Stupid EV Tricks: Drive up a Mountain...

[FFEFTW]

Drive up a Mountain burning 64% of your battery, then drive home burning just 1% more :lol:

 

[WattsUp]

Is that Mt. Hamilton in the San Jose Bay Area?

Check this thread (and our photos at the end):

Mt Hamilton Hill climb - June 7th San Jose, CA - w/ PHOTOS

It was perhaps more fun coming back down and charging the battery back up!

 

[FFEFTW]

Yup, that's Mt. Ham.

When I reached the top the GOM said I had only 13 miles of range left with 36% battery remaining.
Coming down hill I got the battery up to 45%, but was having more fun driving than hypermiling...
When I reached home (in downtown SJ), with 35% battery remaining, GOM said 113 miles until empty.
GOM so silly... :roll:

 

[campfamily]

I did the same thing down here where I live....drove up Glendora Mountain Road. Left the house with a full charge. Got to the top, a bit less than 20 miles, had about 20 miles remaining on the GOM. Had a nice lunch with the wife, then came back down. Used no electricity going back down, and arrived back home with a fuller charge than when we left the top of the hill, and the GOM showing about 130 miles remaining.

 

[electrons]

FFEFTW, that Focus looks exactly like mine, got it 3 months ago.
This subject is interesting. I live near-ish to the I-70 entrance to the Rocky Mountains (Denver).

I'm wondering if I can make it to the town of Idaho Springs, Colorado, on I-70, a climbing difference of 1,800 ft elevation over 42 miles one-way!!!

If you're calculating if you can make it up a mountain, divide your elevation rise in feet by 225 to get miles of range "lost" to going up the mountain. If FFEFTW's Mt. Ham is a 3,000 feet rise (guessing), you would do: 3,000/225=13 mile "penalty" for all that "up"!

Calculations: Assuming 3,800 lbs Focus and 1 driver, efficiency of 3 miles per kWH, elevation rise eats 1 kWH per 700 feet up, yadda, yadda,.... my calculations say I "lose" 2.6 kWH rising 1,800 feet elevation to Idaho Springs. Therefore, 3 x 2.6 = 7.8, about 8 miles we'll call it, lost to gaining elevation up the mountain.

Good news is you can get most of that energy back when you go down the mountain, if you are easy on your brakes and not too fast on speed (little additional air drag). Mild braking or putting the car in Low means your battery takes it in at about an 80% efficiency rate for the big Li-Ion battery back there, when you're not just coasting freely.

For my Idaho Springs trip of 42 miles there one-way, and up 1,800 feet, I'd lose 8 miles of range "penalty" for going up, yet I could probably get back 6 miles "bonus" coming down the mountain, making for a net loss of 2 miles round-trip in range cost. Not bad really. You have to do the "up" mountain calculation though to make sure you can get there in the first place, right?!

My Ford Focus Electric (same as FFEFTW's):

 

[electrons]

Update: I drove yesterday to a mountain town just off I-70 (Genesee), left home with a full charge, drove 58 miles round trip, elevation rise was 1,500' feet going to there.
Arrived home with about 1/4 of the battery charge left, not bad. Like 17 miles or so margin.

The battery looked pretty sapped of energy when I got to the top, then the long roll down I-70 charged almost all the "lost" energy component used to get the elevation rise.

 

[FFEFTW]

LOL, very nice. FWIW Mt. Hamilton in the SF Bay area is a bit over 4K feet:
https://en.wikipedia.org/wiki/Lick_Observatory

I can see it now, the FFE-Maximum-Elevation-Gain-and-return-to-start-on-one-charge challenge!

 

[electrons]

Mt. Hamilton being 4000' ft elevation, and starting from Sea Level, you would have a penalty of about ~6 kWH, about 1/4 a fully battery charge, just to get up that mountain. (My trip, I was already starting from about 5800', and went to 7300' and back, not a real stress-test in my case.)
Add about another 1 kWH for every extra 200 lbs you carry as well for your 4000' rise.

