Why the LEAF Gen 2 and not the 220 miles Tesla Model 3?

Nope, the Leaf gen 1.5 is not the smart choice. Better looks than gen 1 and more battery but it doesn't go far enough with a few things.

Probably only 110ish freeway miles at 65 mph at normal ambient temperatures but still NO thermal cooling for hot temps and charging. Is it better than the three Leafs currently in our family? Yes, on range but not up to speed to compete with Bolt and Tesla.

Nissan is still suspect when it comes to battery degradation and rated distance. Other than that, it is a well made car and we love our cars. We are disappointed that Nissan has not stepped up to the plate to have equaled the range of the Bolt or Model 3. It is also equally a let down that they have not truly addressed their battery degradation problems.

I believe they got caught flat footed...

GetOffYourGas said:

EatsShootsandLeafs said:

Who knows. Maybe Nissan engineers are just too stupid to come out with an EV that doesn't suffer range loss at 5X (?) the rate of Tesla.

Click to expand...

To play devil's advocate here...

The Leaf keeps getting compared to other EVs. Especially Tesla. But the smallest battery Tesla ever made was 2x the size of the largest battery Nissan made (60kWh versus 30kWh respectively). That means that Leafs have at least 2x the number of cycles to travel the same number of miles. On average, it's more like 3x the cycles.

I'm not saying that lack of TMS is not an issue. The Leaf certainly has trouble in hot climates. What I'm getting at is this: we don't know for sure how much of the degradation is due to temperature versus other factors.

Consider only cycle life. If Nissan's batteries are good for 1000 cycles, and the car goes 80 miles per charge, that's only 80k miles. If a Tesla is good for 1000 cycles and goes 200+ miles per charge, that's over 200k miles.

My Leaf is down to about 80% capacity after 45k miles and 5.5 years. If I started with a 40kWh battery rather than a 24kWh battery, would I still see 20% loss in this time? Maybe, maybe not.

Bottom line, I am happy with my Leaf and would be willing to take a risk on a new one. If you don't feel the same, perhaps a Tesla is better for you.

Click to expand...

There're others on this forum who think logically and rationally on the issue!

lorenfb said:

GetOffYourGas said:

EatsShootsandLeafs said:

Who knows. Maybe Nissan engineers are just too stupid to come out with an EV that doesn't suffer range loss at 5X (?) the rate of Tesla.

Click to expand...

To play devil's advocate here...

The Leaf keeps getting compared to other EVs. Especially Tesla. But the smallest battery Tesla ever made was 2x the size of the largest battery Nissan made (60kWh versus 30kWh respectively). That means that Leafs have at least 2x the number of cycles to travel the same number of miles. On average, it's more like 3x the cycles.

I'm not saying that lack of TMS is not an issue. The Leaf certainly has trouble in hot climates. What I'm getting at is this: we don't know for sure how much of the degradation is due to temperature versus other factors.

Consider only cycle life. If Nissan's batteries are good for 1000 cycles, and the car goes 80 miles per charge, that's only 80k miles. If a Tesla is good for 1000 cycles and goes 200+ miles per charge, that's over 200k miles.

My Leaf is down to about 80% capacity after 45k miles and 5.5 years. If I started with a 40kWh battery rather than a 24kWh battery, would I still see 20% loss in this time? Maybe, maybe not.

Bottom line, I am happy with my Leaf and would be willing to take a risk on a new one. If you don't feel the same, perhaps a Tesla is better for you.

Click to expand...

There're others on this forum who think logically and rationally on the issue!

Click to expand...

It actually is a very good point. The follow up question is, "are the Leafs driven as far as the Tesla vehicles". If you assume the answer is yes, charge cycles should definitely be considered.
I would think that could be accounted for by comparing battery degradation of a Leaf at 50,000 miles with a Tesla at 100,000 miles?

Oils4AsphaultOnly said:

2. That's great for you! I recently QC'd for 30 mins in 90F ambient and saw a 34F increase (18C) to 123F (9 bars)! Since ambient was still 87F by the time I had parked for the night, my pack temp was still at 118F. It took over 10hrs until the following morning before the pack temp had reduced to 98.6F (still 7 bars).

IF there was a TMS set to cool while charging, then my pack would've spent many HOURS less time at elevated temperatures.

Keep in mind that your 4C increase was above ambient (and most likely during cooler weather too). And it was only for 12-15mins. A higher ambient, means higher peak temps during charging and driving, exactly the times that a TMS would be most effective. We're not looking to keep the battery cooler than ambient. We're trying to limit how far above ambient that the pack temp rises to.

Click to expand...

