lorenfb
Posts: 2393
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Tue Apr 03, 2018 11:06 pm

LeftieBiker wrote:
Just multiply Volts X Amps shown on the charger screen to get kW, i.e. (38, 34, 25, 23, 12, 8 kW). The voltage in all cases is essentially
constant at about 390 volts, except when the QC is delivering 100 amps and the output voltage drops a little.
Yes, and I know. I don't want to do that for every charging screen I see.

What is different about the 40kwh Leaf? Higher energy density, apparently from larger cells squashed into a space that used to have a little airflow inside to aid the modest convection cooling. As other car companies ensure that their packs are actively cooled, Nissan is going in the exact opposite direct - making sure that their packs get cooled as little as possible. The only reason I'm likely to lease a 2018 Leaf, aside from the lack of direct competition, is that I believe I can fit it in my garage, and then cool the garage during heat waves. But that doesn't mean I'm not pissed off about it, or that I'm sure I'm not making a big mistake.
I agree with your concern. The more we understand, the better we can make decisions.
#1 Leaf SL MY 9/13: 76K miles, 47 Ahrs, 5.0 miles/kWh (average), Hx=70, SOH=78, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 10.3K miles, SOH 109Ahrs/115Ahrs, 5.2 miles/kWh (average), DOD > 20%, temp < 105F

cwleaf2
Posts: 7
Joined: Fri Mar 23, 2018 11:52 am
Delivery Date: 20 Apr 2018

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Wed Apr 04, 2018 2:14 pm

OrientExpress wrote:
Hello, did you check your battery temperature when starting the quick charges?
Yeah for that one it was left of center.

Today I did the first of my 18 LEAF tests with a RT from south San Jose to Monterey and back. It was a total of 128 miles RT and I had 17% stated reserve or 31 Miles left at the end. I L2 charged last night for about 4 hours to get to 100%. Temp was left of midrange when I started. The road course was highway @65, Canyon and hilly twisties, @45, Highway 1 @ 55, and city driving @35. When I finished the Battery Temp was mid range.

I did do one thing different than I normally do when I drive this road, I kept to the posed speed limits, much to the chagrin of my fellow drivers! I did find that I could outdrive them on the twisties using e-Pedal to modulate speed and the Vehicle Dynamic Control for the turns. The only other car I had driven with VDC was a 911, and it really helps carving into the curves.

Observations of the 18 LEAF in general:
This was my first time spending extended time with the car since the Las Vegas product reveal, and my overall impressions were good. ProPilot is great, much better than the competing systems from Toyota, VW, and GM. Better logic for seeing and reacting to things ahead. Ride is smooth and firm, seats are comfortable, cabin climate and the Apple play are good. Only thing I noticed is the cabin picks up a lot of tire and some wind noise. No rattles so far.

I QC'd at the Drive the Arc L3 by my house, and ran it for 45 minutes. It started out at 100A (35.5kW), at 30 minutes I was at 98A (34.79 kW), and when I finished at 45 minutes I was down to 62A (22.01kW).

Battery Temp when I finished was right of center mid-way. Went from 17% to 86%. I'll L2 it up to 100% tonight.

Image

Image

Image

So far nothing observed out of the unusual compared to every other LEAF I've QC'd (and I have done every model year since 2011)

Wednesday will be the important test, when I continue the trip from San Jose to South Lake Tahoe. This will have more interstate, and of course big elevation gains on Highway 50. Nice thing about 50 is that it is mostly 2 lane, and drivers aren't in a hurry. We expect that trip including Charge stops should be about 7 hours vs 5.5~6 hours if we drive and stop for lunch.
Mid-center on the jauge seems to be around 30ºC (86º F). at that temperature you are supposed to get 39 kW charge so with your 35-36 kW you are even lower than average. But it gets interesting if you're doing a second and third QC with higher temps on the jauge.

lorenfb
Posts: 2393
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Wed Apr 04, 2018 7:45 pm

For those that have access to a 2018 Leaf, do QC charging, and use LeafSpy, your help obtaining battery data on that vehicle
would be very useful in determining what battery parameter could be contributing to having the charging time progressively
lengthened during a long distance trip. It appears that the 2018 Leaf’s BMS controller is reducing the charging current as the
battery gets progressively warmer during a lengthy trip. This has not been the case for earlier Leafs even though the BMS does
reduce the charging current over time for the earlier Leafs, but it appears not based on temperature nor based on the number
of previous QCs during a trip.

