internalaudit
Posts: 72
Joined: Wed Aug 09, 2017 9:34 am
Delivery Date: 09 Aug 2032

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

Tue Sep 12, 2017 8:36 pm

^ Thanks for the information but what does this all mean? Does this mean the Tesla battery is less efficient, meaning less range per kW of battery? Is this why Tesla uses bigger battery packs?

I'm not very good with physics and chemistry. :(

SageBrush
Posts: 1416
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

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

Tue Sep 12, 2017 9:05 pm

internalaudit wrote:^ Thanks for the information but what does this all mean? Does this mean the Tesla battery is less efficient, meaning less range per kW of battery? Is this why Tesla uses bigger battery packs?

I'm not very good with physics and chemistry. :(


Highway MPGe:
Leaf: 101
Model 3: 120

For metric conversions, a gallon = 33,700 Wh
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California with 63.9 Ahr after 22k miles
Car is now enjoying an easy life in Colorado

internalaudit
Posts: 72
Joined: Wed Aug 09, 2017 9:34 am
Delivery Date: 09 Aug 2032

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

Tue Sep 12, 2017 9:15 pm

So what is so bad with Tesla batteries with TMS?

I did read chemistry is less stable and a little more prone to fire but that's about it.

Oils4AsphaultOnly
Gold Member
Posts: 267
Joined: Sat Oct 10, 2015 4:09 pm
Delivery Date: 20 Nov 2016
Leaf Number: 313890
Location: Arcadia, CA

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

Tue Sep 12, 2017 9:49 pm

lorenfb wrote:
Oils4AsphaultOnly wrote:
Thanks for the details. And again, great for you. The rest of us have to use our car in a manner that works for us. You still haven't told me how I could've NOT abused my leaf?

Indeed a TMS isn't going to help in your situation, since ambient was so low. But what if it was anything like 2 weeks ago, where it was 105 every day? Had I visited my friend and needed to QC (I make it a point to avoid this as much as possible) during one of those days, I would've been looking at 130+F (54+C) battery temp (~11bars) for the rest of the night. Not something I look forward to, and not something an average car owner should have to worry about either.


Yes, I''m faced with the same issues when visiting my customers around SoCal. Last year I could make a round
trip to north Pasadena and back from LAX. Now I need to QC on the way back, but only need about 10 -15 minutes
of QC. Previously I could travel to Oxnard and L2 charge there for a return. Now my range not enough and there're
no QCs on PCH to Oxnard.

I wish I had simple answer for you. You just have to plan your drives based on the limitations
of the Leaf. You may just have to use a L2 if it's really hot and plan on the extra time if you don't
wish to further hinder your battery.

From the viewpoint of having had TMS which would operate when QCing, it questionable as to the capacity needed
from a TMS to offset the thermal rise, what the cost would be, and if it would easily fit in the Leaf.


Doesn't that make the case for a TMS? Sure we don't know how much adding a TMS would cost, or how big and heavy of a chiller (or just fan + heatsink) would be needed. But having it with its known energy cost is easier to plan against than constant capacity loss. Wouldn't having a reliable 95miles of range that degrades slowly, be better than having 110 miles of range that degrades quickly?

If you haven't been following the 30kwh loss thread, it seems that Nissan is so unsure of their pack reliability that they've resorted to changing the capacity levels for each indicator bar. The first bar seems to drop after 20% capacity loss, while the 2nd drops after another 15%!! So a 4 bar loss could very well be near the 50% mark. That's a significant lack of confidence (not to mention that it's visually deceptive)!
[2013 leaf traded for 2016 leaf S30:
build date: Sep '16 :: purchased: Nov '16
1 May 2017 - 7300 miles & 363 GIDs
6 Sep 2017 - 13k miles & 359 GIDs
26 Oct 2017 - 15.5k miles & 344 GIDs]

GetOffYourGas
Posts: 1648
Joined: Tue Dec 20, 2011 6:56 pm
Delivery Date: 09 Mar 2012
Location: Syracuse, NY

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

Wed Sep 13, 2017 3:18 am

lorenfb wrote:
GetOffYourGas wrote:
lorenfb wrote:
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.


camasleaf wrote: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."


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.


