LEAF plugged in but not charging... what is climate control power source: battery or grid?

[DaveinOlyWA]

Interesting. So the last two answers seem to contradict. I guess I'll contact Nissan to (hopefully) get a firm answer.

the real world answer varies. its realistically from the battery 100% of the time BUT it is possible that the CC would use enough power to restart a charge to the battery.

so how you choose to look at this is up to you since in the grand scheme of things, it doesn't really matter

 

[DaveinOlyWA]

If we are talking about cold air temperatures, i.e. down in the teens or colder, the heat pump is ineffective and the heating system on an SL/SV with the hybrid heater is basically preheating using resistance heat (PTC).

that is a myth.

Arnis; its becoming apparent your World is simply different than what we have here.

 

[Dooglas]

that is a myth.

What is a "myth"? That heat pumps are less efficient at lower temperatures, or that the SL/SV Leafs have a hybrid heating system which is supplemented by resistance heat?

 

[DaveinOlyWA]

that is a myth.

What is a "myth"? That heat pumps are less efficient at lower temperatures, or that the SL/SV Leafs have a hybrid heating system which is supplemented by resistance heat?

well you did not say "less efficient" I believe you said "inefficient" which is far from true. you would have to go significantly below the teens to make it true.

 

[LeftieBiker]

Dave, you have your facts wrong. It's true that some newer home heat pumps can work well down into the single digits Fahrenheit, but the one that is actually in the Leaf becomes ineffective below the mid twenties, and is pretty much not helping at all below the mid teens. This is well established.

 

[arnis]

Dave, you have your facts wrong. It's true that some newer home heat pumps can work well down into the single digits Fahrenheit, but the one that is actually in the Leaf becomes ineffective below the mid twenties, and is pretty much not helping at all below the mid teens. This is well established.

Darn how I hate those numbers :lol: mid twenties. teens, wtf :lol:

Heat pump stops functioning at -15C, aka +5F. It is very slightly efficient at that temperature, COP 1.2-1.3*.
At -10C / +14F it is still somewhat efficient, depends on other factors in addition to outside temperature.
COP is at least 1.4. So imagine 1500W constant draw and getting 2100W of heat, max 2250W.
Most habitable cold regions have temperatures during days in winter months around -5C, down to -10C.
Only few days (5...15) per year temperatures drop below -15C, -20C.
Usually it is like -5C, aka 23F. And COP is way above 2.0* at that point. Above freezing it might be even 3.0.

Heat pump is a very good option for cold climate. But if it hardly gets below freezing, not sure.
How much does Leaf consume if it is a degree above freezing outside? Lets say fan at 3 bars, 63F selection.
After driving for 20 minutes or preheated (not heatup period).
Same question if it is "mid twenties" outside.

*my observations

 

[DaveinOlyWA]

Dave, you have your facts wrong. It's true that some newer home heat pumps can work well down into the single digits Fahrenheit, but the one that is actually in the Leaf becomes ineffective below the mid twenties, and is pretty much not helping at all below the mid teens. This is well established.

Lately, we have had a LOT of weather in the mid 20's and lower but not a single word on heat pump ineffectiveness. so I will have to check back with you on that but I am guessing your comments are more based on personal comfort levels than anything else.

 

[Dooglas]

Lately, we have had a LOT of weather in the mid 20's and lower but not a single word on heat pump ineffectiveness. so I will have to check back with you on that but I am guessing your comments are more based on personal comfort levels than anything else.

Aren't people missing the point here? There is no doubt that the SL/SV heat pump is much less effective at temperatures in the teens and below than it is at higher temperatures . There is also no doubt that the SL/SV has a hybrid heater which uses resistance heat to replace the output of the heat pump as temperature drops. The question is not whether the system still blows warm air at lower temperatures. The question is at what temperatures and what rate does the resistance heat phase in and what does that do to battery draw. Seems like there should be a nice graph that shows that, but I have never seen it.

 

[arnis]

PTC heater adds what pump can't give.
If temp.settings is high enough, cabin cold, air flow is also strong, PTC heater is almost
always operational. To minimize PTC usage temperature selection MUST be the lowest
possible option. I've read that selecting the lowest value somehow limits airflow to
PTC element (drawing of heat box explains that) but I highly doubt that because even
with 16C selection (lowest) PTC still draws a lot for few minutes until
a) air in the airbox is hot b) at least some temperature in the cabin has been achieved.
I'm not sure that is possible for a minute if there is not airflow thru PTC element.
Maybe airflow is restricted heavily, then it makes sense.

