tinoale
Posts: 39
Joined: Wed Apr 23, 2014 6:36 am

Re: not charging my iON, cell or CMU or BMU problems

Fri May 17, 2019 11:02 am

About that, what is the exact purpose of this battery age value in the BMU ?

Some have noticed that they could reach 0% of SoC while the lowest cell voltage is still relatively high (3.2V for instance). Thus, not really using the whole battery capacity that they have available.
They suggest that resetting the age value will force the BMU to re-learn the actual capacity of the battery based solely on cells voltage.
This will make the car overestimate the available capacity for a little while, as long as the car learns the actual capacity.

What do you think ?

BTW I have apparently (by mistake) done just that. I went in BMU menus (Diagbox) looking for that option. I did not go into all the screens so I did not think I had actually done anything but this morning I had 45.7Ah in CaniOn, so I guess I went one click too far :idea:
I had 33.7Ah right before.

Anyhow, it is done so... I guess I'll see how it goes from now.

kiev
Posts: 920
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: not charging my iON, cell or CMU or BMU problems

Fri May 17, 2019 11:17 am

That's amazing--we have to figure out what you did to get those results.
kiev = kenny's innovative electric vehicle

DBMandrake
Posts: 133
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: not charging my iON, cell or CMU or BMU problems

Sat May 18, 2019 7:00 am

tinoale wrote:About that, what is the exact purpose of this battery age value in the BMU ?

My guess is that when you replace the entire traction battery with a "new" one, you enter it's age so that the initial Ah capacity estimate is not that of a brand new battery but that of one that has sat in a warehouse for that amount of time.
Some have noticed that they could reach 0% of SoC while the lowest cell voltage is still relatively high (3.2V for instance). Thus, not really using the whole battery capacity that they have available.

I'm not sure that I'd call 3.2 volts relatively high. My car - at least back when I tested a full discharge when it had about 37Ah capacity, shut down completely at 3.63 volts/cell. Keep in mind that voltage falls much more quickly below about 20% SoC, so there is actually very little capacity between 3.63 volts and 3.2 volts - maybe 5% at most.

Also you have to allow for voltage drop under load. For example if you never want your cells to go below 3 volts at any time, discharging to 3.2 volts unloaded would give a voltage below 3 volts when loaded. So a higher cutoff voltage is used to allow for voltage drop under load to prevent the cells going under voltage when you accelerate.
They suggest that resetting the age value will force the BMU to re-learn the actual capacity of the battery based solely on cells voltage.
This will make the car overestimate the available capacity for a little while, as long as the car learns the actual capacity.

What do you think ?

BTW I have apparently (by mistake) done just that. I went in BMU menus (Diagbox) looking for that option. I did not go into all the screens so I did not think I had actually done anything but this morning I had 45.7Ah in CaniOn, so I guess I went one click too far :idea:
I had 33.7Ah right before.

Anyhow, it is done so... I guess I'll see how it goes from now.


kiev wrote:That's amazing--we have to figure out what you did to get those results.

Resetting the BMU's Ah estimate is easy - I've just done it on my car to run the same experiment. (Because, why not ? :geek: )

I took screenshots but since it's a PITA to attach images to this forum I'll just describe it.

In the repair section you go into the BMU, in the maintenance procedures there is one "Traction Battery Replacement Procedure". Running this just takes seconds and at the end of it the Ah capacity reported in Canion jumped up from 34.0 to 45.8Ah.

So I guess that answers the age old question of what is the capacity of a new battery in these - according to the BMS when reset it's 45.8Ah !!! This is very close to the 46Ah I had estimated via other means so I'm chuffed with that... Interestingly in the first few minutes the figure dropped to 45.6 and then 45.3 - this with the car just sitting on the driveway and the key being turned on and off a few times, but it seems to be steady at 45.3 now - until I drive it, when it will no doubt make a large downwards correction. (it's currently charging to 100% and will be used again later today)

Of course the car is now greatly over estimating the usable capacity of the battery which means I need to be careful with my range as "unexpected" appearance of the tortoise is very likely near it's true range when the BMS gets a wake up call... so I'm going to monitor every driving session for the next few days with Canion to see what happens with the Ah figure and how often and when it makes corrections.