The process should only take a couple of minutes during the starting phase of the QC to obtain the data:

1. Once the vehicle is parked adjacent to the QC with the Leaf’s power still on with no accessories turned-on, e.g. the fan/AC,
measure the battery voltage (V1). It should be greater than 325 volts. Then measure the battery temperature (T - degrees C).
Write these values down.
2. Next the charging voltage (V2) and charging current (I) need to be written down immediately once the QC device begins
the charging process
using LeafSpy. If the QC device provides these values, just use those values displayed on the QC
device like in this post; http://mynissanleaf.com/viewtopic.php?f ... 70#p523610
3. Once all the data are taken and time permits, please post them in this thread using the following form;
V1 - XXX, V2 - XXX, T - XX, I - XX
4. The data will then determine the battery resistance by this calculation; battery resistance = (V2 - V1) / I
As an example, V1 = 355 volts, V2 = 365 volts, I = 80 amps, then battery resistance = .125 ohms or 125 mohms.
Battery resistance varies with temperature, so it's critical to determine the temperature at the being of the charging process.

Based on your values and other’s values, a comparative analysis between the early Leafs and the 2108 Leaf should provide
insight into how the chemistry might be different and what one might expect about long term battery degradation the result
of lengthy and multiple QCs combined with high speed driving during a long trip.

Thanks for your help.
#1 Leaf SL MY 9/13: 76K miles, 47 Ahrs, 5.0 miles/kWh (average), Hx=70, SOH=78, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 10.3K miles, SOH 109Ahrs/115Ahrs, 5.2 miles/kWh (average), DOD > 20%, temp < 105F

kennethbokor
Posts: 84
Joined: Mon Mar 14, 2016 12:35 pm
Delivery Date: 30 May 2018
Location: Caledon, ON Canada
Contact: Twitter

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Wed Apr 04, 2018 10:40 pm

lorenfb wrote:
LTLFTcomposite wrote:
lorenfb wrote: After about eight pages of posts about the reduction of charging current during multiple successive charging sessions and the correlation with the battery temperature with the Leaf2 battery, isn't time to now to try and understand what the cause/causes might be?
Isn't that Nissan's job?
Yes it is, but it may help to further understand the evolution of the Leaf batteries from a more technical aspect. Besides, if the battery
resistance is causing heat problems while charging, additional heat from driving will also be problematic.

Well, I think we all know that Nissan is purposely throttling DCFC inputs based on battery temps to keep temps in check and prolong battery life. So I don't think we need more info on this subject stating that fact. I posted a response in this thread from Nissan Corporate that basically said this slowdown is meant to do what it does.

So with regards to why temps are a potential concern?

Here is some info on the new Leaf's Pack:

- 40kWh improved battery pack (33% more density and energy), yet in same packaging/space as previous pack, still retains passive air cooling, 192 prismatic form factor lithium cells, improved chemistry (nickel-manganese-cobalt with graphite anode), .9mm thicker and use a thinner separator to reduce internal resistance, bundled 8 cells per module, 24 modules total. Can retain 90% of its capacity after 500 charge/discharge cycles or over 100,000 kMs/60,000 miles

This info is all from Nissan.

From what I've seen and read, Nissan has confidence in this "improved chemistry" for this pack. However, they know that passive air cooling combined with more dense pack will drive up temps, even with this new chemistry.

So, there is nothing that Nissan is going to do to the BMS (tweak it) or anything else for the 40kWh Leaf. What I've been telling interested folks is that if you can live with the range it gives you and the ability to multi-fast charge successively with a throttle-down after DCFC #1 or #2 (depending on outside weather/temps as in summer the throttling will probably happen after DCFC #1), then buy the Leaf. It's a great car and for a vast majority of users, will do the job. I think Byorn did a great job with his recent testing and summarizing that for DCFC-ing, keep the GOM no lower than 20% before charging and stop at 80% - if you do alot of longer trips. This seems to be the best "formula" for keeping the battery temps in check.

