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Discussion Starter #1 (Edited)






186.8 miles for a full charge and a challenge for you my fellow Volt owners, only if you have time to spare. Most of us are assuming that if you have an all downhill road, the Volt's range can be infinite. But we all know that there's no such thing as an all downhill road. So from our area here in Northern California, I took up the challenge to see how far I can glide downhill on a single full charge of battery. It is one thing to speculate how far, and still another thing to do it in real life.

And starting from the charging station, I was able to achieve 186.8 EV miles on my 2017 Siren Red Volt on a full charge before the gasoline engine switched over. This is an astonishing 13.25 miles per kWh using only 75.5 Watt-Hour per mile for the entire battery pack on mostly downhill run.

I challenge you to find your own hill and beat my score and post it here, to try to push the limits. You may find that your speculation of downhill having infinite miles really don't hold water or electrons for that matter.

To help you in this challenge know that the Volt is about 3519 lbs and assuming the person driving it is 175 lbs, for each 1,000 ft of elevation change, there is a potential energy difference of 1.392 kWh. A full battery pack of the Volt has 14.1 kWh usable state of charge. A difference of 10,135 ft equates to 14.1 kWh. Now you'll have to add more height to account for losses in rolling resistance (depending on tires and road condition), internal resistance, air resistance losses (depending on speed and prevailing wind), and just assume air temperature remained optimal at 85 deg F for the battery.

If you're in California, here's a listing of all mountain pass roads that you can drive your Volt to and to use to glide to beat my score. But you would need a charging station near to your chosen hill.

https://en.wikipedia.org/wiki/List_of_mountain_passes_in_California
 

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Knowing that the Volt has asymmetric resistances climbing up and coasting downhill, and that the energy spent in climbing is almost recovered fully near 100% (after accounting for rolling resistances). I also found out that when you climb hill, the slowest speed you can get by to maximize efficiency and range is at about 18 mph. Coasting down is always at ACC, set to maximum of 35 mph, the efficiency remains the same at its best from 20 mph. No radio, no fan. Empty the trunk including the jack.

I set out to test my observations into a record attempt. I have been eyeing a public charging station that was ideal for my personal best record attempt, that is on a foothill with nearby sloping back roads to coast downhill at speeds that can be low 35 mph. So after fully charging I went uphill, that is to create space for regen, then I coasted all the way down to the valley, and then on flat roads went north on back roads with the delta breeze wind behind my back. I used the fan near the end of the run as I was sweating.

The result is 186.8 EV miles before the gasoline engine took over. That is an astonishing 13.25 miles per kWh using only 75.5 Watt-Hour per mile. It was a grueling, boring torture of a ride for 7 hours! Am not going to do this again. Ever!!!
If you were in a Bolt that would be an estimated 838 miles EV range versus the EPA range estimate of 238 miles!
 

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Discussion Starter #4
Just imagine what we could do if the entire world was downhill.
As they say, the satellites are forever falling, but because the world is round and they follow the curvature as they fall, they never stop falling. Ha ha ha!
 

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Discussion Starter #5
One of our members here, loaded up his Volt atop a trailer and recharge it while being hauled using portable generator, and then coasted downhill to establish one day electric mile record, but hasn't achieved the 186.8 mile per full charge. He has to bring the Volt uphill three times to get a one day record of over 350 miles. Of course it was a Gen 1 Volt.

Would like to hear the maximum range per charge on a downhill run. Too bad our downhill run is only about 65 miles.
 

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I don't understand the value of this "game". If you started 20 miles down from Pikes Peak, used up your battery to get to the top, then turned around and regened all the way back to Colorado Springs, your battery would be more than full at the bottom, and you would likely achieve an even better MPGe. You would have gone about 50 miles on no battery at all.
 

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Would like to hear the maximum range per charge on a downhill run. Too bad our downhill run is only about 65 miles.
Again, this is silly. On a long enough downhill run, the range is potentially infinite -- just as it would be on an ICE car coasting down.
 