Actually, the ambient was about 90 F when mine was QCed for about 10 - 12 minutes and battery temp only increased by a small amount. Sorry your Leaf is abused, given your knowledge of one of the key factors for battery degradation,
extreme battery temps.

lorenfb said:

Oils4AsphaultOnly said:

2. That's great for you! I recently QC'd for 30 mins in 90F ambient and saw a 34F increase (18C) to 123F (9 bars)! Since ambient was still 87F by the time I had parked for the night, my pack temp was still at 118F. It took over 10hrs until the following morning before the pack temp had reduced to 98.6F (still 7 bars).

IF there was a TMS set to cool while charging, then my pack would've spent many HOURS less time at elevated temperatures.

Keep in mind that your 4C increase was above ambient (and most likely during cooler weather too). And it was only for 12-15mins. A higher ambient, means higher peak temps during charging and driving, exactly the times that a TMS would be most effective. We're not looking to keep the battery cooler than ambient. We're trying to limit how far above ambient that the pack temp rises to.

Click to expand...

Actually, the ambient was about 90 F when mine was QCed for about 10 - 12 minutes and battery temp only increased by a small amount. Sorry your Leaf is abused, given your knowledge of one of the key factors for battery degradation,
extreme battery temps.

Click to expand...

Care to explain what I should've done differently? I QC'd from 30% SOC to 81% SOC that night, because I had a bit more driving to do than you did. Should I have stopped at 60% (~15 mins) so that I end up at home at 2% SOC? Which would've been brilliant planning since I was driving through the mountains and all.

Edit: Frankly, your ambient temp claim leaves me with many questions, since my experience was detailed to the tee and completely different from yours.

Edit: Here's my screen captures for that night and the following morning: https://photos.app.goo.gl/H8O3fTTWVAgbXidB3

Yes I charged close to 100%, because Nissan took away the 80% charge limiter, so I sometimes forget to stop the charge at 7am versus 8am (even though the charge timer is set to stop at 10:40am - setting it at 7am would have the car reach 100% at around 4:30am ... because Nissan says there's NO ISSUE TO FIX).

Oils4AsphaultOnly said:

Nubo said:

It might, but the details are important. If the TMS only cools while driving and/or charging, then that leaves a much larger portion of time where the vehicle can still be heat-soaked from ambient temperatures, hot garages, or blistering parking lots. If, on the other hand, it's full-time active cooling, that represents a significant ongoing expenditure of energy 24x7. The sweet-spot of energy cost vs pack longevity vs use cases, might be a lot more complex than first appears.

Click to expand...

"It might ..." ?!?!

Are you saying that an active TMS that cools (remember it's the heat that's killing the batteries) only during driving and charging (when there's an additional 2.5 - 5 KW's of heat (charging/regen/discharging efficiency losses) being added to the batteries ABOVE ambient temps won't make a difference towards extending the life of the battery?!

That's like claiming smoking doesn't cause lung cancer since there's also smog in the air. Although it's technically correct, removing the extra heat, much like removing smoking, WILL help.

Click to expand...

What I actually said is quoted above. Neither you, nor I, know to what degree a part-time TMS would have mitigated the gen1 LEAF degradation. Drive-time heat is only one contributor to the battery temperature in scorching climates like Phoenix. The early batteries were sub-par. Would part-time TMS have helped? To some degree. Would it have been sufficient to have prevented the premature degradation issue in those climates? I have my doubts. A more durable battery may well have been the more effective way to spend resources to mitigate the problem.

At the time, TMS may have not been the best engineering solution to the LEAF 1 problem. And it doesn't mean TMS is best answer for 2018 LEAF and it doesn't mean TMS is the best approach to all battery chemistries.

Zythryn said:

lorenfb said:

GetOffYourGas said:

To play devil's advocate here...

The Leaf keeps getting compared to other EVs. Especially Tesla. But the smallest battery Tesla ever made was 2x the size of the largest battery Nissan made (60kWh versus 30kWh respectively). That means that Leafs have at least 2x the number of cycles to travel the same number of miles. On average, it's more like 3x the cycles.

I'm not saying that lack of TMS is not an issue. The Leaf certainly has trouble in hot climates. What I'm getting at is this: we don't know for sure how much of the degradation is due to temperature versus other factors.

Consider only cycle life. If Nissan's batteries are good for 1000 cycles, and the car goes 80 miles per charge, that's only 80k miles. If a Tesla is good for 1000 cycles and goes 200+ miles per charge, that's over 200k miles.

My Leaf is down to about 80% capacity after 45k miles and 5.5 years. If I started with a 40kWh battery rather than a 24kWh battery, would I still see 20% loss in this time? Maybe, maybe not.

Bottom line, I am happy with my Leaf and would be willing to take a risk on a new one. If you don't feel the same, perhaps a Tesla is better for you.

Click to expand...

There're others on this forum who think logically and rationally on the issue!

Click to expand...

