THE BEST 0.0% SOC EVER

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Malm
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THE BEST 0.0% SOC EVER

Post by Malm »

Image

So, 324 total voltage but 0,0% SoC. Weakest cell at 3,635 V (so far from the lowest limit, 2,75V, but 0,0% SoC).

In my opinion, in the reality, it has more then 10% SoC left (more then 10 km) but don't let me do even one meter.

Why, I told you many times before, my i-MiEV simple fails in getting correctly its SoC sometimes.

This, total voltage of 324 V and 0,0% SoC, only me and my i-MiEV can show. Because it only do this if some conditions happen at the same time (and I know how to gather those conditions). One of them is to have a car that thinks its capacity is 10% lower then it really is.
Last edited by Malm on Tue, 01 Jul 2014, 05:21, edited 1 time in total.
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Post by Malm »

And to the record, not any signs of a fire, not even a bit of smoke. What a disappointment. Image
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Post by Johny »

You really do take it down to a low SOC too often Malm.
I do not think that your vehicle will represent a reasonable indication of battery pack life.

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Post by Malm »

I don't see where is the problem of having cells between 3.635V and 3.7V. For me they seem far from a value that can damage the battery. When we are driving, we have them often lower then that. The car will only cut the energy when a cell is at 2,75 V, so I don't see any reason why having THIS 0,0% SoC can be a problem.

Of course johny is right when he says that going to 0,0% should be something to do once in a life time (or never), but who would believe in that if I didn´t do it???? Who would believe that my 0,0% SoC could be 328 total voltage??? A new one will not show at 0,0% that value of voltage, for sure.
Last edited by Malm on Tue, 01 Jul 2014, 13:23, edited 1 time in total.
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Malm
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Post by Malm »

Just trying to know the limits jonhy. Trying to know the limits. trying to know the car. No one can tell me this things.

I even thought that the car could move with a negative SoC. Now I know that's impossible, even if it has energy to do so.
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Post by antiscab »

Malm - I think you will be the first to find out how to reset the capacity measurement

I wonder if it is something easy like disconnecting the 12v battery and removing the service disconnect on the HV battery so the car "forgets" everything and then has to remeasure

on the other hand, there must be a way to reset with a scan tool
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THE BEST 0.0% SOC EVER

Post by Malm »

Now my weakest teory of all. The car does it by itself, once an year in its birthday. I say this because I saw a change in the capacity of the car, one in march 2013 (when it added more 5% to its initial capacity ) Image and in march 2014 (when it subtracted 27% to its initial capacity). My car was used for the first time in march 2011.

80% chance that i'm wrong.
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Post by g4qber »

Funny how we got 107% soc on ants car
So I wouldn't be surprised if soc went negative
Last edited by g4qber on Tue, 01 Jul 2014, 14:44, edited 1 time in total.
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Post by Malm »

g4qber wrote: Funny how we got 107% soc on ants car
So I wouldn't be surprised if soc went negative


107% of SoC Image Image Image . Never saw such a thing. Amazing. Mine never goes upside 100%. Never.
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Post by me68 »

Hello!

If you touch the left block, beginning with "RR", ending with "Wh/km", you'll get a screenshot file in /sdcard/bt_can. filename starting with pict_

You can also define a screen capture intervall (f.e. every 10 secs) with such files. Then you can easily make a fast motion video f.e. from panel "Batt Status".


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Post by Malm »

Yes, I know that. But I have done it before without that option. Image
Last edited by Malm on Tue, 01 Jul 2014, 18:26, edited 1 time in total.
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THE BEST 0.0% SOC EVER

Post by Malm »

Image

Charging from the 0,0% (328 V) to 100% (360 V). No interruptions ever. Made a correction of SoC at 78%.
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Post by acmotor »

How to read that information ?
Either the Bluetooth link was interrupted for 40 minutes or (Malm says no) the battery capacity is 14% less than the expected (new) capacity ?
If the second is the case and the battery management system is making a correction on the basis of pack voltage then the canion SOC value is not an accurate indication of SOC ?
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Post by Malm »

acmotor wrote: How to read that information ?
Either the Bluetooth link was interrupted for 40 minutes or (Malm says no) the battery capacity is 14% less than the expected (new) capacity ?
If the second is the case and the battery management system is making a correction on the basis of pack voltage then the canion SOC value is not an accurate indication of SOC ?


I´m sure that there was no interruption (I saw this behavior more times). I don't believe in your second option too. What I believe is that the car has the number 11,3 kWh for its maximum capacity, and when it descharges that value (0,0% SoC) stops (but because it is in the reality of 13,6, there will be more 2 kWh that I can't use). So it began charging with 14% SoC (and not the 0,0% that it erroneously mesaured, and then, when almost full, it finds that the 14% were already there and make the correction.
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Post by acmotor »

Ok, another very clear observation.....
The rate of SOC increase is the same from 92% to 100% as for the change up to 78%. THIS IS NOT the case when observing the power meter in the last 10% or so of a charge. The charge rate tapers off. This graph does not show that taper off so the SOC is not directly linked to actual SOC ?
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Post by acmotor »

FWIW, cell #65 is regularly the lowest voltage on discharge and highest on charge in my pack too ...... by a few mV, but canion shows up the highest and lowest of course.
Which temperature sensor is most applicable to cell #65 ?
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Post by Malm »

acmotor wrote: Ok, another very clear observation.....
The rate of SOC increase is the same from 92% to 100% as for the change up to 78%. THIS IS NOT the case when observing the power meter in the last 10% or so of a charge. The charge rate tapers off. This graph does not show that taper off so the SOC is not directly linked to actual SOC ?


