I have tracked actual miles, dash estimates, kWhs, garage temps, and outside temps for the last year.
I charge on the Level 2
EVSE timer set to 4 am so a full 100 SOC doesn’t sit for long in the battery. My garage temps were from 40 to 59 F when outside temps were 8 to 60 F from Jan to Mar.
Almost all the time, I precondition on EVSE power and use seat heater without cabin heat. The EV range estimates ranged from 47 to 59 miles and i didn’t run it down to 0 so I can’t say how much range I actually could have achieved. However past experience shows I usually get about 5 miles less than the EV range estimate.
All this was with no passengers or luggage and ~40/60% city/hwy with speeds 35 to 60 mph.
Looking back over the records, I will say this.
1 All my charging was at garage temps of 40 to 59 F after car had been in garage for at least 6 hours but I have no data for charging outside at colder temps. So I bet that helped but I have no data to say how much it helped. Charging rates went immediately to 7.1 kW as usual and stayed steady except for just 2 times when it started lower and ramped up to 7.1 kW rate. I think this was due to cold battery pack temp that hadn’t equilibrated to the warmer garage before charging started.
2 Cabin heating and defrosting are the overwhelming killers of EV range. Seat heat does not affect range nearly as much. It was hard to tell when I used it and when I didn’t. It seems to be somewhat similar to the drain from A/C usage in summer which is also not that bad. (Caveat: I have full coverage IR reflective tinting so I get a much lower heat gain and less load on the A/C.)
By garaging, preconditioning on EVSE, and seat heating, I was able to avoid cabin heating and defrosting. (Also helps that I’m a empty nest widower and don’t have to keep anyone else warm.) My EV range estimates only dropped from low/mid 60s, to high 40s/50s F. The single time I used cabin heat I only got 40 miles EV range estimate with temps in the 20s F.
3 With garaging, preconditioning on EVSE, and seat heater use only you can avoid large drops in EV range if your commute is not too long. This is especially true if you have an EVSE at work and can do this on the reverse trip.
4 I left the CC off but on fresh so it puts a little outside air in and only had fogging problems twice all winter. I just wiped off the windshield instead of defrost because I was trying to get data on not using any cabin heat or defrost.
5 15 to 30 minutes of preconditioning is only using ~1 to 2 kWh depending on how bad the ambient starting temps are and for me that’s just 10 to 20 cents for a toasty warm car.
So I’ve found that you can significantly reduce winter range loss by garaging, preconditioning on EVSE power and using seat heat instead of a lot of cabin heat. The main culprits are the large cabin and defrost resistance heating elements. If you’re garaging, then ambient temps don’t seem to be as impactful as cabin and defrost heating. If you want or need more EV range you just have to greatly reduce their usage.
Of course my data only goes down to +8 F on clear roads, so all y’all up north suffer through even more EV range loss due to lower temps and more heater/defroster use. And then add in snowy roads and I bet you’re getting EV ranges in the low 30s or high 20s.
Next winter I will use cabin heating along with the above and report back how that changed things. If I just had a heated steering wheel, I could easily forgo cabin heat until it got below freezing with preconditioning and seat heater.
If I had to keep my Clarity outside in the winter, I’d keep it plugged in and precondition 20 to 30 min before leaving and I’d keep it under a car cover that did not go under the car or cover the front radiator air flow. (Even though Honda says not to, I think if you’re smart about not covering the front radiator and obstructing possible battery cooling it should be ok)
Best wishes to our Canadian and northern US friends in the frigid north.
We all are pinning for summer when our Claritys really excel in EV range.
