Preheating cabin use battery

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Yan

New member
Joined
Nov 12, 2019
Messages
4
Hello everyone. I’m the owner of an 2014 Leaf SV. I have a 240v 30 amps capacity charging station at home.

The question is: why do the cabin preheating is reducing the % of charge of the battery pack when the car is full and still pluged in?

It is not supposed to draw the electricity from the charger/charging station?

It is because the heating system use primarly the energy in the pack and the charger kick in when the battery pack pass a % threshold?

This morning the car was plugged in and already full way before the cabin heating program kick in. When I came to drive the car, the % had dropped to 97%. Since my charger capacity into the car is 6.6kW the charging station up to 7.2 kW and energy consumption from the heater never goes over 5 kW.... I dont understand the drain.

Thanks for the explanation.
 
When the battery SOC gets higher and close to 100% the charge rate tapers off. It doesn't run at 6.6kW until 100% but starts to taper down around 90% SOC I think. Eventually, when you charge to 100% it tapers to 0kW then there are 3 small charge bumps while the charger 'tops off' the battery.

If you try the same experiment at 50% SOC I would be surprised if the SOC goes down while the car is plugged in.
 
There is already at least one topic on this, but here is the short answer: the climate control draws power from the battery pack only. The EVSE (via the onboard charger) charges the battery pack only - it doesn't power anything else. So if the EVSE provides charge at a slower rate than the climate control uses it, the charge level drops accordingly. You need at least a 16 amp, 240 volt EVSE to prevent this. If you want to charge at the same time, then at least a 20 amp 240 volt EVSE.
 
^^ I think if you combine the previous 2 replies you have the full answer. Heater draws from the battery, EVSE tries to keep the battery charged, but charge rate is reduced when near 100%. As state of charge drops you will reach an equilibrium point where the charge rate allows the EVSE to keep up. Once the cold-soak of the cabin is eliminated that equilibrium point may shift upwards a bit.

How many percent are you losing?
 
Like I wrote in my first message:

- Car was plugged but the SOC was at 100% several hours before the preheating program start.
-My home charging station a level 2 unit ( not a EVSE) is a 240v 30 amp (7.2 kW) model and capable to do so.
- The cabin preheating started way after the full charge was attained but I loose 3% (SOC dropped from 100% to 97%)

So from here, I dont understand why the car is not asking for charging power from the charging station since the heater was consuming electricity from the battery and depleting it.

When I read user manual, it was supposed to.

3% is about 800-1000 Wh . it’s not a big deal. But in winter time, when it’s minus 15c , every kW count. And using preheating when the car is plugged in, its supposed to avoid this.
 
Is it possible that the car system only ask for charging , in preheating condition, only when battery SOC status is on a particuliar level or threshold?
 
Yan said:
... I dont understand why the car is not asking for charging power from the charging station since the heater was consuming electricity from the battery and depleting it. ...

Almost certainly it IS asking for charging power, and the EVSE is supplying it. But the vehicle won't charge the battery at the full rate when it is near 100%. The following image shows how the charge rate tapers when the battery is nearly full.
Nissan_Leaf_L2_Charging_02_135e7df778.jpg
 
Almost certainly it IS asking for charging power, and the EVSE is supplying it. But the vehicle won't charge the battery at the full rate when it is near 100%.


This is it. I didn't notice that the OP was using a 30A EVSE. My bad for misreading.
 
I believe what's happening(and I've noticed it too with my 30a EVSE and my 6.6kWh Leaf charger) is the battery is near(or at 100%) so it doesn't call for a full 27.5a that the car can draw, it just takes a top off amount which unfortunately isn't enough to keep up with the preheat draw. The only way I've found to avoid this is to set my '13 to 80%(you won't have this option on your '14 :( ) and set to 80% when the preheating starts the battery is low enough to basically draw the full amount the preheat is using from your EVSE. I know this won't do you any good if you want a 100% charge but it's just the way it is. Note you won't really lose more than a max of 3% off 100% from what I've observed but I understand when you want a full 100% you might feel cheated only getting 97%.
 
Sorry for not calling my charging station a EVSE. I always belived that only portable charger was named EVSE.

Thanks for your reply guys. :D
 
Try setting your preheat earlier? The big draw from the heater is at the beginning, the preheat stays on for a while... I’ve heard both 30 and 45 mins, mine seems to top up a bit higher when I’m running late.
 
jjeff said:
I believe what's happening(and I've noticed it too with my 30a EVSE and my 6.6kWh Leaf charger) is the battery is near(or at 100%) so it doesn't call for a full 27.5a that the car can draw, it just takes a top off amount which unfortunately isn't enough to keep up with the preheat draw. The only way I've found to avoid this is to set my '13 to 80%(you won't have this option on your '14 :( ) and set to 80% when the preheating starts the battery is low enough to basically draw the full amount the preheat is using from your EVSE. I know this won't do you any good if you want a 100% charge but it's just the way it is. Note you won't really lose more than a max of 3% off 100% from what I've observed but I understand when you want a full 100% you might feel cheated only getting 97%.

The way to get the most out of preheat in this case, is to make sure it runs long enough to thoroughly warm the interior, not just the air. As the cold-soak is removed, the overall consumption of the HVAC system goes down. And so the equilibrium point of charge rate vs. consumption will shift to a slightly higher state of charge. The pack will "catch up" a bit. And you won't be spending battery power to warm up cold fabrics, metal and plastics.
 
I have a different perspective: My experience with 2015 was that the battery would show only 96% to 98% SOC on dash display, but would have higher voltage (Leaf Spy display) after running climate control while plugged in. Therefore the battery was actually at full charge even though the dash display indicated less.
 
GerryAZ said:
I have a different perspective: My experience with 2015 was that the battery would show only 96% to 98% SOC on dash display, but would have higher voltage (Leaf Spy display) after running climate control while plugged in. Therefore the battery was actually at full charge even though the dash display indicated less.

I wonder if your PTC disengaged early and it was just the heat pump preheating the car, using less power...
 
^That would seem to indicate that the dash display is monitoring the voltage available to the motor, ie total battery voltage - the losses due to internal resistance. I assume the SOC display is just based on a voltage reading so if there is a load on the battery, that would drop the output voltage based on the current being drawn * internal resistance. Or something like that. I assume that is the definition of 'internal resistance' but a battery is far from an ideal voltage source so I'm a little fuzzy on all this stuff.
 
You were plugged in, but the EVSE was not activated.

To turn the heater ON while connected to EVSE: press the start button twice, then you should hear the contactors clack ON and the third blue light will flash. Now press climate control ON and Auto button, then press the front defrost button for max fan speed, increase temperature setting as desired. The AC button will be lit but leave it ON. If you turn if OFF the heat will turn off too. Go to the energy monitor screen to see the power go up to 5kW of heating and it will be coming from the output of the OBC.
 
LeftieBiker said:
GerryAZ said:
I have a different perspective: My experience with 2015 was that the battery would show only 96% to 98% SOC on dash display, but would have higher voltage (Leaf Spy display) after running climate control while plugged in. Therefore the battery was actually at full charge even though the dash display indicated less.

I wonder if your PTC disengaged early and it was just the heat pump preheating the car, using less power...

No, remote activation of climate control for heating while plugged in always used PTC (probably to avoid noise from radiator fans and compressor and to reduce wear on those components). The instrumentation just displayed lower SOC percent than actual charge level (based upon voltage displayed by Leaf Spy and observations that dashboard displayed SOC percentage would not start to decrease for several miles of driving).
 
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