Linearity in Range vs Battery SoC%?

[daemonic3]

I'm only about a week into researching, in the interest of making our next vehicle, fully electric. I currently have a F150 Powerboost and love it, but FULL EV is a wholly different animal!

There is so much information to absorb and answers are not always consistent and information scattered, so I'm going to ask this community with REAL experience directly. The Mach E would primarily be my wife's replacement car, so Level2 home charging (between say 25-75% limits) covers everything, plus our electric company gives overnight EV rate of 8.5c/kWh which is outstanding. Done deal, any Mach E will do.

Now for my concern and anxiety! If I have to commute once per week for a few days at a time to the bay area again (132 miles each way), it would only make sense for the Mach E to be my commute car (>90 eMPG hwy) versus my Powerboost (only 20-22 MPG hwy). Then I have multiple Level2 options once there as my condo association is allowed to use the Kaiser chargers across the street overnight (SemaConnect $1.35/hr) or at work during the day (10c/kWh, limit 3 hrs). Occasionally, I would love to head to Santa Cruz (another 40mi each way) to visit my daughter at college and make it back to San Jose in one trip. Or at some points get all the way from Sacramento to Santa Cruz (170mi) without stopping.

This leads me to anxiety about REALISTIC range! We've ruled out GT and AWD (<270mi) to maximize range, and have eyes on Premium ER RWD (~300mi). I believe these figures assume ENTIRE BATTERY from 100% to 0% and therefore are not realistic unless you want to send it to an early grave (or sell before it's too late!) due to deep cycling/topping.

So my technical question is: Is the battery performance normalized from 0% to 100% so that every % is a matched linear increment? True battery IV curves are non-linear and I don't know how the algorithm reports the SoC% (true, linearized, useable only?). If it is already linearized then realistic range is easy to calculate for desired limits such as 25-75% (50% of range rating) or 20-80% (60% of range rating). But if at the top of the reported SoC% range the increments tick down faster, then by definition that middle (say 25-75%) band gets MORE than half of the total range rating, which would be fantastic.

I hope I'm making sense? This could make or break our decision (we're ordering when it opens up Aug15) on AWD vs RWD because we don't want to cut it too close. I don't want to limp into my garage at 15% as I'd prefer to roll in above 20% w/out ever having to make a stop.

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[mkhuffman]

There is a buffer on both sides of 0% and 100%. The actual battery size is 99 kWh but only 91 kWh is available. It is OK to run your car from 100% to 10% on long trips. If you can make it work, 90% to 20% is best.

Ford recommended normal charge level is 90%. I do that on a regular basis. I also charge to 100% once or twice a week before going out of town.

From what you described, as long as you are staying close to the speed limit, your ER RWD MME should make it with good margin to spare.

It is hard to say how linear the discharge rate is because nobody drives the exact same speed for the entire time. And slowing down adds charge to the battery. 100% to 99% seems to take longer than other changes, but not always. Generally it goes down as expected from my experience, in a fairly linear way.

Weather has a huge impact. Cold and rain will reduce range. You probably already know that.

 

[daemonic3]

Very helpful, thanks! Everything (with some exceptions) out there online is very scary about charge limits so it's good to hear at least one anecdotal support that going to 100% once/week for the long trip is "fine", and Ford's support for 90%.

The full Santa Cruz to Sacramento trip may be to bring her home winter breaks so I may need that margin to avoid stopping in cold weather when the range is cut down.

We really need to test drive a RWD vs AWD to see if how we drive we would EVER notice it. We are not speed demons at take off. I just would hate to order something and regret it if we ever need AWD!

 

[mkhuffman]

Very helpful, thanks! Everything (with some exceptions) out there online is very scary about charge limits so it's good to hear at least one anecdotal support that going to 100% once/week for the long trip is "fine", and Ford's support for 90%.

The full Santa Cruz to Sacramento trip may be to bring her home winter breaks so I may need that margin to avoid stopping in cold weather when the range is cut down.

We really need to test drive a RWD vs AWD to see if how we drive we would EVER notice it. We are not speed demons at take off. I just would hate to order something and regret it if we ever need AWD!

In my opinion the only reason for AWD is performance, but I am sure others will disagree. The MME is not a high riding vehicle so it isn't like you will take it in deep snow anyway. And people have been driving RWD vehicles in the snow forever. The most important factor in bad weather is good tires.

 

[RickMachE]

You seemed focused on range. There are DC chargers...

At 132 miles each way, you will need some charger to make the round-trip safely IMO.

 

[mkhuffman]

You seemed focused on range. There are DC chargers...

At 132 miles each way, you will need some charger to make the round-trip safely IMO.

Maybe I misunderstood the OP. I thought he plans to L2 charge at his destination. If not, 264 miles really is cutting it close at highway speeds. Maybe with a lot of traffic congestion it will be good.

 

[RickMachE]

Maybe I misunderstood the OP. I thought he plans to L2 charge at his destination. If not, 264 miles really is cutting it close at highway speeds. Maybe with a lot of traffic congestion it will be good.

I found it hard to follow. Any Mach-E can do 132 miles without a problem in California, so there would be no range anxiety. I guess I fail to understand what his concerns are.

 

[Mach-Lee]

Yes it’s linear. The longest you should plan on doing is 100% to 10%, which is 90% of the battery. That would be about 200 miles at 75 mph.

You’re not going to be able to do 132 miles there and back without stopping to charge.

In the winter figure more like 140 miles before stopping to charge.

 

[AKgrampy]

I think the simple answer is you just need to scope out what chargers are near your destinations. Then use a trip planner. That should give you an idea of what you can or can’t do. The range can vary a bit as previously mentioned so there is no rock solid answer and you should be prepared to charge if needed.

