Range and AC usage

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getakey

Well-known member
Joined
Feb 23, 2015
Messages
57
Location
Belmont, CA, USA
Now have a 2018 i3.
recently moved from SF Bay Area to Sacramento area. While in SF area, AC usage was minimal. Here in Sac, temps in summer are frequently in the 100s and still getting to the 90s now in Sept.

I am seeing odd behavior of the range when I adjust AC temp. For example, if I have AC set to 72 and adjust upward to 76 the range goes down. This occurs when I am stopped, so it is not adjusting based on driving. Same thing happens if I adjust from 76 down to 72, the range goes up. This is opposite of what I expect to see.
I have watched this frequently and its almost always the same behavior. A few times it behaved as expected, i.e., range goes up if I adjust temp up and vice versa.
 
getakey said:
I am seeing odd behavior of the range when I adjust AC temp.
I assume that you are referring to the estimated rather than actual range.

The range estimation algorithm is a mysterious beast that mere mortals don't understand well and that one should not take too seriously.
 
I dont quite understand this i3 behaviors, so have been using AC manually , and temperature set to 60.

So the the issue is , there is no button to turn off the Heater. Is there ??????
I observed it can turn on above 64 F , weather you set to Auto or Not
The auto button is only for AC , and then there is a AC button too. So i am confused.

If you observer , it will turn on the heating partially incrementally on , above 66F setting
The sound and temperature start to change , above 64

So this is so complex.
So i guess and hope , when you turn ON AC , above 64F, the heater is turned off automatically.
If you leave your temperature to 76 and turn off AC for 5 mins, your heating is ON. ????

This is the first and only thermostat , i have seen , with no Mode , to turn the heater off. You just use the temperature to turn if off and on . Even with my thermostat set to 72 for AC, i dont want my heating to tun on at just 72.

Please advise , how can i just turn off my Heating ?
I dont need it for 6 months , and often find it turned ON ,by the dial above 64F

There are days in CA, when night is cold and days are still hot. Desert temperature. You need sometimes heating and some times AC.
 
Under some circumstances, the computer will turn heating and/or a/c on, regardless of where you have things set to help with things like keeping the windshield clear. I'd have to read the owner's manual again, but I think there is an actual 'off', except for certain circumstances as my example above.
 
alohart said:
getakey said:
I am seeing odd behavior of the range when I adjust AC temp.
I assume that you are referring to the estimated rather than actual range.

The range estimation algorithm is a mysterious beast that mere mortals don't understand well and that one should not take too seriously.

Well that explains it :)

Heading your way in November
 
EVMan said:
So the the issue is , there is no button to turn off the Heater. Is there ??????
A U.S. i3 has an automatic climate control system, not a separate heater and A/C system like many cars. Apparently in some markets, automatic climate control might be optional with a conventional A/C system standard.

I think I understand how the automatic climate control system works. Please correct me if I'm wrong.

The A/C or Auto button turns the climate control system on while the fan speed button turns it off when pressed on the left end enough to turn off the fan. The cabin temperature is controlled by thermostat knob. When the A/C button is pressed, cabin air distribution and speed are manually controlled with only the cabin temperature automatically controlled. When the Auto button is pressed, cabin air temperature, distribution, and speed are all automatically controlled, thus "automatic climate control".

When the thermostat is set higher than the cabin temperature, the cabin air is first cooled to dehumidify it and then heated to raise the cabin temperature to the thermostat set point. So cabin heating could occur when the A/C or Auto button is pressed which doesn't conform with how many people think of A/C. However, A/C stands for "air conditioning" which could be either cooling or heating in conjunction with dehumidifying.

All U.S. BEV's have the heat pump system that is optional in many markets and unavailable in all REx's. A neat feature of the heat pump system is that it can dehumidify and heat the cabin air without consuming any more energy than required to merely dehumidify the air (the heat would otherwise be transferred to the outside air). However, without a heat pump, the refrigerant compressor must be turned on to dehumidify the cabin air with the resulting heat being transferred to the outside air followed by the resistance heater heating the cabin air to the thermostat set point, a much more energy-intensive process compared with the heat pump system.
 
that makes sense and explains why the AC doesn't go off when that button light is off
and, explains why the fan does not adjust automatically when it is lit

thanks
 
It seems as the fan control is more of an aggressiveness adjustment on how it maintains the cabin temp, not directly fan speed by itself.

For maximum range, not running the HVAC would work, but keep in mind, according to BMW, if you need a/c, it's more efficient to use it for speeds above 25mph verses keeping the windows open. Even if 'off', the car will periodically run things to ensure that the cabin air doesn't become stale and potentially dangerous. US rules basically no longer allow a total off position to prevent problems, and require some ventilation, it seems, even if heat or cooling isn't active.
 
