2016-2017 model year 30 kWh bar losers and capacity losses

[SageBrush]

I looked at gross car weights:

The Nissan LEAF 2013 is 4193 pounds
The 2017 Model is 4431 pounds

I'm feeling too lazy to convince myself that the entire weight difference is the battery. Does anybody know ?

BTW, this is a nice article
https://qnovo.com/inside-the-battery-of-a-nissan-leaf/
Did Nissan increase the volumetric energy density for the 30 kWh LEAF ? That would be consistent with a higher weight in the same battery case, and it would also (I think) lead to more heat dissipation problems in a passive architecture like the LEAF battery

 

[lorenfb]

I looked at gross car weights:

The Nissan LEAF 2013 is 4193 pounds
The 2017 Model is 4431 pounds

I'm feeling too lazy to convince myself that the entire weight difference is the battery. Does anybody know ?

Significant changes in battery capacity typically result from adding more cells in parallel, i.e. indicative of a weight change.
As has been noted, tweaking the cell chemistry can result in added capacity per cell, but may result in negative effects,
e.g. volatile chemistry requiring TMS.

Note: Battery weight delta: original (24kWh) ~ 600lbs, new (30kWh) - +200lbs; 30% increase

 

[edatoakrun]

Gross weight is not vehicle weight.

All 2011 to 2017 LEAFs weigh about the same, reportedly from 3291 to 3391 Lbs:

https://en.wikipedia.org/wiki/Nissan_Leaf

 

[cwerdna]

If one wants to know vehicle weight, they should be looking at curb weight not GVWR.

 

[SageBrush]

Note: Battery weight delta: original (24kWh) ~ 600lbs, new (30kWh) - +200lbs; 30% increase

Let's see:
30% increase in battery weight,
25% increase in nominal capacity.

Hmmm .... ... ... ...

 

[lorenfb]

I looked at gross car weights:

The Nissan LEAF 2013 is 4193 pounds
The 2017 Model is 4431 pounds

I'm feeling too lazy to convince myself that the entire weight difference is the battery. Does anybody know ?

Significant changes in battery capacity typically result from adding more cells in parallel, i.e. indicative of a weight change.
As has been noted, tweaking the cell chemistry can result in added capacity per cell, but may result in negative effects,
e.g. volatile chemistry requiring TMS.

Note: Battery weight delta: original (24kWh) ~ 600lbs, new (30kWh) - +200lbs; 30% increase

In any case, even if the weight delta was incorrect, the majority of battery capacity increase most
likely came from added parallel cells.

 

[SageBrush]

As has been noted, tweaking the cell chemistry can result in added capacity per cell,

Can the added capacity occur without a commensurate increase in the (integrated over the charge cycle) cell voltage if the only change is a chemical one ?

Apologies in advance for my poorly phrased question

 

[lorenfb]

As has been noted, tweaking the cell chemistry can result in added capacity per cell,

Can the added capacity occur without a commensurate increase in the (integrated over the charge cycle) cell voltage if the only change is a chemical one ?

Apologies if my question is poorly phrased

Yes. That's the ideal case, i.e. you don't want the cell voltage increasing which then requires a total redesign of the motor & electronics.
You just want the Ahr of each cell to increase.

 

[Oils4AsphaultOnly]

We [Edit: I] know a change of chemical composition (maybe silicon was added?) is responsible for the increased capacity

Evidence ?
Did the car weight stay the same ?

Or ...
Is Nissan overcharging the battery ?!

I see you had revised the question while I was still writing my post.

A chemistry change would also change the volumetric density of the battery. So yes, you can have a weight change (without a corresponding volume change) with simply changing the chemistry.

 

[SageBrush]

We [Edit: I] know a change of chemical composition (maybe silicon was added?) is responsible for the increased capacity

Evidence ?
Did the car weight stay the same ?

Or ...
Is Nissan overcharging the battery ?!

