2011 Leaf brake question - long downhill drive from home

Hi,

I'm new to the forum, although we've had our 2011 Nissan Leaf SV for about a year now.

We just towed the Leaf 1000 miles to our primary residence, which is located at 4000' elevation, and about 10 miles from our nearest town (which is 600' elevation). We installed the 220V charger in our home, and everything works fine. But here is the interesting question. We usually end up leaving the mountains (home) with a full charge. We then descend 10 miles of fairly steep gradient down to town, with no engine braking (regen) to assist. Basically, I think we are putting a lot of wear on the brakes. For all our gas cars we gear down so we don't have to brake so much . . . but the Leaf doesn't really do that (except for regen) so I have to ride the brakes to town.

I'm not sure really what to do. I set up 80% charging, but (a) regenerative braking doesn't work all that great, for me at least, at 80% charge, (b) with 80% charge it doesn't slow you down very much, and (c) then I arrive in in town without much more charge than I left with. And we definitely need the charge to get home...

So I guess my question is whether I'm completely abusing the brakes and should be concerned? Or whether I should just have them periodically checked for wear? Thoughts? Is there an alert when the brake pads get worn down?

Thanks in advance!

Brian

Can you charge to (much?) less than 80% to start?
Might take a few tests to see where you should start your trip to get the best balance between Regen and Charge.

desiv

It also depends on what level of battery degradation you have and if you had the P3227 update done. Both will decrease regeneration, sometimes substantially...

platbr said:

...Is there an alert when the brake pads get worn down?
...

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I don't think so.
Probably just the horrible metal against metal dragging that most disc brakes make when the pads are shot.
Usually before the rotors are destroyed, but sometimes not.

Someone with more mountain experience will have to answer other part.
But most that live on a mountain have stated there is no good solution.
My house is at 1000 foot, exit roads around 400 feet.
But you are right at 80% there isn't much regen.
Especially as you lose capacity, battery resistance increases, or if it is cold or after P3227.
With capacity degradation I now just do 100%.

Note: It isn't an engine. It is motor regenerative braking.

desiv said:

Can you charge to (much?) less than 80% to start? Might take a few tests to see where you should start your trip to get the best balance between Regen and Charge.

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At some point we wouldn't have enough charge to get home . . . so my wife is not enthusiastic about charging to less than 80%. The regen on the hill was *much* less than I was expecting, although it was better than driving down with a full battery.

TomT said:

It also depends on what level of battery degradation you have and if you had the P3227 update done. Both will decrease regeneration, sometimes substantially...

Click to expand...

Battery degradation is not apparently bad, yet (19k miles on the car) . . . although my comparison universe consists of a single data point. I have no idea of the P3227 update.

Check out this thread: http://www.mynissanleaf.com/viewtopic.php?f=31&t=3512" onclick="window.open(this.href);return false;

platbr said:

Hi,

I'm new to the forum, although we've had our 2011 Nissan Leaf SV for about a year now.

We just towed the Leaf 1000 miles to our primary residence, which is located at 4000' elevation, and about 10 miles from our nearest town (which is 600' elevation). We installed the 220V charger in our home, and everything works fine. But here is the interesting question. We usually end up leaving the mountains (home) with a full charge. We then descend 10 miles of fairly steep gradient down to town, with no engine braking (regen) to assist. Basically, I think we are putting a lot of wear on the brakes. For all our gas cars we gear down so we don't have to brake so much . . . but the Leaf doesn't really do that (except for regen) so I have to ride the brakes to town.

I'm not sure really what to do. I set up 80% charging, but (a) regenerative braking doesn't work all that great, for me at least, at 80% charge, (b) with 80% charge it doesn't slow you down very much, and (c) then I arrive in in town without much more charge than I left with. And we definitely need the charge to get home...

So I guess my question is whether I'm completely abusing the brakes and should be concerned? Or whether I should just have them periodically checked for wear? Thoughts? Is there an alert when the brake pads get worn down?

Thanks in advance!

Brian

Click to expand...

Are you driving in regular D mode or Eco mode? I don't know if the 2011 has the B mode or not, but Eco mode is suppose to increase the regen braking, at least it does on the 2013 S model I have.

knightmb said:

Are you driving in regular D mode or Eco mode? I don't know if the 2011 has the B mode or not, but Eco mode is suppose to increase the regen braking, at least it does on the 2013 S model I have.

Click to expand...

The 2011 has just D and Eco (no "B" mode). But when you're fully charged or nearly charged . . . neither D or Eco or brake pedal does any regen braking.

The gauge at the top of the dashboard display (the "bubbles") will tell you how much regen the car is willing to let you use. The regen bubbles (the ones to the left) will show a single circle (instead of a double circle) around the "disallowed" ones. You can't light up the disallowed bubbles, even by pressing the brake. The amount allowed changes with prevailing conditions. At 100% charge, none are available. When your car was new, all were available from 80% charge and down. (Except in cold weather). With the degrading battery, and probably that firmware update (P3227), things will be worse. And they take away regen at higher speeds, too.

