If you live on a hill..

If you live on a hill or mountain, and start your day driving mostly downhill, what would the Leaf do?

It can't use regenerative braking, since there's nowhere to put the energy if the batteries are already topped off. I imagine it would use the friction brakes instead?

You'd be much better off working at the top of a hill.

I live on a mountain (~6000' elevation) and the valley below is ~1000'.

Assuming I go through with purchasing a LEAF, I'm figuring I can stop charging the car at around 70% SOC. According to Nissan, I could limit the charge by limiting the duration of charging, though it would be nice to do this more automatically.

I will be very interested how well Leaf climbs 5000'

smkettner said:

I will be very interested how well Leaf climbs 5000'

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Same here! My estimate is that climbing the mountain will require about half of a full charge, or maybe somewhat less. I'm thinking it would be best to limit speed to 40mph while climbing the 5000' over 14 miles. And we only go down (and up) the mountain once or twice per week.

Thankfully, we can't order until January, which should allow time for some of the SoCal folks with December deliveries to try mountain climbing (ideally, CA Hwy. 330 to Running Springs) and let us know about it, if they could be so kind.

Buying a Prius instead of a LEAF remains a possibility.

Search. There was a long discussion on this issue.

abasile said:

Thankfully, we can't order until January, which should allow time for some of the SoCal folks with December deliveries to try mountain climbing (ideally, CA Hwy. 330 to Running Springs) and let us know about it, if they could be so kind.

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Sure, once I figure out how to get to Highland and back first.

I wonder if that's something that Fontana Nissan would be interested in participating in?

evnow said:

Search. There was a long discussion on this issue.

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Yes, I've already read the prior discussions, including the following on regen:
http://www.mynissanleaf.com/viewtopic.php?f=4&t=343

I'm more interested in real-world experience, which should be coming soon!

mwalsh said:

abasile said:

Thankfully, we can't order until January, which should allow time for some of the SoCal folks with December deliveries to try mountain climbing (ideally, CA Hwy. 330 to Running Springs) and let us know about it, if they could be so kind.

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Sure, once I figure out how to get to Highland and back first.

I wonder if that's something that Fontana Nissan would be interested in participating in?

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Thanks! I do intend to ask Fontana for a mountain test drive come December. They are my Preferred Dealer.

smkettner said:

I will be very interested how well Leaf climbs 5000'

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See http://www.mynissanleaf.com/viewtopic.php?f=24&t=309&p=6025

LEAFer said:

smkettner said:

I will be very interested how well Leaf climbs 5000'

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See http://www.mynissanleaf.com/viewtopic.php?f=24&t=309&p=6025

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Thanks for the link. Good potential energy calculation (though I read/studied it before).

Again, what we really need is some real world experience with the LEAF. Considering that many of us live in Western states with high mountains, I imagine that will come soon.

x2 on seeing actual experience, Noone has posted an actual drive up 5000' that I know of.

smkettner said:

x2 on seeing actual experience, Noone has posted an actual drive up 5000' that I know of.

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True ... we need actual experience. But there is data out there based on the last generation of EVs and the Tesla Roadster. Because the Roadster has such strong regen (recovery on downhill) and less weight, the Toyota RAV4EV probably comes closer to what the LEAF will be like. Below is a useful link with "sub-links" to additional data. And I highlighted a quote for the RAV4EV that ChadS points to.

http://www.teslamotorsclub.com/showthread.php/4238-Question-about-Tesla-range-in-the-mountains

from EVNut for RAV4EV:

Every 1000' of elevation consumes an extra 6-7% SOC. And if you return to your starting elevation, all but 2-3% of that SOC loss can be replaced.

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Since the RAV4's range is also about 100 miles, if we loosely apply this to the LEAF, 6% * 24kWh = 1.44kWh. This closely matches my PotentialEnergy calculation of 1.3kWh per 1,000 feet. (The RAV4EV is about 100lbs heavier than the LEAF and somewhat less aerodynamic. And because its NiMH battery is 28kWh it eats more energy in that EV; that's why I applied the % to the LEAF's battery capacity.)

