Why does Leaf charge when plugged in and pre-conditioning?

[WAM]

I don't think I've seen this question anywhere on this site yet;
Why does the Leaf start charging (or continue charging if already at 80%) when pre-conditioning (remote climate control activation)?
Can't the "plug-in" power only the climate control without activating charging?
I use the charge timer to charge to 80%.
If I turn on the climate control remotely 1/2 hour before driving off, I find I have 11 bars rather than the usual 10.

 

[thankyouOB]

your last sentence makes no sense.

yes, if you start climate control remotely, you also get charging, and the net draw/charge depends on how much power the climate controls requires.

 

[Nubo]

your last sentence makes no sense.

The car is at 80% SOC, then 1/2 before they leave they turn on climate control "remotely" from another room in the house, presumably. I do this myself.

I also wonder why it adds charge to the battery. I suspect it's just simpler engineering to use the battery pack as a buffer and charge at the normal "negotiated" rate while having the heater pull whatever it needs to pull from the pack.

 

[garygid]

The air-conditioning uses energy from the battery only, cooling
using a small amount, and heating possibly using a lot.

The only way to try to make up for this loss, while plugged in,
is to charge the battery. The charging control software does
not realize that you only wanted an 80% charge, and it charges
toward 100%.

 

[GaslessInSeattle]

has anyone verified if the car also charges the battery at the same rate if it's already at a 100% charge. I'm still leery of prewarming/cooling at 100% soc. after all the worry about the battery, I'm not so confident that the BMS is actually preventing overcharing, which I can only imagine would be particularly bad for battery life in hot climates.

The air-conditioning uses energy from the battery only, cooling
using a small amount, and heating possibly using a lot.

The only way to try to make up for this loss, while plugged in,
is to charge the battery. The charging control software does
not realize that you only wanted an 80% charge, and it charges
toward 100%.

 

[thankyouOB]

I don't think I've seen this question anywhere on this site yet;
Why does the Leaf start charging (or continue charging if already at 80%) when pre-conditioning (remote climate control activation)?
Can't the "plug-in" power only the climate control without activating charging?
I use the charge timer to charge to 80%.
If I turn on the climate control remotely 1/2 before driving off, I find I have 11 bars rather than the usual 10.

do you mean "...remotely a 1/2 an HOUR before driving off,....

 

[EVDRIVER]

has anyone verified if the car also charges the battery at the same rate if it's already at a 100% charge. I'm still leery of prewarming/cooling at 100% soc. after all the worry about the battery, I'm not so confident that the BMS is actually preventing overcharing, which I can only imagine would be particularly bad for battery life in hot climates.

The air-conditioning uses energy from the battery only, cooling
using a small amount, and heating possibly using a lot.

The only way to try to make up for this loss, while plugged in,
is to charge the battery. The charging control software does
not realize that you only wanted an 80% charge, and it charges
toward 100%.

The BMS alway protects the battery, it does not perform differently under various situations. You could bypass the charger and the BMS at some point would break the contactor to protect the pack.

 

[vegastar]

Are you guys sure that it continues charging the battery past 80% SOC if it is programmed to charge to 80%? The last time I noticed, I started the remote CC and the three charge LEDs indicators where flashing indicating that the car was charging. After about 10 minutes they stopped flashing and were the three ON, indicating that the charge was complete, but the CC was still functioning. On the gidmeter the SOC was 80% when I started the car. I noticed tha the SOC dropped a little in the beginning (more power used to CC than the wall power) and then slowly reached the 80% SOC where it stopped charging.

 

[defiancecp]

Yes, I'm certain - for a long time I had no climate timer and charge timer set to 80%. It would always be at 10 bars (until way later then sometimes 9 bars).

When I turned my cc timer on it was summer, and for a long time it was always on 11 bars until winter kicked in at which point it was down to 10 (and a few times down to 9 when it was really cold and the heat was drawing more power than it was charging).

But even now if it's more than 65 degrees or so in the morning, I'll always show 11 bars with the climate timer on.

 

[LEAFer]

Just a note: keep in mind vegastar is in Portugal. There *might* be differences in behaviour.

 

[vegastar]

I will test it again with extended time doing the CC.

 

[Ingineer]

Depending on several factors, the Leaf may gain a little or even lose a little charge when pre-conditioning. Do not worry about the few extra percent if you charged to 80%, as you will be bleeding it off in just a few minutes, right? What is bad for the battery is storing the pack at high SoC for a longer time. The few extra percent and only few minutes that it's going to be there is not a problem whatsoever, and will not make any difference in battery degradation in the long run.

Anytime you are delivering power to the leaf from the wall, whether for charging or for preconditioning, the system must close the battery relays, as the climate control can peak at well over the power levels provided by the OBC (On-board charger). If the LBC (Battery controller) is ok with charging, it will allow some extra into the battery. It will never allow overcharge, so there is no need to worry!

-Phil

 

[GaslessInSeattle]

this is confusing to me, if it were just a little electricity than how come if prewarm starting with an 80% charge it will charge up to a SOC of 100% in an hour or so? when it gets cold up here and I have a long way to drive, extended prewarms are necessary. in the process of experimenting with extended prewarming, I've found that the amount of "bypass" to the battery is quite high. this has been true for both the MY 2011 and 2012.