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Discussion Starter #8
Again, this is silly. On a long enough downhill run, the range is potentially infinite -- just as it would be on an ICE car coasting down.
Okay, let's see some actual numbers, instead of speculations. Find the longest downhill that you can and post your results here.
 

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Just imagine what we could do if the entire world was downhill.
I'm looking for a route to/from work that is downhill both ways. Only energy used would be for warmth, as the snow drifts are nine feet high... ;-)
 

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Discussion Starter #10
I don't understand the value of this "game". If you started 20 miles down from Pikes Peak, used up your battery to get to the top, then turned around and regened all the way back to Colorado Springs, your battery would be more than full at the bottom, and you would likely achieve an even better MPGe. You would have gone about 50 miles on no battery at all.
You still have to deal with internal, rolling and air resistances.
 

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Discussion Starter #11
I'm looking for a route to/from work that is downhill both ways. Only energy used would be for warmth, as the snow drifts are nine feet high... ;-)
Coasting downhill from fully charge doesn't work very well, that is why the Chevy Bolt has a setting to allow room for the regen downhill. I initially climbed uphill to make room for regen, while adding EV miles, and then coasting down for regen to add more EV miles, and used whatever battery remained when I reached flat roads at optimal speed of 27 mph.

If the battery on the regen is going to fill the pack, instead of bleeding it out, climb uphill again, then coast down some more, try to push the limits of range. That's the way to rack up the EV miles per charge. Ultimately all of it will be spent on internal, rolling and air resistances.
 

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Discussion Starter #12
Assuming that the Volt is 3519 lbs and the person driving it is 175 lbs, for each 1,000 ft of elevation change, there is a potential energy difference of 1.392 kWh.

So a difference of 10,135 ft equates to 14.1 kWh. Now you'll have to add more height to account for losses in rolling resistance, internal resistance, air resistance losses (depending on speed), and just assume air temperature remained optimal at 85 deg F for the battery.

Our highest road peak here is at 7,500 ft.
 

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You still have to deal with internal, rolling and air resistances.
Of course you do. But if gravity is enough to overcome that, you use no energy (electric or gas). MPG = MPGe = ~infinity.

Where I live it's pretty flat. The longest downhill road is in Tibet. What's the point?
 

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On a different subject where do you host your photo's, am looking to replace PhotoBucket. Oh and nice numbers.
 

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Just imagine what we could do if the entire world was downhill.
Or if you can go to work and home downhill, both ways.

To the OP. Thank you for doing this in the interest of science. But driving for 7 hours to perform this feat puts you into the Ari_C category for crazy.
 

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I'm with those who don't see any practical reason for these kinds of exercises. No real world driving I can imagine would match these conditions. And driving that slowly could be dangerous on most roads. I'd rather get where I am going in a reasonable time without conflicting that much with the flow of traffic.

Maybe if it were a BEV, there might be times when you would want to stretch your range any way possible, but that should not be needed in an EREV.
 

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Again, this is silly. On a long enough downhill run, the range is potentially infinite -- just as it would be on an ICE car coasting down.
Agreed, this is pretty silly but not accurate about the ICE car as you cannot safely or legally turn the ICE off and coast downhill on public roads. You won't use much gas, but you will use some basically idling the whole way.
 

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Assuming that the Volt is 3519 lbs and the person driving it is 175 lbs, for each 1,000 ft of elevation change, there is a potential energy difference of 1.392 kWh.

So a difference of 10,135 ft equates to 14.1 kWh. Now you'll have to add more height to account for losses in rolling resistance, internal resistance, air resistance losses (depending on speed), and just assume air temperature remained optimal at 85 deg F for the battery.

Our highest road peak here is at 7,500 ft.
Your also forgetting charging losses. It takes more than 14.1KWh's of energy to get 14.1KWh of usable.
 
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