Random Use of Preconditioning and the EVSE

[jadnashuanh]

Unless I'm missing something, the only way to get the vehicle to activate the preconditioning and draw the power from the EVSE is if you use delayed charging and set a departure time. THen, it will start preconditioning as it finishes up charging, so that the batteries are not actually being discharged while this is happening as the power in and power out are likely being managed to be equivalent.

What would be useful is to be able to have the EVSE reactivated after a full charge if you then use the remote app to tell the car to precondition itself on an asynchronous timeframe. FOr example, I'm retired, and often just plug the i3 into the EVSE to recharge it, but would like to have the full battery capacity available if I later tell it to turn on the preconditioning. It's my understanding that it will not reactivate the EVSE until the battery capacity drops to 95% after being fully charged, so instead of starting with the full range in this situation, it will drop by whatever it takes to precondition the vehicle which is unlikely to be enough to reactivate the EVSE meaning that you will not be starting with a full charge any more.

So, it would be nice if, even if fully charged when starting, if you ask it to be preconditioned, it would also turn on the EVSE to keep the charge at max. It wouldn't take the full charge rate to do this.

I'm guessing they do not do this because of the potential of trying to overcharge the batteries, but there should be a way to manage the charging level to just enough to keep the vehicle at full charge while preconditioning.

 

[ultraturtle]

I'm guessing they do not do this because of the potential of trying to overcharge the batteries...

I'm guessing that you are 100% correct. The problem is that the EVSE supplies AC power to, and communicates only with the battery charging system. This all takes place on the AC side of the battery. Repeated discharge and charge near max SOC is not good for the battery, so it makes sense to allow for a bit of discharge.

...but there should be a way to manage the charging level to just enough to keep the vehicle at full charge while preconditioning.

Unfortunately, battery conditioning (as well as every other electrical system of the car) takes place on the DC side of the battery. Even if BMW could somehow bridge communication to the AC side, the J1772 communication standard does not accommodate anything other than communication with the charging system.

I suspect that this characteristic is not unique to the i3.

 

[Marki3]

Unless I'm missing something, the only way to get the vehicle to activate the preconditioning and draw the power from the EVSE is if you use delayed charging and set a departure time. THen, it will start preconditioning as it finishes up charging, so that the batteries are not actually being discharged while this is happening as the power in and power out are likely being managed to be equivalent.

I had read these posts and expected the same. I plugged my car into charge immediately last night at 11 pm. So, would have been fully charged by say 3 am. I set preconditioning for 8 am. When I checked about 5 minutes before I left at 8 am the app said 100% battery charge. Went I went to the garage the wall charger light was green as if it were charging and the interior was preconditioned. The charge still showed 100%.

That sounds different to other experiences. I only got my car 4 days ago and it was delayed in LA for the latest software update. Is it possible they modified and fixed this issue?

 

[Zzzoom3]

I could be mistaken, but if you have the vehicle set to charge immediately, then it starts charging when you plug it in unless you also set the "Low Cost Charging" to ON. Setting a departure time is for preconditioning only. Preconditioning is more about warming or cooling the battery. As they heat or cool, you will see fluctuations in the available charge and range accordingly. Then the charger can "top off" the battery capacity.

So putting it in terms of how I see it work, I set a departure time of 7:45am. I set Preconditioning and Low Cost Charging ON. My low cost charge period is midnight to 6:00am. I plug in around 8:00pm. The charger does an initial power check and goes into pause/standby. At midnight, the vehicle tells the charger to turn on and charging starts. Charging ends some time later depending on the beginning charge (I'm sleeping soundly at this point!). Around 7:30am, I hear the vehicle heating/cooling come on (yes I actually stood out in my garage to see what was happening) and the charger will come on and go off periodically during these last 15 minutes before the departure time. The max power I saw the charger using during this time was 2 kW. The temperature in the garage was about 67 degrees.

I don't know if that helps but it is what I have observed ...

 

[Chrisn]

Are you charging on Level 2?

I think for Level 2 chargers, pre-conditioning juice comes from the charger (I've seen it pull 3-3.5kw, but not sustained), but I don't think Level 1 can provide enough juice to avoid some discharge of battery during preconditioning.

 

[Zzzoom3]

Are you charging on Level 2?

I think for Level 2 chargers, pre-conditioning juice comes from the charger (I've seen it pull 3-3.5kw, but not sustained), but I don't think Level 1 can provide enough juice to avoid some discharge of battery during preconditioning.

Yes, Chargepoint CT-500 in the garage ..

 

[Marki3]

I could be mistaken, but if you have the vehicle set to charge immediately, then it starts charging when you plug it in unless you also set the "Low Cost Charging" to ON. Setting a departure time is for preconditioning only. Preconditioning is more about warming or cooling the battery. As they heat or cool, you will see fluctuations in the available charge and range accordingly. Then the charger can "top off" the battery capacity.

So putting it in terms of how I see it work, I set a departure time of 7:45am. I set Preconditioning and Low Cost Charging ON. My low cost charge period is midnight to 6:00am. I plug in around 8:00pm. The charger does an initial power check and goes into pause/standby. At midnight, the vehicle tells the charger to turn on and charging starts. Charging ends some time later depending on the beginning charge (I'm sleeping soundly at this point!). Around 7:30am, I hear the vehicle heating/cooling come on (yes I actually stood out in my garage to see what was happening) and the charger will come on and go off periodically during these last 15 minutes before the departure time. The max power I saw the charger using during this time was 2 kW. The temperature in the garage was about 67 degrees.

I don't know if that helps but it is what I have observed ...

That helps a lot and is exactly what I have observed. But there had been many posts about how preconditioning was drawing on the battery and not activating the charger resulting in less than 100% charge when starting out after preconditioning. Folks had posted that the charger only came back on when the battery level dropped below 95%. So, I was surprised at the behaviour I have seen. But I wonder if that is related to the BEV vs REX. The BEV has a heat pump and perhaps that accounts for the difference in behaviour.

I am on level 2 charger.

 

[Zzzoom3]

Here's a graphic from Friday night charging session. It clearly shows the EVSE supplies power during the Preconditioning period. In this specific case, I set the time of departure for 10:45am, low cost period from midnight to 6:00am. The car started drawing power at midnight charged, completed, waited, then the 3 power spikes during preconditioning at which point I stopped it to be on my way. Kinda cool heh!

https://drive.google.com/file/d/0B5LVemnP3B4sankzczVDU1hUaHM/edit?usp=sharing