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 Post subject: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Sat Feb 17, 2018 7:36 pm 
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Joined: Thu Feb 26, 2015 5:58 pm
Posts: 606
Location: Near Port Macquarie Australia
As part of my ongoing research into the drive battery as mine is showing in the 70s percentage of battery health I wish to run this past the members here what I have learnt so far.

This research is far from finished for me.

But lets bring some quotes from the I think German that has moved to Australia that I first saw on Youtube.

Bert wrote:
I've got a MY14.5 here in Australia, bought it end of 2015 from a dealer. Mid 2017 I lost range and could do only 35km (21mi) on a full charge. I complaint with another dealer and they did a battery cell smoothing procedure and a BMS reset. ........... The capacity was down to 80% state of health already with no more then 58000km (36000mi) driven.

After the procedure I had my full capacity back with 50km+ on pure EV range, but... well other problems occured.


Bert wrote:
Yes, the batteries capacity went back from 80.5% SoH to 99.7% with 38Ah. The first drive I did was 59km on pure EV, half of that on a highway. The very next day though I had already lost 0.1Ah again and until now (3 months later), I'm back to under 90% SoH...


Now I have left some of his quotes out here but according to Bert he was getting 35km at 80% state of health to getting 59km, half of that on a highway :o and 99.7% battery health just by doing a battery cell smoothing procedure and a BMS reset.

Now anko first brought up a refreshment procedure described by jaav as "A service offered by Mitsubishi balancing the cells" back in the other thread I started which I think is the battery cell smoothing procedure described above.

Here is anko's quote:

anko wrote:
June, 2016: 32.5 / 33.4 (before / after refreshment procedure)


So a little lift for anko for "Mitsubishi balancing the cells" to a big lift for Bert for "battery cell smoothing procedure and a BMS reset."

So if I am right they are the same why would a BMS reset lift it up so far. For sure a reset should just "zero" the BMU but not get a increase in range like Bert.

So what is happening?

Well I think the BMU is getting out of "whack".

How do you measure battery capacity?

From my instruments for measuring cell capacity on my RC chargers and Ev pushbike they are measuring current and voltage and time to give a capacity reading ie top to bottom discharge.

But the PHEV never fully discharges its drive battery. So how does it work out its capacity properly?

By "guessing" using algorithms I think.

Now the BMU data list from my battery report from the MUT-III show:

No 400 Cell current capacity (measured) always 0.0 Ah on my PHEV

No 401 Cell current capacity difference always 0.0 Ah on my PHEV.

So I think Mitsi can do full capacity check with the MUT-III and will check with them next week to do so on my PHEV.

I am probably going to also ask for a BMU reset after that test.

Will let you know how I go.

Regards Trex.

Edit change name for searching purposes.


Last edited by Trex on Sun Feb 18, 2018 8:45 pm, edited 1 time in total.

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 Post subject: Re: Drive battery degradation and what I have learnt.
PostPosted: Sat Feb 17, 2018 7:50 pm 
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Joined: Fri Jan 19, 2018 3:26 pm
Posts: 106
Location: San Antonio, TX
I think you nailed it, Trex. I've seen the same thing in my ebike, smart, and (oddly enough) laptop computers.

When I kept my smart between 40% and 80% SOC, the range estimates would get stranger as the month went on. It got better when I charged to 100%, but it wasn't fixed until I drive the car down below ~10% SOC and charged to 100%.

It appears that 'cell smoothing' is just balancing the battery and saving the updated capacity in the computer. The range loss was real, and some of it was due to degradation, but some was also due to the management computer's 'guess' about state of charge diverging from the reality of the cells. 'Smoothing' can't restore capacity physically lost in the cells, but can 'restore' capacity the computer wouldn't let us use because it thought the battery was worse than it was.

