Mitsubishi Outlander PHEV Forum

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Sun Apr 15, 2018 9:12 pm 
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elm70 wrote:
I can't agree with your view

As well, your videos about he PHEV did show multiple times that your EV range and SOC was going down while your car was parked for over 2 hours.

Couple of times you did report that after a trip in 100% EV mode, you did report that the ICE did kick in as soon your restarted the car after over 2h parking ... once was also documented in a video, showing the battery voltage at around 3.76v per cell (even down to 26% SOC the voltage per cell should be never below 3.80v)

These for me these are clear signs that the assumed SOH is above the real SOH .. or at least the SOH is to high for the measured current flow monitored during your car usage

Every time the SOC goes down while parked , it means that the SOH is bigger then what it is in reality (or at least the reality that the PHEV can sense via voltage monitor after over 2h rest and current flow integration and monitoring)

Every time this happen, in my view the PHEV record this error , between the Ah SOC before and after the parking rest .. and based on the history or the accumulation of these error over days, the PHEV may decide to reduce the SOH (but if may even decide to increase the SOH if the car detect that after parking there is more capacity then what predicted)

The tricky part of my "assumption" .. is about:
A - How the PHEV will update the SOH if the car is never charged and used all the time in ICE mode ...
B - How the PHEV will update the SOH if the car is immediately charge after every EV usage, without any "rest" time for check the voltage level

About A ... I guess the PHEV may not bother to update the SOH .. as long the car is used in pure hybrid mode.. the real SOH is not relevant ...

About B ... maybe the PHEV has some tricky way to allow the battery to rest for check the real SOH/SOC before starting the charging process

Anyhow .. I can't say the software is garbage in the PHEV ... I also don't see how SOH and SOC can be monitor in EV without ever allowing fully discharge the battery ...


Well, before the software update during the recall last year, the algorithm never seemed to downgrade the EV range while parking. In Winter it kept the the same range or a small gain and in summer it bumped it up to 2-5km. Unfortunately I did not have the Dog at this time so could not really see what was going on. I only could monitor the EV km on the GOM which was.. well it's a GOM. Now with the Dog we can see what is happening and be more precise in our assumptions.
Again, after the reset why did the car have so much pure Ev range without changing the voltage range at all. It can be only related to the software which was protecting the real SoH before that. Otherwise the capacity would not have come back.
Of course the true and real capacity can only be determined by fully discharging+charging the battery and storing these information in the BMS. This will never happen in the PHEV though for known reasons. The software should therefore be capable of calculating the SoH itself and not providing us with false information. Not any other EV/PHEV I've ever heard of has 20% loss of capacity due to degradation within the first 50.000km or almost 30% at 80000km as seen by others. That would be the worst battery ever, not suitable for any EV! If other EVs suffering from such a degradation it would have been made public you think already?
You can only measure two things on a cell directly, the voltage and the temperature. For everything else there is already a calculation necessary which may or may not be accurate. And I still think the current software is not good enough to do that job. I also doubt Mitsubishi will ever update this software on the older models as from an economical perspective, selling new cars is far more profitable than keeping existing ones alive.

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Sun Apr 15, 2018 11:18 pm 
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For me it is very logical and quite correct on Mitsubishi side

As far as I know also the Nissan Leaf especially the 1st generation did/does suffer from battery degradation .. but since Nissan did guarantee some % of SOH inside X years and Y miles ... degradated battery from the Leaf get substituted once they get too bad.

Anyhow ... the battery stress in our PHEV is bigger then in normal EV ... our PHEV is requested to be discharged up to 60kw and charged up to 35kw .. and for a 12kwh battery these are big number ... especially normal driving require often burst over 40kw , and regen brake over 15kw ... so in normal usage the battery get get a high stress ... think of a tesla with a 100kwh pack ... in normal driving hardly is needed more then 70kw. and regen does not need to be more then 50kw ... for a 100kwh battery these number are so low that the voltage of the pack does possibly never get depressed like our PHEV (I have notice up to 3.3v per cell, in our PHEV which bounce back to 3.80 at rest ... a sign of a huge stress for the battery .. something I believe can't happen on big tesla)

For example the Lead had 80kw power, and 24kwh battery ... so worst scenario is a power usage 3.3:1 vs 5:1 .. and normal usage in Leaf possibly is around 30kw power burst ... so almost 1:1 vs 3:1 ... so ... you can see how much more stress the PHEV battery get compared to other EV

I think that our PHEV battery does degrade relative fast ... and it is not a software error .. the only "responsibility" of the software is to have the "dirty task" to calculate and show the battery degradation.