If anybody tries this, just make sure your battery is at least half-full before starting a major elevation rise, just so you make it up the mountain, and you'll gain back 75% or so(?) on the trip back down.

There is a 14,000' foot peak near Idaho Springs, Colorado (30 miles from Denver), Mt. Evans. If I try that one, I would need about a half-full battery just for the distance alone to the peak from Idaho Springs (at 7300'), then about ~8kWH just to rise in elevation, so my battery had better be 5/6th battery level to make it up the mountain without running out on the way up!

I can get a full charge in Idaho Springs while stopping to eat. Public stations there, not used much.

 

[couchracer]

From my house to the Palomar Observatory in San Diego County is 46.7 miles the short way with almost 7000' of elevation gain. Accounting for my wife and myself using the numbers above, it looks like I would make the top with 0%!! :shock: Looks like I'll have to make a stop at one of the casinos on the way or hit a charger in Escondido to make it. I would love to try it, though. Might have to contact the little store at the top or the Observatory to see if there are any 120V outlets available. Then I would have to rely on regen for the 1200' of elevation loss on the trip to the top to squeak by.

 

[WattsUp]

From my house to the Palomar Observatory in San Diego County is 46.7 miles the short way with almost 7000' of elevation gain. Accounting for my wife and myself using the numbers above, it looks like I would make the top with 0%!! :shock:

Well... the good thing about a mountain climb attempt is that, even if you can't make it, you can always turn around at any time and "get your money back".

 

[couchracer]

Made the run today. I did make a stop at Harrah's. Good thing. Made it to the observatory with 7 miles on the GOM after a 5.71 kW charge. Started again at the top with th 7 miles and warnings on the dash to return home.

Here's after a one hour blink charge again at Pala Casino:



Guess-o-meter is right!! :lol:

 

[electrons]

couchracer, So you added about 5 kWh on an on-road charging stop, giving you 28 kWh in the battery to make it up there.
Subtracting 10 kWh to make the 7000' elevation rise happen, that means you were working with 18 kWh to go 47 miles distance. Then you said you had 7 miles left when arriving at the top, so your 18 kWh was actually good for 47+7=54miles, so your driving efficiency was about 54/18=3 kWh/mile driving efficiency, about what I'd expect from any Focus Electric like mine.

At the top of the mountain with 7 miles (about 2.2 kWh worth) remaining, you got back about 10 kWh going down, for 12 kWh to go 47 miles, and with an efficiency of about 4 kWh per mile, you made it home. Cutting it close.

 

[electrons]

I've got a possible 7,000' foot elevation rise I could try one day.
Idaho Springs (240v charger there) to the top of Mt. Evans is about 7,000 feet or so. (Colorado, I-70 Denver area). I'd need about a 2 hour 240v charge session in Idaho Springs, then up to Mt. Evans, and it would make it I'm sure.

 

[WattsUp]

couchracer, So you added about 5 kWh on an on-road charging stop, giving you 28 kWh in the battery to make it up there.

electrons, your assumptions and other calculations are a little off.

While it's true the battery in the FFE is rated at 23 kWh total capacity, the actual usable capacity when fully charged is only about 19 kWh (and that's under ideal circumstances).

If you're lucky (brand-new FFE, warm weather, etc.) you can use up to 19 kWh from a full charge. So, charging back 5 kWh in the middle of a trip, would make more like 24 kWh total usable (over time), not 28.

The reason for all this is that the car reserves buffers of about 10% at the "top" and 10% at the "bottom" of the true capacity of the battery in order to protect it. Fully charging or fully draining a li-ion battery can actually be severely damaging, so the FFE takes these measures to ensure that neither ever occurs. Note that the "100%" level of charge shown on the dashboard factors in the buffers, and so a "fully charged" FFE actually has somewhere around a 90% charge (of the battery's true capacity).

Btw, don't feel cheated, this type of behavior is not unique to the FFE... all EVs work this way. That said, some EVs, like the Leaf, allow the user to manually override the protection and achieve much closer to a true 100% charge, with the very real risk that doing so routinely and/or carelessly will hasten battery degradation.

