The true cost of ECO

Well, seeing few Leafs drop as much as 15% capacity in a year, made me think... What is the true cost of driving in ECO? obviously it saves some electricity, but is it saving you money if it degrades your battery faster?
Just think about driving in hilly area, when you drive 5 mins downhill, then uphill, then 5 mins downhill again, on those 5 min downhill stretches you can put as much energy to the pack as level 3 charging. and if you doing it while you are at 80% battery level, is it as damaging as topping off after 80% using QC multiple times? Which is worst case scenario for the battery AFAIK, especially if the pack will be heated by going both uphill (due to high consumption) and downhill (due to high regen).
So, the $10,000 (the possible cost of pack replacement in the future ) question is, should we use ECO always, sometimes or never?

On a related note, does anyone knows if Leaf high-voltage bus is working in parallel or in sequence in terms of consumption/regen? I mean if I run heater at 6kW, will my regen power go to heater first and battery will be used to provide delta if it is not enough, or all regen will go to battery somehow and heater will use 100% power from the battery? I know that the latter is counter-intuitive, and I actually don't know how it can be done physically, unless you do some kind of high-frequency switching or something, but why I contemplating this is because I have noticed that if you have 100% charge, crank up heater and press brakes, there's NO regen...
I would expect 6kW going to the heater even if battery is full, but I don't see that happening according to leaf's energy monitor

I would think any of that would be offset by the gentler use of the battery. Not only that, but added range is always a good thing.

adric22 said:

I would think any of that would be offset by the gentler use of the battery. Not only that, but added range is always a good thing.

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What do you mean exactly by offset?
I have those hills on my daily commute...

Regen only does like 30 kW right? You can pull a heck of a lot more out of the battery in normal drive mode.

Would everybody PLEASE CALM DOWN. Take a 'Lude (or I guess the modern equivalent is 'Take a Val (ium)' ).

Why the heck is anyone thinking that ECO is bad for the battery? What EVIDENCE is there ANYWHERE that this is true? If anything there is logical evidence that regen has NO EFFECT on capacity as it follows known conservative charging tactics: there is little or no regen over 11bars, the regen is very low when active and scales back starting at 10bars. One can see that right on the dash (double circles on the regen side disappear as the battery gets beyond 10bars). Yes there has been talk that 'topping off' is bad, but you are not going to go from 11 to 12 bars on regen, it doesn't happen, you can feel the car begin glide faster down hill as you get to 11bars.

From ICE owners I expect to hear things like "I changed tires on my LEAF and my battery lost capacity", "Watch out if you replace the wiper blades on one of those EV's you'll loose 15% of your range" or "If you don't use premium gas in your LEAF you'll loose battery capacity" but not from LEAF drivers on MNL. However after reading MNL the last few days I'm not sure what kind of hysterical stuff I'm going to read.

The true cost of ECO is that you can't accelerate as fast or coast as far. End of story.

I agree with the previous post. Nissan actually recommends driving in ECO:

"NISSAN recommends you use the following driving and charging habits, where possible, to help maximize the battery's useful life:

...

Use of ECO mode."

[2011 Revised LEAF manual, at p. EV-23.]

UkrainianKozak said:

Just think about driving in hilly area, when you drive 5 mins downhill, then uphill, then 5 mins downhill again, on those 5 min downhill stretches you can put as much energy to the pack as level 3 charging.

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This is a non-issue. I drive over Sepulveda Pass on 405 freeway in L.A. 4 days a week. From memory, 1300 feet up one side, 700 feet down the other side, then reverse that when going home. Here is my typical regen:

Going down the shorter, but steeper side with speed set at 60 MPH: 15-20 Kw regen for perhaps 2 minutes (battery is already down to 70% or less by the time I get there anway)
Going down the longer, but less steep side at 52 MPH: regen is 3-10 Kw depending on the exact portion of the freeway.

Neither of these is anywhere close to L3, and are for pretty short periods of time anyway.

The people who have steep, prolonged downgrades at the beginning of their drive (e.g., abasile) don't charge as much before the trip so they can get the energy back from regen. Abasile recently reported something like 280 Gids for a 100% charge after about a year of owning his Leaf. Of course, he has those cool mountain temperatures, but also probably puts more stress on the battery going back up the mountain 6600 feet.

UkrainianKozak said:

On a related note, does anyone knows if Leaf high-voltage bus is working in parallel or in sequence in terms of consumption/regen? I mean if I run heater at 6kW, will my regen power go to heater first and battery will be used to provide delta if it is not enough, or all regen will go to battery somehow and heater will use 100% power from the battery?

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Power does not go anywhere "foirst".. its all tied together at the high voltage bus and current flows according to ohms law. Think of it as a complicated sprinkler system and how the water flows

Your question about ECO is very interesting, my guess is that only Nissan knows, and only if they bothered to create a good computer model taking all that into account. They might not have bothered checking for it.

padamson1 said:

The true cost of ECO is that you can't accelerate as fast or coast as far. End of story.

