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Drive battery degradation . Houston, do we have a problem?
http://www.myoutlanderphev.com/forum/viewtopic.php?f=10&t=2937
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Author:  anko [ Mon Dec 03, 2018 7:17 am ]
Post subject:  Re: Drive battery degradation . Houston, do we have a proble

elm70 wrote:
How accurate you can monitor the charging current via OBD2 ?
Amps: 0,01. Volts: 0,1.

elm70 wrote:
The DOG, apparently can't report anything below 1Amp ... so even monitoring the full charging process, there will be too much error if the charging current is integrated over the time
In theory, the Dog has access to the same granularity. But the number of readings per second (if any ;-)) will be far less.

elm70 wrote:
But, if you can monitor the charging current at 0.1A accuracy ... then you should be able to integrate this current and have a precise number of Ah which get push into the battery while charging.

Only in this way you can know if the SOC above 100%, is due to the fact that the battery got more Ah then expected by the SOC % delta + SOH .. or for some different type of estimation error.
I have no reason to think the Ah count is wrong. I think either SoH is wrong or SoC at beginning of charge is wrong. If we calculate Ah ourselves, there are two outcomes.
- We get the same Ah value and still have no answer to my question
- We get a different Ah value and the answer to my question MAY BE neither. But we may also still have no ansewr.
still The SoC number we see is not a result of integration done by the Dog or myself. It comes directly from the BMU.

elm70 wrote:
PS: In my case, today, I got the SOC above the real (similar to how reported time ago) ... the DOG reported my morning trip to be started with 33.1Ah and 4.05v max (97.9% SOC) .. after a 10min pre-heat via keyfob hack ... since car was not charging while pre-heating at best the SOC should have been 31.6Ah ... but I also doubt that the car got charged up to 35.3Ah .. so ... it must be that sometime the SOC don't count in the pre-heating ... sometime .. since sometime it is looking it is properly counted inside the SOC (even when this is activated by keyfob hack)
I have done three FOB initiated pre heats yesterday, and the end result was the beginning of the charge in the next post.

Author:  anko [ Mon Dec 03, 2018 7:21 am ]
Post subject:  Re: Drive battery degradation . Houston, do we have a proble

You see Remaining Ah and SoC follow exact same path. So, i think SoC is calculated by dividing Current Capacity (SoH) by Remaining Capacity or Remaining Capacity is calcultated by multiplying Current? Capacity (SoH) by SoC

Image

Author:  elm70 [ Mon Dec 03, 2018 11:56 pm ]
Post subject:  Re: Drive battery degradation . Houston, do we have a proble

Very interesting graph Anko.

It is not very clear why the charging process did stop for few minutes (5?) ... and while the charging process was pause the SOC got raised by 5%

This rise of 5% (actually a bit more then 5% right ?) then cause to have the end of SOC 105% ... so not only the pausing of the charging process is a mystery, but as well it is looking wrong the decision to rise the SOC

Anyhow ... with all approximation from reading a graph (XLS would give more precise info) .. it is looking that the charging process did need a bit less current then expected, but due to the overshot on SOC, the end SOC number was massively wrong.

Based only on this charging info .. apparently the SOH of your battery is a bit less then what is known by the BMU

PS: The only reason for pause a charging process would be to unbalance or if one of the cell is above 4.10v (again unbalance) ... while the charging process stop with an unbalance of 0.06v .. and resume with 0.04v .. still it did not stop later on when same unbalance was present ... so it is quite a mystery why it did pause


PPS: The rise of SOC, must be due to the mapping between voltage and SOC which the car has inbuild ... still it is "odd" that 2 or 3 minutes of rest from charging, it is consider a safe time for read the voltage level and consider this voltage equal to a rest voltage

Author:  anko [ Tue Dec 04, 2018 11:57 am ]
Post subject:  Re: Drive battery degradation . Houston, do we have a proble

I thought this pauze would be the cell balancing phase? It appears quite often exactly at 80%, so I think it is planned and not ad-hoc.

What I still don't understand is this: if SoC is derived from cell / pack voltage, how is it possible that neither of these changes a bit after SoC reaches approx. 92%. Maybe I am to blond, but I don't get that bit.

Author:  elm70 [ Thu Dec 06, 2018 5:08 am ]
Post subject:  Re: Drive battery degradation . Houston, do we have a proble

A "programmed" pause at 80% while charging .... very strange indeed

Maybe they use the 80% rest Voltage level as one of the many error accumulated parameter for their SOH logic

Still ... strange logic

On the parallel world ... I saw an interesting card from you:

SOC 14.8% / 3.9Ah
301.5v (3.77v per cell)

You must have been play hard with the per-heating function :ugeek:

Anyhow ... It sounds quite pessimistic only 14.8% left at an healthy level of 3.77v

Based on LEV50N specs ... nominal voltage is 3.75v ... and the operating voltage is reported to be 2.75v to 4.10v
Also discharge graph from producer of LEV50 do show a discharge from 4.1 to 2.75 ... till 3.5v there is plenty of capacity left .. per the graphs ...

I don't understand this maniac from Mitsubishi to protect the battery on low SOC , and have zero protection over max SOC

I would have assumed to block the battery cycle between 4.00v down to 3.70v ... it is way better then between 4.10v and 3.82v as it implemented by Mitsubishi ... but possibly/hopefully ... they did their homework :mrgreen:

PS: Possibly old PHEV don't have the LEV50N battery shrink to 40Ah version ... in the new(er) LEV50N , I see it is granted 80% SOH after 5500 cycles ... which even with two cycle a day .. it is still over 80% SOH after 7y (in theory ... since battery decline in performance with by when unused , even if kept in the ideal storage voltage)

PPS: New Outlander PHEV I think, should have much better SOH when ageing, since GS Yuasa, made apparently significant progress in the last years ... I'm wondering it the BMU firmware has been tuned for the different chemistry which have been used in different version of our PHEV in the last 5 years ...

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