ICE staying running even after a full SOC (2012 MKZ)

[jediboytj]

Hey guys,

 

I know this forum is mostly filled with 2013+ models, but I know a few of you guys at least owned a 2010-2012 hybrid model at some point.

 

(quick backstory)

I bought this MKZ preowned about 6 weeks ago, and have put about 2200 miles on it since (had a couple road trips mainly). And its pretty much been a trouble free *knock on wood* 2200 miles.

I spent weeks researching these hybrids, and how they work, watching youtube videos, reading this and other forums top to bottom, and feel I got a pretty good understanding of these cars (at least on paper lol).

 

Anyway, I *think* I understand what the car is doing, but I just wanted to make sure there wasnt a problem.

 

So today I went and started to car as normal, took a 2.5 mile ride to the gym, and noticed that even when the engine was warmed up it would not go into EV mode. The ICE stayed on all the way until the SOC was full. It worried me a little because im not used to seeing the SOC go above 50/60% and even when it got to 100% it stayed charging. Now when I finally got to the gym (it was like less than 10min), and parked, then it finally went into EV mode (but only like 20mpg for that trip!). On the way back, it seemed to function normally again, and the trip back got 61mpg, so it pretty much averaged out.

 

Now, my assumption (correct me if im wrong, thats why im here!), is that the battery was calibrating itself (I believe I read something on this forum that talked about auto-calibration, but I thought it came with a message or something saying thats what its doing). I cant recall the car doing this since i bought it, so it caught me off guard.

 

Sorry for the long winded post, and sorry if this is a dumb question!

[tr7driver]

I had that happen to me on Christmas morning in my 2010 Merc Milan Premier HY. That has been the only time I’ve noticed it do this, but my wife drives it more than I do. I do believe it was a battery calibration event. Once finished, the car was back to its usual self. I wish there was some kind of message that would inform you what it happening, but I didn’t see one.

[jeff_h]

I had this happen several times on my 2010 FFH and it seemed to fit into one of the two situations, here are the non-technical descriptions:

 

1 - Descend long hill where the regen charges the HVB all the way, and when stopped at the bottom of the hill the SOC on the HVB shows full on the display and ICE is still running... but in this case it is apparently not running to charge the HVB but to 'bleed off' (for lack of a better term) some of the charge with the ICE. Like I said, this is non-technical and maybe others can give more more concise description.

 

2 - Out of the blue the ICE keeps running and charging the HVB for unknown reason and even after getting to fully charged on display it keeps going and going (which sounds more like your condition) and makes driver freak out like the HVB is gonna fry because something has gone wrong (as least I thought that, the first couple times).. but as noted above, it's just a calibration/routine cycling type event and unless warning lights start to go off, it's normal.

 

My Prius used to do the same thing every now and then too.

[jediboytj]

I had that happen to me on Christmas morning in my 2010 Merc Milan Premier HY. That has been the only time I’ve noticed it do this, but my wife drives it more than I do. I do believe it was a battery calibration event. Once finished, the car was back to its usual self. I wish there was some kind of message that would inform you what it happening, but I didn’t see one.

 

Yeah I wish there was a message or something too. But in the back of my mind I was thinking if there wasnt any message or dash light popping up, then I was ok.

 

 

I had this happen several times on my 2010 FFH and it seemed to fit into one of the two situations, here are the non-technical descriptions:

 

1 - Descend long hill where the regen charges the HVB all the way, and when stopped at the bottom of the hill the SOC on the HVB shows full on the display and ICE is still running... but in this case it is apparently not running to charge the HVB but to 'bleed off' (for lack of a better term) some of the charge with the ICE. Like I said, this is non-technical and maybe others can give more more concise description.

 

2 - Out of the blue the ICE keeps running and charging the HVB for unknown reason and even after getting to fully charged on display it keeps going and going (which sounds more like your condition) and makes driver freak out like the HVB is gonna fry because something has gone wrong (as least I thought that, the first couple times).. but as noted above, it's just a calibration/routine cycling type event and unless warning lights start to go off, it's normal.

 

My Prius used to do the same thing every now and then too.

 

No hills in FL so rarely does my regen braking give it more than a 60-75% charge (except when the ICE stays on for the first few mins to warm up).

 

Yeah I was mainly thinking something might of been going wrong since I pretty much never see it more than 75% tops. But I figured with all the computers and sensors and error messages that could generate, that something would of triggered a fault message if anything was wrong.

[acdii]

The 10-12 Hybrids do what is called a battery conditioning cycle where it runs the ICE to fully charge(peak charge) the NiMh batteries, while also propelling the car. No EV is used during this time, except for brake regen. Perfectly normal and random, the computer determines when it should do a battery cycle depending on miles and key cycles. First time it did it I was like WTH?!?!?!, then it went back to normal. The last time it did it I got nearly 50 MPG where I normally got 40, so not complaining about that at all.

 

During a peak charge the battery computer tests each and every cell for voltages, and does what I believe is a battery balancing cycle, so each cell is kept in top condition. If a cell were to show weak, even after a full cycle, then a warning would show along with a check engine light(CEL).

 

Too soon to tell yet if the 13 Hybrid does the same thing, but considering different battery technology and a totally different battery cycle I doubt that it needs to.