Are some sub-systems reading the wrong battery level?

gduprey

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Something I'm trying to investigate and thought I'd share in case this lines up with anyone else experience.

We received a X4 on Saturday and have about 200 miles on it. Everything seems good. Did a few level 2 charges to the default 100% and all was fine.

Yesterday, we were out cleaning the car and ran into a problem where the lift gate would open normally, but whenever you tried to close it, it would just beep a few times and do nothing. We tried all sorts of things to get it to close, and other than manually pulling it closed, nothing worked and no warnings/errors on any display. Opened reliably every single time, but wouldn't budge when asked to close. I started thinking maybe a safety sensor was malfunctioning and saying something was in the way. It seemed logical as the car had no problems at all opening.

I read here about various problems people are having with the 12V battery being low and how things start misbehaving when that happens. I did a test and our 12V battery was fine (13-14V).

But something in the back of my head merged with the various oddities reported here and I remembered that at some point the day before, I had lowered the max charge level to 85%. It struck me that if for some reason, the car thought the 12V battery was at 85%, it might start acting odd or refusing to do things. Granted, the 12V battery was not (it was as close to 100% nominal as a 12V battery can be), but the main battery was (actually was down to about 80% at the time).

So today I first confirmed the lift gate still would not close on it's own. I then set the charge level back to 100% and plugged the car in. After it hit 100%, low and behold, the lift gate now reliably opens AND CLOSES. I rechecked the 12V battery and it was still in the same 13-14V range - no change there.

I'm a software guy and while I have no way to confirm it, it "feels" like somewhere a "DC OK" type check is reading the current battery level from the main battery instead of the 12V battery. Just picking the wrong register to read.

Or not.

I accept there could easily be other conditions (yesterday was warmer, today was much colder and wetter). But the idea of some subsystem picking the wrong battery to check and limiting operation because of it seems like the sort of thing relatively young software might encountered.

I'd be curious if anyone else with low-battery-voltage weirdness had their charge levels set to something less than 100% (or just were at lower charge levels)?

Gerry





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gduprey

gduprey

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Well, it's happened a few more times now and I think maybe it is tied to the LVB. I've never measured under 12V, but I have measured 12.0V or very close the last 3 times it has happened. It always seems to "get better" and close automatically again after a charge.

Just in case anyone else runs into this....
 

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Well, it's happened a few more times now and I think maybe it is tied to the LVB. I've never measured under 12V, but I have measured 12.0V or very close the last 3 times it has happened. It always seems to "get better" and close automatically again after a charge.

Just in case anyone else runs into this....
FWIW (which may be nothing), if I have the rear liftgate of my C-Max open, I disconnect the battery and reconnect it. It will not close. I have to manually close it. Then it will auto-close after that just fine. Its like it forgets if its opened or closed while the LVB is disconnected.
 

JCHLi

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Just curious, is there any misalignment on the rear hatch or something that would cause an excessive load on closing?

A minor change to the voltage shouldn't cause this issue by itself, could be a combo or the voltage, temperature and some extra resistance.
 
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gduprey

gduprey

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No - and it works most of the time.

When it doesn't, it doesn't even attempt to budge even a tiny bit - just beeps a few times and nothing else. When we manually close it, there is no binding, pinching and other than "fighting" the gas shock, it goes down smoothly.

I cannot absolutely state that it's battery related and at first, it didn't seem to be (but those were also early days with it). But the last two times, the LVB is at 12.0 or 12.1 - which seems OK, but based on other peoples LVB reports, maybe not
 

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I had experienced this the first time while taking delivery. a few times while opening and closing the trunk to test the fob and the trunk , it would not close by pushing the buttons on the trunk - just the beeps and nothing. I did leave by PAAK enabled phone in the front and I thought may be that was the reason. Was not sure what caused it as it was Ok after forcibly closing it. But same experience. I have not tried it a lot though afterwards.
 

benk016

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My Edge had this issue as well. It would just randomly not close on its own. Or sometimes it wouldn't open on its own. That was the fun one. Back full of groceries and it wouldn't open. I had to like get back in the car, start it, put it in gear, back to park, turn it off and it finally opened.

But there were plenty of times I'd push the button, and it would just beep and do nothing. Or not even beep. Or it would close about 3/4 of the way and come back up. Usually just trying it again worked though.
 

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I charge to 85% and have not had this issue.
 

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