bobakka
Posts: 36
Joined: Mon Nov 03, 2014 8:03 am
Location: Oslo, Norway

Re: Canion Battery Readings

Sun Dec 07, 2014 1:57 am

I have done som more test.
Yesterday I started with 99,5 SoC and drove until 12.0, charged up to 96,5, drove down to 13 and charged back up to 99,5
The resulting Canion screenshot is below.

https://www.dropbox.com/s/u30w12uocdc8n ... 0.png?dl=0
Image

The result is that WhOut is almost 10% higher that WhReg.
WhOut should have been some % lower that WhReg due to internal losses in battery (and electronics?).

That means that the CanBus values Canion reads is not accurate - at least not with respect to Wh.
I assume from the discussion on this forum that we trust WhOut values, but not WhReg values.
Last edited by bobakka on Sun Dec 07, 2014 2:47 am, edited 3 times in total.
iMiev; New Feb 2011; 119000 km January 2017

bobakka
Posts: 36
Joined: Mon Nov 03, 2014 8:03 am
Location: Oslo, Norway

Re: Canion Battery Readings

Sun Dec 07, 2014 2:39 am

BlueLightning wrote:
Charge efficiency for a 10 Amperes charge is 88.0 %, for my 16A charge, 81.2%



Hi BlueLightning
Is the 16A charger less efficient than the 10A charger? I thought it was the other way around.
And how do you calculate charge efficiency?

I find that WhReg is around 77% of what you call "Wall Kw-h" measured with external kWh-meter.
Given that WhOut is around 10% higher that WhReg (shown in my previous reply) and that WhOut is "correct",
I find that my 16A charger has a charge efficiency of 85%.
iMiev; New Feb 2011; 119000 km January 2017

siai47
Posts: 363
Joined: Fri Jun 14, 2013 5:54 pm

Re: Canion Battery Readings

Sun Dec 07, 2014 7:44 am

In answer to bobakka's 20% loss post, I would go back to the point that the BMU "masks" the battery degradation by limiting how low the cell voltages go until a minimum is reached and then the true capacity loss starts to be noticed. New I-MiEV's don't use all the available capacity of the pack until this point therefore the range doesn't change and no perception of loss is noticed by the driver. I think there are so many variables to determine an actual capacity number for the pack that Mitsubishi uses the amp hour storage of the pack as a reference. Amp hour capacity of the pack can determine the percentage of degradation without doing the complex calculations of the continuous voltage drop during discharge to come up with a KWH value which (if done) leads to the same conclusion. The hall effect transducer in our pack just measures the number of amps passing through it over time. This number, not range, AC watts going in to charge, trying to calculate charger losses, balancing losses, vehicle loads during charge, cutoff points, etc. just complicates what needs to be known. If you start with a known pack voltage (in our case 4.105 per cell) and discharge it to a known cutoff point (the lowest point the weakest cell can be safely taken to) and measure the amount of amps that were delivered from the pack of 50 amp hour cells---then you have the answer. Our cells are rated by Yuasa at 50 amp hours with a nominal voltage of 3.6 volts. Multiply 50 X 3.6 and you have 180 WH per cell. 88 cells X 180 WH equals 15,840 watt hours or 15.84 KWH which is the actual rating of a new I-MiEV pack. So, for example, if you found during the M.U.T. III test that your pack had 39 amp hours capacity, you would know that 39 X 3.6 X 88 = 12,355 watt hours or 12.355 KWH of capacity is available. Dividing it out you've lost around 22% of the original possible capacity. Going back to the first sentence of the post, the pack capacity was always falling but not noticed because of the BMU. Li-Ion batteries tend to fall off in capacity quickly at first and then start to level off. The BMU hides this by giving the driver a constant usable capacity even though the actual capacity is dropping.

bobakka
Posts: 36
Joined: Mon Nov 03, 2014 8:03 am
Location: Oslo, Norway

Re: Canion Battery Readings

Sun Dec 07, 2014 8:45 am

siai47 wrote: Mitsubishi uses the amp hour storage of the pack as a reference.

