30kWh minimum cell voltage

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Thanks Goldbrick for putting yourself through what sounds like the perfect résumé of EV ownership! Range, infrastructure and morons. You got it all, 😭.

But, I can't see your images. Is it me? All I see is two grey "no entry" signposts. I've logged in and can see other pics... Any ideas?

My Leaf goes to --- at 6 or 7% on the dash as well. Used to be 5%... But what with inflation and all 😉. I'd love to compare the rest when I can see. Maybe do a the same screen grabs when you've got her fully charged again. I've just done that, I'll attach them later and we can compare top and bottom ends.
 
Dang! I thought I had cracked the nut on how to post the pictures. I'm at work now and I can see them and I could see them at home when I posted them. Maybe it's because they are on my account? I put the sharing mode to public as far as I know but maybe there is more I need to do. I'll take another look later or post them somewhere else if need be.
 
It could be me! I am aghast at how difficult it is to insert pics on this forum. I had to go read through pages of suggestions in the faq before I found someone clever who posted how to modify the links given by Google photos so they would show up here... It was almost coding (well for a non coder anyway!).
 
Nope I can't see diddly. I've tried on PC and mobile, just get the same 'no entry' sign. as, I'm sure this is of limited interest to others maybe I could just pm you my email?
 
:D

Yep, that works!

I'm still not very good at undertaking leafspy, but it looks as though the car was taking a 5kW charge when you took those pics. If that is the case then of course the voltages would be being pulled up by the charger. I don't know by how much, but I don't think it would be viable to compare them to my one where I was in fact still driving so the voltages were being pulled down.

Otherwise it would seem an interesting comparison. You seem to have almost exactly the same dégradation as me, even Hx, yet with far less than half the mileage covered, virtually none of my 200 fast charges and only a fifth of my slow charges! I can't remember, has yours had the BMS update? If it has then why do we have the same battery capacity? It would seem to suggest that nothing we do makes any difference! If not, well then you probably would benefit significantly from it!
 
tomhanman said:
It would seem to suggest that nothing we do makes any difference! If not, well then you probably would benefit significantly from it!
SoC, pack temperature, pack age, and pack variability from the factory are very important variables you have not (and mostly cannot) account for.

This is why the sort of 2 car comparisons you are indulging in is worthless, and leading you to at best unsupportable, but actually wrong, conclusions.
 
Pretty dreadful quoting there, choosing to miss off the IF and the conditions associated at the start of my statement. But I guess tabloid journalism is everywhere.

But Hi.

I don't think what you said makes much sense.

Sure there are always many factors, and that is important to consider. In this case we have purposefully ensured the two batteries are at the same 10% SoC before taking readings. So what is your problem with that?
 
And of course if you've read the start of the thread, what I am trying to find out about is the cell voltages in a Leaf when turtle is triggered and then when run lower.

Determining that in a brand new Leaf and comparing to mine would be a poor comparison, but as Goldbrick's seems to have a battery in an identical state, and he has been good enough to make the effort to provide some data, it would make an excellent source of information.
 
And IF his voltages are for example significantly different to mine, and IF the only difference turned out to be that he had not had the BMS software update, then it would seem to me a very safe conclusion that the software update changes the protection at the bottom end of discharge.

We are not there, and may never be. If you would care to provide something useful to make this more valid in your eyes, then feel free.

I can think of nothing better than accumulating a huge database of Leaf turtle cell voltages with BMS software version. Want to help?
 
tomhanman said:
Pretty dreadful quoting there, choosing to miss off the IF and the conditions associated at the start of my statement. But I guess tabloid In this case we have purposefully ensured the two batteries are at the same 10% SoC before taking readings. So what is your problem with that?
Doing so is pretty much irrelevant. I was talking about the triple integral of heat, SoC and time as variables affecting degradation
 
tomhanman said:
I agree there is a wide spread, But at such a low voltage I just don't see where the 10% is hiding, and I don't see why turtle didn't step in earlier. I thought that turtle mode showed up as the first cell reached 3V, not once they had all gone past it!

tl;dr -- use the Gids remaining (or percentage of Gids remaining) for range

Long story:
Turtle is invoked when any cell hits ~ 2.5v. The drop from 3.2v to 2.5v is pretty quick. Gids calculates from the weakest cell

LeafSpy also reports kWh remaining. This is based on pack voltage and is increasingly a range overestimate until turtle as cells differ one from another in the pack.

