Hyundai IONIQ Forum banner

1 - 20 of 49 Posts

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #1 (Edited)
To get a better approximation of the range for low and high temperatures it is useful to take into account the losses in kW power for heating or AC. I made a computational model with some parameters for this and I want to ask whether from your experiences the values for certain temperatures are too high, too low or OK. I assume preconditioning took place and this indicates only the average power in kW to maintain the interior temperature during the driving. Note that it sometimes fluctuates between lower and higher, so then an average should be considered.

This is the graph for the current settings (with interior set point 20 °C).

P.S. I modeled the case that a heat pump is used (until -10 °C), as you can see in the curve of the line. For resistance-based heating you have to draw the straight line from -10 °C to the point 0 at 20 °C; see the dotted line in the second graph.
 

Attachments

  • Like
Reactions: Oshawapilot and iet

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #2 (Edited)
I also asked this question on some other Ioniq fora, among which the German one. Based on some first reported experiences I adjusted some of the parameters a bit. For example, now I estimate the heat loss rate of a driving Ioniq at 80 Watt per °C temperature difference between inside and outside temperature. The graph below shows this update, assuming an interior temperature set at 22 °C; the reported experiences are depicted as dots.

Still more experienced numbers are welcome!

Added later: an experience of @pmiddeld for +4 °C with temperature maintenance heating power level 0.5 kW, reported here. The graph was updated only by adding this data point, which turns out to fit well to the previously determined parameter values.
 

Attachments

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #3 (Edited)
The above post was updated today by adding another data point for +4 °C outside. Note that this post addresses the case of maintaining the interior temperature at some level, for example 22 °C (assuming it has this temperature already at the start due to preheating), and finding out how much power in kW you take from your battery for this temperature maintenance.

Maybe some more explanation is useful. An important entity for the above post is how much heat is flowing out of the car each minute or hour, which is called the heat loss. This heat loss depends proportionally on the temperature difference between inside and outside, according to the so-called heat loss rate, which is a parameter that indicates heat loss for just 1 °C difference in temperature. The heat loss rate was now estimated at 80 Watt per °C difference in temperature between outside and inside. For example, when the outside temperature is +4 °C and the interior is at 22 °C, then this temperature difference is 18 °C, so the heat loss is 80*18 Watt = 1440 Watt. You can interpret this in the sense that the car heats the outside air as if it was a 1440 Watt heater.

To compensate for this heat loss, and thus maintaining the interior temperature at the same level, you need to add the same amount of heat by the car's heater. Fortunately, under these conditions a heat pump can produce 1440 Watt by only using a fraction of that amount of energy, in this case about 500 Watt. To know how much in kWh this will take from the battery you can just multiply this number by the duration of the trip in hours. For example, for a two hour trip it will cost your battery 2*500 = 1000 Wh = 1 kWh. This reduces the available full charge of 28 kWh by 1/28 = 0.036, which is almost 4%. You can expect a reduction in range by the same percentage due to having the heater on.

This is all about maintaining the interior temperature at the same level, assuming the car was already preheated at that level at the start. In my next post here I will address the case that you did not do preheating: how much in kW do you take extra from your battery then, and for how long, to get the car's interior at the right temperature during the first couple of minutes, and how much in kWh in total does that take from your battery?
 

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #4 (Edited)
Besides keeping the interior temperature at a certain level, for example 22 °C, the car's heater is also used to bring the temperature at that level in the first place. This happens when no preheating was applied. For example, when the car is at temperature +4 °C when you leave, then the heater has to increase the temperature by 18 °C until it is 22 °C. The amount of energy needed for this depends proportionally on the difference in temperature with a rate that is called the heat capacity of the car. The heat capacity is a parameter that indicates the amount of energy needed to increase the car's interior temperature by 1 °C.