Interestingly after running the battery swap procedure it tells you:

"If the new traction battery was manufactured more than 3 months ago, carry out the traction battery maintenance procedure the date of production of the battery is indicated at the rear of the traction battery and is accessible through the rear LH wheel arch".

I've run the traction battery maintenance procedure once before and I don't remember it asking for a manufacture date of the battery.

The maintenance procedure is very simple and it basically just instructs you to turn the car on and set the heating to maximum and wait until "a" cell voltage is between 3.75v and 3.775 volts, (which is approx 20% SoC) then gets you to plug the charger in to do a 100% charge - at the end of that a correction is made to the Ah figure.

Back when I ran this I was already seeing more rapid degradation of my battery, and the figure went down from 37.6Ah before the test to 36.1Ah after the test :? although it did rebound by itself to 37.1Ah about 400 miles later...

Interestingly today I noticed a page in the BMU called "BMU capacity after maintenance". This has many rows of "Maximum capacity of the cells after the last traction battery maintenance" and "Minimum capacity of the cells after the last traction battery maintenance".

For the first pair it gives 41.0Ah for maximum capacity and 38.1Ah for minimum capacity - this will have been recorded during the same test where it adjusted the usable Ah capacity to 36.1Ah and then rebounded to 37.1Ah. The remaining rows are all zero which presumably means the test has never been run before in the life of the car.

So my interpretation of this is that running the battery maintenance routine measures the spread of cell capacity from the worst to best cell, and at that time (more than a year ago) there was already a 3Ah spread. I'd love to know what the spread is now, so I might try running the test again next weekend. (As it takes nearly a whole day to run counting discharging and charging, and I need to use the car this weekend...)

One thing we've learnt from this is that it's unfortunately very easy to temporarily fudge the Ah capacity to a high value by using a diagnostic tool, just like you can on a Leaf, which means it's something unscrupulous sellers could do...
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

kiev
Posts: 920
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: not charging my iON, cell or CMU or BMU problems

Sat May 18, 2019 7:53 am

Thank you Simon that is very informative. As far as i know, nobody over here has a real MUT that will perform these tasks such as your Diagbox tool.

Are you able to call up individual data list items or does it just give the entire list? For example items 56 and 57 deal with the eprom.

ref: CMU DATA ITEM LIST, http://mmc-manuals.ru/manuals/i-miev/on ... 500ENG.HTM

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p.s. As far as the "learning value" age in months, i would guess it is used for warranty claims purposes
kiev = kenny's innovative electric vehicle

DBMandrake
Posts: 133
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: not charging my iON, cell or CMU or BMU problems

Sat May 18, 2019 10:52 am

kiev wrote:Thank you Simon that is very informative. As far as i know, nobody over here has a real MUT that will perform these tasks such as your Diagbox tool.

Are you able to call up individual data list items or does it just give the entire list? For example items 56 and 57 deal with the eprom.

ref: CMU DATA ITEM LIST, http://mmc-manuals.ru/manuals/i-miev/on ... 500ENG.HTM

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There are two pages that show the lists you show yes, but you can't go any further into the individual items, they are just a list with parameter name and value. For example the EEPROM will just say normal or abnormal. It lists them as EEPROM 1 and EEPROM 2 however, and the first EEPROM says abnormal on all my CMU's and Normal for the second EEPROM - no idea the significance of this.

If you look at Rupert's 10 May diagnostic zip file at cmu08 etat.fr.en.pdf it will show the list you're referring to already translated (poorly!) to english. cmu08 tension.fr.en.pdf shows the second table you list with the voltages.
p.s. As far as the "learning value" age in months, i would guess it is used for warranty claims purposes

I can't find anywhere to enter a battery pack age even when telling it that the battery has been replaced. All it says is if the battery is over 3 months old when fitting to run a calibration... so I'm not convinced there even is a place to enter a battery age.
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

DBMandrake
Posts: 133
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: not charging my iON, cell or CMU or BMU problems

Sat May 18, 2019 11:17 am

DBMandrake wrote:
tinoale wrote:BTW I have apparently (by mistake) done just that. I went in BMU menus (Diagbox) looking for that option. I did not go into all the screens so I did not think I had actually done anything but this morning I had 45.7Ah in CaniOn, so I guess I went one click too far :idea:
I had 33.7Ah right before.

Anyhow, it is done so... I guess I'll see how it goes from now.


kiev wrote:That's amazing--we have to figure out what you did to get those results.