So I agree with this OP, I don't think we need more pages of data on why this happens and accept that fact that it does and its part of the design/build of the new Leaf.
---------
New Leaf Owner: Just ordered Feb 24 2018, 2018 Leaf SL in Jade Frost. Expected ETA by May 30 2018.

Joe6pack
Posts: 163
Joined: Tue Oct 09, 2012 4:57 pm
Delivery Date: 07 Oct 2012
Leaf Number: 025854

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Thu Apr 05, 2018 6:22 am

@kennethbokor +1
2012 Leaf SL leased October 4th, 2012
Braselton, GA

SageBrush
Posts: 4907
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: NM

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Thu Apr 05, 2018 6:23 am

Nissan screwed the pooch on QCFC, although it remains to be seen (or figured out) whether even one charging session at 45 kW will be available in warm/hot weather.

The no less important question is how hot the battery gets throughout the summer. I asked Joe "the mechanical engineer" in another thread how much heat dissipation drops on a 95F day compared to 35F based on a simple model of conduction but no answer was forthcoming so I'll provide it here: 75%

Ignoring just for a moment other variables in play like specific heat, better ventilation during driving and time, we are starting the game from the sqrt(0.25) = 50%, or about 11 kW based on the reports of 22 kW throttling when the battery reaches 115F. I am not saying that the LEAF will be throttled to 11 kW in the summer or that the battery will live at 115F for months on end. I am saying that the LEAF battery in the 40 kWh model appears to be even more vulnerable in warm climates than prior models and more information is absolutely required to be an informed buyer.

Caveat Emptor. Or just plop down $30k based on "confidence" from Nissan Corporate and a battery warranty that will keep the car running at something over 60% of new range for 8 yrs/ 100k miles.
2013 LEAF 'S' Model with QC & rear-view camera
Bought off-lease Jan 2017 from N. California
Two years in Colorado, now in NM
03/2018: 58 Ahr, 28k miles
11/2018: 56.16 Ahr, 30k miles
-----
2018 Tesla Model 3 LR, Delivered 6/2018

SageBrush
Posts: 4907
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: NM

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Thu Apr 05, 2018 7:01 am

lorenfb wrote:There's been essentially no discussion or focus of what's causing the Leaf2 battery to increase in temp more rapidly than early batteries.
Yes, most obviously it's the chemistry and potentially the battery's thermal resistance to ambient. But specifically what measurable
battery parameter has a changed, causing the higher rate of change of battery temperature. The most obvious and easiest to
determine is the battery's internal resistance, where battery power consumption and heating is I^2 (charging current squared)
times the battery's internal resistance. This can be determined easily, as has been expressed numerous times on the forum.
So if it turns out that this Leaf2 battery has a higher internal resistance, e.g. from chemistry change, that would help example the greater
rate of change of Leaf2's temperature while charging. Additional tests could easily be developed to the determine if the thermal
resistance of the Leaf2 battery may have changed too, further contributing to the battery's higher remaining temp after multiple QCs.

After about eight pages of posts about the reduction of charging current during multiple successive charging sessions and the correlation
with the battery temperature with the Leaf2 battery, isn't time to now to try and understand what the cause/causes might be?
The quick jump in temperature while quick charging sure seems to imply a higher resistance, but impaired heat dissipation in the summer is the more important question overall since it is the proximate cause of degradation. Unluckily for LEAF owners, these two effects work in concert.
Last edited by SageBrush on Thu Apr 05, 2018 7:17 am, edited 2 times in total.
2013 LEAF 'S' Model with QC & rear-view camera
Bought off-lease Jan 2017 from N. California
Two years in Colorado, now in NM
03/2018: 58 Ahr, 28k miles
11/2018: 56.16 Ahr, 30k miles
-----
2018 Tesla Model 3 LR, Delivered 6/2018

User avatar
hill
Gold Member
Posts: 1870
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Delivery Date: 27 Mar 2011
Leaf Number: 0659
Location: Lake Forest, CA

