Costs/Hours to charge 2021+ MX/MXP 100kWh battery on Level 2 48A Wall Connector from 0-80% and 0-100% ?

[ev919]

Seems like this topic would have been discussed to death, but searching here doesn't quite turn up similar discussion.

So, 2021+ MX is shown as having 100kWh battery.

MXLR 335 miles range, EPA est, at 100% SoC.
MXP 326 miles range, EPA est, at 100% SoC.

On paper, charging speed from max miles of range per hour of charge using 11.5 kWh from power at 240 volt Level 2 Wall Connector on 48 amp max output:

0-80% SoC, ~80 kWh --> ~7 charging hours
0-100% SoC, ~100 kWh -->~9 charging hours


Duke Energy Summer rates:

Residential: $0.1161/kWh (fixed)
80% --> ~$9.35 charging cost **********
100% --> ~$11.61 charging cost **********


Residential TOU-79: $0.10467/kWh Off-Peak, $006814/kWh Discount
80% --> 5 hours@discount, 2 hours@off-peak, $6.33 **********
100% -->5 hours@discount, 4 hours@off-peak, $8.37 **********


Residential TOU-Demand-79 (haven't calculated this scenario)


Is my math's above are what folks (sort of) use to estimate their charging costs?

 

[jjrandorin]

Seems like this topic would have been discussed to death, but searching here doesn't quite turn up similar discussion.

Probably because its going to depend directly on your SPECIFIC LOCAL electricity rates, whether they are tier based and go up when you use more energy or based on a time of use plan, how much energy your SPECIFIC house uses (as even 2 tract homes in the same neighborhood with exact same floorplan can have vastly different electrical usage, and other specific characteristics of your specific situation.

Thats why any thread on a topic like this has to be, at best "for you" (meaning the thread title should actually be "

Costs/Hours to charge 2021+ MX/MXP 100kWh battery on Level 2 48A Wall Connector from 0-80% and 0-100% for EV919"​

 

[ev919]

the title should really be, "hours", to see what the folks are seeing to charge to 80% and 100% on their 2021+ MX with 100kWh battery, using Level2 240V level 2 charger at 48A,

0-80% SoC --> ~7 hours
0-100% SoC --> ~9 hours?

Hours to charge 2021+ MX/MXP 100kWh battery on Level 2 48A Wall Connector from 0-80% and 0-100%​

 

[E90alex]

Well first of all you’ll probably never do 0-80% or 0-100% unless you constantly drive like 300+ miles a day.

You should be charging daily and on average most people probably use 10-20% of battery a day. So you’re only charging 20 kWh at most, which should be done under 2 hours. That should be able to easily fit entirely within your cheapest rate period.

Even if you do return from a long trip with a low battery charge, you can just lower the charge limit to fit in your cheapest rate period. You don’t always have to charge it to 80-100% if you don’t need to use the whole battery range the next day. For example I only charge mine to 50% daily.

 

[Tronguy]

So, here's maybe a better way to handle this, at least in general.

Over at the EPA, they have the following for energy usage per mile on the MXLR and MXP, as follows:

• MXLR: 320 W-hr/mile
• MXP: 350 W-hr/mile

So, I point at you, sir, and say, "What are your driving habits in terms of miles per year?"

In addition, I throw in that you have to tell me how much of that is local, versus driving, say, 300 miles and using Superchargers.

Let's say, for fun, that you do 10,000 miles a year driving around the local landscape, charging up at home. In this scenario, all you need to know is how many kW-hr's of energy you're using a year.

With the MXLR: That'd be 3.2 MW-hr of energy.
With the MXP: That'd be 3.5 MW-hr of energy.

Now, the general idea is that if you've got yourself a Tesla Wall Connector (or equivalent), you can charge, given 240VAC * 48A = 11.52 kW. That works out, in general, to 11.52 kW/(320 W-hr/mile) = 36 miles of charge per hour on the MXLR and 11.52kW/(350 W-hr/mile) = 32.9 miles of charge per hour.

But! Say you're charging at home and, when the battery gets low, say, 20% charge, you want to charge to 80%, that's 60% change in the amount of charge, or, given that you've got a 100 kW-hr battery, that's 60 kW-hr. That'll take (roughly) 60 kW-hr/11.52 kW = 5.2 hours. No matter which car we're talking about.

That 5.2 hours? That's called, "Overnight". Ya gotta sleep sometime.

(And if you're going to sleep in the dead of night, may as well have the car charge then, too, and save a few bucks, see below.)

