tinoale
Posts: 25
Joined: Wed Apr 23, 2014 6:36 am

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

Thu Mar 15, 2018 4:07 pm

JoeS wrote:Tinoale, glad the problem has gone away (at least, for the time being).

Very disconcerting about the dramatic loss in range - especially with the heater OFF. More confusing is the slow drop on the evening return trip. And, they average out to normal for the round trip?

From my perspective, your video did not demonstrate an unusual situation, as the the bars hop around as the car discharges and is no longer sitting at 100%SoC. I would be tempted to simply plug the car in and let it fully fully charge up and go through the balancing cycle, perhaps a couple of times.

At this point in time, there could be many sources of the problem and your speculations are but some of the ideas. I would simply continue using the car normally until it starts to repeatedly demonstrate something - for this, CaniOn is invaluable.

Sorry, I can't offer any concrete suggestions.


Did you watch the video carefully ?
happens at 00:04, 00:10 and 00:22 : cell #77 voltage drops just for an instant.

Definetely unusual and not normal at all. It is like for an instant, the reported voltage of one cell (and always that one 77) is completely off by some large amount.

In the morning the gauge would drop very very quickly. The BMU sees one cell with a low reported voltage but just seconds at a time. I don't know how it computes that information exactly, but it does lowers it's estimate of the whole pack SOC accordingly.

In the evening, the issue is gone but at the same time, there are probably safeguard in the BMU programming to prevent showing increasing SOC without power input (from charging or from regen). So the SOC would just stay there while driving until the actual SOC would really go down.

When I got back home in the evening the SOC was as usual, and I have all reasons to believe that the SOC issue only existed in the morning and the evening drive just compensated for it...

Another cold wave is coming our way, maybe it will start acting up again, this time I will try to isolate the issue to temperature only if I have enough time.

tinoale
Posts: 25
Joined: Wed Apr 23, 2014 6:36 am

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

Thu Mar 22, 2018 2:28 pm

Update,

Again the issue appeared after a sub-zero °C night and a full battery.

Did not have the chance to test a cold night and a partially discharged battery. Thus I can't determine if the temperature is the sole factor or if it is a combination of the cold AND a full SOC that creates the issue.

But the behavior was consistent with what I have seen previously. At least it is consistent and repeatable. And always on the same cell #77.

tinoale
Posts: 25
Joined: Wed Apr 23, 2014 6:36 am

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

Sat Nov 03, 2018 7:33 am

Update again.

So after my last message in march 2018 the problem simply disappeared and I did not get a single glitch in months.
Until temperature dropped again around 5°C a few weeks back.

With Canion this time I noticed more than one cell was acting up. Dropping from around 4+ volts down to 3.870V and back up. I noticed 3 cells doing this, although one was doing it way more than the others. BTW I noticed I mistakenly talked about cell 77 previously in fact it was cell #71. Cells 73 and 74 also acted up, they are all within the same module.

My conclusions at this point was :
- problem is temperature related, 100% sure
- problem seems confined within module CMU10
- problem probably within the analog section of the CMU10 board (cracked solder joints, or analog-to-digital component LTC6802 failing)

Temperature went back up, battery continued to show the behavior until temp went above 10°C when it stopped again. So, there is some kind of hysteresis behavior related to temperature.

That was until today.

Again, temps went down as low as sub 5°C. When trying to drive, after a very short while, battery SOC went straight down to 0 (no bar at all) along with the exclamation mark.

Pulled Canion, reset the car, this is when things changed from the previously described behavior :
- during the brief time the car is showing a SOC and exclamation mark not on, I read normal cells voltages. NO drop as seen before.
- after a short while (maybe 10-15 sec) the SOC drops to 0 and exclamation mark turns on : I instantly lose Canion readings


Turning the car off then on reset the SOC to the previous number of bars minus 1 bar. Needless to say, I didn't take long to reach 0 bars. And the car won't charge in that state (which is a non issue by itself considering the actual SOC is in fact nearly full).

Now I'm having a hard time interpreting this new behavior ! Until now I was assuming the LTC6802 was the culpit, that or a cracked capacitor or cracked solder joints. Basically anything that could produce false voltage readings on cells and trump the BMU which would lower the SOC reading.

Loosing the SOC entirely with no anomaly on the cells voltage readings makes me think something else (something more ?) is faulty.

What if it was the CMU master component (the one that stores the VIN and communicates with the BMU ) that was failing since the beginning ? could it explain both the previous behavior as well as the new one ?

Kinda lost here !! I've got one big paper weight now

kiev
Posts: 810
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 Nov 03, 2018 8:27 am

tinoale wrote:...Loosing the SOC entirely with no anomaly on the cells voltage readings makes me think something else (something more ?) is faulty.

What if it was the CMU master component (the one that stores the VIN and communicates with the BMU ) that was failing since the beginning ? could it explain both the previous behavior as well as the new one ?


The CMU master is the BMU located under the rear seat. It could be the culprit, but why would it only show as affecting CMU10 and not all the modules?

What is the age and condition of your 12V Aux battery? An old, weak or worn out aux battery can cause a multitude of problems across various systems on these cars.

i tend to agree with your assessment that there is a temperature-related element to this issue, and a bad solder joint is a prime possibility. Maybe you could park in a warm garage and use a space heater to heat up the pack to see if something changes. And maybe remove the rear seat and heat up the BMU if you think the issue is there.
kiev = kenny's innovative electric vehicle

tinoale
Posts: 25
Joined: Wed Apr 23, 2014 6:36 am

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

Sat Nov 03, 2018 3:51 pm

Hi !

I forgot to mention that in order to rule out a bad 12V battery, I have hooked up a new 12V battery in parallel to the original one.
Resting voltage was nearly 13V as it is brand new and well charged.

That didn't make any difference (I sure wish it did!)

I'm going to need to check how to access the BMU under the read seats.

Until the recent behaviors everything was consistent with a defect on the CMU10 board but with the latest behavior, I am not sure really what to think anymore ! :,/

tinoale
Posts: 25
Joined: Wed Apr 23, 2014 6:36 am

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

Sun Nov 04, 2018 3:57 am

BTW I can't help but notice I seemingly have an issue with CMU10, the same as the one the OP has an issue with... coincidence or ?

kiev
Posts: 810
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

Sun Nov 04, 2018 8:18 am

That does seem to be an unusual coincidence.

The CMU master component (a microcontroller chip) is shown near the top of the photo on page 2. There are also 4 aluminum electrolytic capacitor not shown in that photo. Plus numerous tiny ceramic chip capacitors. Failure of any of those, such as a hairline fracture in the ceramic, could disrupt the proper operation of the board.

In my experience the ceramic caps are difficult intermittent culprits and require a temperature change to detect. They can be working, then apply some heat or cold, and they short. Then the temperature changes back and they work again--very frustrating to troubleshoot.

With the complete collapse of the SOC there is likely a new or different DTC thrown, which may give some clue if you can get a readout.

So need to look for DTC codes stored in the EV-ECU related to the BMU, e.g. loss of CAN, low supply voltage, abnormal cell count, etc.
kiev = kenny's innovative electric vehicle

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