Canion Battery Readings

[bobakka]

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.

Mitsubishi gave us a 80% capacity guarantee for 5 years / 100000 km in the Norwegian market. It is also documented in elbil.no. But I have never heard ony any that has been claiming that guarantee. I problems is maybe how you measure the capacity reductions. Probably it is by using amp hours.

 

[RobertC]

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.

From the service manual, checking the battery capacity is a quick procedure using the MUT-III scan tool.

I wish that battery capacity was part of Canion, then Mitsubishi i EV owners could compare battery capacity all around the world.

What an awesome database that would be!

 

[siai47]

I've looked at that line in the diagnostics before and think it would be an indication of capacity but not true capacity. I think that what you would be looking at would be the BMU's calculation of the capacity based on time since new, cycles and miles driven---not actual capacity. The actual capacity test involves a complete discharge of the pack while connected to the M.U.T. III and takes several hours to complete. I don't know if a successful full test resets the BMU's calculation or not.

 

[RobertC]

The actual capacity test involves a complete discharge of the pack while connected to the M.U.T. III and takes several hours to complete. I don't know if a successful full test resets the BMU's calculation or not.

Yes. I saw that capacity test in the service manual also. It involves connecting the scan tool, selecting "Traction Battery Capacity Automatic Measurement", and turning on the car's air conditioner while the car charges to full.

From the Warranty and Maintenance Manual Addendum:
"As a result of improved software, check main drive lithium-ion battery for capacity has been eliminated from the regular and severe maintenance schedule."

I was wondering if the improved software helped to calibrate the battery capacity number, so that this longer test was not necessary.

 

[jsantala]

It's not really that hard to determine your current battery capacity.

Connect OBDLink dongle and fire up the Canion Android app. Fully charge to 100% SOC and drive until the car doesn't move. Check the Wh out on Canion. That's your absolutely maximum usable battery capacity as measured by the car. How you drive or what you use during the drive makes no difference. Temperature will, so do this as near to room temperature as possible.

If you don't want to drive to empty, note Canion SOC % state, drive for as long as you like, note Canion SOC % and Wh out. Divide Wh out with percentage of battery SOC % lost during the drive and multiply by 100. That is the capacity of the car battery as calculated by the car at that moment. It's not as accurate as the first method, but not nearly as troublesome either. Also it doesn't put extra stress on your pack.

 

[JoeS]

If you don't want to drive to empty, note Canion SOC % state, drive for as long as you like, note Canion SOC % and Wh out. Divide Wh out with percentage of battery SOC % lost during the drive and multiply by 100. That is the capacity of the car battery as calculated by the car at that moment. It's not as accurate as the first method, but not nearly as troublesome either. Also it doesn't put extra stress on your pack.

jsantala, thank you for this concise explanation of a very simple technique for deriving battery capacity as calculated by the car.

Although I suspect the information is buried in CaniOn's data files which could be uploaded to a computer (I only did a CaniOn file transfer once a long time ago), a simple manual-entry table on a piece of paper should suffice. In addition to Date, SoC%, WhOut, Pack Voltage, and Ambient Temperature, and then calculation fields for ∆SOC%, ∆WhOut, and finally kWh. Anything else for such a table? ... or should I stop being a Luddite and import those Canion files into my Mac and then parse them and manipulate them in a spreadsheet?

I expect to take such data over a period of days?, weeks? months? on each of my two i-MiEVs and then try to figure out what it tells me about each car. :roll: Anyone have any thoughts or critiques?

 

[Malm]

If you don't want to drive to empty, note Canion SOC % state, drive for as long as you like, note Canion SOC % and Wh out. Divide Wh out with percentage of battery SOC % lost during the drive and multiply by 100. That is the capacity of the car battery as calculated by the car at that moment.

The real limit that makes the car to stop is 2,75 V in one cell. My car reach that value in the past showing 14,5% SoC. So, unless 2,75V in one cell and 0,0% SoC happen simultaneously, the value obtained will not be the true capacity.

In my last measurements done without special tricks, my car stops with 0,0% SoC and voltage in every cells above 2,75V (but not much), so I can say that capacity measured by that method will be less then the real one. And more, 100% SoC is not the same voltage every time, at least for me.

For me, undoubtedly, capacity should be taken from 4,105 V in every cell and discharging to 2,75V in one cell. That can or not be the same as going from the 100% to 0,0% SoC, as calculated by the car.

I also think that the i-MiEV don't change is measured capacity every day. I think that is wise, because that can change significantly with battery temperature. It waits some time to get a number on its real capacity. The Nissan Leaf, on the other way, gets the number every time and do a calibration of is real capacity every day, I think.

 

[JoeS]

Malm, I am attempting protect my pack and avoid depleting it, which is why I liked jsantala's approach of ∆SoC% and ∆kWhOut readings in lieu of the full-discharge technique.

Yes, one cell hitting 2.75v is effectively the lower limit of that pack's capacity, no matter what the SoC% readout says. Would we not expect the i-MiEV to recognize that the first time it sees this and then recalibrate its capacity?