EXAMPLE:
Your pack is 96 "cells" in series
Say you have 95 cells at 3.5V and one cell at 3.0V
KWh remaining would start its calculation using (95*3.5v + 3) volts
Gids would calculate starting from (96*3) volts
 
FWIW, my Leaf has had the BMS firmware performed (bars went from 6 to 10 afterwards).

And yeah, my bad on taking the measurements while the car was plugged in. I'll try again sometime and get a reading with it unplugged.
 
FWIW, my Leaf has had the BMS firmware performed

Ok, so we'll need to revisit with more comparable data, if and when you feel like taking the risk!

All of what sagebrush says is, I'm sure, very precise. I don't really know of what relevance any of the gids or kWh references made are to this experiment. We have only used %SoC and compared like to like. There appear to be altogether too many ways to skin this cat. Anyway the bit that I'm interested in - the point at which turtle kicks in, and the point at which the car refuses to run any further is still murky.

I still find it hard to believe that any measurement of a Li-ion cell gives 10% of its capacity below 2.5V. I believe that would be more like 3%, so I remain confused.

And I think, despite any other points of view, it is fascinating to compare the two situations. The batteries are currently so similar both with the BMS update but after such completely different lives, actually just as mine and John Locke's were at one stage. He definitely lives in a very much warmer climate than me, and his degraded much faster as we compared values monthly.

Whereabouts are you, and what (for those of us ignorant on such matters) is your climate like? Do you in fact live in a desert?

Regards Tom.
 
tomhanman said:
Anyway the bit that I'm interested in - the point at which turtle kicks in, and the point at which the car refuses to run any further is still murky.

Your answer is a simple Google search away.
But keep in mind that the SoC difference between say 2.5 and 2.6 Volts is tiny. Look at this somewhat idealized Volts Vs SoC graph for Li-ion:

Li-ion%20Discharge%20Voltage%20Curve%20Typical.jpg


Once your weakest cell hits ~ 3.25V you are a couple SoC percentage points away from turtle. A "30 kWh" LEAF with 30% pack degradation has about 28*0.7 = 19.6 kWh usable, so about 196 Wh per SoC percentage point. If you are a gentle driver, have no AC running, and are driving on flat land at 40 - 60 kph you can manage 1 mile (1.6 km) per SoC percentage point. In this range of the discharge curve a drop of 0.7 mV is only some 3,000 meters of range, so that last 0.1 mV drop is perhaps good for 400 meters. Maybe. Or you get going from a red light and turtle anyway.
 
Tomhanman,

I'm in Boulder CO. So climate is fairly moderate. We hit 100 for a few days every other year or so but even on those hot days it gets down to 70 at night. My Leaf hasn't hit 7 temp bars in years since I've learned to park in the shade and charge when it's cool. I think the lowest I've ever had the car is 9% SOC. I've been to 100% SOC a handful of times but try to keep it under 80% most of the time.

All this is on my original Leaf. I bought another one to see if I could get a warranty battery. That is the one that I went to turtle with and the one the LeafSpy shots above are from. That one is at 75% SOC at 27k miles (after BMS update). It was 48% SOC or something when I bought it but the BMS update brought it back significantly. It behaves much more normally after the update so I believe the latter numbers much more the former.
 
. I had LeafSpy running at the time since the dash was all --- but I can't remember the details except that it said I had about 1% SOC left when it quit.
wait I thought turtle mode will kick in before the car stops altogether. So you did’nt get the turtle first? Just 1% then stop?
 
If you have a car with 90 miles of range then consider yourself lucky and stay away from driving at the bottom end. For a year or two i drove a 24 mile daily commute with a 40 mile range pack and never ran it till it died or hit turtle.

Why do it if you don't need it? Pulling cells so low and with the extreme delta V of min/max does not make for better cells. Charge up to 90 instead of 80 to get your extra 10% if it is needed for the commute.

Also LS is just an app that reads CAN buss Pids and gives you some pretty pictures with no clue how the VCM actually processes and responds to the data. Only knowing the details of the controller firmware could give you the answers and explain the puzzling turtles.
 
wait I thought turtle mode will kick in before the car stops altogether. So you did’nt get the turtle first? Just 1% then stop?

It was in turtle mode for a while before it quit. I can't remember how far it went in turtle mode but I'm sure someone here has posted that info in the forum.
 
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