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

Re: Canion Battery Readings

Mon Dec 01, 2014 5:34 pm

I don't mean to step in here and stir things up, but you cannot get 16 KWH out of a I-MiEV pack the way it is configured in the vehicle. I have had the battery apart and the 8 cell modules are rated at 1440 KWH and the 4 cell modules are rated at 720 KWH. There are 10 8 cell modules and 2 4 cell modules in the pack for a total of 15,840 KWH available when new (with some disclaimers). To get this output, the battery cells (according to the LEV-50 data sheet) must be charged to 4.2 volts and discharged to 2.75 volts. Neither voltage is reached in the I-MiEV. To increase the life of the battery pack the charge voltage is limited to 4.105 volts per cell as a upper limit by the BMU. On the discharge side, the lower limit (on a new pack) is well over 3 volts when shutdown occurs. Therefore, no where near 16 KWH is actually available for use. I have mentioned in another thread, I think the BMU allows the lower limit to drop as the battery ages allowing the masking of actual pack degradation until the 2.75 volt threshold is reached on the weakest cell in the 88 cell string. After this point is reached, the first significant loss in range will be noticed by the vehicle operator. There are a number of ways to determine the health of the pack but none are easy to do with accuracy without placing a device called an electronic load on the individual cells so you discharge at a constant current that will not impacted by the change in cell voltage as it decreases. The current has to be as specified by the manufacturer of the cell ("C" rate) to really see what's going on. Each cell in the string needs to be monitored as the pack is only as good as the capacity of the weakest cell. With the CANION you need to see what the cell voltages and balance are looking like when the pack is close to or at vehicle shutdown. If those voltages are near 3.25 volts you are in decent shape, if approaching 2.75 volts, you've got some serious degradation starting. If you use other methods you will be able to monitor the percentage and rate of capacity loss in you pack but not really be able to see the actual KWH number of the pack

offgridQLD
Posts: 101
Joined: Wed Jul 17, 2013 4:13 am

Re: Canion Battery Readings

Mon Dec 01, 2014 6:46 pm

Small correction, 15,840whr not 15,840kwh. That would be bigger than a submarine traction pack ;)

Kurt

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

Re: Canion Battery Readings

Tue Dec 02, 2014 6:43 am

my bad (about the KWH vs. WH) :oops: . But just think how many miles the range would be!

PV1
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Re: Canion Battery Readings

Tue Dec 02, 2014 7:38 am

siai47 wrote:my bad (about the KWH vs. WH) :oops: . But just think how many miles the range would be!


[sarcasm]
I can't buy the i-MiEV. It only goes 61,380 miles on a charge. I can't drive back and forth to work and take road trips. I'll run out of charge while driving down the road. Besides, it can't recharge in 2 minutes, so that just proves it won't work for me.
[/sarcasm]

:lol: :mrgreen:

I saw the next gen Yuasa batteries will be 150 Ah instead of 50 Ah. How does a 186 mile range sound?

When I did my range/health check a while back by driving down to 9%, my cells ranged from 3.675 volts (cell 88) to 3.650 (cell 9) at rest.

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

Re: Canion Battery Readings

Tue Dec 02, 2014 10:21 am

BlueLightning wrote:This is where my coefficient come from, 13.44 x 1.2 = 16 kw-h

A ratio of 60/50 or a coefficient of 1.2 is the best match for my iOn electric car which have a 16kWh battery capacity. In other words, this coefficient seems to give a proper result, but for my car only...

Now I understand where you get 60/50 or 1.2 from. But that is based on your assumption that your car has a 16 kw-h battery capacity. But that is not achievable.. How old is your imiev? and with how many km? Maybe you only have 15 kw-h..?

BlueLightning wrote:
While driving, I get a higher slope, 0.1527 kWh per % SoC, but this number is also too low because those kW-h are a mixture of Wh-out when I press the accelerator and Wh Reg when I slow down.

But you do not know if this slope is too low or too high. If Wh-out is correct and Wh-reg is too low, this slope will actually be too high..

BlueLightning wrote:
No matter about no coefficients, your equation will give a number, if by the time your battery capacity decreases, this number will also decrease.....


I have done some testing today and yesterday. I find slope to be 11,64 and 11,60 for charging. Correcting with your factor 1.2 that is 13.97 and 13.92. I find slope to be 12,43, 12,32 and 13,27 when driving. Assuming that SoC is correct, the the formula for my car Wh-out/Wh-reg is between 1,07 and 1,14.

I see a difference between Wh-reg and Wh-out that is unexplainable by physical processes (i.e. it is not possible to drain more energy than is supplied to the battery) and it must be due to measurement or computing problems.
I will do more testing to find how consistent the numbers are on my imiev.
I today drove the car as low as a SoC of 17.0 in the morning and in the afternoon the slope increased by almost 7% for the same drive the day before.