 

[electrons]

couchracer, the 23 kWH battery rating already takes into account the residual levels you mentioned. This is important because the residual charge (not usable, stuck inside the battery) can vary with battery chemistry from Teslas, Leafs, etc., so the rating already takes it into account for practical comparison purposes.
Notice the EPA says the FFE is 310 WH per mile efficient, a combined City and Highway efficiency, and it gets an official 76 mile range based on that same city/highway test they did.

310 WH/mile x 76 miles = 23.5 kWH battery rating, the actual usable energy extracted from the battery.

Reference: http://avt.inl.gov/pdf/fsev/fact2013fordfocus.pdf
which is from http://avt.inl.gov/fsev.shtml

 

[WattsUp]

310 WH/mile x 76 miles = 23.5 kWH battery rating, the actual usable energy extracted from the battery.

Not quite. You've got things a bit backwards.

23.5 kWh is the energy needed "from the wall" to fully charge the battery, which stores about 19 kWh of usable energy in the battery (under ideal circumstances). 19 kWh is the maximum you could ever expect to extract from a fully charged FFE battery.

Remember that EV charging is about 80% efficient, so it takes about 20% more energy than is stored in the battery to actually store it!

23.5 kWh (required from the wall) * 0.8 = ~19 kWh (stored in the battery)

The extra 20% is wasted mainly as heat during the charging process, but it is still "consumed" as part of the cost of fueling an EV. And this is why the EPA rates the FFE at 310 Wh/mi, since the true "wall to wheels" consumption is computed with the energy "from the wall" like so:

23.5 kWh (from wall) / 76 miles (traveled) = 310 Wh/mi

The display inside the FFE, however, will show a typical consumption of 250 Wh/mi for the same 76 miles of travel. Is something weird going on? No, the display in the FFE is based only on the energy consumed from the battery:

19 kWh (stored) / 76 miles (traveled) = 250 Wh/mi

Note that 250 is about 80% of 310, which is naturally reflective of the 20% loss during charging.

 

[electrons]

WattsUp, thats close to what Intertek (Idaho Nat. Labs) got when they tested the FFE.

You are talking about a second concept now, Charging Efficiency vs. Battery Output (DC), not the first concept you outlined before, the unusable chemical internal charges.

Its hard to keep it all straight, yet they came up with 25 kWH from the wall charger, wasting about 20% as heat, to get 19.5 kWH out from the battery, line A+ below from Reference: http://avt.inl.gov/pdf/fsev/fact2013fordfocus.pdf:

 

[WattsUp]

You are talking about a second concept now, Charging Efficiency vs. Battery Output (DC), not the first concept you outlined before, the unusable chemical internal charges.

Maybe a confusion of terms. I was not referring to battery chemistry, or "unusable chemical internal charges".

By "usable energy" (a phrase we use a lot here in this forum), I specifically meant the energy that the car (through software) allows us to consume from the battery.

The FFE battery is rated for total possible storage capacity of 23 kWh (if actually fully charged and then every last electron discharged). But the car's software does not allow this full capacity to be utilized. The software prevents the battery from ever being actually fully charged or discharged, by reserving "buffers" somewhere under 10% and over somewhere about 90% of the total possible charge of 23 kWh.

What's left (somewhere north of 80% of the total possible, or about 19 kWh) is what I call the total "usable energy".

Its hard to keep it all straight, yet they came up with 25 kWH from the wall charger, wasting about 20% as heat, to get 19.5 kWH out from the battery

Yes, for a brand-new FFE under ideal circumstances, that's about what you should see.

 

[Pearl]

So what should a fully charged battery report in kW when hooked up to ODB? I use FORScan and my battery shows 18.6 kWh BAT_TO_EMPTY.

 

[ptt007x]

did the same thing down here where I live....drove up Glendora Mountain Road. Left the house with a full charge. Got to the top, a bit less than 20 miles, had about 20 miles remaining on the GOM. Had a nice lunch with the wife, then came back down. Used no electricity going back down, and arrived back home with a fuller charge than when we left the top of the hill, and the GOM showing about 130 miles remaining.





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