I see you had revised the question while I was still writing my post.

A chemistry change would also change the volumetric density of the battery. So yes, you can have a weight change (without a corresponding volume change) with simply changing the chemistry.

Fair enough, although LorenFB seems to think that the weight change is mostly explained by more modules. That makes sense to me since I think that the 'chemistry changes' we read about are in the dopants, meaning that even even if the Molec weights being swapped are quite a bit higher, the overall battery weight would change little.

 

[lorenfb]

Gross weight is not vehicle weight.

All 2011 to 2017 LEAFs weigh about the same, reportedly from 3291 to 3391 Lbs:

https://en.wikipedia.org/wiki/Nissan_Leaf

So there was a 100lbs weight increase. Could a weight saving have been found in the 2017 to provide for
the additional needed weight of more cells versus a chemistry change? Even with more cells, there's
still the possibility of a chemistry change, e.g. cost.

 

[Oils4AsphaultOnly]

I see you had revised the question while I was still writing my post.

A chemistry change would also change the volumetric density of the battery. So yes, you can have a weight change (without a corresponding volume change) with simply changing the chemistry.

Fair enough, although LorenFB seems to think that the weight change is mostly explained by more modules. That makes sense to me since I think that the 'chemistry changes' we read about are in the dopants, meaning that even even if the Molec weights being swapped are quite a bit higher, the overall battery weight would change little.

Unlike the chemistry change, adding more modules requires having physically more space, and there hasn't been any signs showing that the new pack is physically larger, nor has there been any indications of more than 192 cells in a pack (or did I miss a post somewhere?).

As for the change in "dopants", a 10% change in molec weight in the electrolyte, anode, OR cathode, would translate to ~3.3% increase in pack weight. For a 900lb pack, that's ~30 lbs. Replacing C in the anode with Si, yields an increase of 150% in molec weight (just for illustrative purposes). When dealing with chemistry, the devil's in the details.

 

[edatoakrun]

Gross weight is not vehicle weight.

All 2011 to 2017 LEAFs weigh about the same, reportedly from 3291 to 3391 Lbs:

https://en.wikipedia.org/wiki/Nissan_Leaf

So there was a 100lbs weight increase..

No.

Go to the link you just posted. Weights varied between model years due to the many changes in the LEAF over time.

IIRC, it was reported that for the 2016 MY the "30 kWh" pack weighed ~40 lbs more than the "24 kWh" pack, but I wouldn't rely on that as a fact.

 

[SageBrush]

adding more modules requires having physically more space

Or not. The volumetric energy density of the 24 kWh LEAF pack is really low. Read the article I referenced earlier.

 

[Oils4AsphaultOnly]

[adding more modules requires having physically more space

Or not. The volumetric energy density of the 24 kWh pack is really low. Read the article I references earlier.

Not the same thing. The "volumetric energy density" is how much charge per unit volume (liters or gallons) of battery (cell or pack - different values, but same results). The internal volume of the battery pack however is fixed and should've been pretty much filled to the brim, otherwise passive thermal management through conduction won't work very well. Air is an insulator, so having less of it within the battery pack, the better (even for cold climates, because the cabin space is going to be warmer than ambient, so you'll want to insulate the bottom of the cells, not the top).

So unless the pack size/shape has changed, there's no way to fit more cells/modules into it.

 

[SageBrush]

Or not. The volumetric energy density of the 24 kWh pack is really low. Read the article I references earlier.

Not the same thing. The "volumetric energy density" is how much charge per unit volume (liters or gallons) of battery (cell or pack - different values, but same results). The internal volume of the battery pack however is fixed and should've been pretty much filled to the brim, otherwise passive thermal management through conduction won't work very well. Air is an insulator, so having less of it within the battery pack, the better (even for cold climates, because the cabin space is going to be warmer than ambient, so you'll want to insulate the bottom of the cells, not the top).

