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

[ThudnBlundr]

I do. But I think we can also get that using B0 + brake pedal? I am close to having a valid claim. For this capacity must be below 26 Ah before performing a recalibration procedure and must stay or drop below 26 Ah after the procedure. Procedure was performed at 25.9. Ah went up to 28. Now back at 27.4. It is a matter of time and distance. But I am running out of distance (still 3 years but only about 15.000 km before warranty expires), so I don't think this is the right time to start nursing my battery ;-)

Lower 'B' settings lower the amount of regen available from the brake pedal, if the power readings from PSideP are accurate. This means that you'll be using your disks more in B0 but not putting the same amount of power in as B5

 

[anko]

I do. But I think we can also get that using B0 + brake pedal? I am close to having a valid claim. For this capacity must be below 26 Ah before performing a recalibration procedure and must stay or drop below 26 Ah after the procedure. Procedure was performed at 25.9. Ah went up to 28. Now back at 27.4. It is a matter of time and distance. But I am running out of distance (still 3 years but only about 15.000 km before warranty expires), so I don't think this is the right time to start nursing my battery ;-)

Lower 'B' settings lower the amount of regen available from the brake pedal, if the power readings from PSideP are accurate. This means that you'll be using your disks more in B0 but not putting the same amount of power in as B5

Exactly what I worte in another topic this morning (and have been writing since early 2013):

All the B0-b5 settings do is set where the neutral point on the accelerator is between acceleration and regen

I don't think this is true. When my battery was still in a better shape I have done tests that showed that max regen in B5 produces a higher charge current than max regen in B0 does. So B0 is heavier on the brakes, B5 is heavier on the battery.

Why would that be? Would Mitsubishi perhaps know that high regen is not good good on the battery (and have forgotten to tell us)?

Today, after almost 5 years of mostly B5, my battery is at about 67% SoH and max regen is strongly limited by the car's brains. So I don't see this difference anymore.

But, like I wrote in the last line, I think this only applies to batteries in more decent state.

 

[HHL]

This might be of interest to people worried about driving often with B5 regen set:
www.mdpi.com/2032-6653/7/1/41/pdf

 

[elm70]

This might be of interest to people worried about driving often with B5 regen set:
http://www.mdpi.com/2032-6653/7/1/41/pdf

Moreover, regenerative
braking has prolonged cycle life by reducing
the depth of discharge.

This sounds so strange to me .. that in my view it totally disqualify this research

Why they need to discharge further battery when regen braking is NOT used ?
Cars are designed to have fix discharge level .. independently by using or not the regen.

Furthermore ... I find this text

This can be explained by a decreased depth of discharge
after the driving cycles: The more charge recovered
by regenerative braking, the higher the SoC
remains at the end of the driving cycle. Thus, the
subsequent constant-current (CC) charging period
becomes shorter. As lithium plating is reduced,
when the CC charging periods become shorter, the
CC charging periods appear as the main driver of
lithium plating. Consequently, it is not the short recharging
with high current rates during regenerative
braking that promotes lithium plating, but the longlasting
charging periods, when the vehicle is recharged
by the grid, although the current rate is considerably
lower.

If this would be true ... why nobody ever though to charge Lithium battery using burst of current .. instead charging battery at constant charge ?

Also ... very very strange ... storage at 0% SOC .. is what preserve at best the battery capacity .. (ok 0% SOC is consider 3.0v .. for cells that can be discharge down to 2.5v .. so not a real 0% SOC, but quite a low SOC)

Anyhow .. these test have been done over 18650 panasonic cells ... which are the similar one used in a tesla ... our PHEV has quite a different lithium cell ...
Max charge is 4.1v on our PHEV .. why is 4.2v on the 18650
30% SOC in our PHEV is 3.8v vs 3.6 on the 18650

So ... different type of chemistry .. and questionable results, for my questionable point of view

 

[anko]

[

Moreover, regenerative
braking has prolonged cycle life by reducing
the depth of discharge.

This sounds so strange to me .. that in my view it totally disqualify this research

Why they need to discharge further battery when regen braking is used ?
Cars are designed to have fix discharge level .. independently by using or not the regen.

Maybe they mean that at the end of a short trip well within EV range the final SOC is higher when regen is used instead of friction brakes. Simply because less energy is used.

 

[elm70]

Maybe they mean that at the end of a short trip well within EV range the final SOC is higher when regen is used instead of friction brakes. Simply because less energy is used.

I made a typo on my previous post

By checking the PDF ... these are purely bench test .... nothing real

My understand is that they simulated regen braking by interrupting a discharge process with some burst of charging current

Apparently they don't account these bursts for make the discharge process longer, for ensure that not only the initial SOC is same, but also the final SOC should be at the same level.