I support your view there. Amp hour is easy to measure and calculate.

siai47 wrote:
Our cells are rated by Yuasa at 50 amp hours with a nominal voltage of 3.6 volts.
.. if you found during the M.U.T. III test that your pack had 39 amp hours capacity,
.. you've lost around 22% of the original possible capacity.

I support your view here also.

One question is however what the M.U.T. III measure when capacity is hidden from the user.
Does it measure available or total capacity?

The other question is when the warranty kicks in?
Given 39 amp hours capacity and 22% degradation, is this above or below the 20% guarantee?
iMiev; New Feb 2011; 119000 km January 2017

siai47
Posts: 363
Joined: Fri Jun 14, 2013 5:54 pm

Re: Canion Battery Readings

Sun Dec 07, 2014 11:09 am

I don't know what they measure (total or available capacity) when they are doing the capacity test. However, it seems like it must be a total capacity test. The car never charges to the full 4.2 volts that the LEV-50 cell is capable reaching nor does it normally drop to the lower limit of 2.75 volts. The cell needs to be cycled fully to reach 50 amp hours, therefore to get near that number when the car was new, at a minimum they must be going down to the 2.75 volt threshold with the M.U.T. III. I assume the scan tool could force the BMU to adjust both the maximum and minimum voltages the pack could see if Mitsubishi wanted to do that. As far as capacity loss for warranty purposes is concerned, I have never read the warranty policy (I voided mine right off the bat anyway). Again, I am pretty sure that Mitsubishi knows exactly what the amp hour capacity of each pack was when the car was delivered. My dealer stated that a capacity test was required on each car prior to delivery. In my opinion, that would be the starting point. In my example I used 39 KWH (which is a little lower then bobakka's actual) but if you knew what Mitsubishi recorded at delivery and what was recorded at the last test and that calculation exceeded 20% then I would think you met the requirements for a failed battery if 20% is the threshold.

Barbagris
Posts: 237
Joined: Wed Feb 20, 2013 8:34 am
Location: Bilbao, Spain

Re: Canion Battery Readings

Mon Dec 08, 2014 2:27 am

bobakka wrote:I have done som more test.
Yesterday I started with 99,5 SoC and drove until 12.0, charged up to 96,5, drove down to 13 and charged back up to 99,5
The resulting Canion screenshot is below.

https://www.dropbox.com/s/u30w12uocdc8n ... 0.png?dl=0
Image

The result is that WhOut is almost 10% higher that WhReg.
WhOut should have been some % lower that WhReg due to internal losses in battery (and electronics?).

That means that the CanBus values Canion reads is not accurate - at least not with respect to Wh.
I assume from the discussion on this forum that we trust WhOut values, but not WhReg values.


Great job, thanks.

In my hilly conmute I usually see in caniOn 27%-30% of Wh regenerated; I wonder how to use some kind of correction coefficient.
...learning...

bobakka
Posts: 36
Joined: Mon Nov 03, 2014 8:03 am
Location: Oslo, Norway

Re: Canion Battery Readings

Wed Dec 10, 2014 6:34 am

siai47 wrote:In answer to bobakka's 20% loss post, I would go back to the point that the BMU "masks" the battery degradation by limiting how low the cell voltages go until a minimum is reached and then the true capacity loss starts to be noticed.


If I understand you correct your hypothesis is that the cell voltage for SoC = 0 decreases as the the battery and car gets older?

That is for example when new SoC = 0 is equal to a cell voltage of for example 3.5 V
and when driving 10 000 km SoC = 0 the cell voltage is 3,4 V
and when driving 20 000 km SoC = 0 the cell voltage is 3,3 V - and so on..

