Drive battery degradation . Houston, do we have a problem?

[greendwarf]

I just notice that our PHEV battery pack can be acquired on ebay ... people in UK can get them for just 2000 Euros ... from Germany I have seen one for 3000 euros.

Can't find anything on ebay - have you got the link?

Was ebay.de .. but actually the pack is somewhere else .. in Latvia

https://www.ebay.com/itm/Mitsubishi-Outlander-III-HYBRID-PHEV-Akkumulator-Batterie-EV-BATTERY-PACK/132521270193

The guy that made a video for disassemble the PHEV battery pack, he is saying he paid much less then what is asked in this ebay offer.

So this a second hand one in unknown condition - I don't think I would be interested even if a third of the price of a brand new guaranteed one

 

[elm70]

For what you stated somewhere else ... it happen many time that your PHEV got as low as 16% SOC and kick on extra power ... since the Parallel mode was still not able to cope with the EV load.

Perhaps. Although, normally the car switches to serial mode at 20% and then SOC will go back up. Very seldom I have been below 20%. But maybe once is all it takes .... :shock:

Considering the errors on SOC from the PHEV ...

What errors are you referring to?

As you know the PHEV can't know the real SOC ... it is an educated guess what the car make for know the SOC ... especially if ICE is running.

As you may have seen .. somebody .. like magic after a "wrong" battery smoothing procedure got the SOH from 80% back to 100%

A wrong SOH in the PHEV temporary configuration cause a wrong SOC especially at low level of SOC

Apparently our PHEV calculate the SOC .. by knowing SOH .. or better knowing the "actual" Ah at 100% SOC ... and then the PHEV monitor the current going in and out from the battery pack for determinate the real time SOC while the PHEV is moving.

So .. we have the error from SOH which possibly is optimistic .. plus monitoring the current from and to the battery does cause extra error ... so .. it is possible to bring the real SOC below the designed limits.

For instance ... via a wrong battery smoothing .. is possible to assign 100% SOH, when in reality the car has only 80% SOH .. as consequence ... the PEHV will allow to discharge 70% of the theoretical 38Ah battery capacity ... so 26.6Ah discharge are allowed .. but the real SOH was 80%, so only 30.4Ah capacity .. this means that due to a wrong SOH the battery can be drain down to 12.5% SOC ... and this is what I believe did happen multiple times to our "friend" in Australia, until the PHEV did readjust automatically the SOH

Anyhow ... I know that a very wrong SOH was never a problem on your car ... but if SOH is reduced, is because the PHEV detect (with a delay) that the real SOH is below what was previously guessed by the car.

So .. with an optimistic SOH, with all the error on measuring current flow ... with going down to SOC 16% or 20% due to towing .. the risk to have reach a very low SOC is possible

As far as I know .. the PHEv need 2h of rest for readjust the SOC with a more accurate value .. so if towing did happen on long trip without any pause over 2h ... it is possible that SOC has been below the designed values.

I also believe that Mitsubishi is aware of the error in the SOH and SOC "guessing" .. and for this reason .. they assume that our battery is only 38Ah as new, instead as 40Ah (which is the real capacity) .. and as well .. they assume 30% of SOC is when voltage is ~3.81v .. which in reality the SOC for a Li-Ion cell at this voltage is higher then 30% .. all these buffers are for avoid to over discharge the main battery ... but ... when bringing down the theoretical SOC below 20% ... it is possible to reach undesired real SOC level.

 

[elm70]

So this a second hand one in unknown condition - I don't think I would be interested even if a third of the price of a brand new guaranteed one

Where you can get a band new and guaranteed battery pack for the Outlander PHEV ?

Anyhow ... people that got 2nd hand batteries from crashed cars .. so far they do report happy results.

Still ... as low is the price as higher is the risk

 

[anko]

For instance ... via a wrong battery smoothing .. is possible to assign 100% SOH, when in reality the car has only 80% SOH .. as consequence ... the PEHV will allow to discharge 70% of the theoretical 38Ah battery capacity ... so 26.6Ah discharge are allowed .. but the real SOH was 80%, so only 30.4Ah capacity .. this means that due to a wrong SOH the battery can be drain down to 12.5% SOC ... and this is what I believe did happen multiple times to our "friend" in Australia, until the PHEV did readjust automatically the SOH

This is not an error from the PHEV. This is an error from the dealer But like you already said, never happened to me. I don't think my SOH is over estimated perse.