When regen is available, pressing the brake will add in any that it's not calling for. But after that...friction brakes. By the way, that horrible screeching Tim Lee mentioned is the warning--it's a feature built into the brake pads.

platbr said:

our primary residence, which is located at 4000' elevation, and about 10 miles from our nearest town (which is 600' elevation)
...
I set up 80% charging, but (a) regenerative braking doesn't work all that great, for me at least, at 80% charge, (b) with 80% charge it doesn't slow you down very much, and (c) then I arrive in in town without much more charge than I left with. And we definitely need the charge to get home...

Click to expand...

How fast is the road up/down from your home, and how much driving do you do while in town?

3500' of climbing uses around 5.25 kWh of energy (about 1.5 kWh per 1000 ft of climbing is a good rule of thumb). With one bar lost, you probably have around 10.5 kWh usable from 80% to the first low battery warning (let's assume you start back up the hill at around 80% charged). So that leaves you over 5 kWh to travel 10 miles which is a piece of cake - you could go twice as far before you get the first LBW which would still leave you with at least another 10 miles of range before turtle.

So I'm curious - why do you think you need the extra range to get home?

+1^ You may just be worried needlessly. It helps if you get Leaf Spy, and learn exactly how many GIDs you have left to drive on.

Definitely leave the house at or under 80%, in ECO. A light touch on the brake pedal will give more regen before the physical brakes activate, IIRR.

No place to charge in town?

I would do some test runs. Try to measure how much capacity you lose on the drive up the mountain. Do a few runs so that you can have confidence in how stable the result is. Then, do a few runs down the mountain starting with different amounts of charge. Try to find out what's the minimum you can start with and still arrive at the bottom of the mountain with enough to get back. Hopefully the minimum (X) will be significantly below 80%. Then maybe make a habit of charging to half way between X and 80 when at home on the mountain.

edit: I wouldn't be too concerned about overuse of brakes. Replacing brake pads isn't expensive, and there is almost surely a warning of some kind telling you to do it. If not, get some wheels with enough space between the spokes to check by eye.

Driving down a sizable mountain and then back up again is definitely one of the more challenging use cases for the LEAF, given its lack of automatic charge settings below 80%, its "excessive" limits on regenerative braking, and its sub-Tesla battery size.

Relying mostly on friction braking for our mountain descent (4900') turned out over time to not be feasible. Once the brake pads heat up, the car tends to shake violently when braking. Perhaps the rotors are a bit warped. Our local mechanic (on the mountain) doesn't see anything obviously wrong, though. Needless to say, we do everything possible to avoid allowing the brakes to heat up, even if that means stopping a couple of times on the descent to let them cool down. Descending at a lower state of charge helps the regen in a major way, but as you stated, you then have to make sure to have enough charge to return home unless it is feasible to charge somewhere.

In warmer weather, your off-mountain drive is short enough that it should be a piece of cake if you leave home with maybe 60% charge. To minimize friction braking, drive as slowly as you can get away with on the descent, as the LEAF has an inexplicable, much-hated software bug that reduces regen as you drive faster. Even apart from that bug, basic physics and chemistry dictate that more of your "potential energy" should be able to be put back into the battery if you descend more slowly. The optimal speed is probably about 20-25 mph, but even if 40 mph is the slowest you can go, that is still a lot better than 55 mph. Our mountain road has turnouts so that I can let others pass.

Once you learn how much energy is needed for the ascent, don't be afraid to arrive home with a low battery warning. With our mountain climb, which 20+ miles and 5000' above the nearest public charging stations, arriving home with a low battery warning is par for the course, but your situation should be easier. If you find yourself running a little lower on charge than usual, then the general solution is to slow down.

Your biggest challenge will be when the battery is cold, regen is more limited than usual, and a larger percentage of your charge is needed for the return climb. In those conditions, I personally prefer to tough it out, but my wife will just drive a different car. I can't blame her for wanting to do better than just barely make it home, or have to sit and charge somewhere.

drees said:

How fast is the road up/down from your home, and how much driving do you do while in town?

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Speed limit is about 50mph the whole way. But the distance (10 miles) is really just to the edge of town. It's another ~4-5 miles through town to get to my children's school, and frequently we'll need to do things at some of the business centers that are on the other side of town.

drees said:

3500' of climbing uses around 5.25 kWh of energy (about 1.5 kWh per 1000 ft of climbing is a good rule of thumb). With one bar lost, you probably have around 10.5 kWh usable from 80% to the first low battery warning (let's assume you start back up the hill at around 80% charged). So that leaves you over 5 kWh to travel 10 miles which is a piece of cake - you could go twice as far before you get the first LBW which would still leave you with at least another 10 miles of range before turtle.

So I'm curious - why do you think you need the extra range to get home?

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I think your mileage calculations are spot on. It seems like ~4+ bars to get home, depending on how aggressively you drive up the hill. I don't think we need the extra range . . . and probably the best thing to do is just charge to 80%. One good thing is that where we live electricity is almost free (fixed price at $0.027 per kWh) so most of the chargers in town are free.