Open the pod bay doors, Hal.
I'm sorry Dave - you've only got 1% charge left and I need that to run the intercom.
Dangit Hal - I know I plugged the ship in last night! (Dave floats around while digging for the end of the StarshipWatchdog cable...) :lol:

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2018 Outlander PHEV
2015 smart Electric Drive "The Bumblebee" (returned at end of lease)
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 Post subject: Re: Drive battery degradation and what I have learnt.
PostPosted: Sat Feb 17, 2018 11:19 pm 
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Joined: Thu Feb 26, 2015 5:58 pm
Posts: 606
Location: Near Port Macquarie Australia
AndyH wrote:
I think you nailed it, Trex. I've seen the same thing in my ebike, smart, and (oddly enough) laptop computers.

When I kept my smart between 40% and 80% SOC, the range estimates would get stranger as the month went on. It got better when I charged to 100%, but it wasn't fixed until I drive the car down below ~10% SOC and charged to 100%.

It appears that 'cell smoothing' is just balancing the battery and saving the updated capacity in the computer. The range loss was real, and some of it was due to degradation, but some was also due to the management computer's 'guess' about state of charge diverging from the reality of the cells. 'Smoothing' can't restore capacity physically lost in the cells, but can 'restore' capacity the computer wouldn't let us use because it thought the battery was worse than it was.

Open the pod bay doors, Hal.
I'm sorry Dave - you've only got 1% charge left and I need that to run the intercom.
Dangit Hal - I know I plugged the ship in last night! (Dave floats around while digging for the end of the StarshipWatchdog cable...) :lol:


StarshipWatchdog cable, took me a while to get it. :lol: :lol: I am tired. ;)


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 Post subject: Re: Drive battery degradation and what I have learnt.
PostPosted: Sun Feb 18, 2018 12:33 pm 
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Joined: Mon Dec 01, 2014 11:30 am
Posts: 3098
Location: Netherlands, Utrecht area
Hi Trex and others,

There are 10 slots in the BMU ECU for storing "Automatic Capacity Measured Result":
- 402.Auto capa measured result his.1
- 403.Auto capa measured result his.2
- 404.Auto capa measured result his.3
- 405.Auto capa measured result his.4
- 406.Auto capa measured result his.5
- 407.Auto capa measured result his.6
- 408.Auto capa measured result his.7
- 409.Auto capa measured result his.8
- 410.Auto capa measured result his.9
- 411.Auto capa measured result his.10

To get data from these, send this:

ATZ
ATL1
ATH1
ATE1
ATSH761
ATFCSH761
ATFCSD300000
ATFCSM1
2114

For me, this brought back:

2114
762 10 16 61 14 01 20 01 4C
762 21 01 90 01 90 01 90 01
762 22 90 01 90 01 90 01 90
762 23 01 90 41 74 2F EC 41

When you take bytes A+B (0120), convert to decimal (288) and divide by 10, you get 28.8
When you take bytes C+D (014C), convert to decimal (332) and divide by 10, you get 33.2
When you take bytes E+F (0190), convert to decimal (400) and divide by 10, you get 40.0
Same for G+H, I+J, K+L, M+N, O+P, Q+R, S+T you get the same.

So, 28.8, 33.2, 40.0, 40.0, 40.0, 40.0, 40.0, 40.0, 40.0, 40.0.

A few years back, before the first time the procedure was applied to my car, all slots all showed 40. But now, the procedure has been applied twice, first time it came back with Current Capacity 33.4, the second time with current capacity. A 'misalignment' of 0.2, but still.


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 Post subject: Re: Drive battery degradation and what I have learnt.
PostPosted: Sun Feb 18, 2018 2:10 pm 
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Joined: Thu Feb 26, 2015 5:58 pm
Posts: 606
Location: Near Port Macquarie Australia
anko wrote:
Hi Trex and others,

A few years back, before the first time the procedure was applied to my car, all slots all showed 40. But now, the procedure has been applied twice, first time it came back with Current Capacity 33.4, the second time with current capacity. A 'misalignment' of 0.2, but still.


Hi anko,

Are you saying No 400 and 401 have now been populated from the refreshment procedure or as jaav called "A service offered by Mitsubishi balancing the cells".

