ICE running for a few minutes at start of trip on full charge?

Over the past few weeks, I've noticed the engine kick in on my '17 Prime after about a minute when I'm underway on my morning commute. It runs for a few minutes and then goes back to full EV for the rest of the commute. The car's just over a year old and I don't recall it doing this until recently. Conditions are moderate/warm ambient air temp (60s - 70s), full overnight charge, moderate speed (30-40 mph). I've seen it do this in the winter, but only on particularly cold days and when I turn on the heater. Any idea why, all of the sudden, it's decided it needs to run the ICE?

 

Thanks. My daily commute is about 33 miles one way total EV and about 28 miles EV / 5 miles hybrid on the return leg (overall uphill topography driving home, so less EV range). If I use it sparingly on weekends, I can go at least 1 month and often 1.5 months between fill-ups, so the ICE isn't getting a lot of use (I just went 2,227 miles between fill-ups). But it does run some (the daily hybrid portion of my commute home during the work week). Car has just over 20K miles total.

 

Thanks - glad to know it's normal behavior.

 

About 400 feet of steep downhill driveway, then gradual downhill road for a couple tenths of a mile, then a steep uphill climb. I thought maybe the uphill climb was causing the ICE to kick in, but noticed it starts when I’m about halfway down the gradual decline before the big uphill.

 

No, not that I remember.

 

Yep, @fuzzy1 , starting with a full battery. And yes, riding the brake down my driveway, but that’s maybe 10 seconds’ worth. Then, after turning onto the main road, minimal accelerator down the gradual decline. That’s when the engine kicks in. Although it might happen when I let up on the accelerator and regen starts (just before I hit the big uphill climb). I’ll keep a close watch on it Tuesday, when I head back to work and let you know in more detail what it does.

I should add that my routine above is what I’ve been doing every work day the past year I’ve owned the car, but it’s only been doing this the past few weeks.

 

Update: Yesterday and today, the ICE did not kick in at the start of my commute. No change in road conditions or climate. Same time of the morning, same full charge, same use of accelerator vs. coast/regen. The only significant thing that has changed was that I took the car in Friday for the 20K service w/ oil change.

 

Thanks. But to what end does the car run the ICE when the oil’s dirty? Just to circulate and keep sediment from building up?