So .. for me this model is wrong .. since people that use regen brake use this energy for have longer trip and recharge less often not for avoid deeper SOC ... in case of our PHEV using or not the regen .. will cause anyhow to start the ICE when the 30% SOC is reached ...

Anyhow ... strange that deeper SOC is consider "bad" .. since in a different report store cell at deeper SOC was looking to preserve better the battery capacity

 

[HHL]

Well, in day to day driving there is probably not all that much difference in how the different levels of regeneration affect the battery, you will get the odd burst of high charge current in the high setting, but that should not be a problem. Where it gets more interesting is in the mountains where you have a choice between putting 30kW+ into the battery on long descents, or smoke the brakes.............

 

[anko]

It is "strange" to see that at apparently 97.98% SOC, voltage per cell is only 4.03 ... it should be 4.08 at least

Was 4.095 @ 99% this morning (about 5 hours after completing full charge)

OK ... then it is looking 100% normal .. even better then my PHEV

Car is almost done charging:
- SOC is 99.67%
- DC power is 0,791 kW (HV voltage * HV amps)
- AC power is 0,968 kW (from grid)
- Cell#1 is 4,102 volt.
- Cell#10 is 4,102 volt.
- Pack is 328,2 volt.

EDIT: charging completed now. Lowest cell 4,101, highest cell 4,104. Final SOC: 101,5%.

BTW: today my Ah value dropped another 0.5 Ah from 27.4 to 26.9. This gives me this table since last recalibration:

Date			KM		Ah	Comments
16-May-18	143000	25,9	Just before last recalib.
17-May-18	143001	28	Just after last recalib.
13-Jun-18	144140	27,5	
06-Jul-18	145023	26,9

 

[elm70]

Well, in day to day driving there is probably not all that much difference in how the different levels of regeneration affect the battery, you will get the odd burst of high charge current in the high setting, but that should not be a problem. Where it gets more interesting is in the mountains where you have a choice between putting 30kW+ into the battery on long descents, or smoke the brakes.............

:mrgreen:

A long descent is not consider by the simulation done in the above PDF ... a further prove that the above PDF was done by "amateurs" :mrgreen:

I still believe 25kw should be the max recharge that my PHEV battery should ever get for a "burst"

I still have no experience on long descend with my PHEV ... in the past with a ICE ... I was never using engine brake for slow down the car (or not much of it) ... I never got any brake on fire doing even 1500m descend (did this multiple times when I was living next to mountains) .. from 2.000 high down to 500m altitude .. 28km downhill street which take 40min per google maps .. but I'm sure I was doing quicker then this ...

 

[elm70]

@Anko ...

26.9 .. so 0.9 to be on target

At 0.5Ah a months .. by end of summer you should be at target.

But one more cell smoothing will bring you above it again.

Anyhow .. at each cell smoothing, my "logic" tell me that you help to degrade faster your battery ..

So ... I bet in 6 to 9 months time you should be able to be constantly under 26Ah ... so ... it will be interesting then to know how your case will be handled ... I expect you will get almost a new battery pack ... with upgraded cells into it ... since for sure the 2013 battery have an older/outdated chemistry compared to what Mitsubishi is using in the last "months"

 

[Rich]

I am reading this thread with interest, it is very informative. You guys have obviously done a lot of research.

I make a trip around once a week which involves a steep downhill section of around one mile. I normally paddle up to D5 and then still need to apply the brakes at a couple of bends. When I apply the brakes it is not uncommon to see a peak hold of 60kw (using in car display). Am I right in thinking if I use a lower B setting and then press the brakes the level of peak charge will be reduced?

Rich

 

[Rich]

Sorry re-read the last page. It looks like Anko already confirmed that would be the case.

Rich

 

[anko]

@Anko ...

26.9 .. so 0.9 to be on target

At 0.5Ah a months .. by end of summer you should be at target.

But one more cell smoothing will bring you above it again.

Anyhow .. at each cell smoothing, my "logic" tell me that you help to degrade faster your battery ..

So ... I bet in 6 to 9 months time you should be able to be constantly under 26Ah

But for the claim, that 'should' not relevant. What counts (or is supposed to count) is being (or having been) below 26 Ah before and after a recalibration. First requirement has been met. The second requirement requires a drop of 1.0 Ah. At the current rate of desent, that should be around end of August. Maybe a nice birthday present? :mrgreen:

... so ... it will be interesting then to know how your case will be handled ... I expect you will get almost a new battery pack ... with upgraded cells into it ... since for sure the 2013 battery have an older/outdated chemistry compared to what Mitsubishi is using in the last "months"

If it can be the 14.5 kWh version, that would be great :lol: I have no idea. They still might want to try to avoid replacement. Or try to replace it with a refurbished one. We will see ...

 

[elm70]

I am reading this thread with interest, it is very informative. You guys have obviously done a lot of research.