Edit: remember, this predicted energy calculation attempts to estimate the ADDITIONAL energy needed to climb the 1,000 feet. You still have the normal energy expenditure for the distance traveled at whatever speed (and other conditions) as if on an equivalent flat stretch of road. (Which is why it does not matter what the degree of the incline is.)

I am unconcerned with regen going down. Just curious how many miles are actually lost on a drive climbing a sustained grade up 5000'
Yes I have read the calculations

Ok. Let me try "guessing". Closest guesstimate wins ... what ?

Assume 24kWh/100 miles (i.e. you are driving efficiently ... or LA4 cycle ... 240Wh/mile) on a flat stretch of roadway; this will probably be at 50-55mph (no wind conditions).

Most mountain passes are limited to 6% grade. This means a rise:run ratio of 1:16.666. So, a 5,000' climb would require 83,330 feet or 15.78 miles. The flat roadway would "eat" 15.78 miles.

The climb would eat 1.3kWh (from my previous prediction; 3,500lbs LEAF, incl. driver) per 1,000, or 6.5kWh for 5,000 feet. At 240Wh/mile (assumes the "calculator" in the LEAF is properly averaging) this 6,500Wh "eats" 27 miles.

Conclusion: you "use" 42.78, call it 43 miles of LEAF range to climb your 5,000 foot mountain.

(The 15.78 mile "flat" section distance needs to be adjusted for actual grade conditons.)


Edit: Minor error. Should be 83,480 feet (hypotenuse); but too minor to affect the result.

So it sounds like abasile's original estimate was right on the money.

abasile said:

My estimate is that climbing the mountain will require about half of a full charge, or maybe somewhat less.

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planet4ever said:

So it sounds like abasile's original estimate was right on the money.

abasile said:

My estimate is that climbing the mountain will require about half of a full charge, or maybe somewhat less.

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Well ... I'm only guesstimating. "Right on the money" will only be after someone actually does it in a LEAF. What were abasile's conditions ? ( I guess I should search for that quote ... )

(Never mind ... I'm getting tired ... it's on the first page. :roll: )

At least you will not lose performance as you gain altitute like a naturally asperated ICE.

GroundLoop said:

If you live on a hill or mountain, and start your day driving mostly downhill, what would the Leaf do?

It can't use regenerative braking, since there's nowhere to put the energy if the batteries are already topped off. I imagine it would use the friction brakes instead?

Click to expand...

The Leaf will not be able to handle all braking situations -- panic stops etc -- with regen. My guess would be that regen would be able to handle maybe .2g or .25g, nothing more. Therefore, like all BEVs, the Leaf will have friction brakes which not doubt can stop the car by themselves. But they'll be sized assuming regen is available, so the Leaf, like all BEVs, will leave a buffer in the SOC. The Leaf seems to be leaving 15%, which means you can live at the top of a very big hill and not worry about it.

But realistically, if you're living at the top of a really big hill (mountain), figure out how many kWh you'll get on regen and don't charge the battery fully. That way you won't have to pay for electricity you don't need.

SanDust said:

GroundLoop said:

If you live on a hill or mountain, and start your day driving mostly downhill, what would the Leaf do?

It can't use regenerative braking, since there's nowhere to put the energy if the batteries are already topped off. I imagine it would use the friction brakes instead?

Click to expand...

The Leaf will not be able to handle all braking situations -- panic stops etc -- with regen. My guess would be that regen would be able to handle maybe .2g or .25g, nothing more. Therefore, like all BEVs, the Leaf will have friction brakes which not doubt can stop the car by themselves. But they'll be sized assuming regen is available, so the Leaf, like all BEVs, will leave a buffer in the SOC. The Leaf seems to be leaving 15%, which means you can live at the top of a very big hill and not worry about it.

But realistically, if you're living at the top of a really big hill (mountain), figure out how many kWh you'll get on regen and don't charge the battery fully. That way you won't have to pay for electricity you don't need.

Click to expand...

The Leaf has standard brakes that work with regen. If you're still applying the brakes and the battery SOC is nearing 100%, why doesn't the regen simply stop and the manual brakes become 100% of your stopping/slowing power? That seems the easiest solution to me. I think people are over-thinking the problem!