Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24 KWh

[EVDRIVER]

I don't have the upgrade yet, and my display does not have that dial looking thing next to the energy economy meter, the part on the right takes up my entire display, is that a new change that I missed?

 

[Ingineer]

...
I would appreciate guys if you give me any reasonable explanation.

I just explained why this is a few posts ago. No big mystery here!

-Phil

 

[Stoaty]

I just explained why this is a few posts ago. No big mystery here!

Yes, but we don't like that explanation, even though it is probably right! We want an explanation that shows Nissan is trying to fool us. :lol:

 

[Ingineer]

I just explained why this is a few posts ago. No big mystery here!

Yes, but we don't like that explanation, even though it is probably right! We want an explanation that shows Nissan is trying to fool us. :lol:

Ahh, ok, then this isn't the post you're looking for! :lol:

-Phil

 

[GeekEV]

I don't have the upgrade yet, and my display does not have that dial looking thing next to the energy economy meter, the part on the right takes up my entire display, is that a new change that I missed?

That dial thing is what shows up when you turn on cruise control. The existing display reformats to take up less space on the right and that cruise control indicator appears. It's not some tricky new thing after the update. :lol:

 

[EVDRIVER]

I don't have the upgrade yet, and my display does not have that dial looking thing next to the energy economy meter, the part on the right takes up my entire display, is that a new change that I missed?

That dial thing is what shows up when you turn on cruise control. The existing display reformats to take up less space on the right and that cruise control indicator appears. It's not some tricky new thing after the update. :lol:

Thanks, I won't be seeing it then.

 

[Herm]

Guys, keep in mind the battery is not a "perfect tank" like a gas tank is. There is a phenomenon called "Peukert's Law" that allows a mathematical model to constructed of the battery to show how this non-linearity works.
-Phil

The efficiency of lithium-ion is about 99% within 80% of the SOC, driven in a moderate way obviously.
Its about time someone instrumented the cables coming out of the battery so we would know for sure..

 

[Boomer23]

I would appreciate guys if you give me any reasonable explanation.

First off, if you drove until your battery was drained, you'd likely get more than the 4 miles shown on the dash. When I ran mine down to turtle it ran 8 miles until turtle showed up after 4 miles showed on the dash. So maybe you'd get 70.5 plus 8 = 78.5.

78.5 miles / 4.9 miles/kWh = 16.0 kWh

Then, your math is wrong. You can't add 20% of the kWh at 80% charge to calculate your theoretical kWh at 100% charge. You're taking 20% of the wrong figure. Instead, you take your kWh at 80% charge and divide by 0.8.

So 16 / 0.8 = 20 kWh at full charge.

It's not 21, but it's not 18 either.

 

[jason98]

So 16 / 0.8 = 20 kWh at full charge.

It's not 21, but it's not 18 either.

Thanks, seems reasonable to me. Good catch, should have added 25% not 20.
But questions still remain:

-No matter how hard I try (no a/c, low speed, no head lights), I can't seem to go over 100 mile range, and according to Nissan I should be able to get it. That was one of the selling points for me.
-Why is the range always too optimistic after recharge? I believe they use some kind of average over the last few miles (which again I have consistently about 5 miles per kwh).

Also I would like to hear from you guys how the average economy translates to the total range.
Mines seems pretty consistent:

5 miles per kwh -> 100 miles range.

 

[Smidge204]

I think the problem with a lot of these calculations is, they rely on the output from the dashboard / Carwings which are suspected by many to be woefully inaccurate. I do believe it was concluded that if you run the battery down as far as you can, it will suck up ~24kWh of juice upon recharging to 100% as measured externally to the vehicle. It was then concluded that the customer available capacity is 24kWh and the total pack capacity is slightly more to provide a buffer.

In other words, don't rely the car's reported mi/kWh or remaining range indications for calculations.
=Smidge=

 

[EVDRIVER]

I think the problem with a lot of these calculations is, they rely on the output from the dashboard / Carwings which are suspected by many to be woefully inaccurate. I do believe it was concluded that if you run the battery down as far as you can, it will suck up ~24kWh of juice upon recharging to 100% as measured externally to the vehicle. It was then concluded that the customer available capacity is 24kWh and the total pack capacity is slightly more to provide a buffer.

In other words, don't rely the car's reported mi/kWh or remaining range indications for calculations.
=Smidge=

Based on your definition that is not "usable"capacity. Since there are no actual claims it is only more Nissan double speak. The Ah rating is 27kwh in the system based on Consult. Total usage may also be capped based on temp and other factors on each drive to protect the pack. Who knows what the car does with the regen number, even if one goes right to the pack they would need to turn off regen, charge to 100% and drive to where the car stops to get a good number. Easy to do on a DC conversion but more difficult here as subtracting regen and recharge efficiency is not 100% accurate but a good estimate. Even an E meter on the pack would get this info. It sure does not look like there is 24kw usable as a Nissan exec has boasted in public.

 

[Smidge204]

Who knows what the car does with the regen number, even if one goes right to the pack they would need to turn off regen, charge to 100% and drive to where the car stops to get a good number. Easy to do on a DC conversion but more difficult here as subtracting regen and recharge efficiency is not 100% accurate but a good estimate. Even an E meter on the pack would get this info. It sure does not look like there is 24kw usable as a Nissan exec has boasted in public.

