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 Post subject: Evbatmon and Phev watchdog is showing the wrong SOH amount.
PostPosted: Fri Mar 15, 2019 7:02 pm 
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Location: Near Port Macquarie Australia
Now as the title says Evbatmon and Phev watchdog is showing the wrong SOH amount. Now that is IMHO. Why do I think this? Well lets get some history on how they are working it out first.

I will bring in a quote from anko from another thread that I started:

anko wrote:
The capacity % is calculated by comparing Current Capacity Ah with Current Capacity when new. As this number is not known, Daniel Santos (WatchDog) uses 38 as a baseline value. I can only guess Jeremy does the same.


Now as anko states both are using 38 Ah as a baseline for measuring because in that thread I had current capacity of 29.9 Ah divided by 38 Ah gives approx 78.68% SOH and Evbatmon was showing 78.68% and Phev watchdog was showing 78.7% at the time.

Now Mitsubishi have stated we have a 40 Ah cell capacity so I not sure why this 38 Ah is used as a baseline or anko states that this number is not known unless it is because that is mainly what they read on the OBD device when a new PHEV gets to a customer. Hell I have even seen people write that the difference between the two values is the top side buffer ie the amount not used to reduce degradation of the drive battery. Even a value for this top side buffer has been placed as 5%. I think they work this out by 38 Ah divided by 40 Ah gives 95% subtract from 100% gives that 5%.

So lets see some examples of where Mitsubishi have stated we have a 40 Ah battery capacity:

Trex wrote:
Phev high voltage battery opened,

Image

12 kwh 40 amp/hour and 184kg weight.

MMC via anko.

This one from MMC.

Image

Regards Trex.


Now you can see in both these images we have a 40 Ah battery ie 12 kWh or 12,000 watts divided by 300 volts nominal gives 40 Ah as well as being called a LEV 40. ;)

Now as another example of our battery being 40 Ah and not 38 Ah, on my battery report from the MUT-III after a drive battery recalibration (auto capacity measured procedure)
BMU data list number 18 gives me the Battery current capacity of 28.3 Ah (BTW up from 26.8 Ah ) and the BMU data list number 401 Cell current capacity difference of 11.7 Ah. Add those two ie 28.3 plus 11.7 gives 40 Ah. ;)

Now back to my previous example above where I had a current capacity of 29.9 Ah Evbatmon and Phev watchdog should be showing 74.75% SOH (29.9/40) and not 78.68% (29.9/38) IMHO.

Also about that top side buffer I was writing about previously, this should be above that 40 Ah capacity and NOT shown as part of that 40 Ah capacity because we can never use it at the moment unlike the bottom side buffer ie below approx 26-30% SOC that can be accessed in some special circumstances.

Now I wanted to bring this up as there is so much misrepresentation IMHO about this out there I think it needs mentioning. Hell, I think, Mitsubishi have been trying to tell us the truth for years.

Regards Trex.


Last edited by Trex on Sat Mar 16, 2019 2:46 pm, edited 1 time in total.

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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sat Mar 16, 2019 2:18 am 
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Location: Netherlands, Utrecht area
When you have a new pre-2019 car delivered to you, SoH reported by the BMU is approx. 38Ah, not 40. To me that is 100% SoH. Otherwise health would be down 5% already upon delivery.


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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sat Mar 16, 2019 4:17 am 
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Joined: Wed Oct 29, 2014 8:23 pm
Posts: 313
Location: Dee Why
Trex wrote:
Now as the title says Evbatmon and Phev watchdog is showing the wrong SOH amount. Now that is IMHO. Why do I think this? Well lets get some history on how they are working it out first.

I will bring in a quote from anko from another thread that I started:

anko wrote:
The capacity % is calculated by comparing Current Capacity Ah with Current Capacity when new. As this number is not known, Daniel Santos (WatchDog) uses 38 as a baseline value. I can only guess Jeremy does the same.


Now as anko states both are using 38 Ah as a baseline for measuring because in that thread I had current capacity of 29.9 Ah divided by 38 Ah gives approx 78.68% SOH and Evbatmon was showing 78.68% and Phev watchdog was showing 78.7% at the time.

Now Mitsubishi have stated we have a 40 Ah cell capacity so I not sure why this 38 Ah is used as a baseline or anko states that this number is not known unless it is because that is mainly what they read on the OBD device when a new PHEV gets to a customer. Hell I have even seen people write that the difference between the two values is the top side buffer ie the amount not used to reduce degradation of the drive battery. Even a value for this top side buffer has been placed as 5%. I think they work this out by 38 Ah divided by 40 Ah gives 95% subtract from 100% gives that 5%.

