Normally when I am driving in HV mode the battery charge will fluctuate up and down a couple miles and continue doing that for the trip. Today on the way to work I decided since it was cold I was going to use HV mode hoping not to use any of the battery charge. As I was driving on the hwy I notice the battery charge was going down very slowly and not staying within a range like it normally does in HV mode. I am wondering if this is a normal condition in very cold weather. I did try hold down the HV button for a couple seconds to see if it would start charging the battery since the battery was below 60 percent. The message I got was I needed to plug the car in to have it charged. Anyone else have this issue?
I drove about 400 miles yesterday in HV mode, with temperatures mostly between 5 and 10 F. The battery did deplete some but not a lot. The ICE seemed to rev more than normal and never shut off even while going down hill.
I preheated the car this morning and left it plugged in overnight. During the drive in using HV my mileage dropped about 5 miles and after that it maintained the charge level on the battery, temp outside was 2 F. I am guessing what the car is doing is warming up the battery before it starts charging. When I got off the hwy I also notice I could only get 2 chevrons, when I try to add one more they blink for a second or two and go back to 2 solid ones. Learning how the car functions in cold weather and HV mode is a challenge. I usually just leave the car in EV mode even when its below zero and everything works fine. I am planning a 400 mile trip in two weeks and want to make sure the HV mode functions properly.
It is very bad to rapid charge a cold battery, most likely the car was protecting the battery by not charging it and relying on engine power and a small amount of battery power. The engine charges the battery at DCFC rates.
Painful as this sounds, the battery is heating the engine on cold start, so you will see a drop using HV mode initially. When the engine is up to temp, the charge should be maintained going forward (in time, not geographically). I see a lot of what I consider "odd behavior" in cold weather that appears to be related to cold battery protection. Engine runs long, even on downhills and throttle tapers with load instead of ON/OFF that I am used to in summer. I have also seen a few times where the engine races up to 4000RPM with very light load (almost coasting on a level highway) and full battery. I expect this is either to keep coolant temp up for cabin heat or to keep oil hot enough to remove condensation from the internal workin's. There are others with more tech info that might have a better explanation, but we all see similar symptoms.
Is there any documentation on what the DC Fast Charge rates are when the engine is running? Any rough calculations from observations? You have peaked my curiosity.
