Posts: 22
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.

Posts: 22
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


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.

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