TimPhev
Posts: 11
Joined: Sat Sep 10, 2016 5:16 am

BMU Cell voltage smoothing

Mon May 08, 2017 1:48 am

BMU Cell voltage smoothing

PROCEDURES FOR SMOOTHING CELL VOLTAGE
1.After the electric motor switch is "LOCK" (OFF) position, connect the M.U.T.-III to the diagnosis connector.
2.Turn the electric motor switch to the READY position.
3.Select "BMU" (№22) from System Select Screen of the M.U.T.-III.
4.Select "Special Function" from BMU Screen.
5.Select " Cell voltage smoothing" from Special Function Screen.
6.Press the OK button to smooth the cell voltage.
7.Check the "Execution status" displayed on the M.U.T.-III and check that the "Active" changes to the "Not Active".

Note: It may take a maximum of 2 hours until smoothing the battery cell voltage is completed.

A prerequisite! The laptop should not go into sleep mode!
It is best to connect it to the mains.
If go into sleep mode or save screen, will update error.

After the operation, while not shown, the temperature of the air after a while everything is restored.
Russia Saint Petersburg
Mitsubishi Outlander PHEV 2014

GreyBigFoot
Posts: 77
Joined: Fri Feb 10, 2017 2:22 am
Location: Lisbon, Portugal

Re: BMU Cell voltage smoothing

Tue May 09, 2017 12:13 am

Now that's interesting.

Is this the cells balancing procedure done at the dealer that could increase a bit the total battery capacity?

jaapv
Posts: 4634
Joined: Mon Dec 16, 2013 1:18 pm
Location: Netherlands

Re: BMU Cell voltage smoothing

Tue May 09, 2017 1:34 am

No, it is not quite the same but similar, but the dealer should be able to carry this out for you, it is an official service protocol by Mitsubishi. The factory procedure takes a bit longer than this and is usually carried out overnight.
The above might work, though, but carries the risk of being interrupted (if the laptop does go to sleep unexpectedly ot the connection gets lost, etc)
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elm70
Posts: 1156
Joined: Mon Sep 26, 2016 11:18 pm
Location: Poland
Contact: Website

Re: BMU Cell voltage smoothing

Tue May 09, 2017 3:11 am

Does anybody has any issue on unbalanced battery pack on the PHEV ?

Per EvBatMon .. I never spot any difference bigger then 0.02v in my pack .. and normally is just 0.01v or less.

I have experience on keeping balanced the battery pack for my RC Hobby model aeroplanes, since over a decade ... and the only real need is to have all cell balanced when the pack is fully charged ... balance and charge on the same time will grant to have pack balanced once is fully charged .. so there is no need for additional slow balancing procedure

Bert
Posts: 45
Joined: Tue Dec 08, 2015 1:59 pm
Location: Lockyer Valley, QLD, Australia
Contact: Website

Re: BMU Cell voltage smoothing

Wed Nov 08, 2017 9:56 pm

I had severe degradation down to 80% after 3.5yrs and 58.000km. The EV range dropped to only 35km in summertime.

After the cell smoothing procedure it got up to 99.7% and 37.9Ah. I'm currently documenting this all on my YT channel (https://www.youtube.com/channel/UCCwvk6 ... _qhfRyczOg)
(not trying to harvest more viewers, it's all without monetisation :) )

Mitsi did this for free as they admitted the capacity was a bit down. Looks like it's a comBination of cell smoothing and recalibration of the MCU. I got over 60km on the GOM every morning and can easily do 50km now.

Cheers
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zzcoopej
Posts: 272
Joined: Tue Apr 14, 2015 1:57 pm
Location: Gosford, Australia
Contact: Website

Re: BMU Cell voltage smoothing

Wed Nov 08, 2017 10:39 pm

Bert wrote:I had severe degradation down to 80% after 3.5yrs and 58.000km. The EV range dropped to only 35km in summertime.....
can easily do 50km now.
Interesting. Please post whether the "new" capacity holds after a month or 2, as other users who have had this procedure done say it is short-lived.