Interesting observation. It should taper of. In the last 10% or so of charge, the rate of increasing SoC should be lower. I saw the last minutes of many charges and SoC went up lower in the end. This time it didn´t happen (maybe it stoped before the real 100%, thinking that reached 100% or did that slower phase of charge all at 100% SoC (some cars take many minutes charging at 100%).

Another thing, the last to bars to charge are of 7% and 8% (the others are of 5% SoC), so they will naturally take longer time to charge.
Last edited by Malm on Wed, 02 Jul 2014, 13:19, edited 1 time in total.
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Post by Malm »

acmotor wrote: FWIW, cell #65 is regularly the lowest voltage on discharge and highest on charge in my pack too ...... by a few mV, but canion shows up the highest and lowest of course.
Which temperature sensor is most applicable to cell #65 ?


Image

#49 or #43

Is one of the hottest cells of the pack, because of the internal position.

In me68, #65 is one of the weakest too:

Image
Last edited by Malm on Wed, 02 Jul 2014, 12:54, edited 1 time in total.
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Post by acmotor »

Yes, Temp sensors 48,49,54,55 are typically high and cells 65 and 74 swing lower and higher than others.
For vehicles on the other side of the planet to both show this it is likely that cell layout / temperature is a factor.

Now, those last two bars being 7 and 8 % rather than 5% may the the lost power by the battery equalisation circuit ? Or the tapered off charge meaning the coolant pump and other circuits with reasonably constant load are making the bars appear different but actually the same ? Maybe a full charge at 6A vs one at 13A could shed some light on this.

Still, that lack of SOC rate taper at the end of charge flags to me that canion is only as good as the data sent to it and you really can't read it to 1%.
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Post by Malm »

"Now, those last two bars being 7 and 8 % rather than 5% may the the lost power by the battery equalisation circuit ? Or the tapered off charge meaning the coolant pump and other circuits with reasonably constant load are making the bars appear different but actually the same ?"

Just giving may opinion (sometimes I will be wrong). No, Mitsubishi did it on purpose. When discharging, we will have more energy in that two bars. That´s why 100% of i-MiEV owners say that can do more miles with the 16 bar (the last to charge)then with the others when it is new).
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Post by offgridQLD »

Ac motor the last two bars are the same 7 -8 % when your discharging as well as charging. So has nothing to do with balancing.

I agree that canion is only as good as the data it is being sent.

Though it's being sent the data from the battery management unit on the Imiev. This BMS has full control over our battery's. So what the BMS is saying and thinks is very important.

You can measure things from the wall but your wall plug has no control over your car when your out driving it. The BMS has full control. It even has control of when your charging and can tell your wall plug to stop sucking power from your wall meter.

The BMS calls the shots. We need to know how it's SOC is calculated what it's set points are for a host of things and why we see odd behavior when we do.

Canion is our only window into whats going on at this stage. I'm sure there is more data that can be had and that could answer some questions.

Calculating battery SOC and trying to represent it reliably isn't easy.


There is some funky stuff going on people charging to over 100% others only charge to 95%. Some pull the pin and wont let you drive the car when there is clearly a voltage at the cells that doesn't represent a that low SOC. Wouldn't it be great if we just had the book on the Imiev BMS .

I guess Malms issue is at some point the Imiev decides to flash the turtle and then at some point it decides to pull the pin and not let you drive any more. What is the criteria that the BMS uses to make the two decisions? It cant be voltage . Though I'm sure there is a set point for low / high voltage every good BMS has that. I'm sure there is one for temp to. Though we are not hitting temp or voltage limits. Giving the BMS control based on capacity (however that's calculated) it looks like this can get it wrong a little and we are reaching what i would call a (soft cut off limit) wont let you drive the car but not temp or under voltage triggered.

Kurt



Last edited by offgridQLD on Sat, 05 Jul 2014, 19:00, edited 1 time in total.

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Post by Malm »

Yesterday, I drove for something like 105 km. Full charge (100%) in the beginning. Arrived with 15% of SoC and 325 total voltage. Going up hill more then 250 meters. I think I could do more 20 km until 0.0% SoC. This time, as most of the times, the SoC was right. 50 km/h medium velocity.

That 0.0% SoC - 324 V is just to open your eyes. That only happens when we gather some conditions. For those who were criticizing me because I was discharging it so much, maybe now they can understand that 0,0% SoC is not always the same thing. Voltage, with car not in movement, is the right number.

Malms I-MiEV, is getting its SoC right (well, most of the times), is capable of making trips of 140/150 km at 50 km/h in flat areas, can charge 16 kWh from the wall from 0,0% to 100%. The thing that isn't right is that the car established erroneously last march that it is of 11,6 kWh. It will be, some day, but for now it is of 13,9 kWh.

Last edited by Malm on Sat, 05 Jul 2014, 21:42, edited 1 time in total.
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