Hill consumption?

I live on top of a hill and am curious how much juice we will need to consume to get home. At the end of my trip I will need to climb about 1000 ft in 2 miles. Has anyone climbed roughly 1000 ft in elevation and how much energy did that require?

My wife's commute is about 25 miles each way, and she has 115V charging at work, so I'm not worried about range, but it would be good to know how much energy to leave before I get home.

Our car is scheduled for a March delivery. I hope it holds!

Toshi

The general rule of thumb is that one mile of hill climb equals three miles of level, assuming a 6 percent grade. You are more like 10 percent so I'd guess it would be something like 10 miles in your case.

ttoshi said:

I live on top of a hill and am curious how much juice we will need to consume to get home. At the end of my trip I will need to climb about 1000 ft in 2 miles. Has anyone climbed roughly 1000 ft in elevation and how much energy did that require?

My wife's commute is about 25 miles each way, and she has 115V charging at work, so I'm not worried about range, but it would be good to know how much energy to leave before I get home.

Our car is scheduled for a March delivery. I hope it holds!

Toshi

Click to expand...

See Leafer's analysis here.

Roughly, to be safe, assume an extra 1.5kWh per thousand feet in addition to the normal usage for the miles covered. I think that's more useful than what mogur suggests, because it is independent of steepness.

planet4ever said:

Roughly, to be safe, assume an extra 1.5kWh per thousand feet in addition to the normal usage for the miles covered. I think that's more useful than what mogur suggests, because it is independent of steepness.

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Great, so assuming 24kWh/100 miles, this is 5.4 miles for 1000 feet of climbing, +2 miles of normal distance, which would be roughly 7.4 miles total energy consumption.

--Now what is the regeneration efficiency? If I assume 5.4 miles of potential energy, then 5.4% of 100 miles total distance could potentially be recovered. Should I assume 50% regeneration recovery or maybe less? It will be fun to test out. We could start with a 98% charge (if you can tune the charging to that level) and see if we can get to 100% near the bottom of our hill...

Thanks,
Toshi

Charge to 80% not 98. You will not get a 1/1 ratio and since the LEAf does not have very powerful regen longer regen grabs vs shorter stops will yield more. Any EV is capable of as much regen as it has output but the LEAF has been limited form the full 80 kw. Just experiment a bit on the downhill.

On steeper downgrades, the LEAF's maximum Regen will not keep the car from gaining speed, so one will need to "burn" energy in the disc brakes.

On more moderate slopes, the Regen might be sufficient, but it is not yet clear (to me) just how much Regen one can get (maybe rather little) without beginning to "burn off" energy in the LEAF's disc brakes.

garygid said:

On steeper downgrades, the LEAF's maximum Regen will not keep the car from gaining speed, so one will need to "burn" energy in the disc brakes.

On more moderate slopes, the Regen might be sufficient, but it is not yet clear (to me) just how much Regen one can get (maybe rather little) without beginning to "burn off" energy in the LEAF's disc brakes.

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Gary...

On the little hills here in San Diego, I get about max 10kW regen, maybe a little more. I never see it max out at 30kW unless I'm using the brake as well. I think you'd have to be on a pretty steep hill, use N to gain speed and THEN ask regen to slow you down before you'd max it out and be forced to use the brake.

You saw 10kW in ECO-mode foot-off Regen?

I have seen 18 kW using the brake, but it was probably in D-mode.

If gentle braking just added Regen, that would be great.
But, it is not clear when the discs start "eating" energy, right?

So, have any LEAF owners tried driving up a "real" mountain yet? (i.e., Mt. Wilson, Mt. Palomar, Mt. Lemmon, Mt. Hood, Mt. Baldy, etc.) If yes, what was the distance and elevation gain? What was your approximate power consumption? (Yes, we've estimated what the consumption "should" be, but there's no substitute for hard data.) How much regen did you pick up on the way down? Did the battery temperature become a concern?

Thank you. (As I live on a mountain, I'm hoping for some data before my Blue SL-QC delivery date, which seems likely to be in May or perhaps as early as April.)

I frequently go down Mission Village Drive into San Diego's Qualcomm stadium. I max out the regen to 30kW in ECO mode simply by coasting down the hill. Sometimes I have to use the brakes to stop at the bottom, but 30 kW is all you get....

ttoshi said:

I live on top of a hill and am curious how much juice we will need to consume to get home. At the end of my trip I will need to climb about 1000 ft in 2 miles. Has anyone climbed roughly 1000 ft in elevation and how much energy did that require?