So lets see some examples of where Mitsubishi have stated we have a 40 Ah battery capacity:

Trex wrote:
Phev high voltage battery opened,

Image

12 kwh 40 amp/hour and 184kg weight.

MMC via anko.

This one from MMC.

Image

Regards Trex.


Now you can see in both these images we have a 40 Ah battery ie 12 kWh or 12,000 watts divided by 300 volts nominal gives 40 Ah as well as being called a LEV 40. ;)

Just out of interest when the battery is fully charged and when new it is actually approx 13 kWh ie 4.1 V x 80 cells in series gives 328 V x 40 Ah gives 13,120 watts or 13.12 kWh.

Now as another example of our battery being 40 Ah and not 38 Ah, on my battery report from the MUT-III after a drive battery recalibration (auto capacity measured procedure)
BMU data list number 18 gives me the Battery current capacity of 28.3 Ah (BTW up from 26.8 Ah ) and the BMU data list number 401 Cell current capacity difference of 11.7 Ah. Add those two ie 28.3 plus 11.7 gives 40 Ah. ;)

Now back to my previous example above where I had a current capacity of 29.9 Ah Evbatmon and Phev watchdog should be showing 74.75% SOH (29.9/40) and not 78.68% (29.9/38) IMHO.





Regards Trex.


You can't just multiply the peak voltage with Ah, as it goes down (initially quite rapidly) as the battery discharges. That's why battery capacity is now more commonly stated in Wh (or kWh). The fact that it peaks at 4.1V/cell is not relevant, as it doesn't stay there for very long when you start discharging. Also, the cells will have a "nominal" 40Ah rating, perhaps when they are charged to a higher voltage (4.2V?), or discharged to a lower voltage than what actually happens in the PHEV. Mitsubishi can of course still call it a 12kWh battery, but that doesn't mean that capacity is available the way the car is designed to use it.


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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sat Mar 16, 2019 5:33 am 
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Joined: Thu Feb 26, 2015 5:58 pm
Posts: 874
Location: Near Port Macquarie Australia
HHL wrote:
You can't just multiply the peak voltage with Ah, as it goes down (initially quite rapidly) as the battery discharges. That's why battery capacity is now more commonly stated in Wh (or kWh). The fact that it peaks at 4.1V/cell is not relevant, as it doesn't stay there for very long when you start discharging. Also, the cells will have a "nominal" 40Ah rating, perhaps when they are charged to a higher voltage (4.2V?), or discharged to a lower voltage than what actually happens in the PHEV. Mitsubishi can of course still call it a 12kWh battery, but that doesn't mean that capacity is available the way the car is designed to use it.


Ok HHL, I reckon I can get at least 13.12 kWh out of a new PHEV battery but I will let you work out how I will do it and I will not charged it above 4.1 V per cell.


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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sat Mar 16, 2019 2:55 pm 
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Joined: Thu Feb 26, 2015 5:58 pm
Posts: 874
Location: Near Port Macquarie Australia
Trex wrote:
HHL wrote:
You can't just multiply the peak voltage with Ah, as it goes down (initially quite rapidly) as the battery discharges. That's why battery capacity is now more commonly stated in Wh (or kWh). The fact that it peaks at 4.1V/cell is not relevant, as it doesn't stay there for very long when you start discharging. Also, the cells will have a "nominal" 40Ah rating, perhaps when they are charged to a higher voltage (4.2V?), or discharged to a lower voltage than what actually happens in the PHEV. Mitsubishi can of course still call it a 12kWh battery, but that doesn't mean that capacity is available the way the car is designed to use it.


Ok HHL, I reckon I can get at least 13.12 kWh out of a new PHEV battery but I will let you work out how I will do it and I will not charged it above 4.1 V per cell.


Now I will remove that section from my first post above about the 13.12 kWh because I do not want the thread to get waylaid from the main point I was trying to make that we have a 40 Ah rated battery and I was falling into the trap myself :oops: of not using Mitsubishi's rated capacities which is what the thread is about. It is NOT a 38 Ah rated battery but according to Mitsubishi a 40 Ah rated battery that gives us 12 kWh of total energy at the nominal voltage of 300 V.

But in most normal circumstances they will ONLY let us use approx 70-74% of that rated 12 kWh because of the bottom side buffer. The top side buffer which we cannot use should never be included in that measurement IMHO and it appears when Mitsubishi measures the true capacity of the the drive battery (Edit. by emptying that bottom side buffer) using the MUT-III they are not including it as well from what I can see ie they are only charging it to approx 4.1 V and they are then comparing the measured result with a 40 Ah rated battery.


Last edited by Trex on Sat Mar 16, 2019 6:53 pm, edited 1 time in total.

