snowfall + preheat = icy slushy mess

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specialgreen

Well-known member
Joined
Mar 26, 2017
Messages
246
Location
Minnesota
I tried using the preheat; it was great, for about a week. Then we got a couple inches of snow. The preheat turned the snow on the windshield to slush. The channel at the base of the window was about 3 inches deep with water/slush. I tried scooping it out with the windshield brush, then my hands (wearing gardening gloves... it was about 0F). I couldn't get all of it, and what was left froze and plugged-up the drain.

In retrospect, I could have tried a shop-vac on the slush; then bought a bottle of winshield cleaner at room temperature, and used it to rinse-out the windshield drain. But... I think, if it's going to snow, you're probably better off preheating the car manually, after you have brushed the snow off the windshield.

This probably isn't a Leaf-specific problem; I just had never used a car preheater before.
 
Yes, you want to clear the windshield while the car is preheating, not afterwards. You might also consider just preheating it for ten minutes instead of longer.
 
I've got the S-model, so I only get to pick the end-time. It looks like today, it finished charging at 3am; then it drew about 1.8 kw of power from the EVSE for about 90 minutes, ending at my programmed departure time.

The car was down to 91% SOC when I started it, so it looks like it lost about 2.5 kw-hrs while heating-up, despite being plugged-in. That should mean it was heating for 90 minutes, drawing 1.8 kw from shore power, plus 1.7 kw from battery. I'm not sure why it didn't max-out the shore power. It is clearly drawing 1kw more during charging cycle, than during heating cycle.

I will try setting the "departure time" to 60 minutes after actual departure, and see if that works better with the snow. That should get the warming period down to 30 minutes (plus, save about 4 or 5 percent SOC).
 
That's still going to produce slush on the windshield. You are wasting quite a bit of power this way, and making clearing the car less pleasant than it would be with 10-15 minutes of preheating.
 
specialgreen said:
I've got the S-model, so I only get to pick the end-time. It looks like today, it finished charging at 3am; then it drew about 1.8 kw of power from the EVSE for about 90 minutes, ending at my programmed departure time.

The car was down to 91% SOC when I started it, so it looks like it lost about 2.5 kw-hrs while heating-up, despite being plugged-in. That should mean it was heating for 90 minutes, drawing 1.8 kw from shore power, plus 1.7 kw from battery. I'm not sure why it didn't max-out the shore power. It is clearly drawing 1kw more during charging cycle, than during heating cycle.

I will try setting the "departure time" to 60 minutes after actual departure, and see if that works better with the snow. That should get the warming period down to 30 minutes (plus, save about 4 or 5 percent SOC).
If you program in your departure time the car will wake up 30 minutes before that time and only heat until that time, shutting off after that :)
Note your cars heater can draw up to 6 kW(or more) but generally starts ramping down after the first 5 minutes or so, as things heat up.
Using L1 I would NOT program in your actual departure time but rather 20 minutes after you plan on leaving, this will start your preheat cycle 10 minutes before your actual departure time. If you had a 16 or better yet 30a L2 EVSE I'd say go for the full 30 minute preheat, that should give you a nice toasty car in all but sub zero temps where it will give you just a warm car.
 
jjeff said:
If you program in your departure time the car will wake up 30 minutes before that time and only heat until that time, shutting off after that

I'm definitely seeing the car draw the full EVSE power, starting 90 minutes before the programmed Cliimate Control time (on Leaf S), then drop down to about 1.8kw after 3 to 9 minutes, and continue using less than 2kw until the programmed time. In the graph below, the Climate Timer was set to 8am. Charging finished at 2:15am; and climate heating ran from 6:30 to 8am, then stopped.

uc


UPDATE: I moved the preheat timer to 9:10am last night, and this morning it started drawing power at 7:40am. So it is still activating 90 minutes before the scheduled time. I'll watch it to see if that 90-minute lead time changes with ambient temps.
 
The preheat on my '13S is pretty cut and dry, it starts heating at 30 minutes before my departure time and turns off at the departure time, every time. Now I've always used L2 for preheat, not sure if that would explain the differences....
In your case it would be interesting to be around more than 30 minutes before departure time to see if it's truly heating(HVAC lights on) or if it's just doing more charging and balancing. Personally I wouldn't want any preheating to start more than 30 minutes before departure time, heck I even program my departure time 10-20 minutes later than actual so it only preheats for 10-20 minutes, as you probably know our timer only lets us set departure time in 10 minute increments, I would have loved a 15 minute option but that is not a choice :cry: With a good L2 connection(18+ amps) you don't need nearly as much as 30 minutes preheat, any more just wastes electricity IMO.
 
Thanks, Jeff. It's possible that the preheat duration is based partially on the EVSE amperage. I have a 12A L2 EVSE (2.88 kw), so it's twice as fast as the factory L1, but it's about as slow of an L2 as you're ever likely to see. Maybe below 3kw of EVSE output, the car triples the preheat duration. Or maybe the 2017 is different. Or maybe "it's just me."

As a side note, if Nissan shipped a 16A L1/L2 (like EVSEUpgrade/AmazingE/Duosida) as the stock EVSE, then I think many Leafers would never bother to upgrade. With 16A 240v, you can charge from 20% to 80% in about 4.5 hours; and if you park for 8 hours per night, you can be at 100% every morning. You would need something faster if you needed more than one "tankful" per day; and did not have a chance to charge for 2 or 3 hours during the day; and had no DCFC nearby.
 
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