I yesterday drove to SoC = 10,5 in minus 6 C (battery voltage above 15 C) with cell voltage from 3,615 down to 3,575.
(I see however in my iMiev that SoC and cell voltage does not have a consistent relationship. I assume that is either due to large fluctuations in SoC calculations, temperature or driving style prior to measurement time)

If your hypothesis is right, Pier with a new battery pack should have with same SoC higher cell voltages than my iMiev.
Agree?
iMiev; New Feb 2011; 119000 km January 2017

Malm
Posts: 449
Joined: Mon Jul 22, 2013 12:16 pm
Location: Tábua - Portugal

Re: Canion Battery Readings

Wed Dec 10, 2014 5:45 pm

"If I understand you correct your hypothesis is that the cell voltage for SoC = 0 decreases as the the battery and car gets older?

That is for example when new SoC = 0 is equal to a cell voltage of for example 3.5 V
and when driving 10 000 km SoC = 0 the cell voltage is 3,4 V
and when driving 20 000 km SoC = 0 the cell voltage is 3,3 V - and so on.."


Yes, I agree with it. So, in first two years, many of the i-MiEV owners don't get any loss in autonomy. The real limit is 2,75V, no matter what the SoC is.

Another thing we always should remember, 100% SoC is not the same amount of energy in every i-MiEV. In my i-MiEV, when it was new, 100% SoC was more or less 16 kWh in the battery. Then after 2 years, my car recalculated the capacity to something like 100% SoC = 17 kWh (that´s why I have the record shared with Mrannen of 175 km mRR).
But after three years, It assumed something like 14 kWh = 100 SoC, and that´s why I can go, after three years to 0.0% SoC with more then 2,75 V in the weakest cell. But I have now less about 18% autonomy compared with when it was new, I think.
Riding an i-Miev since 4/2011 in Portugal, 100.000 kms.

jray3
Posts: 1700
Joined: Tue Dec 06, 2011 1:05 am
Location: Tacoma area, WA
Contact: Website

Re: Canion Battery Readings

Fri Dec 12, 2014 2:03 pm

bobakka wrote:I have owned my imiev for almost 4 years and been driving 77777 km. My 80% capacity guarantee expires in 14 months or 22222 km. I am positive that I have a range decrease, but it is very difficult to calculate how much. So how do I open a guarantee case against Mitsubishi if I need to?


What 80% capacity guarantee? Is that unique to the Norwegian market, and where else? IIRC, the US-market cars have no capacity guarantee.

Btw, I got the dealer to run a battery capacity test during the rusty bolt recall work, and it came back at 42.6 Ah. That figures 15% below original spec after 30,000 miles (48,280 km), though it's been said (Malm, IIRC) that new cars didn't even hit 50 Ah.
I still have all 16 bars and no change in daily RR estimates (often 81 this summer, typically 56 on freezing mornings).
Last edited by jray3 on Mon Dec 15, 2014 8:22 am, edited 1 time in total.
2012 i-SE "MR BEAN" 110,300 miles
2016 KIA SOUL EV, 90 kW, 27 kWh, 34k miles
2000 Mazda Miata EV, 78 kW, 17 kWh
1983 Grumman Kurbwatt EV,170 kW, 32 kWh
1983 Mazda RX-7 EV 43 kW 10 kWh
1971 "Karmann Eclectric" EV 240 kW 19 kWh

Malm
Posts: 449
Joined: Mon Jul 22, 2013 12:16 pm
Location: Tábua - Portugal

Re: Canion Battery Readings

Sat Dec 13, 2014 9:21 am

Mine after 3 years and 62000km had 36,4 Ah (something like that). And now, with 3 years and 9 months, almost 75000 km, the same 16 bars, but each one corresponding to 15 to 20% less energy then when it was new. So I do between 15 to 20% less distance with each bar. I think (one more of my special ideas) all i-MiEV recalibrates its capacity after three years. Mine did that, and now I Know that it is not the only one that did such thing. I know another european I-MiEV that has done exactly the same thing.
Riding an i-Miev since 4/2011 in Portugal, 100.000 kms.

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