It actually is a very good point. The follow up question is, "are the Leafs driven as far as the Tesla vehicles". If you assume the answer is yes, charge cycles should definitely be considered.
I would think that could be accounted for by comparing battery degradation of a Leaf at 50,000 miles with a Tesla at 100,000 miles?

Click to expand...

It is a hypothetical, although my reading of posts on this forum do not support it. I routinely look at LeafSpy photos from people who come hear with battery degradation questions and calculate the average miles between charges. I don't think I have seen a thread yet where the average miles between charges is greater than 30. GoYG himself reports 45k miles over ~ 2000 days, or about 22 EV miles a day. Now, I don't doubt that Nissan's decision to take away the 80% charge limit was short-sighted in terms of DoD cycling count, but they could have limited "100%" to a lower voltage threshold. So at best this is a relatively minor confounding factor in Nissan's view.

Along with what GetOffYourGas and others have said about overall charge cycles, and I know this has been brought up before, but when you're cruising at 65 mph you are basically at 1C on the 24 kWh battery, in an hour, it will be dead. Pulling a battery at 1C vs at C/2 is roughly four times the heat generated internally. The same holds true for the charging side, the larger the pack or rather the charge rate compared to the pack size is what matters with internal heat generation. So the larger the pack, given the same load and charge rate, the less heat it will generate internally.

I know I am an outlier living in Green Bay, WI, we just passed 50,000 miles on our 2013 S and we are at 58.77 Ahr, 89 SOH and 89.32 Hx, with no quick chargers in range. Now if we had double the pack size, I would guess we would be less than half that degradation, for a number of reason including primarly pack cycles as well as pack internal heating due to load. I know the life or time on the pack plays in to this and obviously, I am not in Arizona with the car sitting in heat soaked parking lots, instead, I get in to a car that sat 16 hours at -10F or -23C…

I would prefer TMS, but I would be curious to know what it would add to the cost and complexity of the vehicle as well as the range reduction in winter and summer.

BrockWI said:

Pulling a battery at 1C vs at C/2 is roughly four times the heat generated internally.

Click to expand...

Reference ?

SageBrush said:

BrockWI said:

Pulling a battery at 1C vs at C/2 is roughly four times the heat generated internally.

Click to expand...

Reference ?

Click to expand...

Heat is proportional to the square root of the current. Twice the current means four times the heat.

Long tread, but I likely go with the Leaf since I do not believe I cam lease Model 3. I only need a car for next 3 years.

camasleaf said:

SageBrush said:

BrockWI said:

Pulling a battery at 1C vs at C/2 is roughly four times the heat generated internally.

Click to expand...

Reference ?

Click to expand...

Heat is proportional to the square root of the current. Twice the current means four times the heat.

Click to expand...

And current is related to Voltage as V = I * R. It is not related to capacity in any way. Assuming the same pack voltage, the current is the same. So why again is 1C discharge going to produce 4x the heat of C/2 discharge?

That's not to say that 1C discharge isn't tougher on the battery than C/2. Maybe it is, or maybe it's gentler. I don't know. But I don't see how it relates to heat.

GetOffYourGas said:

camasleaf said:

SageBrush said:

Reference ?

Click to expand...

Heat is proportional to the square root of the current. Twice the current means four times the heat.

Click to expand...

And current is related to Voltage as V = I * R. It is not related to capacity in any way. Assuming the same pack voltage, the current is the same. So why again is 1C discharge going to produce 4x the heat of C/2 discharge?

That's not to say that 1C discharge isn't tougher on the battery than C/2. Maybe it is, or maybe it's gentler. I don't know. But I don't see how it relates to heat.

Click to expand...

Using the relationships from the previous posts (1C & C/2):

Power = I^2 x R, where I is the motor current and R is the impedance of the battery (typically 60mohms @ 70 deg F)

Then at 1C I equals about 60 amps and battery Power = 216 watts.
Then at C/2 I equals about 30 amps and battery Power = 54 watts

The rise in battery temperature is a function of the thermal resistance from the battery to the chassis.
The actual battery temperature over time is a function of the chassis temperature which is a function of
ambient.

GetOffYourGas said:

camasleaf said:

SageBrush said:

Reference ?

Click to expand...

Heat is proportional to the square root of the current. Twice the current means four times the heat.

Click to expand...

And current is related to Voltage as V = I * R. It is not related to capacity in any way. Assuming the same pack voltage, the current is the same. So why again is 1C discharge going to produce 4x the heat of C/2 discharge?

That's not to say that 1C discharge isn't tougher on the battery than C/2. Maybe it is, or maybe it's gentler. I don't know. But I don't see how it relates to heat.

Click to expand...

