Discharge Recharge Battery Pack Capacity Test

[g4qber]

Does anyone know what Mitsubishi is supposed to do when they service the i-MiEV in terms of the battery pack capacity?

Thanks.

[jonescg]

Go for a long drive?

[acmotor]

Given that they have the i for half a day, maybe 4 hours they do not do a charge/discharge/recharge !!! Surely they don't 'claim' to do one ?

The reality is that the BMU and ECU in the i already know from every charge/discharge cycle what the battery capacity is.

Even if they had a CHAdeMO DC fast charger it would only be 80% charge then an hour's drive then another charge....and guess what... it is the BMU that decides what the 80% is 'coz it already knows how the battery is going !

Actually, I don't believe there is any test that the dealers can do that gives more info than the i already gathers itself. Just plug in and download.

If you are wondering yourself how the battery is going, just measure the recharge kWh with an external meter. 16kWh battery pack, 16 divisions on the energy meter.... 1kWh/div. A recharge from 1kWh showing should take ~15.7kWh from the external power meter (95% eff. charger). (oh, and please forget the guessometer RR it will only tell you what a full charge can do based on the last 24km driven, not the next. i.e. it will not return to the same start number after each charge)

[offgridQLD]

I need to play with the OBD scanner and app some more but I don't think zero bars is 0% SOC and all bars are not 1kwh. Just like a gas car there is a reserve and I think that Mitsubishi is hiding some of the capacity. For example 14 or 15kwh divided up into 16 bars.

I was wondering this before as I found it strange that Mitsubishi would allow you to use the pack to such a low SOC.

Just the same as when the pack is full and balanced the OBD scanner is showing 98% SOC.

The only thing that contradicts this is knowing the chargers output and working on a 95% charger efficiency when you recharge the bars seem to roughly represent 1kwh each as you watch them return. There is a few small things like the coolant pump consumes 200w and cycles 30% of the time when charging but that's not much of a error. I just wonder is the charger 95% efficient and is this number based on a assumption that one bar represents one true kwh.I I guess a clamp meter on the battery while charging would confirm this. Anyone have this data?

I only just got the scanner and application on the weekend and I need to do some more tests and will post some data to see what we can all make of it.

If its true that charging is less than 95% efficiency then it just mean our Imievs are even more efficient than I first thought. as we are doing more with less than we were thinking. The spanner in the works is assuming the chargers efficiency. Or this app isn't accurate I will soon find out. I need a good clamp meter to cross check.

I will report back soon with what I have.

Edit: this is what another user of the app found.

    Bar 16 92.5-100% 7.5%
    Bar 15 >=85.5% 7%
    Bar 14 >=80.5% 5%
    Bar 13 >=75.5% 5%
    Bar 12 >=70.5% 5%
    Bar 11 >=65.5% 5%
    Bar 10 >=60.5% 5%
    Bar 9 >=55.5% 5%
    Bar 8 >=50.5% 5%
    Bar 7 >=45.5% 5%
    Bar 6 >=40.5% 5%
    Bar 5 >=34.5% 6%
    Bar 4 >=28.5% 6%
    Bar 3 >=22.5% 6%
    Bar 2 >=17.5% 5%
    Bar 1 >=12.5% 5%
    Zero Bars <=12.0%
    Turtle <= 10.5%

When you think about it if each bar is 1kwh for a total of 16kw. Then each bar should represent 6.25% and you can see that isn't what is showing. 10.5% is roughly 1.6kwh so 14.4kwh is what the 16 bars represent.

after logging a 105km trip home on Monday the imiev was showing 4 bars or 12 bar/kwh consumption but the app was showing just over 10kwh consumption. I'm thinking if you add the 10.5% - 1.6kw from zero bar to turtle then this adds up to almost 12kwh.

While driving The app was showing 16kw being consumed and at the same time the imiev's dash energy gauge was siting on the first line so they seem to agree with each other there and again at full throttle 50.1kw on the app and gauge pegged on the Imiev.



Its defiantly not linear or consistent though as well But show me a SOC meter that is completely accurate over time.

Kurt

[Simon]

I have a manual now. Under Main battery capacity measurement it list the procedure.

disconnect aux battery for 30s and reconnect then connect the M.U.T. III, turn the car to "on" position and perform a reset.

Turn car to "on" position again check for 5 bars (40%) if too high run ac on max or charge if too low.
Discharge to 3.750-3.775V and leave for over 1hr.
Then do capacity measure function on the MUT III and then fully recharge and leave for another hour and then another battery capacity measure function on the MUT III again.

Somehow I don't think service would actually do all this unless there was a problem with bars disappearing rapidly or getting a turtle early.

[offgridQLD]

I agree they wouldn't do a capacity test. It's like taking your gas car in and expecting them to do a compression test. unless you report a issue I don't think they would bother.

kurt

[carnut1100]

The Hobart dealer seems to think they do this as a matter of course. He said services need the car overnight for this reason.
They're doing that to the 2010 demo before I pick it up.

[acmotor]

Perhaps I'm wrong but I think the problem for dealers/service departments is that there is nothing to do at the iMiEV service.

The most significant item at my 15,000km service was filling the washer bottle.
At the 30,000km service the brake fluid was flushed as per the handbook service interval. They got that wrong and didn't bleed the air so the pedal went to the floor when I picked the vehicle up.
A clue of course is that they only put down 500ml of brake fluid on the bill. For those of us who know how to do a BF flush, it can't be done properly with only 500ml, particularly in an ABS system.

Everything else is just a tourist cruise around the vehicle to see if there is any obvious physical damage to cabling etc, or oil leak from the diff. Oh and check the brakes (they may have been used )
All this without lifting the cargo floor hatch I noted.

Service deparments struggle with the EV concept. I have had them offer to rotate the tyres and g4qber was charged for 5 litres of 10W40 !

I still believe that no battery cycles/capacity tests are performed. neither of my services were overnight and what the little i doesn't know already about its battery, the local 'service' department ain't gonna find out !

[Johny]

It looks to me like the battery test is there to pick up bad cells before they cause problems and damage the repuitation of th iMiev. As mitsu gets braver/learns more they may well discontinue this requirement - or not...

[acmotor]

But what I'm saying is that the 'battery test' by the dealer service is a myth and totally not required.