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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Wed Apr 11, 2018 12:49 am 
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Location: Netherlands, Utrecht area
Bert wrote:
Yeah, not quite sure why Mitsubishi dealers are calling it battery cell smoothing procedure when in fact it's a simple MBU reset (takes less than 10min with the MUT III apparently).
I think the "wrong smoothing procedure" (as it was referred to above) takes 10 minutes. The "wrong smoothing procedure" is a reset and is fast. And is what you got. The "right smoothing procedure" is a recalibration and takes much longer.


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Mon Jun 25, 2018 1:34 pm 
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Location: Netherlands, Utrecht area
I have created a battery 'ECG' today. During a short drive with low SOC (< 30%) I captured on very regular basis (roughly once per second):

- Speed (km/h)
- Battery voltage (v)
- Battery Amps (a)
- Battery Power (kw, calculated form the above)
- SOC (%)
- Min cell voltage (v)
- Max cell voltage (a)
- Diff between min and max cell voltage (a)
- Voltages for each cell (a)

Added some colour schema to the cell voltage table and uploaded the XLS to dropbox (
https://www.dropbox.com/s/asdbopog958lj ... .xlsx?dl=0).

Maybe if some of the battery experts can have a look and give a verdict? Cell voltage table looks a bit like this:

Image


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Wed Jun 27, 2018 11:05 pm 
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Location: Poland
Hi Anko

I can't see nothing wrong in the XLS

Yes there is an imbalance up to 0.02v, but I guess this is acceptable ... not ideal, but not too bad either.

What it is maybe strange is to have so low SOC 26% with a voltage a bit above 3.81 ... SOC for this cell voltage level should me around 30%

You did not use lot of power from your car ... I think weak cell can be better seen at high current .. so when you are as close as possible to the 60kw power limit ... in my case I have seen low voltage per cell as low as 3.55v and I was well over 40% SOC (but it was winter time, possibly a sub zero temperature) ... in your XLS the lowest voltage is only 3.76v


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Thu Jun 28, 2018 12:24 am 
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Location: Netherlands, Utrecht area
Thanks for having a look at this!

elm70 wrote:
You did not use lot of power from your car ... I think weak cell can be better seen at high current .. so when you are as close as possible to the 60kw power limit ...


Indeed, I didn't. More or less purposely. As because of the low SOC (and the bad state of my battery) the engine would come on and provide power. And battery discharge would be even lower (if I would not change into charge). I'll give it another shot some time. Maybe I can do this tomorrow. Will try to monitor full daily commute (my wife needs the full EV tomorrow, so I will be driving the plug in :mrgreen: )


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Thu Jun 28, 2018 12:45 am 
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Joined: Wed Oct 29, 2014 8:23 pm
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Wouldn't it be more relevant to look at the cell resistance, I think it is around 1.5 milliOhm on good cells and it would probably only take 1 bad one to stuff things up, as the BMU would probably sense this and limit the current that can be drawn for the whole pack. And the only way it could deal with this is to start the engine.


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Thu Jun 28, 2018 12:59 am 
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Location: Netherlands, Utrecht area
Copied this from another topic:
elm70 wrote:
Did your car got better ?

Some time ago, you reported that your Outlander PHEV was starting the ICE also when battery was almost fully charged for power demands below 40kw ... (maybe with summer time your battery now does behave better ?)

If ICE kick in for just 40kw power from battery, it is looking you will be towing all time with ICE on.

PS: Your experience with your PHEV, since it is looking one with the biggest battery degradation, could be the experience that some of us may experience in the near future ... battery degradation in my PHEV does not seams it was to slow down ... since I got mine .. my battery downgraded from 96% SOH down to 90% .. with a almost regular lost of 0.1Ah a month (with 1 exception of 0.5Ah lost)

Last recalibration, it went up from 25.9 Ah to 28 Ah. Power delivery improved a little bit, but not to the old level (60 kW is not achievable, more like 50). Four weeks later, I was already back at 27.4. Indeed, one step of 0.5 and then one step of 0.1. For me it is common to see steps of either 0.5 or 0.1. I have a feeling one is time related and the other distance related (or something like that).

elm70 wrote:
If ICE kick in for just 40kw power from battery, it is looking you will be towing all time with ICE on.

