where did the savings come from?

Had an interesting thing happen today.

Normally I charge my car to 100% and then drive to work. Its 98% highway. Its twenty miles and usually takes about 21-22% of the battery to get there.

Now I plugged my car in late last night, so I only had a 92% charge when I left for work, however, when I got there, I had only used 17% of the battery. I didn't drive any differently, and traffic was normal. Any ideas on why I might get a five percent difference? Is this just a measurement issue?

going to try charging to only 80% tomorrow and see what happens.

Depends how you drove the day before. If you drive fast you'll have less on the GOM. If you drive super ECO you'll have more on the GOM

Regen is disabled when the battery is full.

Lasareath said:

Depends how you drove the day before. If you drive fast you'll have less on the GOM. If you drive super ECO you'll have more on the GOM

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I'm not looking at the GOM, I'm looking at the percent of battery left.

Nubo said:

Regen is disabled when the battery is full.

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yes, but after driving half a mile It becomes available, that can't be making up a 5% difference.

Limey said:

Nubo said:

Regen is disabled when the battery is full.

Click to expand...

yes, but after driving half a mile It becomes available, that can't be making up a 5% difference.

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That depends on what you do in that first half mile.

Some clarification: regen is not disabled at 100%. It is just severely capped, and gradually increases as battery drops to about 90% SOC. I'm not quite sure how it would work if you started at 100% from a large hill…. It might actually reduce it to 0 at some point.

mctom987 said:

...Some clarification: regen is not disabled at 100%. It is just severely capped, and gradually increases as battery drops to about 90% SOC. I'm not quite sure how it would work if you started at 100% from a large hill…. It might actually reduce it to 0 at some point.

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While I can't speak for the newer LEAFs I will say that regen is zero on my car when it is near "100%" charge and that this is shown clearly by Leaf DD. My experience is that I can't ever regen my way back to anywhere close to "100%" by going down long steep hills, something I do every day. Perhaps that is something that Nissan improved on the newer LEAFs with B mode.

As you say, regen gradually increases as the SOC drops, assuming mild battery temperatures. At cold battery temperatures regen is severely limited, even at rather low SOCs of 30-40% (that may be less apparent in the newer LEAFs, don't know).

dgpcolorado said:

mctom987 said:

...Some clarification: regen is not disabled at 100%. It is just severely capped, and gradually increases as battery drops to about 90% SOC. I'm not quite sure how it would work if you started at 100% from a large hill…. It might actually reduce it to 0 at some point.

Click to expand...

While I can't speak for the newer LEAFs I will say that regen is zero on my car when it is near "100%" charge and that this is shown clearly by Leaf DD. My experience is that I can't ever regen my way back to anywhere close to "100%" by going down long steep hills, something I do every day. Perhaps that is something that Nissan improved on the newer LEAFs with B mode.

As you say, regen gradually increases as the SOC drops, assuming mild battery temperatures. At cold battery temperatures regen is severely limited, even at rather low SOCs of 30-40% (that may be less apparent in the newer LEAFs, don't know).

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well, I will give it a test tomorrow by only going to 80% and see what happens. It's going to be interesting if it is limited that much. Of course, Having full regen isn't going to make up for that extra 20% of that battery I could be using.

Limey said:

well, I will give it a test tomorrow by only going to 80% and see what happens. It's going to be interesting if it is limited that much. Of course, Having full regen isn't going to make up for that extra 20% of that battery I could be using.

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Really depends on your location, temperature, driving habits, and traffic conditions.
I try to charge to ~90% because of the above reasons. In fact, I've driven enough doing both to figure out that charging to 100% gives me the same range as charging to 90%. Why? Because I try to not use the brakes. With a high SOC, the regen is insufficient to stop, especially when a light turns red. This means ~100% of my kinetic energy is wasted in the friction brakes. At 55MPH, each stop wastes 1 mile of range if only friction brakes are used.

From my observations, the "percent battery available" on the dash is not linear. You would think that the difference between 20% and 30% would be the same energy as 70% to 80%, but it's not. They made it that way to give you an extra cushion of energy near 0. It's the same way that some older cars had a needle gas gauge that goes down to half way with very little driving but takes forever to get to empty.

Bob

I jump right on the freeway after leaving home. I never get very good energy economy between 100 percent and 90. Lets say, I average about 4.3 for the whole day... I reset my meter in the morning (100 percent charge), and it displays something like 3.5 for the first 10 miles. If I start at 80 percent, it goes right to 4.3.

