GerryAZ
Gold Member
Posts: 1774
Joined: Mon Nov 22, 2010 6:47 pm
Delivery Date: 12 Jun 2011
Location: Phoenix, AZ

Re: has anyone actually measured the efficiency of the heat pump

Fri Nov 18, 2016 7:48 pm

Since this old thread has been opened, I will provide a couple of comments: The heat pump in the 2015 is significantly more efficient than the resistance heater was in the 2011.

My commute is long enough that I could not afford to let the heat run in the 2011 unless I wanted to stop on the way home for a charge. I used my heated motorcycle vest during the coldest mornings and only ran the heat if I needed defrost. The air conditioner had minimal impact to range during the summer even though it typically worked against higher inside/outside temperature differential compared to heat in the winter.

The heat pump in the 2015 heats the cabin with very little impact to range compared to the resistance heater. I have not been able to measure heat pump power from the wall during preheat because my car always uses the resistance heater when preheating while plugged in to L2 (have not tried 120-volt charging/preheating). The 2011 heater would draw the full 3.8kW that the 3.3 kW onboard charger could take from the wall. The heat pump seems to use a little bit more energy for cooling than the air conditioner in the 2011, but I don't know whether it is due to lower efficiency or the black leather interior absorbing more solar energy.

Gerry
Gerry
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015

arnis
Posts: 896
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Re: has anyone actually measured the efficiency of the heat pump

Sat Nov 19, 2016 4:45 am

Above freezing temperatures heat pump is more than 300% efficient. During near freezing
weather (few degrees above) keeping Leaf at comfy temperature takes less than 300W.
Efficiency drops considerably at -10C/14F. I suspect no more than 200%.
At -15C (+/-2C) heat pump stops working, fan stops, only resistance heater is used.
Sometimes it doesn't start with vehicle at all (most likely temperature sensor data). Sometimes it
starts for up to a minute and then stops. Sometimes it doesn't start but if I drive into warmer
places it will start later. It is not based on outside temperature reading we see on the dash.

In some scenarios heat pump also stops working at temperatures below freezing above -10C/14F.
This is due to evaporator icing. Heat pump will stop, outside fans will stop. Only way to deice is
to start charging process. Process will start about 1-2 minutes after charging has started,
will take about 5 minutes (will run heat pump in closed cycle, just gets hot). Process will not start
until SOC is above 15%. Deicing is not possible while driving. Maybe it will deice even without
charging. Haven't tried jet.


I've not measured efficiency but others can report how much does resistance heater consume
(after vehicle fully warmed up, takes about 15 minutes) at near freezing temperatures.

PS. Heat pump is more efficient at higher speeds. Due to the fact that outside fans should stop
(never heard that but manual says that happens) and more air is pushed past evaporator.

I have a question: does anyone know heat pump electric motor maximum power rating?
I've seen it draw 2250W. At the same time resistance heater draws ~3750W. That should translate
to about 10 000W of heat. This is not sustained for long due to fact that air resistance heater is PTC
based and will not be able to consume that much energy when it gets hot. Neither of those numbers
is the maximum rating, I think...
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

Intrigare
Posts: 3
Joined: Sun Nov 13, 2016 2:54 pm
Delivery Date: 13 Nov 2016

Re: has anyone actually measured the efficiency of the heat pump

Tue Nov 29, 2016 12:43 pm

Thanks for the useful info, arnis.

Look for the A/C compressor maximum power rating. The heat pump "electric motor" IS the A/C compressor. Perhaps you already know that a heat pump is essentially an air conditioner running in reverse.

When you say the heat pump runs in closed cycle to de-ice, do you mean its running in Air Conditioning mode? Is it blowing air into the cabin when it does this?


arnis wrote:Above freezing temperatures heat pump is more than 300% efficient. During near freezing
weather (few degrees above) keeping Leaf at comfy temperature takes less than 300W.
Efficiency drops considerably at -10C/14F. I suspect no more than 200%.
At -15C (+/-2C) heat pump stops working, fan stops, only resistance heater is used.
Sometimes it doesn't start with vehicle at all (most likely temperature sensor data). Sometimes it
starts for up to a minute and then stops. Sometimes it doesn't start but if I drive into warmer
places it will start later. It is not based on outside temperature reading we see on the dash.

In some scenarios heat pump also stops working at temperatures below freezing above -10C/14F.
This is due to evaporator icing. Heat pump will stop, outside fans will stop. Only way to deice is
to start charging process. Process will start about 1-2 minutes after charging has started,
will take about 5 minutes (will run heat pump in closed cycle, just gets hot). Process will not start
until SOC is above 15%. Deicing is not possible while driving. Maybe it will deice even without
charging. Haven't tried jet.


I've not measured efficiency but others can report how much does resistance heater consume
(after vehicle fully warmed up, takes about 15 minutes) at near freezing temperatures.