Google battery 1c meaning

"Charge and discharge rates of abattery are governed by C-rates. The capacity of a battery is commonly rated at 1C, meaning that a fully charged battery rated at 1Ah should provide 1A for one hour. The samebattery discharging at 0.5C should provide 500mA for two hours, and at 2C it delivers 2A for 30 minutes."

camasleaf said:

SageBrush said:

BrockWI said:

Pulling a battery at 1C vs at C/2 is roughly four times the heat generated internally.

Click to expand...

Reference ?

Click to expand...

Heat is proportional to the square root of the current. Twice the current means four times the heat.

Click to expand...

Yes, but keep in mind that the battery is arranged as 96s so you start at a very low current and work your way to charging ;-)

camasleaf said:

GetOffYourGas said:

camasleaf said:

Heat is proportional to the square root of the current. Twice the current means four times the heat.

Click to expand...

And current is related to Voltage as V = I * R. It is not related to capacity in any way. Assuming the same pack voltage, the current is the same. So why again is 1C discharge going to produce 4x the heat of C/2 discharge?

That's not to say that 1C discharge isn't tougher on the battery than C/2. Maybe it is, or maybe it's gentler. I don't know. But I don't see how it relates to heat.

Click to expand...

Google battery 1c meaning

"Charge and discharge rates of abattery are governed by C-rates. The capacity of a battery is commonly rated at 1C, meaning that a fully charged battery rated at 1Ah should provide 1A for one hour. The samebattery discharging at 0.5C should provide 500mA for two hours, and at 2C it delivers 2A for 30 minutes."

Click to expand...

It also is defined at discharging the full capacity in one hour

camasleaf said:

Heat is proportional to the square root of the current. Twice the current means four times the heat.

Click to expand...

Typo?

Power (heat) = I^2 x R

lorenfb said:

Using the relationships from the previous posts (1C & C/2):

Power = I^2 x R, where I is the motor current and R is the impedance of the battery (typically 60mohms @ 70 deg F)

Then at 1C I equals about 60 amps and battery Power = 216 watts.
Then at C/2 I equals about 30 amps and battery Power = 54 watts

The rise in battery temperature is a function of the thermal resistance from the battery to the chassis.
The actual battery temperature over time is a function of the chassis temperature which is a function of
ambient.

Click to expand...

camasleaf said:

Google battery 1c meaning

"Charge and discharge rates of abattery are governed by C-rates. The capacity of a battery is commonly rated at 1C, meaning that a fully charged battery rated at 1Ah should provide 1A for one hour. The samebattery discharging at 0.5C should provide 500mA for two hours, and at 2C it delivers 2A for 30 minutes."

Click to expand...

So we are talking about two different things. Allow me to elaborate. Your numbers are looking at different C rates for the same battery. I was comparing the C rates for two different batteries. Like, for instance, a 30kWh Nissan battery and a 60kWh Tesla battery.

Let's assume both are 360V.

1C of a 30kWh battery (360V * 83.3Ah) = 83.3A
C/2 of a 60kWh battery (360V * 166.6Ah) = 83.3A

Both batteries output the same amount of current, despite having different C rates, due to the different capacities.

P = I^2 * R
Assuming again that both batteries have a 60mOhm internal resistance, they both have a power dissipation of 416W.

GetOffYourGas said:

Let's assume both are 360V.

1C of a 30kWh battery (360V * 83.3Ah) = 83.3A
C/2 of a 60kWh battery (360V * 166.6Ah) = 83.3A

Both batteries output the same amount of current, despite having different C rates, due to the different capacities.

Click to expand...

Trying to wrap my head around this but if I understand this correctly the 60kWh pack is supplying twice the power of the 30 kWh pack in the quote above correct? What I was suggesting is the same load for both packs at the same Ah draw given the same operating voltage, then larger pack would have less internal resistance and thus less heating. Also the larger pack would have more mass (for better or worse) to absorb the internal heat.

BrockWI said:

GetOffYourGas said:

Let's assume both are 360V.

1C of a 30kWh battery (360V * 83.3Ah) = 83.3A
C/2 of a 60kWh battery (360V * 166.6Ah) = 83.3A

Both batteries output the same amount of current, despite having different C rates, due to the different capacities.

Click to expand...

Trying to wrap my head around this but if I understand this correctly the 60kWh pack is supplying twice the power of the 30 kWh pack in the quote above correct? What I was suggesting is the same load for both packs at the same Ah draw given the same operating voltage, then larger pack would have less internal resistance and thus less heating. Also the larger pack would have more mass (for better or worse) to absorb the internal heat.

Click to expand...

No, both packs are supplying the same amount of power. 83.3A * 360V = 30kW. For the 30kWh battery, that is 1C rate. For the 60kWh battery, that is C/2 rate. Same amount of current.

Both packs are also assumed to have the same internal resistance. This is a characteristic of the battery, more or less, and does not change with C rate of discharge.

Therefore both pack have the same internal heating.