Thanks for explaining this in detail.
But can you explain this simple scenario.

In summers. if you just want cooling and, if you Do NOT have a humidity problem( do not need heating, just need cooling), at what setting should you keep the thermostat ?

In Bay area CA , our temperatures at night dip to below 55F at night and at some days sometimes only goes to 70F
But the Sun is very strong, and car gets heated up quickly, and you still need Cooling in day.

i observed in Rex, , the heater element starts to step in at above 66 setting , at manual setting, at least in winters.

Currently, I just keep my setting at 60F at manual , as i know my heating will be surely off that way.

If i were to keep my setting at 72F in Auto
*In Day , i am afraid , my heating may also be ON , along with my AC ??????
*At night, , when i don't need AC, I am afraid to keep my thermostat at 72F , as at night , i am afraid the heating will turn ON , and i don't see any button to keep the heating off. ??????









alohart said:
EVMan said:
So the the issue is , there is no button to turn off the Heater. Is there ??????
A U.S. i3 has an automatic climate control system, not a separate heater and A/C system like many cars. Apparently in some markets, automatic climate control might be optional with a conventional A/C system standard.

I think I understand how the automatic climate control system works. Please correct me if I'm wrong.

The A/C or Auto button turns the climate control system on while the fan speed button turns it off when pressed on the left end enough to turn off the fan. The cabin temperature is controlled by thermostat knob. When the A/C button is pressed, cabin air distribution and speed are manually controlled with only the cabin temperature automatically controlled. When the Auto button is pressed, cabin air temperature, distribution, and speed are all automatically controlled, thus "automatic climate control".

When the thermostat is set higher than the cabin temperature, the cabin air is first cooled to dehumidify it and then heated to raise the cabin temperature to the thermostat set point. So cabin heating could occur when the A/C or Auto button is pressed which doesn't conform with how many people think of A/C. However, A/C stands for "air conditioning" which could be either cooling or heating in conjunction with dehumidifying.

All U.S. BEV's have the heat pump system that is optional in many markets and unavailable in all REx's. A neat feature of the heat pump system is that it can dehumidify and heat the cabin air without consuming any more energy than required to merely dehumidify the air (the heat would otherwise be transferred to the outside air). However, without a heat pump, the refrigerant compressor must be turned on to dehumidify the cabin air with the resulting heat being transferred to the outside air followed by the resistance heater heating the cabin air to the thermostat set point, a much more energy-intensive process compared with the heat pump system.
 
The hassle with the REx is that it does not have the heat pump that the BEV does, so when heat is required, you'll lose range faster than on a BEV. The a/c will come on if the cabin is warmer than the setting, and may also come on if the system detects condensation on the windshield to help dry the air. Otherwise, if the cabin is cooler than the thermostat, the a/c won't come on. If you turn off the a/c switch and set the thermostat low, you'll get neither heat nor a/c unless the system detects condensation. Unless you need the range, I'd just leave it in auto and enjoy at whatever temperature you prefer. IT can help to precondition the cabin prior to leaving if it is attached to an EVSE. You'll still use electricity, but it won't affect your range except to potentially increase it since it comes mostly from the EVSE verses the battery.
 
alohart said:
I think I understand how the automatic climate control system works. Please correct me if I'm wrong.

I don’t think you got anything wrong, Art. But I would add a couple of refinements.

As with all modern BMWs, the fan buttons have multiple functions.

-In addition to turning the system off with the left fan button, you can turn the system on pressing the right fan button.

-When Auto is off, the fan buttons manually control fan speed. The current speed is indicated by the number of lit LEDs, 1 to 5. At the highest speed, all five of the horizontal LEDs stay lit.

-When Auto is on, the fan buttons control the Intensity level of the auto program or how quickly the system brings the cabin to the set temperature. That is indicated by a single lit LED. The far left is the mildest and the far right is the most aggressive. The ability to vary the intensity of the automatic program confuses many people who are accustom to manual AC systems or even automatics from other manufacturers. Going to a higher intensity and moving the single LED to the right, makes it seems as if the driver is changing the fan speed. In fact, the computer maintains control of the fan speed and may increase or decrease it as conditions demand.

To make things more complicated, changing the driving mode further varies the Intensity. Based on my experience, I think the 2nd Intensity level in Comfort roughly translates to 4 in EcoPro.

You can drive with Auto engaged but the A/C function off. In that case, the system will heat incoming air until the cabin reaches the set temperature. But it will not cool air if the outside temperature is higher than the set one.

Unlike an ICE which routes engine coolant to the heater core to passively warm the cabin air, the i3 (and all EVs) must actively heat the air. An ICE with a manual climate system, can be set so no coolant enters the heater core thus the heat is off but air will still flow through the vents. In an i3, the only way to completely turn off the heat function is the shut down the system by pressing the left fan button until the LEDs are off.