Malm, you have been looking at these details a lot longer than I have. I'll start accumulating data and see if there is any pattern; for example, to see if the ratio ∆SoC% / ∆kWhOut is constant at various SoC levels. I've whipped up a quick form to fill in the blanks and hope to start using it despite all the distracting Christmas obligations…

 

[Pier]

Bobakka, here in Canada, Warranty is probably the same as US W. It says «« Main drive li-ion battery is covered for defects in material for 8 years or 160,000 km. ... Gradual capacity loss of Main bat. based on time and usage is NOT covered under warranty. See owner's manual for more info »» In owner's manual it says «« MM estimates that after 5 years, the capacity of the main drive Li bat will be approximately 80% of the original capacity. After 10 years , the capacity should be approx. 70% of original... These are only estimates....»».

So no warranty other than defect in materials. A defective cell is about all we can count on for battery replacement. Otherwise, they have the only authority to decide whether or not it is a defect or misuse by owner.

Jsantala, you are right, driving until empty is the way to see the actual battery capacity, the only capacity that counts for range. But this is not the real intrinsic capacity of the pack. And the computer changes the apparent capacity with time.

For example, my old pack (2 years old) had, from 100% Soc to turtle (10% Soc), most of times in summer, 13.400 kwh. My new pack had on first charge, only 12.000 kwh down to 10%.(around freezing point). I am on my 3rd charge now and it seems to improve. I will tell after more testing.

JoeS, I measured how many watt by 1% Soc I get in a complete discharge. It was 131 watt / 1% soc. But to my surprise, the next charge gave on half discharge 152 watt / 1% soc. I am still trying to figure out what is happening . I will do more test in the coming weeks.

Pier

 

[jsantala]

Capacity of a lithium battery pack is an elusive thing. You can charge the same number of cells to different voltages and different cutoff amps. For example Nissan charges similar cells to around 4.2 V while Mitsu only does 4.1 V. Just a difference in temperature will also change the end result.

I have LiFePO4 packs in my DIY electric motorcycle and my DIY electric car. I could charge them quite a few ways to get different maximum capacities. I choose to charge only to 3.5 V per cell on average to extend the life of the cells. It gets me a certain number of Wh in and out.

My point is that in the end the only thing that counts is how many Wh you get out after you've charged to whatever the charging system in your vehicle considers 100% SOC and how long it lets you drive. That's the only Wh that really counts.

It is true that the SOC meter needs to be well calibrated to get an accurate reading with the simple method (not driving to 0%). If you never get down to turtle or at least the last bar flashing, your SOC calibration can be way off and your readings inaccurate. It might not be a bad idea to drive down to last few bars occasionally, if you'd like to avoid any nasty suprises when you go on that road trip.

 

[JoeS]

Took a drive in Mitti (new used i-MiEV) into town this evening and fired up CaniOn and left it on the whole time even though I parked the car and did some errands. It either never disconnected or reconnected automatically as v.124 CaniOn never dropped out. Here's the recorded and calculated data, each row represents my manually recording off CaniOn when I stopped (first row is beginning values):

Pack°C,Volts,SoC%,WhOut,∆SoC%,∆WhOut,kWh,Comments
18,351,74,0
18.5,348,70,865,4.0,865,21.6,downhill
18.9,345,65.5,1485,4.5,620,13.8,level
19.6,343,55.5,3021,10.0,1536,15.4,level
20.4,337,39.5,5123,16.0,2102,13.1,uphill

Sorry, thought I could simply drop in comma-delimited data and use the "Code" feature to put into nice columns. Too late tonight to fix.

Using SoC%/WhOut for each leg of my short trip shows that my i-MiEV pack capacity in kWh is 21.6 , 13.8, 15.4, and 13.1.
Dunno why the first number is so high, but at least the last three numbers are in the ballpark.

Too tedious doing it manually and I guess I'll need to figure out the CaniOn data upload to my Mac and then parse it ...

BTW, jsantala, I also charge my Headway LiFePO4 4P16S packs to 3.46v/cell, although I normally keep the packs stored at 50%SoC (around 3.3v). Use for electric outboard, electric scooter, and standby power source.

 

[tinoale]

It is true that the SOC meter needs to be well calibrated to get an accurate reading with the simple method (not driving to 0%). If you never get down to turtle or at least the last bar flashing, your SOC calibration can be way off and your readings inaccurate. It might not be a bad idea to drive down to last few bars occasionally, if you'd like to avoid any nasty suprises when you go on that road trip.

My C-zero manual calls for a discharge down to 2 bars followed by a full charge every 2 weeks or every month (can't remember the periodicity). That could be related.

 

[bobakka]

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.

Mitsubishi gave us a 80% capacity guarantee for 5 years / 100000 km in the Norwegian market. It is also documented in elbil.no. But I have never heard ony any that has been claiming that guarantee. I problems is maybe how you measure the capacity reductions. Probably it is by using amp hours.

Here is the documentation of the 80% guarantee:
http://www.elbil.no/elbilforeningen/dokumentarkiv/finish/9-diverse/125-kjopsveiledning-elbilmatrisen

https://www.dropbox.com/s/gmr79rb5u86emsy/Buying%20Guide.png?dl=0

Under BATTERIER (batteries), Minste garanterte kapasitet (Minimum guaranteed capacity) you will see that it is quoted 80% for iMiev.

