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

Posted: Fri Jun 22, 2018 5:56 am
by JPWhite
lorenfb wrote:
Yes. And how about if bars drop based on time now, e.g. a bar every two years. Now that would surely reduce battery liabilities, right?
Using loss of bars is such an arbitrary measure that Nissan can have it represent anything. We'll have to see what happens over time.
While I agree this is an arbitrary measure; lets not lose sight of the fact that Nissan LEAF does have a battery health meter on the dash. Other manufacturers don't present anything to the driver and you are totally at the mercy of the service center to tell you what the battery health is (if they are willing to divulge this information at all).

Capacity bars is an attempt by Nissan at transparency. That is to be applauded. Their continued bungling of the algorithm and adjustments to it undermines any gains from the transparency since many here doubt their intentions in adjusting the algorithms. My mind boggles that 8 years later the same story is playing out with the 30kWh pack as occurred with he 24kWh pack. How could they make the same type of mistakes twice in a row? They must have the B team writing the BMS software.

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

Posted: Fri Jun 22, 2018 9:50 am
by lorenfb
JPWhite wrote:
lorenfb wrote:
Yes. And how about if bars drop based on time now, e.g. a bar every two years. Now that would surely reduce battery liabilities, right?
Using loss of bars is such an arbitrary measure that Nissan can have it represent anything. We'll have to see what happens over time.
While I agree this is an arbitrary measure; lets not lose sight of the fact that Nissan LEAF does have a battery health meter on the dash.
Then why not just display the key measure of any battery's remaining capacity, Ahrs, and not have a fudge factor like bars to tweak on occasion?
From the onset of my Leaf ownership, I never followed the bars and now that my battery warranty has expired, I totally disregard the bars.

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

Posted: Fri Jun 22, 2018 10:55 am
by jbuntz
I did a full discharge test yesterday. Got it down to 9gids on LeafSpy 3.639v 349.62v pack voltage. The qc screen said it was starting at 3% LeafSpy 2.2% soc .7kWh 98° Battery. 100% Charge took 31 minutes. Started at 45kW ended at 20kW. Started ramp Dow at 15 minutes. Ending temp 120F. Charger reported 19.81kWh delivered. (19.81 + .7) / 31.78 = 65% of original capacity?

Also, I was sitting in the car with th ac on for 30 minutes so I should subtract .5kWh from the delivered amount.

This is before bms reset.

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

Posted: Fri Jun 22, 2018 11:03 am
by SageBrush
jbuntz wrote:I did a full discharge test yesterday. Got it down to 9gids on LeafSpy 3.639v 349.62v pack voltage. The qc screen said it was starting at 3% LeafSpy 2.2% soc .7kWh 98° Battery. 100% Charge took 31 minutes. Started at 45kW ended at 20kW. Started ramp Dow at 15 minutes. Ending temp 120F. Charger reported 19.81kWh delivered. (19.81 + .7) / 31.5 = 65% of original capacity?
This is before bms reset.
If I'm not mistaken the top 2-3% of the battery capacity is reserved, so it would not be part of the calculation. If 360V is used as nominal (average) voltage then (19,810*0.875)/360 = 48.15 Ahr usable capacity.

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

Posted: Fri Jun 22, 2018 11:13 am
by SageBrush
lorenfb wrote: Then why not just display the key measure of any battery's remaining capacity, Ahrs, and not have a fudge factor like bars to tweak on occasion?
Exactly

As for other cars, my Model 3 shows rated miles remaining. Division by 4 gives the battery kWh available within ~ 0.5% accuracy. Ed the Tesla troll can use 3.982035928

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

Posted: Fri Jun 22, 2018 11:29 am
by jbuntz
SageBrush wrote:
lorenfb wrote: Then why not just display the key measure of any battery's remaining capacity, Ahrs, and not have a fudge factor like bars to tweak on occasion?
Exactly

As for other cars, my Model 3 shows rated miles remaining. Division by 4 gives the battery kWh available within ~ 0.5% accuracy. Ed the Tesla troll can use 3.982035928
I like that calculation. I use LeafSpy kWh remaining *4 to estimate what I have left. On the Tesla if your miles to destination is more than rated then you just slow down till it equals.

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

Posted: Fri Jun 22, 2018 11:35 am
by SageBrush
jbuntz wrote:
SageBrush wrote:
lorenfb wrote: Then why not just display the key measure of any battery's remaining capacity, Ahrs, and not have a fudge factor like bars to tweak on occasion?
Exactly

As for other cars, my Model 3 shows rated miles remaining. Division by 4 gives the battery kWh available within ~ 0.5% accuracy. Ed the Tesla troll can use 3.982035928
I like that calculation. I use LeafSpy kWh remaining *4 to estimate what I have left. On the Tesla if your miles to destination is more than rated then you just slow down till it equals.
Yeah, it is practical but the actual number is calculated based on EPA fuel economy test results. Thus the "rated miles"

As for destination calculations, the car is way ahead of us. It also takes changes of elevation into account in addition to kWh remaining and consumption history. It is remarkably accurate unless wind or rain are in play.

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

Posted: Fri Jun 22, 2018 2:56 pm
by dwl
jbuntz wrote:I did a full discharge test yesterday. Got it down to 9gids on LeafSpy 3.639v 349.62v pack voltage. The qc screen said it was starting at 3% LeafSpy 2.2% soc .7kWh 98° Battery. 100% Charge took 31 minutes. Started at 45kW ended at 20kW. Started ramp Dow at 15 minutes. Ending temp 120F. Charger reported 19.81kWh delivered. (19.81 + .7) / 31.78 = 65% of original capacity?

Also, I was sitting in the car with th ac on for 30 minutes so I should subtract .5kWh from the delivered amount.

This is before bms reset.
Great info thanks. It is my understanding the under-reporting starts becoming apparent at these GIDs and lower. What does everyone else on this forum think of a reported 2.2% SoC and 349.62V pack, 3.639V cell voltages?

I doubt there is only 0.7kWh usable remaining above turtle. I have seen some data (obviously different car) with over 8kWh remaining at that voltage. Looking at it another way - what would be the nominal voltage of this pack knowing it goes to 395V if lowest was near 350V?

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

Posted: Fri Jun 22, 2018 3:06 pm
by dwl
jbuntz wrote:Charger reported 19.81kWh delivered. (19.81 + .7) / 31.78 = 65% of original capacity?
The value of 31.78kWh is an AC charge event at 240V which has significant losses and also probably needs to start from quite flat. If we took (19.81 + .7) / 29 = 70% (nominal amount) I suspect that is much lower than actual due to probable high starting point. I acknowledge might need some corrections if your Hx was low.

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

Posted: Fri Jun 22, 2018 4:26 pm
by SageBrush
dwl wrote: What does everyone else on this forum think of a reported 2.2% SoC and 349.62V pack, 3.639V cell voltages?
My first thought is that pack depletion is determined by the weakest cell.