EVBatMon Readings

[DonDakin]

Hi Kenny,

Thanks for the information. I'm also interested in what is going on with the CAN data on the car. I don't have any equipment to log CAN data but maybe one day when I retire and have lots of time on my hands I could start fooling around with it. I get the feeling it's time consuming to probe the CAN bus and try to map it out by hand. I don't know if anyone has published any CAN data dictionary for the imiev but I would probably want to start off digging building on someone else's work.

I have the car schematics and I look thru them when I have free time trying to understand how the systems works. I would really like to figure out a way to make the charger work while the car is driving. I think that could open up some possibilities.

A couple of things I wonder about regarding the battery capacity value:

What I wonder is how the car determines the capacity of the battery ? It can count amp hours and the charger can bring all the cells up to 4.1 volts so it can make the battery "full", but on the discharge the car never goes "dead". So how does it know to total capacity ?

To get the real capacity you would need to drain the car until it does not move anymore This would be the cars definition of "empty". Then you would charge it completely, count AH's and get a capacity(or you could count down from full to empty). No one does this so I'm a bit wondering how the car defines "empty" when it's computing the capacity parameter.

Also I think we all know as Malm does qualitatively when we loose capacity in the battery. If you have owned the car since new you can probably sense the capacity loss and can ballpark it from your repetitive drives and range remaining. That being said I really like the idea of getting the capacity value from the car, something accurate.

As for the MUT 3 I checked on Ebay and found a few of them. I wonder if anyone has one and can report on it ?
Do the ones for sale on ebay work with the imiev ?

Don......

 

[JoeS]

Having three i-MiEVs that all respond seemingly identically, my curiosity drove me to pick up a ScanTool LX and install EvBatMon. Here are the results:

Mitsi, our original 2012 SE, now with 43,102miles (69366km) on it, 38.2Ah, condition = 79.58. This battery has been babied since birth (except for the two months it sat fully charged in the dealer's showroom :twisted: ), only occasionally charged to 100% and then driven immediately, and never ever seen turtle. My wife is a featherfoot.

Mitti, our used 2012 SE Premium purchased at 24,652miles (39674km) but with battery replaced at 27,942miles (44968km), now with 36,349miles (58948km) and thus 8,407miles (13530km) on the battery, 40.3Ah, condition = 83.96. This new battery has has never seen turtle nor left at 100%SoC and has barely been exposed to high temperatures for long. I'm the primary driver and nowadays am normally a leadfoot and also run at very high speeds on the Interstate, except when hypermiling.

Moto, our used 2012 SE Premium purchased at 16,701miles (26878km), now with 20,766miles (34420km) on it, 39Ah, condition = 81.25. Been babied and featherfooted since we purchased it.

I'll let you'all comment about the above readings. For myself -

a) I wonder how valid it is to assume that a 'new' battery pack is at 48Ah, as reflected by the "condition" parameter?
b) I would have expected a higher capacity from Mitti if the replacement battery had been new.

For me and having become very comfortable using CaniOn, the most useful feature of EvBatMon is its ability to provide the battery pack state of health - invaluable when buying a used car. For daily use I'm sticking with CaniOn as the MyTrip is now configurable and Wh/km and battery temperature are my most-used trip interval parameters.

Um, zzcoopej, how does your database deal with more than one i-MiEV owner? :roll:

 

[PV1]

That's interesting about Mitti's capacity. Mine is at 43.1 (was 43.2, but just dropped) Ah with 8,500 miles on my second pack, and it's been abused a couple of times (several quick charges in one day, sub-freezing charging).

 

[jsantala]

Regarding the original capacity of the cells, we know that the cells are LEV50s with 50 Ah nominal capacity. Also if you calculate the number of cells times nominal voltage of these cells times their capacity you get 88 * 3.7 V * 50 Ah = 16280 Wh. Newer European models only have 80 LEV50N cells which gives us 80 * 3.7 V * 50 Ah = 14800 Wh.

Also, from the original LEV50 paper:

"Furthermore, regarding the calendar life, capacity retention of 65% is anticipated after 10 years storage at 25 °C from our life prediction formula. The cycle life test at 25 °C after 1000 cycles showed capacity retention of 85%."

http://www.gs-yuasa.com/en/technic/vol5/pdf/05_1_021.pdf

The newer LEV50N cells should fare a lot better:

"These new cells retain 80 % of the initial capacity after 5.500 charge/discharge cycles (100 % DOD @ 25°C). The new product has higher durability in a hot environment and more than two times longer life under given conditions."

http://pushevs.com/2015/11/04/gs-yuasas-improved-cells-lev50-vs-lev50n/

Wouldn't mind swapping my old and tired LEV50 cells for 88 of the newer LEV50N cells.