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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sat Mar 16, 2019 3:16 pm 
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Joined: Thu Feb 26, 2015 5:58 pm
Posts: 874
Location: Near Port Macquarie Australia
HHL wrote:
You can't just multiply the peak voltage with Ah, as it goes down (initially quite rapidly) as the battery discharges....................The fact that it peaks at 4.1V/cell is not relevant, as it doesn't stay there for very long when you start discharging.


Now I will say something about these statements HHL. The amount of decrease in voltage in batteries is dependant on the amount of load placed on the battery I am pretty sure you will find ie it will not go down rapidly if a "light" enough load is applied.


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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sat Mar 16, 2019 4:01 pm 
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Joined: Thu Feb 26, 2015 5:58 pm
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Location: Near Port Macquarie Australia
anko wrote:
When you have a new pre-2019 car delivered to you, SoH reported by the BMU is approx. 38Ah, not 40. To me that is 100% SoH. Otherwise health would be down 5% already upon delivery.


Anko, so because you, and I think probably Jeremy and Daniel who make the apps, believe that 38 Ah is 100 % SOH and not what Mitsubishi state we should use ie 40 Ah, to me that sounds presumptuous of you three to start your own definition of how the SOH should be measured IMHO.

This is starting to sound like ,from memory, maby writing a planetary gearbox is not a gearbox or series mode is a CVT transmission IMHO. Hell, lets all just start making up our own rules and definitions. Should be fun I think. :lol: I will definitely be voting for calling series mode cereal mode. :lol:

Just because the BMU "estimates" (and I think quite badly in some circumstances) the capacity of approx 38 Ah at that point in time when the customer gets his PHEV which could be some time after the PHEV was built and delivered from over the seas and oceans some people should be inventing a new SOH formula.:roll: Sorry anko, but I totally disagree with that sentiment.


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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sat Mar 16, 2019 9:21 pm 
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Location: Gosford, Australia
Trex wrote:
Anko, so because you, and I think probably Jeremy and Daniel who make the apps, believe that 38 Ah is 100 % SOH and not what Mitsubishi state we should use ie 40 Ah, to me that sounds presumptuous of you three to start your own definition of how the SOH should be measured IMHO.


Trex, while I get what you are saying (and agree with the pedantic semantics), you really should not paint us all with the same brush. In EvBatMon from the beginning I specifically used the label "PMC" which I coined myself as "Percentage of Manufactured Capacity", and not SOH, as I did not believe I was calculating a true SOH value. I actually meant it to be a real-world rather than nominal value, ie "how much has the battery deteriorated since I've owned it", which is very lenient on Mitsubishi (best case).
The current Ah capacity is the real value, so feel free to use 40Ah and you have your SOH and eat it too. Sweet!

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2010 iMiEV, 2015 Outlander PHEV
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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sat Mar 16, 2019 9:36 pm 
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Location: Near Port Macquarie Australia
zzcoopej wrote:
Trex wrote:
Anko, so because you, and I think probably Jeremy and Daniel who make the apps, believe that 38 Ah is 100 % SOH and not what Mitsubishi state we should use ie 40 Ah, to me that sounds presumptuous of you three to start your own definition of how the SOH should be measured IMHO.


Trex, while I get what you are saying (and agree with the pedantic semantics), you really should not paint us all with the same brush. In EvBatMon from the beginning I specifically used the label "PMC" which I coined myself as "Percentage of Manufactured Capacity", and not SOH, as I did not believe I was calculating a true SOH value. I actually meant it to be a real-world rather than nominal value, ie "how much has the battery deteriorated since I've owned it", which is very lenient on Mitsubishi (best case).
The current Ah capacity is the real value, so feel free to use 40Ah and you have your SOH and eat it too. Sweet!


Gday zzcoopej or Jeremy,

How the bloody hell are you? Long time no "see". :) Still work on the app sometimes?

Ok, point taken about the "PMC" which I coined myself as "Percentage of Manufactured Capacity", but now you can fix it to be the proper BMU "estimated" SOH amount as people are using that P.M.C. as such and use 40 Ah as specified by Mitsubishi IMHO.

Now as for "The current Ah capacity is the real value," I would disagree unless it's read reasonable soon after a BMU recalibration but I think I know what you mean.

Pedantic semantics, Ok I am not sure I would have used that term. I would call it trying to get to the bottom of all the misrepresentations I see about this topic.

Regards Trex.


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 Post subject: Re: Evbatmon and Phev watchdog is showing the wrong SOH amou
PostPosted: Sun Mar 17, 2019 4:00 pm 
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Further on this, reports are that the BMU shows 40 Ah when the capacity measurement procedure is carried out on the new batteries that are being installed in some Australian cars.

It seems as though the 38 Ah is some sort of default setting in the BMU.


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