It would have been interesting to know what would be the result after a proper battery smoothing in your PHEV, unfortunately the dealers in Australia are doing this procedure in the wrong way .. instead of doing the smoothing they just reset some BMU parameters ... causing even more problems .. even if for a short time this look like that the battery in the PHEV is again as good as new

PS: A very significant case .. is in one of your video .. you did show that after having used the car in EV mode .. after 2h or more of rest ... voltage per cell was 3.75v and the ICE did kick in as soon as you switch on the car ... this is a clear sign that the PHEV did allow to overdischarge the battery ... and this is due to the fact that in your PHEV at the time the SOH was bigger then what was in reality .. so .. if the SOH is bigger then the real SOH .. it is normal that the software does reduce SOH and reduce EV range after usage and rest without charging.


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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Mon Apr 16, 2018 2:29 pm 
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Location: San Antonio, TX
Bert wrote:
Well, before the software update during the recall last year, the algorithm never seemed to downgrade the EV range while parking. In Winter it kept the the same range or a small gain and in summer it bumped it up to 2-5km. Unfortunately I did not have the Dog at this time so could not really see what was going on. I only could monitor the EV km on the GOM which was.. well it's a GOM. Now with the Dog we can see what is happening and be more precise in our assumptions.
Again, after the reset why did the car have so much pure Ev range without changing the voltage range at all. It can be only related to the software which was protecting the real SoH before that. Otherwise the capacity would not have come back.
Of course the true and real capacity can only be determined by fully discharging+charging the battery and storing these information in the BMS. This will never happen in the PHEV though for known reasons. The software should therefore be capable of calculating the SoH itself and not providing us with false information. Not any other EV/PHEV I've ever heard of has 20% loss of capacity due to degradation within the first 50.000km or almost 30% at 80000km as seen by others. That would be the worst battery ever, not suitable for any EV! If other EVs suffering from such a degradation it would have been made public you think already?
You can only measure two things on a cell directly, the voltage and the temperature. For everything else there is already a calculation necessary which may or may not be accurate. And I still think the current software is not good enough to do that job. I also doubt Mitsubishi will ever update this software on the older models as from an economical perspective, selling new cars is far more profitable than keeping existing ones alive.

My 2018 North American model updates with a higher SOC more days than not after sitting. Let me know how many kWH you're missing and I'll stuff them in a box for the boat ride south. :lol:

There are three things that can be measured by a decent BMS - voltage and temperature as you noted, and charge in and out (Coulomb counting). Voltage and temperature measurements should be reasonably accurate and precise, but the error bars expand for energy tracking. The thing that cannot be measured is the actual capacity of a cell for that particular age and temperature. To know the actual cell (and thus battery) capacity, one would have to run a full discharge-charge cycle - and that would increase the rate of battery degradation.

Since we can't know the actual capacity of the battery at any particular time, we can't know the exact state of charge. The problem here isn't the software or the battery, it's the faulty expectation of the operator. This isn't a Mitsubishi problem - this is the reality for all portable devices.

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Mon Apr 16, 2018 10:05 pm 
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Location: Lockyer Valley, QLD, Australia
AndyH wrote:

My 2018 North American model updates with a higher SOC more days than not after sitting. Let me know how many kWH you're missing and I'll stuff them in a box for the boat ride south. :lol:

There are three things that can be measured by a decent BMS - voltage and temperature as you noted, and charge in and out (Coulomb counting). Voltage and temperature measurements should be reasonably accurate and precise, but the error bars expand for energy tracking. The thing that cannot be measured is the actual capacity of a cell for that particular age and temperature. To know the actual cell (and thus battery) capacity, one would have to run a full discharge-charge cycle - and that would increase the rate of battery degradation.

Since we can't know the actual capacity of the battery at any particular time, we can't know the exact state of charge. The problem here isn't the software or the battery, it's the faulty expectation of the operator. This isn't a Mitsubishi problem - this is the reality for all portable devices.


I cannot see this as a fault of the operator. Other EVs do not seem to have this problem, I'm sure someone would have noticed and made this public as #parkinggate or something. Furthermore, before the update the BMS has calculated the SoC correctly (in my eyes) and gave me more KM after a rest and temperature rise of the battery during parking. The new version does not do this anymore. I have not changed but the software has...
If they do an update on your 2018 model and it now shows 1Ah less after parking would you say that's OK and think that's better and more accurate than before?