Note the difference with the loss rate in the above post. Loss rate depends on the surface or 'skin' of the car's interior, such as the roof, the windows, the floor, the doors, and how well insulated this skin is. In contrast, capacity depends not on the surface, but on the volume and/or mass of the interior, how much heat energy the interior in a sense stores or absorbs by heating it. If some material stores a lot of energy, you need a lot of heat to let the temperature rise, if it stores less energy, less heat is needed to let it increase.

When for some cases you know the amount of heat delivered by the heat pump and/or resistance heater, and also how many degrees °C the interior has increased in temperature, you can estimate the heat capacity parameter. For example, when for 5-6 minutes the heater works at 5-6 kW (as reported by @pmiddeld here), then the total amount of produced energy can be calculated by 5.5*5.5/60 = 0.5 kWh. This energy also is taken from the battery, so that for a two hour trip as in the above post your battery spends 1.0 + 0.5 = 1.5 kWh on heating. This is 1.5/28 = 0.054 of the whole battery, which is 5.4 %. By this percentage also your range will be reduced. Assuming the increase in temperature was 18 °C (from 4 to 22), this gives an estimate for the heat capacity parameter of 0.5/18 = 0.028 kWh per °C increase.

However, the above calculations assume that the increase in temperature is fully based on the resistance heater. When the car also has a heat pump, then this will probably also contribute to the increase. As it increases very fast in only a few minutes time, it is probably not only the heat pump; maybe most (or almost the whole) of the increase is due to the resistance heater.
 

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #5 (Edited)
Although I seem to be a bit alone in this thread, at least from the likes I noticed, I conclude that three of you are reading this thread sometimes. So, this gave enough motivation to make the next step that I will show in this post.

In the previous post I have shown an example calculation of one situation. Now I made a computational model that gives an indication for each outdoor temperature what the initial heating to increase the car's temperature to 22 °C will cost you in kWh from the battery (when you did not do preheating). See the graph below; in this graph two cases are compared: heating only based on a Resistance Heater (RH) in purple, and heating based on a Heat Pump (HP) in combination with a Resistance Heater in light blue/grey.

It can be seen that the heat pump only has a very modest advantage over the resistance heater for this initial heating. Roughly spoken this initial heating may cost you 0.5 kWh (for +5 °C) up to 1.5 kWh (for -20 °C).

I assumed that when a heat pump is available, the initial interior temperature increase is for 80% based on the resistance heater and for 20% on the heat pump (and only for -10 °C and higher). This is based on an assumption on the maximal power the heat pump can take (1200 W) and the related maximal production capacity of the heat pump. As the initial heating takes place very fast, as a kind of boost, I think it is reasonable to assume that the resistance heater plays a main role in it.

For these graphs the heat capacity of the car was assumed 0.0286 kWh per °C increase, which made that the data point from @pmiddeld mentioned in the previous post is on the curve. Of course, again more data points are welcome.

In the thread on Electric Range I will post implications for the range, both for initial heating as addressed in this post, and heating to maintain the interior temperature addressed in previous posts above.
 

Attachments

·
Registered
Joined
·
131 Posts
Very interesting analysis. I might buy an external ceramic heater to preheat the car in winter and use the sunroof in summer.
 

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #7
If this ceramic heater uses electricity like a resistance heater, then the analysis above also applies to that: at how much power can it work? In the graphs you can see how much power is needed.
 

·
Registered
Joined
·
131 Posts
It will be a small ceramic heater which will be plugged into the standard home outlet, instead of using the battery.
 

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #9
So, also then the limitation in power to at most 1.44 kw will apply, do you consider to use it via a separate wire together with the car's heater? Then in principle you can double the power that is brought in the car to 2.88 kW.
 

·
Registered
Joined
·
131 Posts
So, also then the limitation in power to at most 1.44 kw will apply, do you consider to use it via a separate wire together with the car's heater? Then in principle you can double the power that is brought in the car to 2.88 kW.
That is an interesting concept of running both at the same time. I didn't think about that. Portable Ceramic heaters are usually around 0.7 to 1 kW, depending on the size.
 