Consider a 60kWh battery as being two 30kWh batteries in parallel. The result also affects the effective output
impedance of the combined batteries (a 60kWh resulting battery). It's now 1/2 of the single 30kWh battery.
The combined battery can obvious supply 2X the current output of the original 30kWh.

So driving at the same speed for either a single or parallel 30Ahr (60Ahr) battery results in the same power consumption,
as would be expected. Also, the total heating effect of the 60Ahr battery will be less than the single 30Ahr battery,
i.e. the lower output impedance of the 60Ahr battery.

Example - 2 parallel 30kWh

P (for each) = (I/2)^2 x R
P (for combined (60kWh)) = 2 x (I/2)^2 x R) = I^2 /2 x R = I^2 x R/2

That is P = 1/2 the 30kWh battery losses for the 60kWh battery.


Yup, I'm with you now. We definitely started with different assumptions. You reasoning makes sense. In the end, though, a 2x battery would have 1/2 the heating, not 1/4, as you just showed.
~Brian

EV Fleet:
2011 Torqeedo Travel 1003 electric outboard on a 22' sailboat
2012 Leaf SV (traded for Bolt)
2015 C-Max Energi (302A package)
2017 Bolt Premier

SageBrush
Posts: 1416
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

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

Wed Sep 13, 2017 6:16 am

duplicate post
Last edited by SageBrush on Wed Sep 13, 2017 6:27 am, edited 1 time in total.
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California with 63.9 Ahr after 22k miles
Car is now enjoying an easy life in Colorado

SageBrush
Posts: 1416
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

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

Wed Sep 13, 2017 6:18 am

SageBrush wrote:
internalaudit wrote:So what is so bad with Tesla batteries with TMS?

I did read chemistry is less stable and a little more prone to fire but that's about it.

Nothing. They are state of the art.
You are being influenced by Ed the Tesla troll.
And by the way .. Nissan wants to use LG batteries. I'll give you one guess what chemistry they use.

Has your time on the Tesla forum not taught you anything ?
Have you not noticed that majority of threads here are people trying to manage severe battery degradation ?
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California with 63.9 Ahr after 22k miles
Car is now enjoying an easy life in Colorado

User avatar
RegGuheert
Posts: 5583
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Leaf Number: 5926
Location: Northern VA

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

Wed Sep 13, 2017 6:40 am

GetOffYourGas wrote:In the end, though, a 2x battery would have 1/2 the heating, not 1/4, as you just showed.
It is 1/4 the heating per unit volume. If you consider the example of two 30 kWh batteries given, then each battery dissipates 1/4 as much heat as one installed alone in a car would dissipate.
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 30K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

internalaudit
Posts: 72
Joined: Wed Aug 09, 2017 9:34 am
Delivery Date: 09 Aug 2032

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

Wed Sep 13, 2017 6:49 am

SageBrush wrote:
SageBrush wrote:
internalaudit wrote:So what is so bad with Tesla batteries with TMS?

I did read chemistry is less stable and a little more prone to fire but that's about it.

Nothing. They are state of the art.
You are being influenced by Ed the Tesla troll.
And by the way .. Nissan wants to use LG batteries. I'll give you one guess what chemistry they use.

Has your time on the Tesla forum not taught you anything ?
Have you not noticed that majority of threads here are people trying to manage severe battery degradation ?


I see. Maybe it's going to be different this time around? I didn't read a lot of threads here except on the Leaf 2 and winter road handling. I can't take possession of a Model 3 until late 2018 anyway so I'll be perusing this, the TMC forum and others.

GetOffYourGas
Posts: 1648
Joined: Tue Dec 20, 2011 6:56 pm
Delivery Date: 09 Mar 2012
Location: Syracuse, NY

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

Wed Sep 13, 2017 6:57 am

SageBrush wrote:Have you not noticed that majority of threads here are people trying to manage severe battery degradation ?


Doesn't seem like the majority to me. At least, not looking at recently activity. And have you noticed that the majority of those complaints are made by the same people, in hot* climates?

I believe in the philosophy of "the right tool for the right job", and today the Leaf is not the right tool for a hot climate.

And funny that you would call out Ed for being a troll, and follow it immediately by an exaggeration like this.
~Brian

EV Fleet:
2011 Torqeedo Travel 1003 electric outboard on a 22' sailboat
2012 Leaf SV (traded for Bolt)
2015 C-Max Energi (302A package)
2017 Bolt Premier

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