Elevation -- effect to battery usage?

[Wolverine]

Sylvain: thanks for the info. I followed your ABRP link and it said in relevant part: " As soon as you move fast enough, ABRP will switch to driving mode and display a graph of the next route leg including elevation and expected battery State-of-Charge % (SoC) together with estimated arrival time." Do you know if that means ABRP takes elevation into account only if you're using the app in the car and moving up the incline?

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[Wolverine]

Summary is shown at 8:20 -



From a physics perspective, you are only going to get back the gravitational potential energy coming back down. The drag and rolling resistance losses you don't get back. So if you drive 50 miles up a mountain and 50 miles down, you will effectively use the same energy as driving 100 miles plus a little bit more to account for regen losses.

You can calculate gravitational potential energy required to go uphill: https://www.omnicalculator.com/physics/potential-energy?c=USD&v=g:1!g!l,mass:5000!lb,height:7500!ft (change energy units to kWh)

As you can see it takes about 14 kWh to go up 7500 ft which is about 15% of the extended battery. Let's say you average 2.8 mi/kWh driving on flat ground, we can calculate the energy and % required to go up and down.

Uphill:
50 mi / 2.8 mi/kWh = 18 kWh (drag)
+7500 ft = 14 kWh (elevation)
TOTAL = 32 kWh or 36% battery required

Downhill:
50 mi / 2.8 mi/kWh = 18 kWh (drag)
-7500 ft = -14 kWh * 80% efficiency = -11 kWh (regen)
TOTAL = 7 kWh or 8% battery

Add them together you need 39 kWh or 44% battery for the trip, so you should start with that % or higher to make it. Compared to about 40% battery to go 100 miles on flat ground.

Lee: thanks so much for this link and patient explanation.

 

[RedStallion]

Ignoring the secondary effects, the potential energy is m*g*h. That's the only formula you need to know to calculate efficiency.
So, for example, assuming gross weight 2000kg, climbing 100m, Mach-E would need to spend approximately 2MJ, or about 0.56kWh.
Here is another example, assuming you have 3mi/kWh efficiency driving on a similar flat surface, climbing at a slope of 10 degrees, it's easy to calculate your efficiency would drop to 1.74 mi/kWh.

 

[superdave80]

I've calculated (assuming 80% efficiency, 4500lb vehicle) that it takes about 2.2 kwh to rise 1,000 ft. At 3.3mi/kw, you will lose around 7 miles of range for evek 1,000 ft. So, for example, if you are going from sea level to 5,000 ft elevation, subtract 35 miles from your range.

 

[Kamuelaflyer]

Does anyone have experience or calculations to share about the effect of driving uphill on your battery depletion?

I'm contemplating a trip through Kings Canyon/Sequoia National Parks. Whether I enter the parks from north or south, it looks like I will have to drive uphill to about 7,500 foot elevation (and then down again). There is nowhere in the parks to recharge an EV! According to my ABRP planning, I should be able to make it through, but I'm wondering if the effect of the uphill drive may wipe out my charge before I can get out.

I live on the side of a dormant volcano. While my average miles/kWh since new is 3.5 my miles/kWh when leaving home and heading south for the first 5 miles is between 1/kWh and 1.2. Returning home from either direction yields the same. The result is that my GOM thinks I barely have 200 miles range on an AWD ER car. I get more than 300. It also means I better not be heading home from the main roads at 10% battery or less. I might not make it.

Departing the subdivision is a 1-mile drive with elevation climbing from 4400 ft to 5000 ft., that exit is 1 mile/kWH. Heading south from the exit I have 5 miles of climbing in rolling hills trending higher. I top out at a bit above 6000 ft. Coming home from the north I have 7 miles of climbing that goes from 2400 ft elevation to 5000 ft elevation. Heading home from the south I can have 15 miles of climbing, including two brief 10% slopes, several 8% slopes, and an average well above 6%.

The reverse is also true though. When heading to Kona, which is just short of 50 miles away I start at 80% SOC and arrive at 74% - 76%. The round trip takes 30% charge with about 15% being on the steep climb home if I go that route.

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