Resetting the BMU's Ah estimate is easy - I've just done it on my car to run the same experiment. (Because, why not ? :geek: )

WARNING, WARNING, WARNING! :shock:

Despite thinking I was well prepared I nearly ended up stranding myself half a mile from home due to resetting the battery capacity.

I had been out and back running errands having done a total of 40 miles and the car was reporting a no doubt very optimistic (due to the reset) range remaining of 25 miles implying a total range of 65 miles.

So I equipped myself with two 15 metre extension reels, the granny charger, laptop with Diagbox and Canion and set off to carefully drive out the remaining range in ever decreasing circles around my neighbourhood as the battery ticked down.

A year ago when I did a run flat test the car reached 10% SoC at 330 volts at which point the tortoise light came on, however I was able to drive about another 4 miles before any reduction in power. I then parked the car on the driveway with the heater on and left it and found that the high voltage system shut down completely and would not come back on once it reached 320 volts. So 320 volts was the cutoff voltage back then.

Today the BMS allowed the voltage to go far below that. It was still driving with no tortoise light or reduction in power as low as 310 volts.

However not long after that when I tried to accelerate there was a "stumble" and the tortoise light flicked on then went off when eased up on the accelerator. I was only about a mile from home so I thought I'd be OK, so I turned around and drove carefully towards home..... for about 200 metres before almost all power was removed! :o The car slowed right down to 7 mph so I was trying to creep along on the side of the road desperately trying to make it to a slight crest so that I could coast the rest of the way down the hill to our house in Neutral.

I barely made it. Despite being limited to 7mph the car was still cheerfully reporting 1 bar and Canion reported 15%!

From the first stumble when accelerating until being restricted to 7 mph was only a couple of hundred meters, not the usual several miles warning you get in tortoise mode. I noticed that tortoise mode would flash on when the weakest cell got below about 3 volts but then go back off again when I eased off the accelerator. (At least for a while)

So my conclusion from this is that there are actually two separate and distinct triggers for the tortoise light.

1) When the calculated SoC gets below about 10% the light comes on and stays on but acceleration is not restricted. When you get to 0% the car just stops.

2) When the instantaneous voltage of any cell goes below about 3 volts under load power is immediately restricted to a very low level, however if you ease off and voltage goes above 3 volts again the light goes back out.

Because the SoC estimate was wildly optimistic (about 20% higher than the "real" value) the BMS just let the car keep driving until the 3v cutout threshold was reached. Normally this would never happen because it would hit a calculated 10% SoC well before then.

So watch out tinoale - if you try to drive it right down to tortoise mode like I did after the Ah reset you'll probably find yourself phoning recovery services - I was VERY lucky that I was so close to home with a down hill to coast down half the way or I would have had to phone for recovery for sure. :( Unlike normal tortoise mode that gives you a few miles warning and lets you drive at normal speed, this tortoise mode limited me to 7mph and probably would have done half a mile at most.

It will be interesting to see what Ah capacity is reported after a full charge - it was still cheerfully reported 45.3 Ah before I plugged it in, so it apparently makes Ah corrections during charge rather than discharge...
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

kiev
Posts: 920
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Simon's big adventure

Sat May 18, 2019 2:41 pm

Wow what a great experience you've had--thanks for sharing the story, and thank goodness you went out prepared with extension cords and level I, even if not needed. You are definitely exploring new territory of these packs and cars, and every little bit helps understand what they do and how they work...
kiev = kenny's innovative electric vehicle

DBMandrake
Posts: 133
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: Simon's big adventure

Sat May 18, 2019 4:55 pm

kiev wrote:Wow what a great experience you've had--thanks for sharing the story, and thank goodness you went out prepared with extension cords and level I, even if not needed. You are definitely exploring new territory of these packs and cars, and every little bit helps understand what they do and how they work...

Great experience is not quite the wording I would have used. :o :lol:

Well it finally finished charging after an extra long charging session - with a long period of balancing at the end where it pulled my two weakest cells (25 and 70) down at the end as they reached full charge voltage first.

It stopped at "97%" indicated SoC, and reports a hilarious 85 miles of range :lol: but has still not updated the Ah estimate which is still on 45.3Ah.... :?

Which means next time I drive the car I have the risk of reaching turtle mode unexpectedly like I did today. I wonder how quickly it will adapt the Ah figure ?