So unless the pack size/shape has changed, there's no way to fit more cells/modules into it.

From the qNuvo article (my bolding)

But for the added safety of the LMnO material, Nissan incurs some important penalties. First, the intrinsic energy density of the individual pouch is only about 320 Wh/L. Compare this to nearly 700 Wh/L for the Panasonic cells used by Tesla. Why does it matter? Energy density translates directly to range, and range, or rather lack of it, is right now the #1 challenge for electric vehicles. This is precisely why the Tesla pack weighs only twice more than the Leaf pack, yet delivers 3x more driving range.

Huh. What does 'intrinsic energy density of the pouch' refer to ? I agree that the pack looks pretty full but I don't think I have seen it all, and I don't know what the inside of a module looks like.

 

[Oils4AsphaultOnly]

Or not. The volumetric energy density of the 24 kWh pack is really low. Read the article I references earlier.

Not the same thing. The "volumetric energy density" is how much charge per unit volume (liters or gallons) of battery (cell or pack - different values, but same results). The internal volume of the battery pack however is fixed and should've been pretty much filled to the brim, otherwise passive thermal management through conduction won't work very well. Air is an insulator, so having less of it within the battery pack, the better (even for cold climates, because the cabin space is going to be warmer than ambient, so you'll want to insulate the bottom of the cells, not the top).

So unless the pack size/shape has changed, there's no way to fit more cells/modules into it.

From the qNuvo article (my bolding)

But for the added safety of the LMnO material, Nissan incurs some important penalties. First, the intrinsic energy density of the individual pouch is only about 320 Wh/L. Compare this to nearly 700 Wh/L for the Panasonic cells used by Tesla. Why does it matter? Energy density translates directly to range, and range, or rather lack of it, is right now the #1 challenge for electric vehicles. This is precisely why the Tesla pack weighs only twice more than the Leaf pack, yet delivers 3x more driving range.

Huh. What does 'intrinsic energy density of the pouch' refer to ? I agree that the pack looks pretty full but I don't think I have seen it all, and I don't know what the inside of a module looks like.

Intrinsic - contained wholly within the organ on which it acts.

It's a superfluous adjective in this case. If you've see the inside of the battery pack, then you've seen the modules. Those "tin cans" are the pouch cells.

The article refers to the volumetric energy density of the pouch cell (aka battery cell). There are 4 of them per module, and 192 cells (48 modules) per battery pack in a Nissan Leaf (applies to both 24kwh AND 30kwh). So the only way you can get more capacity out of a battery pack is:
- more cells (what lorenfb is saying, but is physically impossible without changing the pack size/shape)
- more active material per cell (requires thinner cell walls, thinner connectors between cells, etc - marginal improvements at best)
- more energy dense chemistry (and the associated higher risks of fire and degradation)
- or combinations of the above 3.

 

[lorenfb]

Gross weight is not vehicle weight.

All 2011 to 2017 LEAFs weigh about the same, reportedly from 3291 to 3391 Lbs:

https://en.wikipedia.org/wiki/Nissan_Leaf

So there was a 100lbs weight increase..

No.

Go to the link you just posted. Weights varied between model years due to the many changes in the LEAF over time.

IIRC, it was reported that for the 2016 MY the "30 kWh" pack weighed ~40 lbs more than the "24 kWh" pack, but I wouldn't rely on that as a fact.

Provide the link for this info.

 

[ironmanco]

So - these questions may be rhetorical...but based on the last 20-30 postings the following questions arise:

1) For those that will be getting a 30kWh warranty replacement battery, when will it have been mfg. and will it have any better reliability than the one that came stock with the vehicle?

2) Hijacking this thread but since we are knee deep into battery detail, how about the 40kWh 2018 battery? Any news on it being vastly different from the 30kWh that would indicate better longevity?

 

[lorenfb]

In any case, the 30 kWh battery needs 25% more Ahrs. I'm sure you guys will figure it out.