at what percent of charge should the ICE turn on when parked?

2008,156000 miles,original battery pack,new 12 volt

I recently noticed the ICE only comes on when my battery is down to the last 2 bars (pink/purple/whatever color they are). I had the car on in park no ac or radio on for about 25 or 30 mins and ICE didn't turn on the entire time.
It runs until I have one blue bar then turns off..

is this normal? If not what does it indicate the problem could be?
I never have that screen on the display, always the NAV. so I haven't noticed this before..

 

moved it out of the driveway to cut and edge the lawn and forgot to turn it off...when it started I was like, oh $#!t and saw how low it was.

 

OK thanks..I always thought it came on at around 60% built up to 80% than shut off..first time I let it sit this long so I wasn't sure