PS. Heat pump is more efficient at higher speeds. Due to the fact that outside fans should stop
(never heard that but manual says that happens) and more air is pushed past evaporator.

I have a question: does anyone know heat pump electric motor maximum power rating?
I've seen it draw 2250W. At the same time resistance heater draws ~3750W. That should translate
to about 10 000W of heat. This is not sustained for long due to fact that air resistance heater is PTC
based and will not be able to consume that much energy when it gets hot. Neither of those numbers
is the maximum rating, I think...

DaveinOlyWA
Posts: 13131
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Feb 2018
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: has anyone actually measured the efficiency of the heat pump

Tue Nov 29, 2016 1:21 pm

don't have a lot of experience with heat but in my 2016 S30, I ran it about 20-30 mins or so for a passenger and even on a day with fairly heavy rain and constant toggling of defrost, I still probably would have had 105 miles of range or so. Contrast to my normal days (driving alone) of 110 miles on similar days.

granted hardly a scientific observation but still surprised there was not a bigger hit. Now it wasn't cold (low 40's) and heat was only set to 65 º and this is no heat pump but also felt the heat in the 2013 was better than the 2011 so even resistive heat seems to have improved a little
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 8743 miles, 485 GIDs, 37.6 kwh 111.39 Ahr , SOH 96.49, Hx 114.98
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

arnis
Posts: 896
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Re: has anyone actually measured the efficiency of the heat pump

Tue Nov 29, 2016 2:38 pm

Intrigare wrote:Thanks for the useful info, arnis.

Look for the A/C compressor maximum power rating. The heat pump "electric motor" IS the A/C compressor. Perhaps you already know that a heat pump is essentially an air conditioner running in reverse.

When you say the heat pump runs in closed cycle to de-ice, do you mean its running in Air Conditioning mode? Is it blowing air into the cabin when it does this?




It is not technically running compressor reversed. There are 2 valves, they are switched so the gas flows differently.
Compressor and motor are technically two different parts in one unit (not possible to buy separately). I'm interested how much power that compressor's inverter motor is capable to draw. Yesterday I saw 2300W for a minute.
I found it's model: Compressor Model: AES28AV3AA and 92600-1MG0A

Defrost cycle runs with weird valve combination mode (normal split-type heat pumps don't have that second valve AFAIK). It doesn't blow anything at all. Only after defrost is done it purges water with fan (outside evaporator).
Check this out:
Image
And heating cycle:
Image
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

philip
Posts: 122
Joined: Tue Nov 27, 2012 8:18 pm
Delivery Date: 25 Aug 2015
Leaf Number: 327341
Location: El Cajon, CA

Re: has anyone actually measured the efficiency of the heat pump

Tue Nov 29, 2016 3:45 pm

Do you happen to have a diagram of the air-side? I'm surprised to see a constant refrigerant flow through the inner condenser and I am wondering what the air path and damper arrangement is like through the evap / inner condenser / PTC heater.
2015 SV
Old 11/11/15: 2012SL, SOH76% 49.97AHr 35,644mi vin 26790
LEAF press kits

arnis
Posts: 896
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Re: has anyone actually measured the efficiency of the heat pump

Tue Nov 29, 2016 4:18 pm

Image
Image


There is something wrong with C - D and E - F positions. I've tried min and max temperature settings
and during cold weather PTC element and inner condenser have airflow :roll:
Also between A and B there is also a half-position (active if AUTO or hold recirculation=double-blink)
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

philip
Posts: 122
Joined: Tue Nov 27, 2012 8:18 pm
Delivery Date: 25 Aug 2015
Leaf Number: 327341
Location: El Cajon, CA

Re: has anyone actually measured the efficiency of the heat pump

Tue Nov 29, 2016 6:05 pm

Thank you.
2015 SV
Old 11/11/15: 2012SL, SOH76% 49.97AHr 35,644mi vin 26790
LEAF press kits

Intrigare
Posts: 3
Joined: Sun Nov 13, 2016 2:54 pm
Delivery Date: 13 Nov 2016

Re: has anyone actually measured the efficiency of the heat pump

Wed Nov 30, 2016 1:49 am

arnis wrote:Defrost cycle runs with weird valve combination mode (normal split-type heat pumps don't have that second valve AFAIK). It doesn't blow anything at all. Only after defrost is done it purges water with fan (outside evaporator).

Interesting. To me it looks like in deice mode the whole system operates under a single pressure. The liquid refrigerant from the condenser is captured in the accumulator, and there it remains until the next heating cycle.

arnis wrote:There is something wrong with C - D and E - F positions. I've tried min and max temperature settings
and during cold weather PTC element and inner condenser have airflow :roll:
Also between A and B there is also a half-position (active if AUTO or hold recirculation=double-blink)

Perhaps the lowercase "e" has something to do with it? It seems position E is unnecessary during cold weather.

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