I know if I run the battery calibration it will do it within the one charging cycle, but I'm tempted to let it go and see how long it takes to figure out the difference...
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

tinoale
Posts: 39
Joined: Wed Apr 23, 2014 6:36 am

Re: not charging my iON, cell or CMU or BMU problems

Sun May 19, 2019 10:59 am

Hi,

I also believe we don't quite understand how the car estimates and/or updated the SOH of the battery.

When you cleared the Ah value which initially went back to 45+ Ah, then hit a very low actual SOH indicated by cells voltage, I don't quite understand why the car did not instantly update the Ah value of your pack. Why is it still 45+ Ah after recharge and how long is the car going to take to update that value, that's pretty unclear. You could run into a very low cell voltage again which is silly...

So when I accidentally reset the Ah value of my pack, it showed a whooping 45.7Ah value. I had 33.7Ah before.
I was tempted to let the car update capacity value by itself, little by little, out of curiosity, while being careful to avoid a distress situation.
But I was also curious about the capacity test and thought I wanted to update that value once and for all.
Chew on it a bit then decided I wanted to run a battery capacity test so I tried it.

The test went well. I carefully drove until I had 2 bars left. Headed back home. Started the procedure, which used the heater to deplete the battery. I don't know what the lowest cell voltage was when the heater automatically stopped and the charge started, gauge was showing 1 bar when that happened. I did not plug CaniOn while the test was running. I can only assume a given cell voltage triggered the start of the charge.
I let the car do it's full charge. Next day, I read 13kWh from my TP-Link HS110 monitoring. Then started the car and plugged Diagbox. Tried to read the tests results but a "communication error" prevents me from reading the official test results. Duh !

Went to read the Ah value and it was updated to 32.7Ah. I guess that's the test result that I wanted.

Apparently, the test did force an update of the Ah value which is good to know. I will let the car update it by itself from now on, will keep en eye on it in Canion. May be run another capacity test in a few months.

Now, I wonder if I did not reset my Ah pack value prior to the capacity test, would the result be any different ? I have no idea.

If you accidentally erase that value like I did, I do recommend a capacity test to force an update of the estimated Ah. Now my car displays 90+ km left when fully charged but if that's only the truth then so be it. I only need 50km of actual range in winter to keep using it 12.000km a year.

DBMandrake
Posts: 133
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: not charging my iON, cell or CMU or BMU problems

Sun May 19, 2019 1:11 pm

I spent most of today trying to perform the battery calibration without success. :( I've done the calibration before so I'm not entirely sure why it refused this time...

First I discharged the battery to 3.76v for the lowest cell voltage - Ah capacity remained at 45.1Ah and did not update.

Step one of the calibration process seems to reset the SoC. (not SoH) Before step one it was reporting the battery was still about 30% SoC and about 4 bars, after step one was completed the SoC dropped to 15% and one bar flashing. I assume this is done by using voltage estimation, which can be done at a low voltage like 3.75 - 3.775.

It then tells you to turn off the key and wait an hour before doing step 2 - which you can't bypass. (I tried tweaking the clock in the laptop but it didn't work... :mrgreen: )

So after an hour I go to step 2 and I get "Preparation to measure the traction battery state of health has failed. The traction battery charge status does not permit starting of the procedure". :(

At this low SoC my two weak cells are over 100mV below the highest cells, so I assume that the divergence in cell voltage is too great for the test to start, as most of the cells were above the allowable voltage range. I then tried discharging the battery further until the high cells were within the correct voltage range and the lowest cells were below it, waited the hour, tried to start it again - failed.

So I am unable to start step two of the test because it is apparently unhappy with the spread of voltages of the cells at the start of the test - nothing I can do about that! :evil:

So I just let it charge up normally, it stopped at a reported 96% and still remains at 45.1Ah, so it has not learnt yet that the capacity of the cells is well below what it thinks. Also the SoC suddenly jumped from 82% to 92% during the charging process (probably due to top end voltage estimation kicking in) and despite that it didn't adjust the Ah capacity.

So I kind of wish I hadn't touched it now. I'm still going to have to drive carefully and keep in mind the reported range is about 15 miles further than my real range or I could find myself at risk of stranding again.

When I get home from work tomorrow night if the voltage is near the correct voltage range I'm going to have another go at starting the calibration.
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

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