Bob said:

From my observations, the "percent battery available" on the dash is not linear. You would think that the difference between 20% and 30% would be the same energy as 70% to 80%, but it's not. They made it that way to give you an extra cushion of energy near 0. It's the same way that some older cars had a needle gas gauge that goes down to half way with very little driving but takes forever to get to empty.

Bob

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I doubt that they made it that way on purpose. The main reason for accuracy issues with the %SOC gauge is that it is calculated from such things as battery pack voltage, and that varies with charge/discharge/resting conditions, temperature, and the like. The lack of accuracy of such a gauge was one reason that Nissan gave for not including it on the first LEAFs IIRC. So, my take on the variation in energy content of a percent SOC at different charge levels is that it is an artifact of how it is measured and calculated, as opposed to being deliberate. Measuring the SOC of a battery accurately is a hard thing to do.

johnrhansen said:

I jump right on the freeway after leaving home. I never get very good energy economy between 100 percent and 90. Lets say, I average about 4.3 for the whole day... I reset my meter in the morning (100 percent charge), and it displays something like 3.5 for the first 10 miles. If I start at 80 percent, it goes right to 4.3.

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Not so sure about that then, might just be gauge inaccuracy (real vs reported vs measured). As others have said, the meter is not perfectly linear. 80-70% is not the same energy as 30-20%.

Otherwise, the initial low mi/Kw hour can be attributed to kinetic energy. This is mostly because you spent so much energy getting up to speed. Basically, it takes ~250Wh to get to 65MPH. Assuming best case scenario, you just spent ~250Wh to go 1/10mi. This comes out to 0.0001mi/kWh. Absolutely horrible. Once you're going 65MPH, it only takes 18kW to maintain. This comes out to 3.6mi/kWh, for a total range of ~76mi. This is likely the reason the mi/kWh meter displays "---" for a mile or so after being reset.

all I know is that that first 10 percent goes away awfully fast!

Limey said:

Nubo said:

Regen is disabled when the battery is full.

Click to expand...

yes, but after driving half a mile It becomes available, that can't be making up a 5% difference.

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It's not a binary thing. After driving half a mile the regen is still severely limited. There is simply nowhere to put 40kW; it's simply too high a charge rate for a 100% full (or 99.5% full) battery, not to mention the risk of overcharging the pack.

mctom987 said:

...Basically, it takes ~250Wh to get to 65MPH. Assuming best case scenario, you just spent ~250Wh to go 1/10mi. This comes out to 0.0001mi/kWh.

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6 inches per kWh?

I think that would be 0.4 mi/kWh.

Nubo said:

6 inches per kWh?

I think that would be 0.4 mi/kWh.

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lol
Not sure how I goofed that one. Looks like I tried to divide twice…

Yes, 0.4mi/kWh

I was compzring my economy at 80 percent charge vs 100. All those things are the same in moth measurment scenarios.. the only difference is regen, and I canceled thar kut too by reseting tge indicator as soon as I hit the freeway. Still a substantial difference between 80 and 100

johnrhansen said:

I jump right on the freeway after leaving home. I never get very good energy economy between 100 percent and 90. Lets say, I average about 4.3 for the whole day... I reset my meter in the morning (100 percent charge), and it displays something like 3.5 for the first 10 miles. If I start at 80 percent, it goes right to 4.3.

Click to expand...

I do the same, from 100%, I use 2% to get to the freeway, rest of the trip is all freeway. But I don't really see any drain difference between being in the 90% range vs 80% (minus a hilly area in the beginning). Overall, I'm getting a little under a mile per percent while on the freeway.

Limey said:

Had an interesting thing happen today.

Normally I charge my car to 100% and then drive to work. Its 98% highway. Its twenty miles and usually takes about 21-22% of the battery to get there.

Now I plugged my car in late last night, so I only had a 92% charge when I left for work, however, when I got there, I had only used 17% of the battery. I didn't drive any differently, and traffic was normal. Any ideas on why I might get a five percent difference? Is this just a measurement issue?

going to try charging to only 80% tomorrow and see what happens.

Click to expand...

I'm finding the car is sensitive to other factors such as wind. My own one-way commute energy consumption floats in a range from as high as 42% to as low as 35%. Typically this averages out on the return trip. I noticed the higher consumption days are typically windy (either headwind or crosswind).