I believe the best way to use the system is to engage Auto, set the temperature to your prefence, and start with Intensity at 3 (middle LED). Move the Intensity up or down depending how you prefer air flow, etc. Once you have your ideal, leave it alone. Let the program do its thing rather than trying to stay ahead of it as you must with a manual system.
 
alohart said:
EVMan said:
So the the issue is , there is no button to turn off the Heater. Is there ??????
A U.S. i3 has an automatic climate control system, not a separate heater and A/C system like many cars. Apparently in some markets, automatic climate control might be optional with a conventional A/C system standard.

I think I understand how the automatic climate control system works. Please correct me if I'm wrong.

The A/C or Auto button turns the climate control system on while the fan speed button turns it off when pressed on the left end enough to turn off the fan. The cabin temperature is controlled by thermostat knob. When the A/C button is pressed, cabin air distribution and speed are manually controlled with only the cabin temperature automatically controlled. When the Auto button is pressed, cabin air temperature, distribution, and speed are all automatically controlled, thus "automatic climate control".

When the thermostat is set higher than the cabin temperature, the cabin air is first cooled to dehumidify it and then heated to raise the cabin temperature to the thermostat set point. So cabin heating could occur when the A/C or Auto button is pressed which doesn't conform with how many people think of A/C. However, A/C stands for "air conditioning" which could be either cooling or heating in conjunction with dehumidifying.

All U.S. BEV's have the heat pump system that is optional in many markets and unavailable in all REx's. A neat feature of the heat pump system is that it can dehumidify and heat the cabin air without consuming any more energy than required to merely dehumidify the air (the heat would otherwise be transferred to the outside air). However, without a heat pump, the refrigerant compressor must be turned on to dehumidify the cabin air with the resulting heat being transferred to the outside air followed by the resistance heater heating the cabin air to the thermostat set point, a much more energy-intensive process compared with the heat pump system.


I experimented with it today and I think if Auto is on it "trumps the A/C button. I did not see a variation with A/C off or on when Auto is lit in terms of fan speed.
Only if Auto is Off, then the system is totally manual for the fan
 
"You can drive with Auto engaged but the A/C function off. In that case, the system will heat incoming air until the cabin reaches the set temperature. But it will not cool air if the outside temperature is higher than the set one. "

I do not find that to be the case. If Auto On and A/C Off, the temp is still cooled.
 
Even if Auto is off , the heater still works. To turn it off , it need to be at 60F. That is my problem. No setting to turn of Heat.
What i do not know is that in Auto at off , if i set it to 70F , is it temperature limited , or just a stepping from 60 to 80 ( 60=0 , 80= Max heat)


getakey said:
"You can drive with Auto engaged but the A/C function off. In that case, the system will heat incoming air until the cabin reaches the set temperature. But it will not cool air if the outside temperature is higher than the set one. "

I do not find that to be the case. If Auto On and A/C Off, the temp is still cooled.
 
EVMan said:
Even if Auto is off , the heater still works.
Even after pressing the left side of the fan speed button until no climate control LED's are illuminated? Here in Honolulu, I never encounter conditions in which heating is necessary, so I have no heating experience.
 
alohart said:
EVMan said:
Even if Auto is off , the heater still works.
Even after pressing the left side of the fan speed button until no climate control LED's are illuminated? Here in Honolulu, I never encounter conditions in which heating is necessary, so I have no heating experience.

OK , You want to make sure , it does not run , as i found out in Manual mode , it was running , at least in winters, when it was easy for me to test.
 
OK, now after experimenting again today, I cannot figure out what changes when Auto is lit and you turn off/on A/C
Sometimes fan speed changes when both are on and sometimes not. It seems like when A/C is off in Auto mode, the Auto is less aggressive at lowering the temp
 
getakey said:
It seems like when A/C is off in Auto mode, the Auto is less aggressive at lowering the temp
Does cooling occur with A/C off? The Owner's Manual describes the A/C button as controlling the "cooling function", so my interpretation would be that with Auto on and A/C off, only automatic heating would occur.

Our 2000 Honda Insight had climate control rather than separate cooling and heating controls. Its user interface was just a confusing as that on our i3. Doesn't seem like a good climate control user interface should be that difficult.
 
got in hot car today
90 degrees outside and car was sitting in sun, so cabin was hot
turned on Auto and A/C OFF
System blew cold air with somewhat high fan rate - not as fast as Max cool
then turned on A/C and there was no change in any behavior
turned A/C off/on several times waiting in between and nothing changed

in previous times after car had cooled down there seemed to be a minor change in behavior with A/C on or off and Auto On
 
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