Perhaps charging to just 80%, and slower driving down the hill would maximize the regenerative braking, as well. My wife is still new to the Leaf and has pretty bad range anxiety . . . but I suppose we'll work through that in time.

abasile said:

Driving down a sizable mountain and then back up again is definitely one of the more challenging use cases for the LEAF, given its lack of automatic charge settings below 80%, its "excessive" limits on regenerative braking, and its sub-Tesla battery size.

Relying mostly on friction braking for our mountain descent (4900') turned out over time to not be feasible. Once the brake pads heat up, the car tends to shake violently when braking. Perhaps the rotors are a bit warped. Our local mechanic (on the mountain) doesn't see anything obviously wrong, though. Needless to say, we do everything possible to avoid allowing the brakes to heat up, even if that means stopping a couple of times on the descent to let them cool down. Descending at a lower state of charge helps the regen in a major way, but as you stated, you then have to make sure to have enough charge to return home unless it is feasible to charge somewhere.

In warmer weather, your off-mountain drive is short enough that it should be a piece of cake if you leave home with maybe 60% charge. To minimize friction braking, drive as slowly as you can get away with on the descent, as the LEAF has an inexplicable, much-hated software bug that reduces regen as you drive faster. Even apart from that bug, basic physics and chemistry dictate that more of your "potential energy" should be able to be put back into the battery if you descend more slowly. The optimal speed is probably about 20-25 mph, but even if 40 mph is the slowest you can go, that is still a lot better than 55 mph. Our mountain road has turnouts so that I can let others pass.

Once you learn how much energy is needed for the ascent, don't be afraid to arrive home with a low battery warning. With our mountain climb, which 20+ miles and 5000' above the nearest public charging stations, arriving home with a low battery warning is par for the course, but your situation should be easier. If you find yourself running a little lower on charge than usual, then the general solution is to slow down.

Your biggest challenge will be when the battery is cold, regen is more limited than usual, and a larger percentage of your charge is needed for the return climb. In those conditions, I personally prefer to tough it out, but my wife will just drive a different car. I can't blame her for wanting to do better than just barely make it home, or have to sit and charge somewhere.

Click to expand...

Thanks for this -- your response is a great guideline re: mountain driving. Very helpful, and very much appreciated. I've noticed the car "shaking," as you put it, when the brakes heat up from the descent. However, I've also noticed that with the brakes on our other cars, as well. Braking doesn't seem to be much impacted, though . . . just shaking!

I think this is probably going to be a fine solution: (1) charge 80%, (2) go more slowly down the hill, and (3) charge in town when needed. Multiple free 220v charging locations next to great shopping and restaurants makes this an easy use case. And if I keep it slower on the descent -- as you advise -- then the regen will be more effective. All good suggestions, and very much appreciated!

platbr said:

...One good thing is that where we live electricity is almost free (fixed price at $0.027 per kWh) so most of the chargers in town are free.
...

Click to expand...

Are you sure about that?
2.7 cents per kWh?
I didn't think it was that cheap anywhere in the US?
Is that the commercial or industrial power usage rate, and then there is a very large demand charge based on the highest kW demand for the month, or in some cases installed capacity, varies a lot among utilities?

gbarry42 said:

The gauge at the top of the dashboard display (the "bubbles") will tell you how much regen the car is willing to let you use. The regen bubbles (the ones to the left) will show a single circle (instead of a double circle) around the "disallowed" ones. You can't light up the disallowed bubbles, even by pressing the brake....

Click to expand...

Wow, I learn something new everyday. I never noticed that before, but I guess because it is so subtle to notice 1 circle instead of 2. Seems like it would have made more sense to just darken the whole circle to give a visual cue that regen to that level is not available yet. Great tip!

TimLee said:

Are you sure about that?
2.7 cents per kWh?
I didn't think it was that cheap anywhere in the US?
Is that the commercial or industrial power usage rate, and then there is a very large demand charge based on the highest kW demand for the month, or in some cases installed capacity, varies a lot among utilities?

Click to expand...

Yup, it's that cheap (almost free). Just 2.7 cents flat rate residential. Link: http://www.chelanpud.org/rates.html" onclick="window.open(this.href);return false;

platbr said:

Yup, it's that cheap (almost free). Just 2.7 cents. Link: http://www.chelanpud.org/rates.html" onclick="window.open(this.href);return false;

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That wonderful free renewable fuel hydropower
82% of electric power provided is hydropower
Of course there is that $7.70 per month service charge, which based on US annual average kWh use is a bit less than 1 cent per kWh for the service charge.
But yes really cheap.
An electric bill that is less than the water and wastewater bill in quite a few places.

platbr said:

I think this is probably going to be a fine solution: (1) charge 80%, (2) go more slowly down the hill, and (3) charge in town when needed.

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In your shoes I definitely would try leaving home with less than 80% charge. I think you'll be much happier with the regenerative braking that way. You can set up a charge timer with no start time and with an end time. Then try unplugging the car maybe 60-90 minutes before that end time. Of course, you'll probably want to experiment to see what works best for you. At least you have charging options down the hill, so you won't be stranded if you miscalculate.