jadnashuanh
Well-known member
There are at least a few conflicting issues regarding power use while plugged into an EVSE.
Throwing in a low-cost charging window just complicates things.
Then, consider that there are two things that can be conditioned on an i3: the cabin for personal comfort (and it can help with energy use once on full battery since the cabin is already at the desired temp - it doesn't have to come from the batteries to get it there); and, the batteries themselves.
If you tell the car to precondition the cabin, you can do it in several ways. One is when leaving the car, you can tell it to essentially keep the car conditioned while you say go into the store to pick something up. Another is to request the car precondition the cabin when setting a departure time. Or another from the app by using the fan icon.
One thing that has not been particularly clear is that setting a departure time is useful in that it preps the main battery pack, and conditioning the cabin is optional. The ideal temperature of the batteries is around normal room temperature. And, until recently, I'd not considered that because the battery pack is nearly 500#, it can take quite a bit of time AND energy to warm it up. It's in the order of hours, not minutes, depending on the actual ambient temperatures.
So, what does that do when you ask the car to charge during off-peak power? This is my take on it, and I admit I may be wrong, but this is a discussion. IF the car is below some minimum state of charge, it will bump the SOC up some when you first plug it in. There appears to be a bug, and it may or may not continue either then, or later when the off-peak time window opens. But, it isn't unusual when it's cold out for it to charge at least some when you first plug it in.
Then, if all is working properly, it would try to fully charge the car during the off-peak time window. Now, another reason why it may initially turn on the EVSE when you first plug it in is to sample the EVSE's pilot signal which announces how much power it actually can provide - this would give the car an idea what it has to work with. It might NOT be able to fully charge in the off-peak time window if the SOC is low AND the EVSE isn't at least 30A, so, I think that is one reason why it turns things on temporarily even if you tell it to wait for the off-peak window.
Then, consider that you also asked it to precondition in addition to the departure time. If your actual departure time is outside of the low-cost, off-peak window, the car WILL need to turn the EVSE back on again to minimize the battery SOC drain when preconditioning the cabin AND (and this takes several hours) to precondition the batteries as well. Otherwise, heating the 500# of batteries and the cabin could take a big chunk out of the SOC, making a big compromise on your maximum range. FWIW, if you are not plugged in and have a departure time, it won't do much unless you also tell it to precondition the cabin. AT least that seems to be the case. The batteries do warm themselves when driving as a natural function of making current flow. I'm ignoring cooling for this discussion.
So, while the actual batteries may only be charged during the off-peak window, it could easily look like they weren't because of preconditioning the batteries and possibly the cabin when your departure time is outside of that window. Depending on the time between that off-peak window and your departure time could easily mean any preconditioning done while IN that window would be wasted since things would cool back off again before you were to depart. My guess is that the logic would detect that, and not do much conditioning of the batteries (other than to ensure life) if the departure time was too far outside of the off-peak charging window.
Hopefully, this is actually correct, and can be followed by anyone interested. If I'm wrong, please fill me in. If nothing, it is logical.
Throwing in a low-cost charging window just complicates things.
Then, consider that there are two things that can be conditioned on an i3: the cabin for personal comfort (and it can help with energy use once on full battery since the cabin is already at the desired temp - it doesn't have to come from the batteries to get it there); and, the batteries themselves.
If you tell the car to precondition the cabin, you can do it in several ways. One is when leaving the car, you can tell it to essentially keep the car conditioned while you say go into the store to pick something up. Another is to request the car precondition the cabin when setting a departure time. Or another from the app by using the fan icon.
One thing that has not been particularly clear is that setting a departure time is useful in that it preps the main battery pack, and conditioning the cabin is optional. The ideal temperature of the batteries is around normal room temperature. And, until recently, I'd not considered that because the battery pack is nearly 500#, it can take quite a bit of time AND energy to warm it up. It's in the order of hours, not minutes, depending on the actual ambient temperatures.
So, what does that do when you ask the car to charge during off-peak power? This is my take on it, and I admit I may be wrong, but this is a discussion. IF the car is below some minimum state of charge, it will bump the SOC up some when you first plug it in. There appears to be a bug, and it may or may not continue either then, or later when the off-peak time window opens. But, it isn't unusual when it's cold out for it to charge at least some when you first plug it in.
Then, if all is working properly, it would try to fully charge the car during the off-peak time window. Now, another reason why it may initially turn on the EVSE when you first plug it in is to sample the EVSE's pilot signal which announces how much power it actually can provide - this would give the car an idea what it has to work with. It might NOT be able to fully charge in the off-peak time window if the SOC is low AND the EVSE isn't at least 30A, so, I think that is one reason why it turns things on temporarily even if you tell it to wait for the off-peak window.
Then, consider that you also asked it to precondition in addition to the departure time. If your actual departure time is outside of the low-cost, off-peak window, the car WILL need to turn the EVSE back on again to minimize the battery SOC drain when preconditioning the cabin AND (and this takes several hours) to precondition the batteries as well. Otherwise, heating the 500# of batteries and the cabin could take a big chunk out of the SOC, making a big compromise on your maximum range. FWIW, if you are not plugged in and have a departure time, it won't do much unless you also tell it to precondition the cabin. AT least that seems to be the case. The batteries do warm themselves when driving as a natural function of making current flow. I'm ignoring cooling for this discussion.
So, while the actual batteries may only be charged during the off-peak window, it could easily look like they weren't because of preconditioning the batteries and possibly the cabin when your departure time is outside of that window. Depending on the time between that off-peak window and your departure time could easily mean any preconditioning done while IN that window would be wasted since things would cool back off again before you were to depart. My guess is that the logic would detect that, and not do much conditioning of the batteries (other than to ensure life) if the departure time was too far outside of the off-peak charging window.
Hopefully, this is actually correct, and can be followed by anyone interested. If I'm wrong, please fill me in. If nothing, it is logical.
