffer. So I doubt many people really do that. (Again, this only applies to public chargers; if charging at home, you just plug in and let it run all night.)

 

[dbsb3233]

also I am getting the drift from all of you that we are hoping ford can solve the fast charging aspect to make is fill like at home charging where it acts more like going to the gas station and getting a steady stream of gas.

That's more than just Ford. That's the nature of battery technology in general. With current battery technology, there's always going to be a curve, and degradation issues, etc.

But some manufacturers get closer than others. Like the Audi with the eTron. They probably have the most impressive charge curve, maintaining max charge rate up to about the 78% mark. That would be wonderful, and maybe Ford can get closer to that with fine tuning. I'm not sure how Audi achieves that (safely). I think part of it may be heat management. More and faster charging means more heat generated. They may have better (and surely more expensive) heat management built into the battery pack (probably part of why the eTron costs more). The Ford guy I quoted earlier suggested that was a compromise on the Mach-e to keep the price more affordable.

 

[dbsb3233]

That would be great, but I'm highly doubtful. The quote I posted earlier from the Ford guy said "briefly" (at 150 kW). Suggesting it'll be more like the Model 3 curve above.

Also, the "10-80% (ER) in 45 minutes" Ford advertises. If the Mach-e maintained 150 kW for nearly all of that 70% window like the e-Tron does, it would only take roughly 25 minutes, not 45 minutes. Either that 45 minute stat is way wrong (unlikely), or the taper starts way sooner than the e-Tron (likely).

Hopefully they can get it somewhere in between though with further tuning (35 minutes?).

 

[eastern refugee]

I found this. Can you guys interpret what this is saying.

https://fordauthority.com/2020/03/o...rts-supplier-has-worked-with-ford-since-1922/

 

[dbsb3233]

I found this. Can you guys interpret what this is saying.

https://fordauthority.com/2020/03/o...rts-supplier-has-worked-with-ford-since-1922/

In regards to the batteries, you mean? EV batteries are quite high powered. Charging and discharging batteries produces heat -- a lot of heat when dealing with high power. Heat can be both dangerous, and degrade the batteries. So EV battery packs incorporate cooling systems controlled by a thermal management system. Usually by pumping a fluid around and through the battery pack. Thus the company referenced in your link.

Here's a brief video of the process...

 

[eastern refugee]

In regards to the batteries, you mean? EV batteries are quite high powered. Charging and discharging batteries produces heat -- a lot of heat when dealing with high power. Heat can be both dangerous, and degrade the batteries. So EV battery packs incorporate cooling systems controlled by a thermal management system. Usually by pumping a fluid around and through the battery pack. Thus the company referenced in your link.

Here's a brief video of the process...

thanks!!!! Fascinating.Only $2B to EAand $9B to technology. Ford must be doing the same. Sounds like these two will be working somewhat together. As such it is VERY possible if Audi is the top dog in battery charging so will Ford.

 

[Billyk24]

Excessive use of L3 is likely going to cause additional degradation when compared to L2 charging with occasional L3 usage. Some owners on TMC have reported Tesla has throttled back their charging capabilities for this.

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