·
Registered
Joined
·
328 Posts
I could be wrong as I don't have the vehicle yet.

The 1.3kW should be able to do the preheat cycle without dipping into the battery reserve if it is not too cold as long as the battery is fully charged.
 

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #12
Yes, and the graph gives an estimate of what is to be considered as 'not too cold'.
 

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #13
Now the heating season has gone for most of us, we enter the opposite season: using AC to keep the car cool enough. Yesterday during a longer trip I monitored what power the AC was taking. It was sunny, the outdoor temperature was 26 °C, and the cabin temperature was set at 21 °C, so 5 °C difference. The fan was blowing mostly two bars.

Although it fluctuated a bit, the average power usage by the AC was around 0.4 kW. By the way, the accessories (including the radio and the screen displaying the power levels) took about 0.25 kW. Are there any other numbers observed (average over a longer time period)? For example, if the difference is 10 °C (outdoor temperature 31 °C), is the AC power usage than double, so 0.8 kW? Or less or more?
 

·
Registered
Joined
·
159 Posts
So, if you use the pre-heat option and set a departure time, does it use the mains electricity to heat/cool the car, or the battery?

Does the battery need to be fully charged?

What happens if you don't get to the car at the exact time? Is the temperature maintained and for how long?

Will it defrost ice?

How much earlier than your departure time does it start and what would be noticeable from the outside? (Fan blowing etc)
 

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #16 (Edited)
So, if you use the pre-heat option and set a departure time, does it use the mains electricity to heat/cool the car, or the battery?
From the wall.

Does the battery need to be fully charged?
No, if you let it start not long before the departure time it will preheat or precool while the battery will not get much extra charge, because it doesn't get enough time for that. For example, you can do it just during the last 15 minutes before departure.

What happens if you don't get to the car at the exact time? Is the temperature maintained and for how long?
No, the connection to the wall will be disconnected at departure time, and nothing will happen from then.

Will it defrost ice?
Yes, that is a very nice effect. The car gets so warm that everything melts.

How much earlier than your departure time does it start and what would be noticeable from the outside? (Fan blowing etc)
The charging starts long before if you give it that time. The preheating or precooling mainly in the last half an hour as far as I know.
 
  • Like
Reactions: Patrick

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #17
In another thread @Alien-S (post #17) reported another data point for temperature maintenance for cabin temperature 22 °C: average power level using a heat pump 0.6 kW at 7 °C. I added this data point to the most recent graph above. See the new graph below. I didn't see a reason yet to adapt the parameters of the model for this new data point. Now for most of us it gets colder again, more empirical data points are welcome to get a more accurate graph.
 

·
Registered
Joined
·
47 Posts
Yesterday night, i take a few minutes to register the heating power using Torque Pro. Graph is attached.
You have to know that in Torque Pro there is not data specificaly for the climate, so i use total kW and i subtract 0.60 for the electronic. And also i wait until the power stabilize before to drive.


The outside temperature was 2 °C. The Inside was set to 22 °C.


The energy required to maintain temperature fit pretty much with your graph.
 

Attachments

·
Super Moderator
Joined
·
1,643 Posts
Discussion Starter #19
Nice picture!
 
  • Like
Reactions: reald

·
Super Moderator
Joined
·
8,235 Posts
Yesterday night, i take a few minutes to register the heating power using Torque Pro. Graph is attached.
You have to know that in Torque Pro there is not data specificaly for the climate, so i use total kW and i subtract 0.60 for the electronic. And also i wait until the power stabilize before to drive.


The outside temperature was 2 °C. The Inside was set to 22 °C.


The energy required to maintain temperature fit pretty much with your graph.
which set of PIDs are you using for torque pro?

I know a few members are using it, but PIDs are a modified set from Kia soul EV

you seem to have details I have not seen available before
 
1 - 20 of 49 Posts
Top