Depending on several factors, the Leaf may gain a little or even lose a little charge when pre-conditioning. Do not worry about the few extra percent if you charged to 80%, as you will be bleeding it off in just a few minutes, right? What is bad for the battery is storing the pack at high SoC for a longer time. The few extra percent and only few minutes that it's going to be there is not a problem whatsoever, and will not make any difference in battery degradation in the long run.

Anytime you are delivering power to the leaf from the wall, whether for charging or for preconditioning, the system must close the battery relays, as the climate control can peak at well over the power levels provided by the OBC (On-board charger). If the LBC (Battery controller) is ok with charging, it will allow some extra into the battery. It will never allow overcharge, so there is no need to worry!

-Phil

 

[Ogi]

Depending on several factors, the Leaf may gain a little or even lose a little charge when pre-conditioning. Do not worry about the few extra percent if you charged to 80%, as you will be bleeding it off in just a few minutes, right? What is bad for the battery is storing the pack at high SoC for a longer time.

At what percentage of charge is there a problem - and if held for exactly how long?

 

[ebill3]

At what percentage of charge is there a problem - and if held for exactly how long?

Be interesting to see if you get a definitive answer. I think the best you are going to get is: "Longer at higher is bad". You can find charts that show predicted degradation based on voltage and time, but where it becomes a problem is your choice.

Bill

 

[Nubo]

this is confusing to me, if it were just a little electricity than how come if prewarm starting with an 80% charge it will charge up to a SOC of 100% in an hour or so?

The power consumed by the heater during pre-heat can be initially high, but then drop down a lot once the cabin has reached the set point and the heater is just working to maintain the differential between 77F and the ambient temperature. If you watch the energy usage screen while driving you've probably seen this. It will be even more pronounced in a garage where there's no wind blast robbing heat from the car. Even less power is needed in an attached garage where the temp is a bit warmer. And the garage itself is getting a bit warmer from the car's heat loss... Once you get to where the heater is only drawing maybe 0.5 to 1 kW, the leftover power is giving you a pretty hefty battery charge.

What are your temperatures, and is your car garaged?

 

[Ogi]

At what percentage of charge is there a problem - and if held for exactly how long?

Be interesting to see if you get a definitive answer. I think the best you are going to get is: "Longer at higher is bad". You can find charts that show predicted degradation based on voltage and time, but where it becomes a problem is your choice.

Bill

Let me put it to you this way: If I decided to charge my battery to 100% each morning before I drive it that day, using 220V-10amp and I had the climate control timer on as well......would this degrade the battery in any meaningful way?

 

[ebill3]

Let me put it to you this way: If I decided to charge my battery to 100% each morning before I drive it that day, using 220V-10amp and I had the climate control timer on as well......would this degrade the battery in any meaningful way?

First, forget the CC aspect. It is the state of charge of the battery that is of concern, not what caused the charge. Also, I think you would have to preheat at 10 Amps for quite a long time (another relative term) in order to increase the charge from 80% to 100%.

Next, a couple of cop outs:
I have no idea what is meaningful to you.
I am not an EE or any other kind of engineer. (except when operating my model RR)
There are several different chemistry lithium cells.

Take a look here - especially figure 3. http://powerelectronics.com/portabl...y_charger_ics/804PET22li-ion-battery-life.pdf

Note that figure 3 compares charging to 4.2 volts per cell vs. 4.1 volts per cell. Nissan considers 4.1 volts per cell as 100% charge; 80% a bit lower voltage. Lower is better in both cases.

It is rather clear to me that just charging to 100% will result in more degradation than charging to 80%, but how long the battery sits at 100% will also contribute to the degradation.

Bill

 

[Ingineer]

this is confusing to me, if it were just a little electricity than how come if prewarm starting with an 80% charge it will charge up to a SOC of 100% in an hour or so? when it gets cold up here and I have a long way to drive, extended prewarms are necessary. in the process of experimenting with extended prewarming, I've found that the amount of "bypass" to the battery is quite high. this has been true for both the MY 2011 and 2012.

You are obviously Pre-conditioning way too long. Precondition for the minimum time needed to get the car comfortable and the extra charge will not have time to happen.

FYI, the Leaf pack never makes it to 100% SoC. It tops out around 95%, so from 80% to 95% is only 15% more.

-Phil

 

[Ingineer]

At what percentage of charge is there a problem - and if held for exactly how long?

There aren't boundaries. They are called factors for a reason:
[extreme SoC] x [time] x [temperature] = degradation amount. (SoC factors are highest at either of the ends; discharged/fully charged)

So if you keep it at very high SoC (or very low) for a very short time it has very little effect, especially if it's cold. If you charge to full, then let it sit for a few days, and it's hot out, that's the worst-case.

I always charge to 80%, then if I think I might need the extra capacity at all, I bump it up to the full (~95%) right before I leave. It spends almost no time in that top 15%, as it falls off fast when driving.

-Phil