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

Posted: Thu Nov 09, 2017 4:10 pm
by arnis
If there is no buffer to knock off 20% in summer, then vehicle is useless in winter.
I keep mine at 80% for majority of them time. Except winter (3temp bars or lower),
when 80% is not enough for my trips.

For old 2011-12 Leafs, 90% charge (4.06V) is too much at hot climate.
80% charge state as well (4.0V). Voltage must be even lower to reduce parasitic
reactions enough. Though now it is too late to think about that. 2011-12 packs
are already degraded and nothing will bring those back.

Learning from Jeff's measurements, Nissan picked the wrong chemistry years ago.
Whoever doubts, just look at his old presentation available on YouTube.
4.3V 4.4V charge cycles kill cells way too fast. The lower it gets, the less problems there are.
As 4.1V cycles still degrade cells too fast in hot climates, need to lower that limit even more.

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

Posted: Thu Nov 09, 2017 4:40 pm
by Oils4AsphaultOnly
arnis wrote:If there is no buffer to knock off 20% in summer, then vehicle is useless in winter.
I keep mine at 80% for majority of them time. Except winter (3temp bars or lower),
when 80% is not enough for my trips.

For old 2011-12 Leafs, 90% charge (4.06V) is too much at hot climate.
80% charge state as well (4.0V). Voltage must be even lower to reduce parasitic
reactions enough. Though now it is too late to think about that. 2011-12 packs
are already degraded and nothing will bring those back.

Learning from Jeff's measurements, Nissan picked the wrong chemistry years ago.
Whoever doubts, just look at his old presentation available on YouTube.
4.3V 4.4V charge cycles kill cells way too fast. The lower it gets, the less problems there are.
As 4.1V cycles still degrade cells too fast in hot climates, need to lower that limit even more.
:(

Well, I've been at 6 temp bars all summer (sometimes 7), and even now when it's almost winter, I'm still seeing 6 temp bars. The only time I've seen 5 is when it's 50F or below. I've noticed accelerated degradation lately, and will update my stats after trying to rebalance my pack first.

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

Posted: Thu Nov 09, 2017 4:45 pm
by ironmanco
Oils4AsphaultOnly wrote:Well, I've been at 6 temp bars all summer (sometimes 7), and even now when it's almost winter, I'm still seeing 6 temp bars. The only time I've seen 5 is when it's 50F or below. I've noticed accelerated degradation lately, and will update my stats after trying to rebalance my pack first.
I noticed in your sig that you only reference GID as a representative of the condition of the battery. Is it always a 1:1 relationship of the SOH of the battery and the GIDs?

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

Posted: Thu Nov 09, 2017 4:51 pm
by Oils4AsphaultOnly
ironmanco wrote:
Oils4AsphaultOnly wrote:Well, I've been at 6 temp bars all summer (sometimes 7), and even now when it's almost winter, I'm still seeing 6 temp bars. The only time I've seen 5 is when it's 50F or below. I've noticed accelerated degradation lately, and will update my stats after trying to rebalance my pack first.
I noticed in your sig that you only reference GID as a representative of the condition of the battery. Is it always a 1:1 relationship of the SOH of the battery and the GIDs?
I think so. And I think 380 GIDs was 100%? I don't have a concrete number since I didn't get the leafspy stats on day one. I did think it was rather odd that SOH was showing 100% all way to 7000 miles (~4.5 months of winter-spring driving)! So for me, I trust the GID number more, since it's a more detailed number than X %

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

Posted: Thu Nov 09, 2017 5:46 pm
by SageBrush
DaveinOlyWA wrote: you would be a perfect "80%" candidate. I think we need to lobby Jim to add custom charge levels to LEAF Spy!

With 24 and 30 kwh packs, there is not enough range to not charge to full but with 40 kwh, I would be ok with a standard 90% charge. Doing just this is supposed to reduce degradation several fold in warm weather.
My 24 kWh car is routinely charged to 80% SoC

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

Posted: Thu Nov 09, 2017 8:56 pm
by johnlocke
Oils4AsphaultOnly wrote:
ironmanco wrote:
Oils4AsphaultOnly wrote:Well, I've been at 6 temp bars all summer (sometimes 7), and even now when it's almost winter, I'm still seeing 6 temp bars. The only time I've seen 5 is when it's 50F or below. I've noticed accelerated degradation lately, and will update my stats after trying to rebalance my pack first.
I noticed in your sig that you only reference GID as a representative of the condition of the battery. Is it always a 1:1 relationship of the SOH of the battery and the GIDs?
I think so. And I think 380 GIDs was 100%? I don't have a concrete number since I didn't get the leafspy stats on day one. I did think it was rather odd that SOH was showing 100% all way to 7000 miles (~4.5 months of winter-spring driving)! So for me, I trust the GID number more, since it's a more detailed number than X %
I'd check with GaryGID to say for sure but I've never seen a report of more than 363 GID's on a new car even when the owners reported AH values over 82 AH from Leaf Spy. I think the value is software limited by the BMS. That would explain why some cars report the same value (363) for months before the the GID's value starts to drop.

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

Posted: Thu Nov 09, 2017 9:12 pm
by ironmanco
So - did a quick charge this evening to about 80 SOC (as reported by LSP). Dash said that I was at 6 bars for battery temp and it pretty much stayed at that when I drove home (~12 miles). I'm now at SOH=83% and my AHr = 66.16 (odo = 34,618)

Image

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

Posted: Thu Nov 09, 2017 9:48 pm
by LeftieBiker
Six bars covers a range from "probably OK" to "definitely too warm for a healthy pack. I think one of the other pages shows pack temp(s)?

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

Posted: Thu Nov 09, 2017 9:54 pm
by ironmanco
The chart has the temp on it as does the top,of it. At the end of the charging it was about 81f

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

Posted: Thu Nov 09, 2017 10:02 pm
by lorenfb
DaveinOlyWA wrote:
The cathode (positive electrode) develops a similar restrictive layer known as electrolyte oxidation. Dr. Dahn stresses that a voltage above 4.10V/cell at elevated temperature causes this, a demise that can be more harmful than cycling a battery. The longer the battery stays in a high voltage, the faster the degradation occurs.
There are three variables, i.e. time, temperature, & battery voltage, mentioned which interact and contribute to degradation. Other than the
mention of voltage, the interaction of all three and the degree to which degradation occurs based on each variable is not mentioned.
So, as an example, to state that allowing the battery to remain at 100% SOC for a few hours at 75-85F repeatedly is going to result in
significant degradation over time as would being at 100% SOC for a month at 100F is naive. Also, there's no mention that charging to 100%
is detrimental. Given that, let's avoid taking what was stated out of context, assuming the worst case, and mis-leading forum members.
Of greater concern should be excessive battery temperature the result of ambient, charging current (QC), and motor current while driving.