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Fri Apr 20, 2018 6:18 pm 
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Location: San Antonio, TX
Bert wrote:
AndyH wrote:

My 2018 North American model updates with a higher SOC more days than not after sitting. Let me know how many kWH you're missing and I'll stuff them in a box for the boat ride south. :lol:

There are three things that can be measured by a decent BMS - voltage and temperature as you noted, and charge in and out (Coulomb counting). Voltage and temperature measurements should be reasonably accurate and precise, but the error bars expand for energy tracking. The thing that cannot be measured is the actual capacity of a cell for that particular age and temperature. To know the actual cell (and thus battery) capacity, one would have to run a full discharge-charge cycle - and that would increase the rate of battery degradation.

Since we can't know the actual capacity of the battery at any particular time, we can't know the exact state of charge. The problem here isn't the software or the battery, it's the faulty expectation of the operator. This isn't a Mitsubishi problem - this is the reality for all portable devices.


I cannot see this as a fault of the operator. Other EVs do not seem to have this problem, I'm sure someone would have noticed and made this public as #parkinggate or something.

With respect, the Outlander PHEV is not an EV. It's a hybrid. The 'problem' here is one of intense observation. Batteries are not static devices - they're electrochemical critters that are in a constant state of change. One might as well be monitoring the volume of blood in their body or complaining when their red blood cell count changes. Normal changes in batteries over time aren't cause for concern with most hybrid owners since most don't know how battery performance changes with use and temperature.

Bert wrote:
Furthermore, before the update the BMS has calculated the SoC correctly (in my eyes) and gave me more KM after a rest and temperature rise of the battery during parking. The new version does not do this anymore. I have not changed but the software has...
If they do an update on your 2018 model and it now shows 1Ah less after parking would you say that's OK and think that's better and more accurate than before?

I'm driving the car, not using it as an analysis test bed. As I worked with lithium cells for about 10 years hand-building batteries, I understand how they change and I don't get my panties in a knot when the numbers shift around during the day. If my car's reflashed and now it shows a 1 Ah drop when parking, all I can say is that I don't have enough information to know if it's more or less accurate. There are so many variables that even repeated 'test drives' aren't very useful in deciding how the battery's doing. There's a lot of noise in the data - best to focus on the long-term trend.

ETA... I had a smart EV for three years. It has an analogue battery charge gauge and a guess-o-meter. There are no monitoring programs available (like the watchdog) that provide cell-level information. I had absolutely no stress about how much the thermal management system took from the battery, and had no stress about the way the state of charge changes through the day because the data weren't available. After a few months, I learned that I needed about 20% of charge to make a 18-20 mile drive - that was all the information I needed in order to use the car to it's max capability.

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Mon Apr 23, 2018 10:28 am 
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Location: San Antonio, TX
Here's one example of how state of charge and state of health are estimated:
http://www.analog.com/media/en/technical-documentation/technical-articles/A-Closer-Look-at-State-Of-Charge-and-State-Health-Estimation-Techniques-....pdf

Note that at best, there's a 2% error - and that rage increases:
Quote:
It is noted that the estimation error increases with the algorithm runtime and before the SOH
reevaluation when the battery is fully charged.

As the battery in our cars is NEVER allowed to fully charge (we never get to 'SOH reevaluation') or discharge, we MUST expect more error over time - because the only thing we've got is 'estimation error increase' due to 'algorithm runtime'. Two percent of our 40Ah battery is 0.8 Ah - that's the best we can expect when the car has zero miles/km/light seconds on the odometer. If the 'battery smoothing' process allows a recalibration, we should be able to expect SOH/SOC numbers to come back to the roughly ±0.4 kWh range before they get back to diverging from reality again. Entropy's the law, especially in non-linear critters like lithium batteries. ;)

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Tue May 29, 2018 12:10 am 
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Is there any chance that Mitsubishi dealer using ultrasound technology to check SoH of our battery pack?

http://www.eenewsautomotive.com/news/me ... liable-bms

UPS industry has been using this technology for a while...

Tai

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Sat Aug 04, 2018 7:04 pm 
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Location: Lockyer Valley, QLD, Australia
Tai626 wrote:
Is there any chance that Mitsubishi dealer using ultrasound technology to check SoH of our battery pack?

http://www.eenewsautomotive.com/news/me ... liable-bms

UPS industry has been using this technology for a while...

Tai


That is very unlikely. The BMU uses coulomb count for keeping track of the SoH and SoC. Obviously not very successful...