Apart from that and with all due respect, I have a feeling there is a lot of assuming / speculating going on in your post.

 

[elm70]

For instance ... via a wrong battery smoothing .. is possible to assign 100% SOH, when in reality the car has only 80% SOH .. as consequence ... the PEHV will allow to discharge 70% of the theoretical 38Ah battery capacity ... so 26.6Ah discharge are allowed .. but the real SOH was 80%, so only 30.4Ah capacity .. this means that due to a wrong SOH the battery can be drain down to 12.5% SOC ... and this is what I believe did happen multiple times to our "friend" in Australia, until the PHEV did readjust automatically the SOH

This is not an error from the PHEV. This is an error from the dealer But like you already said, never happened to me. I don't think my SOH is over estimated perse.

Apart from that and with all due respect, I have a feeling there is a lot of assuming / speculating going on in your post.

Did you ever analysed when and how the SOH go down in our PHEV?

Yes I am making educated guesses, but I am quite confident about how SOC and SOH is computed in our PHEV

Unless you know that you did exposed you phev to high temperature, the only reason why your battery is equally degradated can be only due to over discharge

 

[greendwarf]

So this a second hand one in unknown condition - I don't think I would be interested even if a third of the price of a brand new guaranteed one

Where you can get a band new and guaranteed battery pack for the Outlander PHEV ?

From a Mitsubishi dealer :idea:

 

[Antti]

Does any battery test include in normal service at authorized dealer?

 

[jaapv]

Over here it does but you have to ask for the result.

 

[elm70]

Does any battery test include in normal service at authorized dealer?

I don't think it make any difference the test result from a dealer then the numbers that you can get from the "dog"

At the end .. the only thing that really matter is the SOH or in other words the amount of Ah that the PHEV believe are available once the battery is fully charged

PS: Note that our PHEV has 40Ah battery, but m=Mitsubishi decided to consider them as only 38Ah ,,, since they decided to have a double low voltage protection ... once by considering 5% less capacity... and the other to consider 30% capacity left once voltage per cell is ~3.81v .. which in reality is around 35% capacity .. the two numbers (38Ah as new and 35% at 3.81v) are going hand in hand ... so all the time the Ah capacity reported by the PHEV are a ~5% pessimistic .. for "safety" margin

 

[Bert]

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).

As per my observation and measurements, the BMS does not dig deeper into the 30% bottom buffer though, nor does the battery exceed 4.1V after a full charge. However the range was back to 'normal' after that process. I was thinking the same, that Mistu just cheated and used seom the of the reserve but the voltages should have changed then as well, right?

The determination of SoC and SoH is definitely a big limitation of the BMU in this car. I'm back to 86% after a bit over 5 months and can already feel a los in range again (although the outside temperatures are below 20°C during the night now, brrrrrr). The software is overreacting and limits the access to the battery's full capacity. I doubt that we have seen any real battery degradation in these cars so far due to that fact. It is all speculated, assumed and calculated by the software.

Only a full recalibration can fix that, so debleed the battery to 0% and fully charge to 100%. This Ah number needs to go into the BMU software. The lack of software updates will make the car's system fall behind the true SoH after a while though. Clearly there should be new algorithms available for these type of batteries which just need to be implemented in the software and cars need to receive this new 'brain' somehow... I also doubt Mitsu is really interested in doing that for existing cars, as they don't see that there is a real problem and the car still 'functions' as designed. Of course they can make more money selling new cars with perhaps also newer software which may or may not cope better with the determination of SoH and SoC.

 

[anko]

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.

 

[anko]

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/asdbopog958ljb2/cell%20stuff.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:

 

[elm70]

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

 

[anko]

Thanks for having a look at this!

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: )

 

[HHL]

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.

 

[anko]

Copied this from another topic:

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).

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

 

[anko]

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.

 

[elm70]

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

 

[elm70]

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

 

[anko]

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.