For example if it is around freezing. AUTO settings and 20C / 68F has been selected.
Leaf started. Heat pump spins up to 2400W (requires driving speed minimum 25km/h 15mph)
PTC element also has very high duty cycle. For example 2000W. This continues for 10-30 seconds.
Airflow bars go from 1 to maximum. Air gets really hot. In about 1 minute heat pump slows down
to 1500W. PTC usually goes to 0W for a moment. And then picks up somewhere around 250-500W.
If cabin is cold enough heat pump will stay around 1500-1800W, PTC around 250-1000W if airflow
is very high (auto settings). If airflow is adjusted PTC will throttle down a lot. For example at around
0C 3-bars fan speed usually kills PTC completely and heat pump slows down to 800-1100W during
warmup period (usually 10-15 minutes of driving). If temperature selection is lower and interior temperature
sensor detects temperature around selected heat output is further reduced. After 15 minutes at 0C and
comfortable cabin heat pump draws 150-450W, PTC is at 0W.
Heat pump generates around 3x amount of heat compared to draw at that outside temperature.

Unfortunately Leaf's CC is dumb. Even the lowest temp.setting results in huge draw. Fan speed must be
adjusted manually to keep PTC usage under control during warmup period. Ideally preheating, even for 5 minutes,
solves that. Usually 3 bars of fan is good enough for heating up slowly and keeping PTC at minimum.
ECO button does ABSOLUTELY NOTHING. I know manual promises limiting CC but that is not true.
I've tried with all temperatures and all scenarios - there is absolutely no difference ECO or not.

Those who do not own OBD adapter and want to optimize CC draw to get most heat out of least energy:
keep recirculation in AUTO (not fresh, not recirc due to fogging), temperature setting minimal during heatup period.
Idea is to keep climate overall draw below 2kW. When it falls down below 0,5kW temperature can be raised for comfort.
Most likely fan speed must be reduced from max down to at least 4 bars, depends on outside temperature.
Fan speed 2 and less is also not very efficient during heatup period as heat pump radiator in the heatbox does not
get hot anyway. The higher the air flow the more efficient pump system is (does NOT apply to PTC heating method).
This is why I say CC is dumb as f*ck. Need more air flow to maximize heat pump efficiency but at the same time due to
high air flow PTC kicks in. I still would like that PTC kill switch that is retrofitted to old Leafs on my Leaf too :lol:

If heat pump interior radiator gets to "hot to touch" temperatures heat pump must throttle down due to system pressure.
blabla, very long story. Same happens with PTC element. This is why it suddenly dies during warmup period. It has maximum
temperature, I believe it was 105C 221F.

 

[DaveinOlyWA]

Lately, we have had a LOT of weather in the mid 20's and lower but not a single word on heat pump ineffectiveness. so I will have to check back with you on that but I am guessing your comments are more based on personal comfort levels than anything else.

Aren't people missing the point here? There is no doubt that the SL/SV heat pump is much less effective at temperatures in the teens and below than it is at higher temperatures . There is also no doubt that the SL/SV has a hybrid heater which uses resistance heat to replace the output of the heat pump as temperature drops. The question is not whether the system still blows warm air at lower temperatures. The question is at what temperatures and what rate does the resistance heat phase in and what does that do to battery draw. Seems like there should be a nice graph that shows that, but I have never seen it.

pretty sure resistive heat starts ASAP. it only needs to put out less because of the help the heat pump gives.

 

[Dooglas]

pretty sure resistive heat starts ASAP. it only needs to put out less because of the help the heat pump gives.

Well, sort of. At temperatures in the 40s and 50s the heat pump is easily capable of producing all the heat the auto temperature system requires. That is not true at 5 degrees when most of the heat will come from the resistance element. My point was, that means that battery draw of the hybrid heater will increase at low temperatures. In other words, as the air temperature drops, you will reach a point where the power draw of the SL/SV hybrid heater will be essentially the same as the resistance heater of the S model.

 

[DaveinOlyWA]

pretty sure resistive heat starts ASAP. it only needs to put out less because of the help the heat pump gives.

Well, sort of. At temperatures in the 40s and 50s the heat pump is easily capable of producing all the heat the auto temperature system requires. That is not true at 5 degrees when most of the heat will come from the resistance element. My point was, that means that battery draw of the hybrid heater will increase at low temperatures. In other words, as the air temperature drops, you will reach a point where the power draw of the SL/SV hybrid heater will be essentially the same as the resistance heater of the S model.

pretty sure the car does not predetermine that before start up

 

[arnis]

pretty sure resistive heat starts ASAP. it only needs to put out less because of the help the heat pump gives.

Well, sort of. At temperatures in the 40s and 50s the heat pump is easily capable of producing all the heat the auto temperature system requires. That is not true at 5 degrees when most of the heat will come from the resistance element. My point was, that means that battery draw of the hybrid heater will increase at low temperatures. In other words, as the air temperature drops, you will reach a point where the power draw of the SL/SV hybrid heater will be essentially the same as the resistance heater of the S model.

pretty sure the car does not predetermine that before start up

Even in 30s heat pump is capable to give 100%. Except first few minutes.
At 5 degrees not the most of the heat but all of the heat. At 5F heat pump is NOT OPERATIONAL.
5F is the point when hybrid heater draws the same as oldschool heater.