 

[JoeS]

What I'm impressed by is that Yuasa's data sheet lists 50Ah as its capacity at a one-hour rate, i.e., 50 amps. Conventional lead-acid batteries are usually capacity-rated at a 20-hour rate; i.e., in this case, 2.5 amps. It's a brave new world! Hey, in four years after the warranty expires it will be fun to experiment... who knows what will be available then in this form factor.

Back on topic, we really don't know how Mitsubishi determines their capacity number that is read by EvBatMon. I would love to get a reading on a brand-new battery pack ... hmmm, maybe a trip to the dealer with an LX and tablet? :roll:

 

[zzcoopej]

Um, zzcoopej, how does your database deal with more than one i-MiEV owner? :roll:

It is currently ok to test more than 1 EV with EvBatMon, however that might change in the future. The website graphing is designed to only support 1 EV per App installation right now. That might change in the future if we get more customers with more than 1 of the same EV however 3 in the 1 household is probably pretty rare?

 

[PV1]

Several of us have two copies, but I think Joe is still the only current owner of 3.

 

[PV1]

Capacity readings for both cars:

Bear - 8,500 miles on an LEV50N pack - 43.1 Ah. PMC is 89.75%.
Koorz - 22,100 miles on original LEV50 pack - 37.8 Ah. PMC is 78.75%.

 

[PV1]

I performed a calibration charge on Bear (2 bars or less to full). Capacity remains 43.1 Ah.

 

[jsantala]

I'd just like to point out that ampacity means current carrying capability, not battery capacity. https://en.wikipedia.org/wiki/Ampacity

 

[PV1]

Thanks for clarifying the terminology. I'll update my posts.

 

[PV1]

Bear's capacity is seeming to drop quickly and is now at 42.8 Ah, making for a .4 Ah drop since the beginning of April (when I downloaded EVBatMon). Bear was quick charged once in this time (from 25% to 96%) and the battery temperature has been kept below 85 F.

I am still within the first year of my new battery, and I've heard there is a rapid capacity drop in the first year and then it stabilizes. Perhaps that is what I'm seeing, and I certainly hope that the capacity drop slows.

 

[Malm]

Bear's capacity is seeming to drop quickly and is now at 42.8 Ah, making for a .4 Ah drop since the beginning of April (when I downloaded EVBatMon). Bear was quick charged once in this time (from 25% to 96%) and the battery temperature has been kept below 85 F.

I am still within the first year of my new battery, and I've heard there is a rapid capacity drop in the first year and then it stabilizes. Perhaps that is what I'm seeing, and I certainly hope that the capacity drop slows.

Mine also lost 0.4 Ah since from 33.8 since March. Now with 33,4 Ah. Maybe it makes an upward correction in the future and the number became softer. It happens sometimes in the Outlander.

 

[JoeS]

Another data point: currently visiting a family friend in New Orleans who bought a 2016 i-MiEV a year ago. Brought my Android tablet and LX with me.

He has put on 5000 miles (8000km) and his battery pack capacity shows 42.1kWh.
Edit: Oops, sorry, that's 42.1Ah

Also, interesting to note that the brand-new pack put into Gyver's car shows 45.8kWh!
Edit: Oops, sorry, that's 45.8Ah
Ref: http://myimiev.com/forum/viewtopic.php?p=27731#p27731
Perhaps we should re-think the starting point for our capacity calculations?

 

[wmcbrine]

He has put on 5000 miles (8000km) and his battery pack capacity shows 42.1kWh.

Also, interesting to note that the brand-new pack put into Gyver's car shows 45.8kWh!

Amp-hours (Ah), not kWh.

 

[JoeS]

He has put on 5000 miles (8000km) and his battery pack capacity shows 42.1kWh.
Also, interesting to note that the brand-new pack put into Gyver's car shows 45.8kWh!

Amp-hours (Ah), not kWh.

Thanks for catching that. Boy, am I embarrassed! Added edit to my original posting.

 

[PV1]

Interesting note. After discharging to 3 bars and recharging, Bear is now showing 43.7 Ah, higher than my 43.2 Ah starting point a couple of months ago.

 

[PV1]

Did another 2 bars to full charge, and now have 44.4 Ah :mrgreen: .

 

[phb10186]

I think battery capacity stats start to become like blood pressure - best not to look at it too often!

Be good to just keep a plot every 3 months against mileage - see the two curves develop. Implement some controls and get a few IMIEVers doing it.

 

[zzcoopej]

Be good to just keep a plot every 3 months against mileage - see the two curves develop. Implement some controls and get a few IMIEVers doing it.

Actually this is already a free option for all EvBatMon App users! In EvBatMon you can elect to upload your battery data automatically from the App to our cloud service to compare your EV to other iMiEV owners.
More info here http://www.evpositive.com/battery-history.html
The sample graph on the above page is from a PHEV, however users get 2 iMiEV graphs - one is battery capacity vs time, and the other is battery capacity vs distance.