When towing, a full charge will last no more than 15 anyway. So, I select Charge as soon as I leave my driveway ;)


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Thu Jun 28, 2018 1:01 am 
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HHL wrote:
Wouldn't it be more relevant to look at the cell resistance, I think it is around 1.5 milliOhm on good cells and it would probably only take 1 bad one to stuff things up, as the BMU would probably sense this and limit the current that can be drawn for the whole pack. And the only way it could deal with this is to start the engine.
Makes sense. But we do not know cell resistance per cell. The overall resistance reported by the BMU is still 1.5. Has never been different.


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Thu Jun 28, 2018 1:35 am 
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anko wrote:
HHL wrote:
Wouldn't it be more relevant to look at the cell resistance, I think it is around 1.5 milliOhm on good cells and it would probably only take 1 bad one to stuff things up, as the BMU would probably sense this and limit the current that can be drawn for the whole pack. And the only way it could deal with this is to start the engine.
Makes sense. But we do not know cell resistance per cell. The overall resistance reported by the BMU is still 1.5. Has never been different.


Cell resistance can be calculated .. a bit tricky but it can b done.

Checking the voltage drop under load, possibly a heavy load ... dV = R * I ...
The tricky part is that this need to be a "current" pulse ... else a constant current will not only kick in the internal resistance but as well it will factor the "voltage depression" that Lithium battery are "suffering"

IR is also a function of the temperature ... this add an extra "complexity" for get an IR value that is "comparable"

Anyhow ... the difference of voltage per cell in Anko case .. did no change much under load nor while recharged ... so ... all cells are looking having similar IR

BTW ... a single high IR cell does not really make much difference in a battery pack .. what cause problem is a single cell with much less capacity compared to the others .. but this is not apparently the case either ... this will be shown as high difference of voltage in cells ... I bet above 0.03v difference (0.02v difference is already 4.7% difference in capacity .. but ~0.005 could be cause by imperfect balancing while charging .. so it is more 4.7% +/- 1% "error")

As seen before ... all the cells in Anko PHEV are looking to have been aged in similar way ... so ... if we consider his battery degradation higher then normal (actually it is not much worst then others from Australia per example) ... then this degradation is looking more to his car usage then not a poor cell inside his battery pack.

My bet is that our PHEV battery suffer high temperature , and high current/power charge, especially when battery is "hot" .. so using B5 in summer or CHARGE in summer on a long trip it may arm these batteries ... I'm quite sure Mitsubishi / GS Yusa did update the battery during these years ... so my 2013 and Anko 2013 PHEV most likely have 1 or 2 generation older battery cells compared to a 2016 PHEV or a 2018 PHEV


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Thu Jun 28, 2018 1:41 am 
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Location: Poland
anko wrote:
Last recalibration, it went up from 25.9 Ah to 28 Ah. Power delivery improved a little bit, but not to the old level (60 kW is not achievable, more like 50). Four weeks later, I was already back at 27.4. Indeed, one step of 0.5 and then one step of 0.1. For me it is common to see steps of either 0.5 or 0.1. I have a feeling one is time related and the other distance related (or something like that).




Do you get re calibration inside the warranty agreement or part of the yearly service or per your request ?

Or better ... how much do you pay for this "service" ?

PS: In my case I would like to get the "fake recalibration" : a BMU total reset and back to 100% .. this would be nicer in my view


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Thu Jun 28, 2018 6:28 am 
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Location: Netherlands, Utrecht area
elm70 wrote:
Do you get re calibration inside the warranty agreement or part of the yearly service or per your request ?
Two times, I did not pay. One time, I paid 10 euros or something like that. Peanuts.


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