It doesn't actually predetermine. I've seen multiple times when heat pump starts pumping at 6-7F and stops
operation for good (outside fans stall) within first 30 seconds (most likely some other temperature sensor
is not cooled down to 5F or something similar).

Today it was 25F and after 5 minutes PTC was 0W and HP was 800-900W.

 

[Dooglas]

At 5 degrees not the most of the heat but all of the heat. At 5F heat pump is NOT OPERATIONAL.
5F is the point when hybrid heater draws the same as oldschool heater.

Well, that is interesting and is a least one answer to the question I had posed. At 5 degrees F the hybrid heater in the SL/SV and the resistance heater in the S are both using 100% resistance heat and are presumably drawing about the same amperage.

 

[LeftieBiker]

At 5 degrees not the most of the heat but all of the heat. At 5F heat pump is NOT OPERATIONAL.
5F is the point when hybrid heater draws the same as oldschool heater.

Well, that is interesting and is a least one answer to the question I had posed. At 5 degrees F the hybrid heater in the SL/SV and the resistance heater in the S are both using 100% resistance heat and are presumably drawing about the same amperage.

Arnis is making it sound like the heat pump provides lots of heat down to 5F and then stops. No. In reality, the heating gets progressively 'taken over' by the resistance heater below freezing, with the car using noticeably more power below about 25F, and below about 14F you may as well have an S, even though the heat pump is technically still providing heat. Keep in mind that many of us have been driving in frigid weather for four years, and know what our cars are doing because we need every miles of that decreasing range. There is general agreement about the temps I gave.

 

[arnis]

At 5 degrees not the most of the heat but all of the heat. At 5F heat pump is NOT OPERATIONAL.
5F is the point when hybrid heater draws the same as oldschool heater.

Well, that is interesting and is a least one answer to the question I had posed. At 5 degrees F the hybrid heater in the SL/SV and the resistance heater in the S are both using 100% resistance heat and are presumably drawing about the same amperage.

Arnis is making it sound like the heat pump provides lots of heat down to 5F and then stops. No. In reality, the heating gets progressively 'taken over' by the resistance heater below freezing, with the car using noticeably more power below about 25F, and below about 14F you may as well have an S, even though the heat pump is technically still providing heat. Keep in mind that many of us have been driving in frigid weather for four years, and know what our cars are doing because we need every miles of that decreasing range. There is general agreement about the temps I gave.

Heat pump system does not retard operation when it gets colder and colder (up until predefined limit -15C). It draws more and more
power when it gets colder. Resistive heater adds to get more heat.
Fact is that heat pump draws up to 2500W (usually up to 2200W stable) and generates about 2300-2600W of heat near -14C
Actually even at that low COP (like 1.1-1.2) if pump draws 2300W it gives at least same amount of heat.
Therefore it does produce heat, just not with additional efficiency.
And PTC is also capable to give as much as it can.
https://goo.gl/photos/mLnWJqpF1V9w4C9L9
Check out some picture. Notice time. Different trips. Blue bar is compressor, violet is PTC.

 

[LeftieBiker]

It draws more and more
power when it gets colder. Resistive heater adds to get more heat.
Fact is that heat pump draws up to 2500W (usually up to 2200W stable) and generates about 2300-2600W of heat near -14C

I see temps in two photos but can't see them in the individual LeafSpy shots. Is the outside temp -3C? If so, then that's still in the heatpump's "comfort zone." I think that the reading may be misleading - that the heatpump ("A/C") reading is somehow including resistance heat. Even if what you say is fully accurate, though, the effect is the same: cars with the heat pump draw as much power for heat at 0 F as those without. I know that home heat pumps include a resistance heater to supplement them, so the question is whether the PTC heater is a completely separate system, or if it "feeds" heat to the heatpump at low temps.

 

[Dooglas]

In reality, the heating gets progressively 'taken over' by the resistance heater below freezing, with the car using noticeably more power below about 25F, and below about 14F you may as well have an S, even though the heat pump is technically still providing heat.

That is my understanding of how the SL/SV hybrid heater system works as well. What I would really like to see is a comparison of the power draw with the SL/SV system and the S system at several temperatures between 40 F and 0 F. I realize there would have to be some sideboards such as a particular setting of the auto controls. I am trying to ask the practical question of what the SL/SV system is worth as far as reducing battery draw and increasing range compared to the resistance heater in the S. The buyer pays a significant premium for the SV/SL. What are the benefits - or at least this particular one?