I make a trip around once a week which involves a steep downhill section of around one mile. I normally paddle up to D5 and then still need to apply the brakes at a couple of bends. When I apply the brakes it is not uncommon to see a peak hold of 60kw (using in car display). Am I right in thinking if I use a lower B setting and then press the brakes the level of peak charge will be reduced?

Rich

60kw of regen … I don't believe it is possible .. as well the car display should have a limit to 30kw

Anyhow … B5 and downhill .. or B5 from high speed and using the brake pedal .. is almost the same as peak regen .. only difference is on downhill the regen is not a peak but a continuous recharge flow

Yes … if you use lower B level … you will use more friction braking and less regen ...

 

[Rich]

I have the MY2017 version. The scale goes up to 60 kw, with half way being 30 kw. I believe this can be set in the MMCS, certainly the scale for how much cumulative regen can be changed between 3/6/12kw for the journey.

I descend down a step hill for approx 1 mile, starting at around 30 mph. I paddle up to remain between 20 and 30 mph as the road allows. As I approach the bottom there are a couple of tight steep bends. I paddle up to D5 and then finally press the brake as the resistance is insufficient. The system records a peak of near 60 kw and this is shown on the in-car display.

Unfortunately it would be a bit tricky to get an picture of this, maybe if I have a passenger!!

Rich

 

[elm70]

I have the MY2017 version. The scale goes up to 60 kw, with half way being 30 kw. I believe this can be set in the MMCS, certainly the scale for how much cumulative regen can be changed between 3/6/12kw for the journey.

I descend down a step hill for approx 1 mile, starting at around 30 mph. I paddle up to remain between 20 and 30 mph as the road allows. As I approach the bottom there are a couple of tight steep bends. I paddle up to D5 and then finally press the brake as the resistance is insufficient. The system records a peak of near 60 kw and this is shown on the in-car display.

Unfortunately it would be a bit tricky to get an picture of this, maybe if I have a passenger!!

Rich

I guess you are speaking about the MMCS page (TRIP), which can show different battery/power status
This possibly have been changed a lot from my 2013 PHEV , and as well I'm not normally using such a MMCS page

I was referring to the main dash of the PHEV, with speedometer on the right and "power meter" on the left .. and this as far as I know, does only show up to 30kw

Anyhow .. it would be nice to see this 60kw regen confirmed by PhevWatchDog ... 60kw power in is really a lot

 

[elm70]

This might be of interest to people worried about driving often with B5 regen set:
http://www.mdpi.com/2032-6653/7/1/41/pdf

I just want to come back to this for make further clarification

The cell used for simulate the car regen braking has been the : NCR18650PD

This is a battery with 2900mAh capacity, which in their simulated regen braking was charged max up to 4A

This is not even 1.4C charging.

Our PHEV has a 12kwh battery, which can get recharged over 40kw via regen ... this is over 3.3C

So . .. the simulation, which use different type of battery ... so not really usable ... still ... does "stress" the battery only with 1.4C vs over 3.3C which our PHEV is exposed. So .. our PHEV is exposed to regen power double then the one in the simulated test

To be fair ... it has to be said that NCR18650PD apparently are rated up to 10A discharge (so 3.5C discharge) .. while our PHEV battery can get discharged up to 60kw .. that is 5C discharge ... so our PHEV has lower IR (per capacity) then the NCR18650PD

 

[Rich]

I guess you are speaking about the MMCS page (TRIP), which can show different battery/power status
This possibly have been changed a lot from my 2013 PHEV , and as well I'm not normally using such a MMCS page

I was referring to the main dash of the PHEV, with speedometer on the right and "power meter" on the left .. and this as far as I know, does only show up to 30kw

Anyhow .. it would be nice to see this 60kw regen confirmed by PhevWatchDog ... 60kw power in is really a lot

I can confirm I'm looking at the MMCS page for the charge measurement. The main dash (above steering wheel) on the 2017 does not show a scale on the power meter. The top section is ECO/Power and when the needle drops it goes into the charge section but neither has a scale.

I don't have PhevWatchDog but perhaps another owner of a MY2017 could see what numbers they are getting. Perhaps the display is showing the potential Regen power available, rather than actually putting 60kw into the car battery?!?

I tried the same journey last night and I found if I paddled down to B3 before the steepest corners when I press on the brake the Regen peaks around 30kw. If I use B5 before braking the peak is closer to 60kw. Although, as we've said this is via the MMCS display.

Rich

 

[ThudnBlundr]

That's very different to my 2015 PHEV. When I have PSideP on the central display, the scale only goes to 30kW regen. It can hit that while braking in B5 and B4, but not in B3

 

[LGAero]

Just needed to point out the Tesla Model S that was publized to go 400,000 km in point of fact had the battery pack replaced twice and is due for a replacement again.