Battery usage duringe pre-heating

[ve2maa]

A simple question.

While "pre-heating" my Leaf, my L2 charger is in fonction but energy from the battery is drained... I often start the car with 97 ou 96% SOC , instead of 100% when I dont pre-heat.

Since the charger is plugged and in function, but not charging the car, why is it so ? Aren't 220V and 30 Amp enough to heat the car without using the battery ?

Just wandering why !

 

[keydiver]

There are a couple recent threads on this that may help you:
http://www.mynissanleaf.com/viewtopic.php?f=9&t=11032" onclick="window.open(this.href);return false;
http://www.mynissanleaf.com/viewtopic.php?f=27&t=15688" onclick="window.open(this.href);return false;

 

[ve2maa]

I've already read those topics.

May be I missed somethings but it doesn't explain why, technicaly, current needs to be drained from the battery since de L2 Charger should be able to give enough power for the cabin's heating.

 

[mwalsh]

I've already read those topics.

May be I missed somethings but it doesn't explain why, technicaly, current needs to be drained from the battery since de L2 Charger should be able to give enough power for the cabin's heating.

No, it doesn't.

 

[Yogi62]

Heating power comes from the battery, at up to 6KW. When the battery is full, the charger tapers down the power to less than 6KW (no matter what the "draw" is). The heater can be draw more than the charger will allow, so you will drop a couple of percent.

 

[ve2maa]

Ok.. If I do understand, that means :

Since the battery is fully charged, the charger will limit current from the L2 EVSE , bringing it down to a level that isn't enough the heat the cabin, that's why some current is drained from the battery to compensate ... Am I right ?

If it is so, that would means that draining from the battery shouldn't occur (or at a smaller lever) if the battery is let say half-full .. ?

 

[mwalsh]

^ What he said, plus this may be edifying:

http://www.mynissanleaf.com/viewtopic.php?f=30&t=18894&p=406999&hilit=Climate+draw+kW#p406999" onclick="window.open(this.href);return false;

 

[TimLee]

... it doesn't explain why, technicaly, current needs to be drained from the battery since de L2 Charger should be able to give enough power for the cabin's heating.

If your profile delivery date is correct you have either a 2011 or 2012 and the on board charger is only rated for 3.3 kW into the battery (or to supply HVAC during preheating or cooling).
The heater can draw up to 6kW when it starts under very cold conditions.
The on board charger cannot do that so you will lose charge from the battery.

The power rating of the L2 EVSE is not relevant unless it was lower than the on board charger rating, it just provides AC to the car.
The power for the heater is coming from DC, either the on board charger or the battery.

 

[truav8r]

I have the same 2% battery drop when I preheat with the CC timer in the morning.

2015 S (so we're talking 6kw onboard charger, and the basic resistance heater)
30A shore power

The full 100% charge usually completes around 6am or so. The CC timer comes on at 7am. When my wife gets in the car at about 7:20am, the battery indicates 98%.

I am left to assume that the resistance heater uses battery power quicker than the 30a shore power can replace it, correct? And that is because of the reduced charging rate when nearing a topped-up battery, correct?

But I'm also seeing reports of folks with the heat pump system experiencing similar battery drop on the CC timer, no?

 

[LeftieBiker]

I'm guessing that the PTC heater comes on along with the heat pump, to speed heating.

 

[truav8r]

What is the "PTC" heater ??

Regardless, I don't have the heat pump on a 2015 S model.

So why can't my 30A L2 shore power keep up with the CC timer heat?

 

[Reddy]

30 amp L2 should generate at least 6 KW to max out the CC. Unless you're below zero, that should be plenty of heat. I'm guessing the 2% is insignificant.

 

[truav8r]

Never gets below 32F in my garage. Usually around 40F even when the outside temp is in single digits.

2% isn't a huge amount, but it's a consistent drain when using the CC timer. Just seems to be a very weird and inefficient climate control for it to drain the battery like that when connected to sufficient power.

 

[Nhinman]

I have a 2015 SV with the heat pump system. I have noticed that mine does the same thing. It will have fully charged during the night, and if I remotely start the heater 10 -15 minutes before I leave in the morning it will read 97% - 98%. This is even if the car is in the garage and it is in the 40's in the garage. I've never tried checking the charge level at below 100% and then running the heater while connected to the L2 to see if there is a drop.

 

[smkettner]

The systems are quasi independent. Heater draws from the battery. EVSE and OBC keeps the battery charged.
Yes it would seem that the OBC would just supply the power but charging near 100% needs to be done a bit slow and careful vs the discharge can go like a rocket with no limit.
So you do get some loss to the battery level. Wait a bit and the OBC should get you back to 100% but by then you are rolling.

 

[TimLee]

...
I am left to assume that the resistance heater uses battery power quicker than the 30a shore power can replace it, correct? And that is because of the reduced charging rate when nearing a topped-up battery, correct?

But I'm also seeing reports of folks with the heat pump system experiencing similar battery drop on the CC timer, no?

There has been extensive discussion of this in other threads.

Appears that it is more related to the accuracy with which the LEAF controls the amperage from the EVSE.

With 6.0 kW on board charger and an EVSE capable of delivering 27.5 amps it should be able to preheat and remain at fully charged.
But it does not.

May be that the LEAF will only show 100% after it goes through the very slow cell balancing.

Likely that the kWh stored difference is extremely small.
Get LEAF Spy Pro if you want real data.
Nissan is unwilling to provide real data on the LEAF.
They seem to think it will scare people and hurt sales :?