I think that my car assumed that battery capacity increased because I emptied the battery more than I have done for a week or two..
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

Tue Dec 02, 2014 10:47 am

siai47 wrote: Therefore, no where near 16 KWH is actually available for use.
If you use other methods you will be able to monitor the percentage and rate of capacity loss in you pack but not really be able to see the actual KWH number of the pack


My question is how I can monitor the capacity loss?

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?

I think the Canion app is a large leap forward, but it has also large limitations as it is based on Can Bus information.
iMiev; New Feb 2011; 119000 km January 2017

BlueLightning
Posts: 53
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Location: Normandy France
Contact: Website

Re: Canion Battery Readings

Tue Dec 02, 2014 2:05 pm

It's a 16 kw-h battery because there is 88 cells, the LEV50's start with 50Ah x 3.7V x 88 cells = 16.28kWh, and it is well documented that the on board computer will not allow to use more than 90% or 95% of the 16 kw-h of the battery, Blue Lightning was built on march the 11th 2011 and is on the road since august the 27th 2012, I have been driving only 24 000 km. I charge the battery with a kill a watt at the wall since the begining and till now this battery is still able to pump from the wall the same amount of electricity. Thanks to Malm, we know that with a lost of capacity, charge is a faster process and that less electricity is loaded.

When I use the heater alone the slope is of 16 kW-h per 100% SoC. Wh out which is a negative value and Wh-Reg which is a positive value while driving are too complicate to handle for me, I do not deal with Wh out and Wh reg for capacity measurement.

bobakka wrote:I have done some testing today and yesterday. I find slope to be 11,64 and 11,60 for charging. Correcting with your factor 1.2 that is 13.97 and 13.92.
(13.92-16.28)/16.28 = 14% lost of capacity, is it bad for 77777 km and 4 years? from now you have these numbers as reference to see the evolution, I advise you to do more measurements to get an average and then to wait a bit. The lost of capacity might be slowing down.

bobakka wrote:My question is how I can monitor the capacity loss?

I trust and use this equation with the help of a kill a Watt on the wall

Capacity = 100 x Charge efficiency x "Wall kW-h" / (SoC final - SoC initial)

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

ImageMesure de charge à la prise
Last edited by BlueLightning on Tue Dec 02, 2014 3:01 pm, edited 3 times in total.

offgridQLD
Posts: 101
Joined: Wed Jul 17, 2013 4:13 am

Re: Canion Battery Readings

Tue Dec 02, 2014 2:11 pm

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?


I'm just trying to relate this to a conventional ICE car.

Complaint...
I have driven 100,000km over 5 year and my engine seems to have a little less compression and doesn't get as good fuel economy as it did when it was new.

Response...
Sure I can sell you a new car.


We all don't want battery capacity decline but hey it's a battery they all wear out. Unless the capacity loss es excessive then I don't think its a issue. My view is Mitsubishi would replace or repair batterys based on there discretion and tests not the data that the customer provides.

Kurt

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

Re: Canion Battery Readings

Tue Dec 02, 2014 4:52 pm

The nominal voltage of the I-MiEV battery is 3.6 volts not 3.7 which gives you 50 amps X 3.6 volts X 88 cells or 15,840 watt hours (got that right this time). This is from the spec sheet for the LEV-50 cell and is actually marked on the 8 cell battery modules. In addition, I had my car's battery capacity checked for reference when it had 30 miles on it by the dealer with the M.U.T III and it had a capacity of 49.5 amp hours. The dealer said he had never seen one with the full 50 amp hour rated capacity. If you are worried about your pack degradation and think it is below the limits specified in the Mitsubishi battery warranty then the dealer is going to have to test it anyway. When I get my recalls done, I am going to have the capacity of the pack measured and find out where I stand after almost 2 years. I have a known starting point (If you ask your dealer everyone might have this starting point as my dealer said that Mitsubishi required them to check the capacity prior to delivery) so I can easily find the amp hour loss since I received the car. That loss, not watt hours is what Mitsubishi is going to use to determine if your pack falls below the warranty threshold. Amp hours available is the only thing the M.U.T III checks for.

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

Re: Canion Battery Readings

Wed Dec 03, 2014 1:23 pm

siai47 wrote: In addition, I had my car's battery capacity checked for reference when it had 30 miles on it by the dealer with the M.U.T III and it had a capacity of 49.5 amp hours.


How does M.U.T. III work? Does it measure available capacity or total capacity??

When my car was testet a year ago at 60000 km it had a capacity of 39.6 amp hours. My dealer did not mention anything about a start point. If my start point was 49.5 amp hours then I already had a capacity loss of 20% last year. But I am pretty sure my available capacity has not been reduced by 20% as I did not see a 20% range reduction (I believe).

I think it does not sound right if M.U.T III measure available capacity and it measures almost 50 amp hours when the LEV-50 battery pack is spec'ed to 50 amp hours as the total capacity and at the same time we know that Mitsubishi is conservative with regards to available capacity. This does not add up.
Last edited by bobakka on Sun Dec 07, 2014 3:04 am, edited 1 time in total.
iMiev; New Feb 2011; 119000 km January 2017

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