Heat "Icon" on the Temperature Dial...

On the temperature control dial, there are two icons to the left of the temperature.

The fan icon seems simple enough. It appears to come on to indicate manual control of the fan. In Auto mode, it turns off.

The heat icon (at least I guess that's what it is), I'm wondering about. I found no mention of it in the manual. I can't test it because outside temps have been in the 50's, so it's colder outside than the coldest climate setting.

Does this icon indicate cabin air is being heated, in general? Or that it's coming specifically from the electric coil heat pack, as opposed to the battery heat exchanger?

In fact, since I'm asking, when the heat exchanger is in use, does the coil pack supplement it? Are there times when the heat exchanger works independently?

eNate said:

The heat icon (at least I guess that's what it is), I'm wondering about. I found no mention of it in the manual. I can't test it because outside temps have been in the 50's, so it's colder outside than the coldest climate setting.

Does this icon indicate cabin air is being heated, in general? Or that it's coming specifically from the electric coil heat pack, as opposed to the battery heat exchanger?

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In November, the same question about the "floor bacon" icon was asked in the Facebook Worldwide i3 Group. There didn't seem to be any definitive answer. Guesses included "heater is on" and "preconditioning is set".

In over 5 years of i3 ownership, I have never seen this icon, probably because the ambient temperature has never been low enough for cabin heating to be on, I have never preconditioned the cabin, and without the seat and battery pack heater option, I would be unable to heat the battery pack.

The only battery pack heat exchanger is the metal plate at the bottom of the battery pack that is cooled by A/C refrigerant while the battery pack is being cooled. The battery pack is heated by electric resistance elements, so no heat exchanger is involved when the battery pack is being heated. So in the probably unusual situation in which the battery pack is being cooled while the cabin is being heated, heat from the battery pack could be transferred to the cabin, but only in i3's with the heat pump option. Without the heat pump option, the cabin is heated only by the electric resistance element in the cabin heating system.

eNate said:

In fact, since I'm asking, when the heat exchanger is in use, does the coil pack supplement it? Are there times when the heat exchanger works independently?

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The i3 heating and cooling systems are described in detail in the I01 Heating and AC Systems Technical Training manual.

All i3's have a coolant heat exchanger that transfers heat to or from cabin air. However, I assume that you are referring to the cabin heat pump heat exchanger that transfers heat between the A/C refrigerant and the cabin "coolant" in heat pump equipped i3's. In such i3's, the electricl resistance heater is activated only when the A/C refrigerant isn't warm enough to satisfy the cabin heating demands. In general, this occurs below -10º C (14º F), probably depending on the cabin air thermostat setting. So the cabin heat pump heat exchanger is the sole source of heat in heat pump equipped i3's but can be augmented by the electric resistance element in very cold weather.

Thanks for the link. I'll read up.

I don't plug in overnight, but do precondition my cabin for my morning departure.

The "floor bacon" (I like that!) icon is on immediately. That leads me to believe it's indicating the coil resistance heater is active.

But later on my drive, when the battery should be producing enough waste heat to warm the cabin, the icon remains on.

Hence my question if the resistive heater supplements the heat exchanger (heat pump). For a driver striving for max efficiency, it would be good to know which heat source is being employed. I'm shocked how much my estimated miles jumps when I shut of climate control. I wouldn't expect such a big jump if my warm air is coming exclusively from waste heat.

I may be wrong, but I don't think any "waste heat" can make its way into the cabin. I believe your only cabin heat source is the resistive element (for we REX drivers) or the heat pump + resistive element (when needed) for BEV drivers. Personally, I leave my heat set at 68 and get along okay. I can gain a few more miles by putting it down to 66, but with the REX, I don't usually do that. I do often wear a light jacket and gloves in the winter while driving, and usually use the seat heater. Not quite as toasty as my ICE, but still comfortable!

jfran2 said:

.. I don't think any "waste heat" can make its way into the cabin. I believe your only cabin heat source is the resistive element (for we REX drivers) or the heat pump...

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That's the waste heat I'm taking about: heat that's a byproduct of propulsion that would otherwise be stripped from the battery and dumped overboard. I'm not suggesting warm coolant is being pumped into the cabin!

I stick with 68° too, which is perfect, although "cold" around here is generally in the 40's. Somewhere between "toasty warm" and OFF though I'd expect to see a jump in range where resistive heat cuts off but the heat pump remains in use. But as I adjust to progressively lower temperatures, I can't find that cutover point.