 

[priusfan]

Hello
Today I checked with mut3 the batt's temperatures...

Here is a screen capture from mut3:

And here a screenshot from canion. This one was made 8 minutes before and all the figures (Volt, SoC, Amp) matched exactly...

The last updated release is here (Martin is not any more interested in updating the playstore).

I also checked the remaining capacity, it is quite low for a car from August 2012...

Xavier

 

[RobertC]

I also checked the remaining capacity, it is quite low for a car from August 2012...

Is the 38.6Ah reading on the same car with 15,559km?
Is there any way that the "Battery current capacity" reading could be made part of Canion?
Thanks again for all of your effort.

 

[priusfan]

Yes, the pictures are coming from the same car....

No, I have no idea how to get the remaining capacity...

FYI, I am using now a Newsmy NU3001 as 2DIN headunit.

It is not perfect, (see details here) but is just fine fine for this car:

 

[jsantala]

Thanks for the updated version! It seems that it reports cell temperatures better now. Previously it showed +3...+5˚C when the cells obviously had to be below freezing. After the update the latest data showed them at -3...-9˚C after some charging, which is probably much more accurate.

Thanks again and do keep up posted! Or is there another site where I could check for updates?

 

[priusfan]

To our nordic europeans ion/C0 users:
for checking yourself the remaining capacity of your cars,
You will need:
a) the right interface. (lexia)
b) the right software. (diagbox)
c) a laptop. (personally, I use a old XP reserved for this use)

z) explore the soft...


you can search googling for "lexia diagbox"

You can also have a look there for instance.

 

[BlueLightning]

Capacity measurement should probably be done at room temperature
For Prius's EV, the lost of capacity with temperature should be only around 4%, (if Prius's battery has been charged at room temperature, otherwise, it's probably more).
Excel LV50 Battery Capacity Lost versus versus temperature LV50 Discharge characteristics versus temperature
Source Development of Large-sized Lithium-ion Cell "LEV50" and Its Battery Module "LEV50-4" for Electric Vehicle
https://www.gs-yuasa.com/jp/technic/vol5/pdf/05_1_021.pdf

Capacity measurement with heater at full power, https://www.dropbox.com/sh/b6rsy6a1k5ug7b1/AABi3PYC7bsw3X-VqyNgAh64a?dl=0 , search for a file "Heater & SoC Battery Capacity test.xls"
I added in the Excel sheet a temperature correction but the EV should be parked preferably at room temperature for charge and then for the discharge test.
This test takes around 15 mn and uses 5 % of SoC through the heater at full power.

Input for the Excel File

1 Full Heat on, car parked , Canion on view "Trip Timer"
2 To start the Test, wait a decrease of SoC and as fast as possible press Canion Reset on top on right , then "Wh Out Summary" is at zero, the test starts.
3 If not fast enough, do it again at the next 0.5% decrease for a correct SoC "zero"
4 Then at every 0.5% SoC decrease, note "Wh Out Summary", please be aware to do this correctly at the SoC decrease or reject this measure and be ready for the next 0.5% drop
5 At least do 6 measures, it's not a problem if it's not done at every 0.5% Soc, it will just take more time, it will take you around 15 mn.
6 Put your data in the blue cells, yellow cells have formulas, with battery average temperature before and after test.

0.5% SoC resolution does not help for precision in a capacity measurement, so get measures only when there is a change of SoC, and use the linear regression by calcul or with the curve "Wh Out Summary" versus SoC, this helps to smooth measurement's errors.
The slope of the straight line "Wh Out Summary" versus SoC should give the battery capacity

Do not ask me if this method is trustable, it just seems OK for my EV but tests are needed.
Some mails exchange with bobakka who tested this method showed there was a problem with temperature and measurement. It is now corrected, that's why you have the graph above.
But still, bad news, bobakka did two measures, first one gave 18% of capacity losted and then the second one gave 12% of capacity losted, and this, at one day interval.... See in the Excel file.
The reason might be that before a test, an autocalibration of the battery below two bars and at 100% charge should have been done recently...

Prius with his mut3 could have the answer if he could try this test.

 

[priusfan]

Hello
I made some tests today...

My method is easier (if you are familiar with excel).
The car was standing in the garage with full heater during 20 minutes.
temp was between 9 & 10°C
After this, I stopped canion and got the seclog_yyyy_mm_dd.txt file and analysed it in excel.
I removed the unnecessary columns,
I created a column WH whose formula is b_amp * b_volt / 3600 ,
I checked the sum of this column 994 WH (canion showed 999 WH) . So it is reasonably accurate...
I made a pivot table summing the WH for each b_soc.
I filled the sheet from bluelightning (it is in his dropbox).

Conclusion:
Uncorrected Battery Capacity is shown as 39.7AH
Mut showed 38.6AH

Xavier

ps: to generate automatically the seclog_yyyy_mm_dd.txt, you should, in settings, tick the option "Export data from today".