Regards Trex.


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 Post subject: Re: Drive battery degradation and what I have learnt.
PostPosted: Sun Feb 18, 2018 2:45 pm 
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Joined: Mon Dec 01, 2014 11:30 am
Posts: 3098
Location: Netherlands, Utrecht area
Trex wrote:
anko wrote:
Hi Trex and others,

A few years back, before the first time the procedure was applied to my car, all slots all showed 40. But now, the procedure has been applied twice, first time it came back with Current Capacity 33.4, the second time with current capacity. A 'misalignment' of 0.2, but still.


Hi anko,

Are you saying No 400 and 401 have now been populated from the refreshment procedure or as jaav called "A service offered by Mitsubishi balancing the cells".

Regards Trex.

I believe it id's merely a recalibration procedure, but yes.


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 Post subject: Re: Drive battery degradation and what I have learnt.
PostPosted: Sun Feb 18, 2018 8:10 pm 
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Joined: Thu Feb 26, 2015 5:58 pm
Posts: 606
Location: Near Port Macquarie Australia
anko wrote:
Trex wrote:
anko wrote:
Hi Trex and others,

A few years back, before the first time the procedure was applied to my car, all slots all showed 40. But now, the procedure has been applied twice, first time it came back with Current Capacity 33.4, the second time with current capacity. A 'misalignment' of 0.2, but still.


Hi anko,

Are you saying No 400 and 401 have now been populated from the refreshment procedure or as jaav called "A service offered by Mitsubishi balancing the cells".

Regards Trex.

I believe it id's merely a recalibration procedure, but yes.


Ok thanks anko. :)


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 Post subject: Re: Drive battery degradation and what I have learnt.
PostPosted: Sun Feb 18, 2018 8:27 pm 
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Joined: Thu Feb 26, 2015 5:58 pm
Posts: 606
Location: Near Port Macquarie Australia
Spoken to dealer and Mitsubishi Australia, who were extremely helpful, to start the ball rolling.

Dealer says I will probably get a new PHEV. I laughed but said I would just like you to reset the BMU please.

Will not do it until further checks are made and given approval from Mitsubishi Australia.

And so it begins. Thursday 1st March the big tests on the battery commence. 8-)

I cannot wait.

I'm so excited and I just can't hide it............ ;)


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 Post subject: Re: Drive battery degradation and what I have learnt.
PostPosted: Mon Feb 19, 2018 2:32 am 
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Joined: Tue Sep 02, 2014 4:01 pm
Posts: 610
Location: Essex, England
Trex wrote:
I'm so excited and I just can't hide it............ ;)


Are you about to lose control and like it though? :P

_________________
Regards, Ray. 2014 GX4H Glacier blue.

It's the 21st century - so where's my nuclear-powered flying car, then?


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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Mon Feb 19, 2018 2:51 pm 
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Joined: Mon Dec 01, 2014 11:30 am
Posts: 3098
Location: Netherlands, Utrecht area
Now sending 2115 to 761 (BMU) in my case gives back:

762 10 16 61 15 50 07 31 15
762 21 00 00 00 00 00 00 00
762 22 00 00 00 00 00 00 00
762 23 00 00 41 74 2F EC 41

Last BMU calibration procedure was done at 131.115 km. Dividing this number by 6.4 (*) yields 20.487 (after rounding). Converting that value to hex yields 0x5007, or bytes A+B. it seems bytes A-B have the odometer for last time procedure was performed.

The BMU calibration before that was done at 80.417 km. Dividing this number by 6.4 yields 12.565 (after rounding). Converting that value to hex yields 0x3115, or bytes C+D. it seems bytes A-B have the odometer for the previous time before that procedure was performed.

* It was a wild guess, but it gives us the hexadecimal representation of odometer in 0.1 km, but then shifted 5 bits to the right, to save space. This approach allows 'them' to register odometer reading up to 419.424 km, with an accuracy of 6.4 km, while using just two bytes :geek:


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