M3 LR RWD Charge Curve for cold soaked battery

[eprosenx]

I just got home from a week long vacation during which time I set my car to only charge to 50% (normally set to 80%). It was parked outside all week not charging in Portland Oregon and it got down to 67%. So when I came home this evening I set it back to 80%.

I have a Wall Connector on a 60a circuit which can charge my car at 240v and the full 48a.

I thought it was an interesting charge curve (using my sense energy monitor) and so that is why I am posting it here just for others reference.

Basically it looks like the car could not absorb even the 11.5kW my Wall Connector can provide until it warmed up a bit. Presumably the car can use up like 6kW just in battery heating, so that is a very small amount of current going in to the battery to start.

Here is a shot of the beginning of the charge curve. I include this just so I can show how many watts were being consumed (I can’t move the cursor location in the sense app so this is the way to show a point in time of consumption). Also note that the house was probably drawing close to 1000w for the furnace and other lights at this time. You can also see the fridge starting up in the top graph, so disregard the small spike.

 

[timk225]

When my 3 LR RWD's battery is low on charge and cold, it'll only charge at 240 volts and 16 of the 32 available amps on my 14-50 plug. After it charges for a while, I stop and restart the charging from my phone app, and it'll go to its usual 32 amps, but not without stopping and restarting the charging.