And boasted to the federal government, it seems.

Response to EPA FOIA Request

I'm not really interested in white-knighting for Nissan, but to claim the battery pack is smaller than claimed is simply wrong. On the other hand, we know the car's software is bugged six ways from Sunday... and since the only tool the average owner has to estimate the battery pack capacity is the output of the software it's reasonable to say the average owner will get the pack capacity wrong through no fault of their own.

So I direct you to the link above, and more specifically this post in that thread, which shows the EPA got 110 miles city driving for a total used battery capacity of 24.47kWh and 95.7 miles highway driving using 24.56kWh. All the documentation from the EPA shows 24kWh capacity. So either we're facing false advertising-turn-conspiracy or you're simply mistaken. *shrug*
=Smidge=

 

[EVDRIVER]

So if we assume our software gives us the same kw access then a good drivers should be able to match those numbers. The issue is I don't think what is displayed is accurate at any point or I can;t be sure so there is no metric to measure from. At times my range has been better then the stated averages.

 

[Herm]

Thanks for the link on that FOIA report, very interesting.

Its time to actually measure the currents and voltages in the main battery cables.. we could get an exact handle on the actual charger efficiency, actual regen under all conditions and true usable battery capacity... not to say that I would love to see a display accurate to a 1/10 of a kwh as you drive.

 

[Herm]

Note that the epa cycles dont use particularly aggressive accelerations, but an experienced hypermiler can still beat the cycle schedule.

 

[evnow]

So I direct you to the link above, and more specifically this post in that thread, which shows the EPA got 110 miles city driving for a total used battery capacity of 24.47kWh and 95.7 miles highway driving using 24.56kWh. All the documentation from the EPA shows 24kWh capacity. So either we're facing false advertising-turn-conspiracy or you're simply mistaken. *shrug*
=Smidge=

You are getting confused between charge at the wall and the battery capacity. They are different.

So, the amount of energy used to charge, we get 2 figures, in close agreement.

City : 24.47 kwh
Hwy : 24.56 kwh

If we assume a battery roundabout efficiency of about 85%, we get to a usable capacity of about 21 KWh.

As I said earlier, either the Leaf m/kwh is wrong or Leaf usable capacity is about 21 kwh.

 

[evnow]

Blink reports 507.47kWh used.
TED reports 503.931kWh used.
Carwings reports 302.4kWh used.

Blink and Ted are <1 % different. Carwings is 40% different. I know Carwings 'adds' the regen energy, but 40%????

To get the Carwings figure ignore the regen and just use the motor + accessories usage. It will be about 90% of your Blink figure - 450 kwh or so.

 

[Lopton]

You are getting confused between charge at the wall and the battery capacity. They are different.

So, the amount of energy used to charge, we get 2 figures, in close agreement.

City : 24.47 kwh
Hwy : 24.56 kwh

If we assume a battery roundabout efficiency of about 85%, we get to a usable capacity of about 21 KWh.

As I said earlier, either the Leaf m/kwh is wrong or Leaf usable capacity is about 21 kwh.

Exactly, people seem to think 24kwh of AC power from the wall can magically be perfectly converted to 24kwh of DC battery stored power, it's just not the case. There are losses in the charging process. This just further proves the point that we can't access the entire pack capacity (probably a good thing for battery life, but obviously a bad thing for range.)

-Matt

 

[planet4ever]

Exactly, people seem to think 24kwh of AC power from the wall can magically be perfectly converted to 24kwh of DC battery stored power, it's just not the case.

No, obviously not. But don't forget that Jimmydreams' TED monitor reported 25.6 kWh at the wall after he drove until just after turtle showed up. (My Experiments With Turtle)

If we assume 21 kWh usable, with 0.5 kWh of that in turtle mode, that gives 20.5/25.6 = 80% charging efficiency.
If, on the other hand, we assume 24 kWh usable, 23.5/25.6 = 91.8% charging efficiency.

I'm about as far from being a battery expert as it is possible to be, but my impression is that the experts who post on this board think the efficiency should be around 90%, and certainly no lower than 85%.

Ray

 

[Lopton]

Exactly, people seem to think 24kwh of AC power from the wall can magically be perfectly converted to 24kwh of DC battery stored power, it's just not the case.

No, obviously not. But don't forget that Jimmydreams' TED monitor reported 25.6 kWh at the wall after he drove until just after turtle showed up. (My Experiments With Turtle)

If we assume 21 kWh usable, with 0.5 kWh of that in turtle mode, that gives 20.5/25.6 = 80% charging efficiency.
If, on the other hand, we assume 24 kWh usable, 23.5/25.6 = 91.8% charging efficiency.

I'm about as far from being a battery expert as it is possible to be, but my impression is that the experts who post on this board think the efficiency should be around 90%, and certainly no lower than 85%.

Ray

True, and good point, one of my other thoughts was that the power goes through another DC->AC conversion from the battery to the motor, wonder which side of that conversion they are measuring the "power used by traction motor", because that is another efficiency hit.

-Matt