 

[Mach1E]

Very helpful, thanks! Everything (with some exceptions) out there online is very scary about charge limits so it's good to hear at least one anecdotal support that going to 100% once/week for the long trip is "fine", and Ford's support for 90%.

The full Santa Cruz to Sacramento trip may be to bring her home winter breaks so I may need that margin to avoid stopping in cold weather when the range is cut down.

We really need to test drive a RWD vs AWD to see if how we drive we would EVER notice it. We are not speed demons at take off. I just would hate to order something and regret it if we ever need AWD!

You shouldn’t be scared.

A couple times a year you make a long trip? As others said, worst case you have to stop and charge at some point along the way.

As far as the model to pick…….. pick the one you want. You could make the trip with a GTPE in the winter, you would just have to stop to charge for 20 minutes at some point on the way there or back.

Only way I would choose a Mach E based on range is if you had a really long daily commute.

No chance in hell I would trade my GTPE for a different model to avoid DC charging a few times a year.

 

[daemonic3]

I found it hard to follow. Any Mach-E can do 132 miles without a problem in California, so there would be no range anxiety. I guess I fail to understand what his concerns are.

If we can do 100% down to 0%, the full range is absolutely not a problem (~300mi or even ~260mi). I see a LOT of things written about only cycling the battery from 20-80% to keep it healthy. So right away we are cutting down the range big time, if you adhere or believe those recommendations. So I just wanted to hear from owners if the USEABLE portion of the battery is realistic for what I may need the car for (and not stopping for any DC fast charging on a time sensitive commute).

Forgive me as my expertise is on the micro scale (smart watches, batteries, chargers, regulators, processors, sensors and consumption thereof) and I feel like I've been cramming for a test studying everything I can for this upcoming leap into EV's. I'll get there!!

Also, I know that in the Powerboost, the hybrid algorithm keeps our battery's reported SoC% between ~40% at the low end, and 60% as the cutoff where ICE won't charge it anymore, and regen braking charging stops around 70%. Basically it keeps the battery always 40-70%! So Ford intentionally keeps it in that band to extend the life. In watches/phones, the IC's used for charging algorithms are really good about using all kinds of conditions to not overwear or kill the Li-ion cells when up near 100% or down around 0%, but I know NOTHING about how EV's do it.

EDIT: I can appreciate the "hard to follow" comment ? When I initially read it back, I was thinking anyone making it to the end without their head exploding deserves a medal!

 

[Mach1E]

I found it hard to follow. Any Mach-E can do 132 miles without a problem in California, so there would be no range anxiety. I guess I fail to understand what his concerns are.

Yeah reading again there are 2 concerns:
132 miles commute once/week (and charge at destination)

170 miles a few times a year (and charge at destination)

Neither should be a problem for any model.

And if it’s really cold and a traffic jam……. Stop at one of the thousands of chargers on the way.

 

[RickMachE]

@Mach-Lee summed it up nicely.

 

[Mach1E]

If we can do 100% down to 0%, the full range is absolutely not a problem (~300mi or even ~260mi). I see a LOT of things written about only cycling the battery from 20-80% to keep it healthy. So right away we are cutting down the range big time, if you adhere or believe those recommendations. So I just wanted to hear from owners if the USEABLE portion of the battery is realistic for what I may need the car for (and not stopping for any DC fast charging on a time sensitive commute).

Forgive me as my expertise is on the micro scale (smart watches, batteries, chargers, regulators, processors, sensors and consumption thereof) and I feel like I've been cramming for a test studying everything I can for this upcoming leap into EV's. I'll get there!!

Also, I know that in the Powerboost, the hybrid algorithm keeps our battery's reported SoC% between ~40% at the low end, and 60% as the cutoff where ICE won't charge it anymore, and regen braking charging stops around 70%. Basically it keeps the battery always 40-70%! So Ford intentionally keeps it in that band to extend the life. In watches/phones, the IC's used for charging algorithms are really good about using all kinds of conditions to not overwear or kill the Li-ion cells when up near 100% or down around 0%, but I know NOTHING about how EV's do it.

EDIT: I can appreciate the "hard to follow" comment ? When I initially read it back, I was thinking anyone making it to the end without their head exploding deserves a medal!

Honestly?

Ignore all the stuff about “keeping the battery healthy.”

If you’re driving far, charge to 100% (which is really only 90% anyways).

Sure, it’s technically best to keep it 20-80%, but even the studies that looked at battery degradation only had like a 3% difference at the equivalent of hundreds of thousands of miles based on charge cycles.

If you run your car from 100% to 0% every day and exclusively DC charge…….. you still have an 8 year warranty on the battery.

 

[daemonic3]

You shouldn’t be scared.

A couple times a year you make a long trip? As others said, worst case you have to stop and charge at some point along the way.

As far as the model to pick…….. pick the one you want. You could make the trip with a GTPE in the winter, you would just have to stop to charge for 20 minutes at some point on the way there or back.

Only way I would choose a Mach E based on range is if you had a really long daily commute.

No chance in hell I would trade my GTPE for a different model to avoid DC charging a few times a year.

Right, plus I want the wife to choose the car she wants! It was her idea to have me commute using it, which really does make sense, and that's where I started wanting to be certain on prioritizing range vs sacrificing what may be "fun" or "cool" for her. Or the performance shocks, which is a whole other subject.

I happen to LOVE my Powerboost and don't mind the commute at all. But paying $80/week vs maybe $15 is a huge difference and financially dumb no matter how much I love my truck.

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