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Thu Apr 05, 2018 7:04 am

kennethbokor wrote:......snip...... I agree with this OP, I don't think we need more pages of data on why this happens and accept that fact that it does and its part of the design/build of the new Leaf.
That's very magnanimous, to simply accept the fact that Corporate Nissan continually churns out traction packs with the resiliency of a POS. Thats great if owners really don't mind an ever larger pack that's ever more prone to loose capacity as fast, or even faster than the 30's - or our original (vin 000659) 21kWh usable original POS.
(Not IF, but) When these larger Nissan packs quickly degrade & end up with a paltry cold weather range of under 50 miles - because Nissan was too cheap or profit hungry or too lazy to manufacture an authentic thermal management system - but instead, chose to continue to pack even more modules close together, where even MORE trapped heat will result in packs faster degradation - especially in all the hot areas of the country ....
all of us poor slobs will welcome all the newcommers - recently suckered into this poorly designed - virtually absent thermal management system.
Yes - THAT'S why your QC Speeds throttle so quick ... it's in hope the packs can make it to the end of warranty before they literally cook their self down to the paltry range of all of us remaining old timers.
"Possible Quick Charge Problems"?
It's not a possibility, & it's not a problem .... it's Nissan's carefully crafted attempt to cover up their thermal management huge fail.
How's THAT for a 'fact' for owners to simply 'accept' .
.

lorenfb
Posts: 2393
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Thu Apr 05, 2018 9:12 am

It’s interesting to hear the head-in-the-sand approach some are advocating when it comes to obtaining a little quantitative
data to better understand the 2018 40kWh Leaf battery QC issues exposed in this thread. Without a simple data gathering
and analysis, would one expect the 2018 40 kWh Leaf battery degradation to follow the same 30 kWh battery degradation,
or worse, that many 30 kWh Leafs have exemplified? Having a quantitative parameter, e.g. battery resistance, as a differentiator
between the 24/30/40 Leaf batteries would provide a valuable insight into the batteries’ chemistries and heat related degradations.
Remember, internal battery heat generation, i.e. charging and driving, just compounds that which develops from ambient.
#1 Leaf SL MY 9/13: 76K miles, 47 Ahrs, 5.0 miles/kWh (average), Hx=70, SOH=78, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 10.3K miles, SOH 109Ahrs/115Ahrs, 5.2 miles/kWh (average), DOD > 20%, temp < 105F

tattoogunman
Posts: 211
Joined: Tue Jun 07, 2016 6:17 pm
Delivery Date: 08 Jun 2016
Location: Plano, Texas

Re: Possible Widespread 2018 Traction Battery Quick Charge Problems

Thu Apr 05, 2018 11:25 am

hill wrote:
kennethbokor wrote:......snip...... I agree with this OP, I don't think we need more pages of data on why this happens and accept that fact that it does and its part of the design/build of the new Leaf.
That's very magnanimous, to simply accept the fact that Corporate Nissan continually churns out traction packs with the resiliency of a POS. Thats great if owners really don't mind an ever larger pack that's ever more prone to loose capacity as fast, or even faster than the 30's - or our original (vin 000659) 21kWh usable original POS.
(Not IF, but) When these larger Nissan packs quickly degrade & end up with a paltry cold weather range of under 50 miles - because Nissan was too cheap or profit hungry or too lazy to manufacture an authentic thermal management system - but instead, chose to continue to pack even more modules close together, where even MORE trapped heat will result in packs faster degradation - especially in all the hot areas of the country ....
all of us poor slobs will welcome all the newcommers - recently suckered into this poorly designed - virtually absent thermal management system.
Yes - THAT'S why your QC Speeds throttle so quick ... it's in hope the packs can make it to the end of warranty before they literally cook their self down to the paltry range of all of us remaining old timers.
"Possible Quick Charge Problems"?
It's not a possibility, & it's not a problem .... it's Nissan's carefully crafted attempt to cover up their thermal management huge fail.
How's THAT for a 'fact' for owners to simply 'accept' .
.
Nissan has said as much - someone I follow on YouTube (Nikki of Transport Evolved) got an official response from Nissan saying the car is designed to throttle back the charging on purpose to prolong battery life. I agree and I really do not understand why Nissan didn't go active thermal management, especially since the 60kWh version is supposed to have it.

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