So, really, the only question is how much you're going to pay for the energy you use. Per year. Well, that's easy:

For the MXLR, 10,000 miles, using the EPA estimate and Time of Day tariffs, your cost per year would be:
3.2e6 W-hr * $0.10467/1000W-hr = $334.944 a year.
For the MXP, 10,000 miles, you'd have
3.5e6 W-hr * $0.10467/1000W-hr = $366.345 a year

If you use the non-time-of-use tariff, which you state is $0.1161, then your costs per year with 10,000 miles driven per year would be:
3.2e6 W-hr * $0.1161/1000W-hr = $371.52 a year for the MXLR and
3.5e6 W-hr * $0.1161/1000W-hr = $406.35 a year for the MXP.

I've generally found that the EPA estimates are pretty close to what one gets so long as one isn't blitzing around most of the time at higher than 70 mph or so; local driving tends to be spot on, or somewhat higher.

As you probably know, charging at Superchargers tends to be ~3x the cost of charging at home.

About the only other comment I'd have has to do with Solar. My place happens to have a 9 kW solar array on the roof, installed back in 2008. That gets me around 12 MW-hr of energy per year, which pretty much zeroes out my electrical bill. Weirdly enough, the SO and I have been gradually replacing all the incandescent lamps with LED and the like over time, so our actual energy usage has been going down over time. So, even with the M3 and MY in the garage, we're still coming up net positive energy being dumped into the grid. We've just switched over a heat pump system.. which'll probably save us money over burning natural gas, although I expect the "cost of electrical energy per year" meter to bump off of zero as a result.

In any case, putting in solar tends to make using electricity free. So, there's that.

 

[John in LB]

So, here's maybe a better way to handle this, at least in general.

Over at the EPA, they have the following for energy usage per mile on the MXLR and MXP, as follows:

• MXLR: 320 W-hr/mile
• MXP: 350 W-hr/mile

So, I point at you, sir, and say, "What are your driving habits in terms of miles per year?"

In addition, I throw in that you have to tell me how much of that is local, versus driving, say, 300 miles and using Superchargers.

Let's say, for fun, that you do 10,000 miles a year driving around the local landscape, charging up at home. In this scenario, all you need to know is how many kW-hr's of energy you're using a year.

With the MXLR: That'd be 3.2 MW-hr of energy.
With the MXP: That'd be 3.5 MW-hr of energy.

Now, the general idea is that if you've got yourself a Tesla Wall Connector (or equivalent), you can charge, given 240VAC * 48A = 11.52 kW. That works out, in general, to 11.52 kW/(320 W-hr/mile) = 36 miles of charge per hour on the MXLR and 11.52kW/(350 W-hr/mile) = 32.9 miles of charge per hour.

But! Say you're charging at home and, when the battery gets low, say, 20% charge, you want to charge to 80%, that's 60% change in the amount of charge, or, given that you've got a 100 kW-hr battery, that's 60 kW-hr. That'll take (roughly) 60 kW-hr/11.52 kW = 5.2 hours. No matter which car we're talking about.

That 5.2 hours? That's called, "Overnight". Ya gotta sleep sometime.

(And if you're going to sleep in the dead of night, may as well have the car charge then, too, and save a few bucks, see below.)

So, really, the only question is how much you're going to pay for the energy you use. Per year. Well, that's easy:

For the MXLR, 10,000 miles, using the EPA estimate and Time of Day tariffs, your cost per year would be:
3.2e6 W-hr * $0.10467/1000W-hr = $334.944 a year.
For the MXP, 10,000 miles, you'd have
3.5e6 W-hr * $0.10467/1000W-hr = $366.345 a year

If you use the non-time-of-use tariff, which you state is $0.1161, then your costs per year with 10,000 miles driven per year would be:
3.2e6 W-hr * $0.1161/1000W-hr = $371.52 a year for the MXLR and
3.5e6 W-hr * $0.1161/1000W-hr = $406.35 a year for the MXP.

I've generally found that the EPA estimates are pretty close to what one gets so long as one isn't blitzing around most of the time at higher than 70 mph or so; local driving tends to be spot on, or somewhat higher.

As you probably know, charging at Superchargers tends to be ~3x the cost of charging at home.

About the only other comment I'd have has to do with Solar. My place happens to have a 9 kW solar array on the roof, installed back in 2008. That gets me around 12 MW-hr of energy per year, which pretty much zeroes out my electrical bill. Weirdly enough, the SO and I have been gradually replacing all the incandescent lamps with LED and the like over time, so our actual energy usage has been going down over time. So, even with the M3 and MY in the garage, we're still coming up net positive energy being dumped into the grid. We've just switched over a heat pump system.. which'll probably save us money over burning natural gas, although I expect the "cost of electrical energy per year" meter to bump off of zero as a result.

In any case, putting in solar tends to make using electricity free. So, there's that.

You nailed it. ! I agree with 320 Wh/mile for MXLR.