I'm very interested in what your charging style and EV driving style has been eg fast chargers, always charging to 100%, drive mostly EV or lots of ICE km?

anko
Posts: 3405
Joined: Mon Dec 01, 2014 11:30 am
Location: Netherlands, Utrecht area

Re: BMU Cell voltage smoothing

Thu Nov 09, 2017 12:04 am

Bert wrote:After the cell smoothing procedure it got up to 99.7% and 37.9Ah.
Quite impressive. Mine was / ius in a far worse shape. During the procedure 'I' went from 27.3 to 29.0. After 4 weeks I am already back at 27.9. Curious to learn what happens to your gain over time.

Will watch your videos shortly ....

SolarBoy
Posts: 429
Joined: Sun Oct 11, 2015 7:46 am
Location: Hampshire, England

Re: BMU Cell voltage smoothing

Thu Nov 09, 2017 10:52 am

My capacity is 86.8% after 11,697 km.

I recharge between 2 and 5 times a day on a 16Amp charger.

Have I broken it?
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6kW East/West Solar PV & Solar iBoost / lektrobay 250 32Amp Charger
Hampshire, England

HHL
Posts: 328
Joined: Wed Oct 29, 2014 8:23 pm
Location: Dee Why

Re: BMU Cell voltage smoothing

Thu Nov 09, 2017 8:05 pm

I wonder if this "smoothing" is really just a way to re-synch what the BMU stored battery capacity is, by performing a more detailed measurement than the normal charge/discharge cycle can do, to try and establish the actual condition and set the BMU to that.
Cell balancing must be done quite often, I would think on just about every normal (not fast) charge cycle. From my observations using EVBATMON, there is rarely a difference between cells, and if there is, it shows 10mV, and that is even at the "empty" level, where it is most likely to show up any cell deviations.
My battery condition currently shows up as 88%, but I can't really say that the range has reduced noticeably.
One thing I find interesting is the charge level vs battery voltage seems to be quite pessimistic. I have just done a reading and EVBATMON says SOC 26% while the battery voltage is 304.8 (3.81V per cell). Unless the chemistry in these batteries is very different from other Li-Ion cells, this cell voltage would suggest a real charge level of close to 40%.
According to the manual, when the battery is depleted the engine will start at around 27% and stop again at 32%, thus cycling all the time in hybrid mode in slow driving. When I took this measurement, I had just returned from a 50km drive and the engine was cycling for the last few km. It had stopped just before I took the reading and it therefore should have been around 30% but showed 26%. So, somewhere along the line things don't quite add up. Happy to say though my car goes as good as when I bought it 2 years ago.

anko
Posts: 3405
Joined: Mon Dec 01, 2014 11:30 am
Location: Netherlands, Utrecht area

Re: BMU Cell voltage smoothing

Thu Nov 09, 2017 10:27 pm

HHL wrote:I wonder if this "smoothing" is really just a way to re-synch what the BMU stored battery capacity is, by performing a more detailed measurement than the normal charge/discharge cycle can do, to try and establish the actual condition and set the BMU to that.
My car has undergone this procedure twice, and both times I have experienced an increased range and observed an increase amount of kWh going through the charge station during a full charge.
HHL wrote:One thing I find interesting is the charge level vs battery voltage seems to be quite pessimistic. I have just done a reading and EVBATMON says SOC 26% while the battery voltage is 304.8 (3.81V per cell). Unless the chemistry in these batteries is very different from other Li-Ion cells, this cell voltage would suggest a real charge level of close to 40%.
Maybe there is a large chunk of unusable capacity 'at the top'. If the BMU takes that into account, the reported SOC could deviate from the actual SOC. Although, it would require a 18.5-ish kWh battery for these numbers to match up.
HHL wrote:According to the manual, when the battery is depleted the engine will start at around 27% and stop again at 32%, thus cycling all the time in hybrid mode in slow driving.
The cycle is much shorter and depends on your speed (and whether the engine already had a chance to warm up). Typical, a high speed cycle is (from the top of my head) 30.5% - 32% and a low speed cycle is approx. 27% to 28.5%. But when driving really slow you can go as low as 25.5% (or even a bit lower when the last part of your trip is in reverse, I noticed yesterday). So, there are several different cycles, but to the best of my knowledge, 27% - 32% is not one of them. Unless you would speed up in the middle of a cycle. But I cannot imagine they would put that in the manual ;)

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