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This is incorrect. You get exactly the same power output (80kW) in eco mode. You just have to put the "pedal to the metal" to get it. Once you do, acceleration will be identical.

Also I find it easier to find the "coast spot" on the accelerator pedal when in eco. In D, the accelerator pedal is much too "nervous" for me.

Well, first of all I think everybody IS calm. I haven't seen anyone who thinks that ECO is bad for a battery, but I know that the battery have a limited charge/discharge cycles, so every charge/recharge cycle degrades the battery by some very small amount, so obviously coasting is better then regen for both efficiency and battery life.
What I'm trying to find out is if it is better to coast/brake on neutral on the hills or is it actually better to use regen, so you can capture energy that cost more than the fraction of the battery capacity lost. Basically if anyone knows if there's any research that gives more or less exact number of capacity loss for Leaf battery per 1kW of regen.
Basically, what is the difference between 1xConsume-1xCharge-1xConsume-1xCharge cycle and 1xConsume-rest-1xConsume-2xCharge cycle.
Or why is it Ok to regen for 5 mins at 30kW while you are at 80%SOC, and not Ok to use DC fast charger for 5 mins to get the same power? Leaf allows you full regen while at 80% SOC, but Nissan discourages even Level2 charging while at 80% SOC... so, what's the deal? Does it mean that 5 mins DC fast charging is Ok while at 80% SOC? What If I'm going down from the mountains and I'm at 80%SOC, is it bad for my battery if I'll use regen for 30 minutes while I'm going downhill?
I'm not trying to plant some panic, I'm just trying to perfect my driving habits so I can be as cost effective for my leaf as possible, taking in account both "battery economy" and energy economy. After all, the more mileage you get from Leaf's battery, the better for environment...

hmm, I'd have to say that the true cost of a nebulous battery warranty combined with claims that 15% loss in 1 year is "normal" is very naturally going to lead to some degree of hysteria. I don't blame people for being worked up and concerned, I put the blame squarely on Nissan for not handling this well. The longer Nissan stays silent, the more this mole hill will become a mountain.

padamson1 said:

Would everybody PLEASE CALM DOWN. Take a 'Lude (or I guess the modern equivalent is 'Take a Val (ium)' ).

Why the heck is anyone thinking that ECO is bad for the battery? What EVIDENCE is there ANYWHERE that this is true? If anything there is logical evidence that regen has NO EFFECT on capacity as it follows known conservative charging tactics: there is little or no regen over 11bars, the regen is very low when active and scales back starting at 10bars. One can see that right on the dash (double circles on the regen side disappear as the battery gets beyond 10bars). Yes there has been talk that 'topping off' is bad, but you are not going to go from 11 to 12 bars on regen, it doesn't happen, you can feel the car begin glide faster down hill as you get to 11bars.

From ICE owners I expect to hear things like "I changed tires on my LEAF and my battery lost capacity", "Watch out if you replace the wiper blades on one of those EV's you'll loose 15% of your range" or "If you don't use premium gas in your LEAF you'll loose battery capacity" but not from LEAF drivers on MNL. However after reading MNL the last few days I'm not sure what kind of hysterical stuff I'm going to read.

The true cost of ECO is that you can't accelerate as fast or coast as far. End of story.

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Please, George, let's not derail this into yet another whining thread of, "But I didn't read the fine print I was signing." UkrainianKozak has made some very good points here, and I believe they are worth thinking about. I'll admit my first reaction when seeing this thread title was, "What, that's crazy!" But the points do add up:

• Total cycle count
• Different impacts on the battery between charging and discharging rates
• Dramatic ramp-down of charging rate during Quick Charge
• The fact that 40kW regen (that's what Phil says the max is) is very close to 48kW QC max

To rebut that, ECO does encourage gentler acceleration, and Nissan does say ECO may "help maximize the battery's useful life." Perhaps really fast (80kW) discharge is even harder on the battery than sorta fast (40kW) charge. Who knows? It could turn out that the best way to prolong battery life is to avoid ECO but employ a very light foot.

Ray

+1!

padamson1 said:

Why the heck is anyone thinking that ECO is bad for the battery? What EVIDENCE is there ANYWHERE that this is true? If anything there is logical evidence that regen has NO EFFECT on capacity as it follows known conservative charging tactics.

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You have to use regen going down a hill, otherwise you would wear-out/ruin your brakes very quickly.

Herm said:

You have to use regen going down a hill, otherwise you would wear-out/ruin your brakes very quickly.

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Not only that.. but think about it. If you don't regen, then when you get home you'll plug the car in and recharge. Either way, the battery is going to complete the cycle whether that power comes from the wall or from regen. So I don't see how use of eco mode would in any way cause additional work for the battery.

I think that doing this calculation is rather over analysing the situation.

The car is designed specifically with regen in mind. Nissan say that ECO is the mode to use to maximise battery life and so why should they say that if it doesn't?

Not using regen may, and I mean MAY, save you something long term but by not using regen you WILL have more brake wear increasing your costs replacing brakes.

