Is range directly tied to charge percent?

Discussion
1

I go to bed with 280 miles of range and 75% battery. When I wake up, the temperature has dropped by about 20 degrees, so obviously, the estimated range drops. But should the charge percentage be dropping too? I feel like it shouldn’t be.

2

Range = battery amount x efficiency.

During colder weather, your efficiency will definitely drop, but I’m not sure if your actual charge is going down.

3

Gabriel said:
Range = battery amount x efficiency.

During colder weather, your efficiency will definitely drop, but I’m not sure if your actual charge is going down.

Yeah, I’m more curious about the charge percentage. Is the battery itself discharging?

4

@Imani
Most of the range drop is the car predicting that you’ll use climate control to warm up the cabin. A bit of it comes from the fact that a colder battery has more internal resistance, so less of the charge is actually available for driving.

However, the state of charge (percentage) of the battery doesn’t change, so the percentage should stay the same.

5

@Imani
There’s no reason the percentage should drop when the car is off. Over a long time, like a few months, you might see a small drop.

6

@Imani
What does it say?

7

Maria said:
@Imani
What does it say?

It didn’t show any warning, but one day last week it dropped from 295 miles at 78% to around 245 miles at 65% when I started it in the morning. The heat wasn’t on or anything, and while it’s in my garage (which isn’t temperature controlled), the temp was probably 25 degrees colder than the night before when I turned it off.

8

@Imani
That’s quite a drop, from 78% to 65%. That sounds like driving for a bit, not just a temperature drop.

9

@Imani
Batteries do slowly discharge, but it should only be around 1% per 24 hours, if that.

10

If you just start driving, the estimate will adjust. Using the heater and fan can also change the range estimate.

11

You can lose or gain a bit of charge due to temperature changes. Lithium batteries perform better when they’re slightly warm, not cold. I’ve charged to 80% before, then the temperature went up by 20 degrees the next day, and it showed 81%.