Click to expand...

We're in the same situation, (are we neighbors?) We've been using approximately one blue segment to make it up our hill, figure 2 kWh. As long as we have at least two blue segments at the bottom, I have no worries about making it home. Daily running around has been averaging 30-35 miles, usually with two trips up the hill. We charge to 80% and use ECO on the way down for max regen. I can usually get 20 kW of regen going down the hill, holding steady at 40-45 MPH. Energy consumption on the way up is 35-40 kW, so we're getting roughly 50% of the energy back.

Achieving regen at the rate of 20-30 kW seems pretty good. For comparison, regen on the Gen II Prius maxes out at 20 kW, and the Gen III Prius rate is likely a bit higher. Given "room" in the battery and a long mountain descent (say 5000'), it seems that 20-30 kW should generally be sustainable without overheating the battery, as that's a lower charge rate than a DC Fast Charge. I wonder who's going to be first to try this. ;-) Getting up a mountain would of course be the prerequisite... :lol:

sproqitman said:

We charge to 80% and use ECO on the way down for max regen. I can usually get 20 kW of regen going down the hill, holding steady at 40-45 MPH. Energy consumption on the way up is 35-40 kW, so we're getting roughly 50% of the energy back.

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Are you going the same speed (40-45 MPH) on the way up? Otherwise, it will take a longer time and you are using more than twice as much energy going up than going down. I am surprised to hear a figure of 50%, as I thought about 30% was all you would get from the regen. I assume there is a KW reading somewhere on the dashboard (haven't followed that part)?

abasile said:

Achieving regen at the rate of 20-30 kW seems pretty good. For comparison, regen on the Gen II Prius maxes out at 20 kW, and the Gen III Prius rate is likely a bit higher. Given "room" in the battery and a long mountain descent (say 5000'), it seems that 20-30 kW should generally be sustainable without overheating the battery, as that's a lower charge rate than a DC Fast Charge.

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Yes, the problem with the Prius is that the battery is so small it fills up from 3/4 full to completely full in about 2 minutes of steep downhill. We take my brother's Gen 3 Prius up Mt. Baldy almost every weekend, and end up using the extra energy to run the AC at full blast if it is hot outside, since it will go to waste anyway. I would love to see how the Leaf does going up Baldy and back.

Stoaty said:

Yes, the problem with the Prius is that the battery is so small it fills up from 3/4 full to completely full in about 2 minutes of steep downhill.

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In the Prius, the key is to use "stealth" EV mode (or full-on EV mode) to run down the battery as much as possible before descending. If I do that in our Gen 3, I can descend up to 1000' in elevation on curvy mountain roads (not as steep as Mt. Baldy Rd., which I know well) before the battery fills. Mt. Baldy Rd. would be an awesome test for the LEAF!

abasile said:

In the Prius, the key is to use "stealth" EV mode (or full-on EV mode) to run down the battery as much as possible before descending. If I do that in our Gen 3, I can descend up to 1000' in elevation on curvy mountain roads (not as steep as Mt. Baldy Rd., which I know well) before the battery fills.

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What is "stealth" EV mode for the Prius and how do I invoke it?

Stoaty said:

Are you going the same speed (40-45 MPH) on the way up? Otherwise, it will take a longer time and you are using more than twice as much energy going up than going down. I am surprised to hear a figure of 50%, as I thought about 30% was all you would get from the regen. I assume there is a KW reading somewhere on the dashboard (haven't followed that part)?

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Going roughly the same speed both directions. I'm using the Energy Display in the nav system. It's far from exact, since it doesn't have a numeric readout. I'm estimating based on the position of the "needle".

Stoaty said:

What is "stealth" EV mode for the Prius and how do I invoke it?

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Roughly speaking, a Prius is in "stealth" when the gas engine (ICE) is off and all propulsion is coming from electricity, even if you haven't selected "EV Mode". Go into ECO Mode and stay to the left of center in the hybrid system "bar" display. There's *much* more info on PriusChat, i.e., http://priuschat.com/forums/gen-iii-2010-prius-technical-discussion/63093-hybrid-system-indicator-stealth-1.html.