To be honest, it is a valid question but isn't this rather looking at it all more closely than is healthy?

In any case, the issue of battery replacement cost is always hugely exaggerated. No one can say how much it will cost when the time comes, if indeed it comes at all. There are two main reasons for this:

- the battery is not a single unit that must be replaced in a single block. There are 90 odd cells and each one can be tested and only the cells that are not performing need be considered for replacement. You never will need to replace the entire battery.

- Secondly, and this is probably even more relevent, none of the cells are likely to need replacing for many years and who know what the cells will cost y then. Battery tech is developing very fast and prices are dropping. I am totally convinced that when the time comes to replace cells the price will be considerably less than it would cost today.

Any talk of battery replacement cost today can only be misleading and to be honest, quite irrelevent IMO.

paulchurchley said:

The car is designed specifically with regen in mind. Nissan say that ECO is the mode to use to maximise battery life and so why should they say that if it doesn't?

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If you looked at the Tesla Roadster, the AC Propulsion eBox, the MINI-E,the ActiveE, and the upcoming i3, they all have one thing in common: very strong regen. The Leaf, even in ECO mode, is toned down compared to these vehicles. From a design perspective, this would not have been done if the batteries could not take it. Similarly with the Leaf, it was designed with QC in mind. While the manufacturer stayed cautious until they had about a year's worth of real-world data, Nissan is now recommending customers to QC liberally if needed.

To sum it up, I would not be worried about regen load on the battery. It's been designed for it. Another thing to keep in mind, when you step on the brake pedal, it will regen first, and the mechanical brake will engage later. The only way you could get around this is to coast to a stop, and that's not a way to drive a car. For most people and most of the time anyway.

paulchurchley said:

In any case, the issue of battery replacement cost is always hugely exaggerated. No one can say how much it will cost when the time comes, if indeed it comes at all. There are two main reasons for this:

- the battery is not a single unit that must be replaced in a single block. There are 90 odd cells and each one can be tested and only the cells that are not performing need be considered for replacement. You never will need to replace the entire battery

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I agree with your post in general, but on this specific point I would caution to say more precisely that you won't ever need to replace the entire battery......at any one single point in time. But obviously during the readonablyexpected lifespan of the chassis, it's likely that most if not every cell would have been replaced at some point. Assuming that you want the car to operate at specified range.

So you can certainly count on replacing the entire battery, just not in one big dramatic money-sucking surprise moment.

paulchurchley said:

I think that doing this calculation is rather over analysing the situation.

The car is designed specifically with regen in mind. Nissan say that ECO is the mode to use to maximise battery life and so why should they say that if it doesn't?

Not using regen may, and I mean MAY, save you something long term but by not using regen you WILL have more brake wear increasing your costs replacing brakes.

To be honest, it is a valid question but isn't this rather looking at it all more closely than is healthy?

In any case, the issue of battery replacement cost is always hugely exaggerated. No one can say how much it will cost when the time comes, if indeed it comes at all. There are two main reasons for this:

- the battery is not a single unit that must be replaced in a single block. There are 90 odd cells and each one can be tested and only the cells that are not performing need be considered for replacement. You never will need to replace the entire battery.

- Secondly, and this is probably even more relevent, none of the cells are likely to need replacing for many years and who know what the cells will cost y then. Battery tech is developing very fast and prices are dropping. I am totally convinced that when the time comes to replace cells the price will be considerably less than it would cost today.

Any talk of battery replacement cost today can only be misleading and to be honest, quite irrelevent IMO.

Click to expand...

It's true that the battery doesn't need to be entirely replaced. It is, also, true that we aren't certain that not driving in ECO mode will save the battery. But in my own calculations (careful, this can be a leap of faith at best) the cost of a set of brake pads every 100,000 miles is cheaper than a battery sector. I know that I would rather be safe than sorry, personally.

adric22 said:

Herm said:

You have to use regen going down a hill, otherwise you would wear-out/ruin your brakes very quickly.

Click to expand...

Not only that.. but think about it. If you don't regen, then when you get home you'll plug the car in and recharge. Either way, the battery is going to complete the cycle whether that power comes from the wall or from regen. So I don't see how use of eco mode would in any way cause additional work for the battery.

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According to what I've read here from battery experts, "cycles" are not really the number of times you charge the battery, but the number of times the total battery's capacity is added to it. So, from a cycle perspective, charging twice from 50% to 80% is the same as charging once from 20% to 80%. And using more regen does add to the cycle count.

But, back to Herm's point, and paulchurchley's related comment, I don't think anyone is trying to claim that mechanical braking is preferable to using regen. As surfingslovak just pointed out, when you press the brake pedal you first get regen, and only with more pressure do you get mechanical braking. This is true whether in D or ECO, though there is more regen there in D, because you used less of your "quota" when you took your foot off the accelerator. The argument for D over ECO in this context is that D is using the battery more gently when you limit or reduce your speed by releasing the accelerator. The counter argument is that, unless you use a very light foot, you put more demand on the battery in D when you accelerate.

Ray