(EDIT - Sorry Leftie, I had previously inserted the wrong quote - error corrected)

 

[LeftieBiker]

The advantage of having a heatpump-equipped Leaf is that in moderate Winter temps (above about 26F) you use much less power for heating. When temps are above about 40F, using the heat is about the same as using the A/C in Summer, as far as consumption goes. So someone in a climate with a lot of cold-ish but not frigid days will benefit more than someone in a climate where it's usually well below Freezing in Winter, because as temps fall through the mid teens (F) the heat pump's advantage becomes negligible.

 

[arnis]

It draws more and more
power when it gets colder. Resistive heater adds to get more heat.
Fact is that heat pump draws up to 2500W (usually up to 2200W stable) and generates about 2300-2600W of heat near -14C

I see temps in two photos but can't see them in the individual LeafSpy shots. Is the outside temp -3C? If so, then that's still in the heatpump's "comfort zone." I think that the reading may be misleading - that the heatpump ("A/C") reading is somehow including resistance heat. Even if what you say is fully accurate, though, the effect is the same: cars with the heat pump draw as much power for heat at 0 F as those without. I know that home heat pumps include a resistance heater to supplement them, so the question is whether the PTC heater is a completely separate system, or if it "feeds" heat to the heatpump at low temps.

Between -5C -3C on all those pictures.
Jep, it is heat-pump's "comfort zone". AC reading is not including resistance heat AT ALL. Only energy that goes to compressor inverter. Vehicle does display climate draw as the sum of those two.

In Europe air-air heat pumps almost never have resistance heater included, I suspect same is in US (as the choice for those devices there is much worse). Air-water or ground-water pumps do as they are expensive and are "all-in-one" solution for heating. But normal heat pumps, (like on Leaf), would suck 1500W of electricity and generate 1,0-1.1x 1500W of heat at -40C :lol: Not with resistance heater! Just apply first law of thermodynamics: use 1500W of energy/power to do some work. If extra heat is not captured after evaporation at outer condenser you just get the same amount of energy when gas gets compressed as heat.
Leaf's PTC heater is standalone system. Electrically. They are very close to each other and both get the same air (according to diagrams amount of airflow can be adjusted between them, I'm not sure that is correct).

What I would really like to see is a comparison of the power draw with the SL/SV system and the S system at several temperatures between 40 F and 0 F. I realize there would have to be some sideboards such as a particular setting of the auto controls. I am trying to ask the practical question of what the SL/SV system is worth as far as reducing battery draw and increasing range compared to the resistance heater in the S. The buyer pays a significant premium for the SV/SL. What are the benefits - or at least this particular one?

Precise comparision is not possible. Heat pump is sensitive to more things than only air temperature. Things like air humidity, frost buildup, airflow on both condensers, interior condenser input temperature, vehicle speed. And some more.
What are the benefits - hybrid heater heats up cold cabin MUCH faster at temperatures between 20F-60F. Heat pump and PTC heater together can generate cabin heat at 6-10kW rate at cold vehicle startup. Even Tesla can't do that. This adds comfort.
Range drop during winter is on average only a third compared to 2011 Leaf.
I can drive 1km per 1% in 20F weather with warm cabin. So about 100km at 55mph. I can do 120km in summer.
Heat pump is more effective if it runs at moderate rpm (something like ICE engine). Therefore after cabin is at stable temperature
heat pump efficiency goes to where it should be. And PTC is usually not used. This is why I recommend choosing lowest temperature setting in the beginning. Then slowly turn it up if gets uncomfortable.

Heat pump also makes sense in urban traffic. To keep cabin warm it requires almost* constant amount of energy per unit of time (not distance). If we cut heating consumption in half we waste much less per distance travelled.
Imagine PTC heater draws 3kW per hour, hybrid heater 1kW per hour (same cabin temperature). If we drive 10mph average with 4miles/kWh we run down 21kWh battery like that:
With regular PTC 3...6...9 kWh power for 3 hours of heat, 10 mph 3 hours 30 miles, 30/4= 7,5kWh on driving. 9kWh on heating, 16,5kWh, 82% of battery. Can theoretically drive 36,3 miles.
With heat pump 1...2...3kWh power for 3 hours of heat, 10 mph 3 hours 30 miles, 30/4= 7,5kWh on driving, 3kWh on heating, 10,5kWh, 50% of battery. Massive difference. Can drive 60 miles!
Those who have PTC heating only tend to keep cabin colder on longer trips to minimize range loss. With hybrid heater in comfort zone it is not a topic any more. It acts like 60+kWh Tesla. Due to the fact that there is more range to start with range loss due to heating is not a noticeable problem. This is why Tesla doesn't even offer heat pump. Also during longer trips battery chemistry heats up and range loss due to cold battery is reduced even more.

*the faster you drive the more are windows cooled down. That also cools down the cabin.