Freezing weather performance

Hi,

I've been shooting Prius Prime cold weather problems and finally got back to running errands with our 2014 BMW i3-REx:

9:00 AM, 25F (-4C)

First time to plug-in L1 in 24 hr, the initial display showed 52 mi gas and 47 mi EV. Ok, no problem. Now to try preconditioning.

I scheduled departure at 12:00 noon but the car did not show charging. So I sent immediate preconditioning and the car started taking a charge. Spot checking at 11 AM, it was charging showing 47 mi EV. No problem, so I got ready for my first errand.

12:08 PM, 32F (0C)

I backed up about 30 yd (~28 m), stopped, and loaded for first trip. When I started, I took a quick photo: 95.5% SOC (huh?), 71 mi gas and 62 mi EV. The loss of 4.5% SOC suggests I should have used my L2 charger. But these ranges did not match the App numbers. Regardless, I went to my first stop, a hardware store and everything look normal except the lower tire pressures from the cold. But when I came out the car showed all four tire pressure error. Knowing it was OK, I went to the next hardware store and the back home.

I used my 12V air pump to bring all tires up. The error cleared about half a mile (0.8 km) when waiting at a traffic light.

9:28 PM, 21.6F (-5C)

Still charging (seems late): 97% SOC, 55 mi gas, and 49 mi EV.

12:00 AM, 18.5F (-7.5C)

Charging complete, 100% SOC, 54 mi gas, and 49 mi EV.

Now showing 97% SOC, charging, 49 mi gas and 55 mi EV.

CONCLUSIONS

It appears a 12A, L1 EVSE is marginal in cold weather. It appears to barely handle cabin heat and battery charge. The loss of 4.5% SOC suggests preconditioning may pull power from the battery. Fortunately, I have a 31A, L2 EVSE that should solve the problem.

The App and 'guess o meter' is just an estimate in cold weather. Your mileage my vary.

Bob Wilson

Bearing in mind that it’s not just cabin heating and battery charging. If you set a departure time for preconditioning and the battery temp is below 10c, the car will also try to raise the battery temp to 10c.

All three loads are surely beyond the capacity of an L1 hence the low SoC levels.

I have a 2017 REX, large battery.

During the Summer, I was averaging 120 mile range.
During the Cold Winter, I am averaging 80 mile range.
Cold, below 10F
I try to preheat, whenever it is on the charger.

So far,

Works perfectly.
I have the REX, have never needed it.
But, I feel better that I have a backup.

Have driven it on ice and snow.
No major issues.

Thank you BMW.

This Global Warming is sure cold

The BEV is a little better on EV than the REX in the cold because of the heat pump unless it is really frigid, then they're about equal when the resistance heat becomes the primary source. The battery heater is 1Kw, cabin heat is probably at least that. 12A at 120vac is 1440W. Something has to give...in some ways, it's surprising that it charged much at all using the OC EVSE in the USA while preconditioning.

0 degrees celcius, four trips of 25km on one charge (no pre-heating/charging): 100km (60 mi).
No highways.
After a charge at the office (warms the battery as well), the range on the meter is 130-135km, at home it shows 100km (after a 25km trip)
Next morning: it shows 80km (so cold battery).
I drive this every day (same 25km), so pretty accurate.

Tested with pre-heating, cabin heating etc ....... for me make no sense.....short trips and I do not charge between trips. Cabin heats so fast no need to preheat.

Done one highway trip with 0 degrees and pre-heat: 90Km.