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Sat Aug 11, 2018 9:11 pm 
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elm70 wrote:
For me it is very logical and quite correct on Mitsubishi side

As far as I know also the Nissan Leaf especially the 1st generation did/does suffer from battery degradation .. but since Nissan did guarantee some % of SOH inside X years and Y miles ... degradated battery from the Leaf get substituted once they get too bad.

Anyhow ... the battery stress in our PHEV is bigger then in normal EV ... our PHEV is requested to be discharged up to 60kw and charged up to 35kw .. and for a 12kwh battery these are big number ... especially normal driving require often burst over 40kw , and regen brake over 15kw ... so in normal usage the battery get get a high stress ... think of a tesla with a 100kwh pack ... in normal driving hardly is needed more then 70kw. and regen does not need to be more then 50kw ... for a 100kwh battery these number are so low that the voltage of the pack does possibly never get depressed like our PHEV (I have notice up to 3.3v per cell, in our PHEV which bounce back to 3.80 at rest ... a sign of a huge stress for the battery .. something I believe can't happen on big tesla)

For example the Lead had 80kw power, and 24kwh battery ... so worst scenario is a power usage 3.3:1 vs 5:1 .. and normal usage in Leaf possibly is around 30kw power burst ... so almost 1:1 vs 3:1 ... so ... you can see how much more stress the PHEV battery get compared to other EV

I actually don't think the very brief bursts of power of up to 60 kW in normal driving are what does the damage. For the most part, that's just removing a bit of surface charge (that may have even been put into the battery in the last regen cycle) and in any case, it doesn't tend to last very long. Remember that HEV batteries are charged and discharged at even higher C rates, not because they're demanding much more power, but because their batteries are absolutely tiny (1.5 kWh is a typical HEV battery size). Let's take the 2018 Toyota Camry Hybrid for example. The LE model has a 1 kWh Li-ion pack, while the XLE has a 1.8 kWh NiMH pack. Both of these models have a motor that will do up to 88 kW so...about 88C discharge rate on the LE and 49C on the XLE. Yikes! And the highest our batteries ever see is around 5C. But HEV batteries last a LONG time, don't they? Well that's because the amount of time the battery is actually supplying that amount of current is YERY short.

What does the real damage is the sustained power demand of up to 2-3C (so 24-36 kW) when driving down the freeway. Mitsubishi is managing the battery very poorly in basically programming the car to use the battery as much as it can, until it gets down to 1 bar on the gauge, and only THEN go into hybrid mode. And they also like to brag about how the car can go up to 78 mph/125 km/h in EV mode (but it doesn't mean it's a good idea to actually do it, especially for an extended period of time). That's why I put the car into Save mode whenever I go faster than about 50 mph/80 km/h. This will either use the ICE to drive the wheels directly, or will use the ICE to run the generator, which generates power and immediately consumes it. In any case, it prevents the battery from having to discharge at 2-3C for an extended period of time. And the other thing I do is obviously I don't use the CHAdeMO port much at all.

I think Mitsubishi really dropped the ball in not putting the car into some sort of automatic Save mode whenever the battery would have to discharge at more than 1C for a long time. But then they'd have to deal with a whole bunch of whiners and complainers who bought a PHEV and are trying to never use any gasoline, and really got the wrong tool for the job. The goal of a PHEV is to reduce trips to the gas station, and the goal for a BEV is to eliminate trips to the gas station. Many people choose the former tool to try to achieve the latter goal, and as a result end up destroying their batteries, and to those people I would ask: why are you lugging around a heavy ICE, cooling system/radiator, gas tank, and a bunch of other stuff you almost never use?


Last edited by STS134 on Sun Aug 12, 2018 7:02 pm, edited 1 time in total.

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 Post subject: Re: Drive battery degradation and the out of whack IMO BMU.
PostPosted: Sun Aug 12, 2018 12:36 am 
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STS134 wrote:
[ Many people choose the former tool to try to achieve the latter goal, and as a result end up destroying their batteries, and to those people I would ask: why are you lugging around a heavy ICE, cooling system/radiator, gas tank, and a bunch of other stuff you almost never use?


Because I don't want the cost of 2 cars (for which I don't have the space) and to hire an ICE car for the relatively few long distance journeys (e.g. holidays abroad) over the lifetime of my PHEV would cost more than a replacement battery when needed - NB. still getting 25 miles EV per charge after 4 years. :mrgreen:

You might also turn the question around and ask those who spending most of their time using the ICE, why they are carrying the extra weight of the batteries, :lol:


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