Inaccurate energy consumption calcs on trip computer???

[DrivingForce]

I have a 2016 Kia Soul EV+. I like to reset the "energy consumption" computer daily on the instrument cluster. However, it seems like it is really inaccurate. I have it set to "manual reset".

As far as I know, the car has a 27kWh battery. Today, I started at 100%. I reset the energy consumption computer. I drove 92.69 miles, charging midway with an EVGo DC Fastcharging station for just 6.83kWh. I finished my drive at the end of the day with 17% remaining. By my calculations:

(100% - 17%) X 27kWh = 22.41kWh

22.41kWh + 6.83kWh (from EVGo) = 29.24 kWh consumed TOTAL

92.69 miles / 29.24kWh = 3.17 miles/kWh

For some reason my energy consumption computer reported 3.8 miles/kWh. Why is there such a discrepancy? Am I missing something?

 

[IanL]

The problem is that we have no calibrated test equipment with which to validate any of the data sources. It seems more likely that the car's measurement of kWh consumed is reliable, and the SOC value of 17% less so. The other data source, the measurement of kWh charged, is also a possible source of error.

So, there is no knowing whether the consumption calculation, or the data with which you are trying to check it, is in error. Perhaps both.

 

[JejuSoul]

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I disagree. none of this data is particularly reliable. The kWh data is probably the least accurate.
The distance driven is probably the best bit of data here, but needs to be confirmed with GPS readings.
The consumption figure given by the car is probably within 10% up or down.
The EVGo figure for kWh is not the energy that goes into the battery. It is the energy that you pay for.
You pay for all the efficiency losses between the meter and the battery. Assume this figure is 20% too high.
The kWh figure you assume for the car's battery may be least reliable. It depends.
Factors to consider include the SOH and the temperature of the battery.

 

[DrivingForce]

So if I want to calculate my energy consumption most accurately, what is the most accurate way to do it? It just seems like in general, the instrument cluster is overestimating. I would in theory like to multiply that figure (mi/kWh) by the battery capacity (27kWh) to get an accurate figure on my range. However, if I multiply 3.8mi/kWh x 27 kWh that is 102.6 miles, and I'm not getting anywhere close to that in reality.

I do have a Bluetooth OBD scanner and Soul Spy, but I don't know what to look at to come up with a better number. Would just multiplying 27kWh by the SOH% give me a better starting point for total battery capacity?

 

[JejuSoul]

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There is a lot of detail in this article by Tony Williams on how to do a standardized range test on a brand new car. Given the usable capacity is known at this point, the energy consumption calcs can be checked for accuracy.

Kia Soul EV Range Autonomy Demonstration Nets More Than 100 Miles - Video

If you perform the same test a few years later under the same conditions, you can compare the range to determine the real drop in the battery capacity. It is unlikely to be totally exact because so many things may change - weather, wear on the tires.

Another method is to use the internal data from the car using the OBD port. The readings you want are the cumulative energy charged and discharged. In Torque I label these CEC and CED.

 

[IanL]

..... Would just multiplying 27kWh by the SOH% give me a better starting point for total battery capacity?

I'm quite doubtful of the accuracy of the SOH from Torque. My understanding is that it's based on values obtained from the best and the worst cells. I don't know how KIA's diagnostic system assesses it, but you'd expect it to take into account the condition of all the cells, not just two.

 

[JejuSoul]

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Calculating the real SOH at a single instant is something best done in a lab.
The value Torque gives is one that matches the value that Kia's own GDS software will use to determine whether or not to give a replacement battery. It is irrelevant to 99% of users whether this value is 'real' or not, they only want to know when to take the car in for a replacement battery.

Only 1 value is used by Kia to calculate the SOH. The value for the cell with the maximum deterioration. This makes no sense initially but ultimately it is absolutely correct, The worst cell determines when the battery will die.

I prefer to calculate the actual SOH using readings over many seasons. Then plotting a linear decay. The instant value for SOH is often + or - 5% from the line. This method works until it doesn't. At some point the linear trend will cease and rapid deterioration starts. I cannot predict when this will occur.

 

[spencerledlow]

My 2016 pretty consistently shows 4.2 miles/KWH if I don't drive 70+ mph. My calculations based on a KWH meter and the indicated miles has also been a consistent 2.8 miles/KWH. Is it possible that charging the battery is only 70% efficient? BTW the KWH meter is an inexpensive add on for L1 charging.

 

[notfred]

If you are charging with L1 at 120V then yes, it is quite inefficient.

The problem is that the car takes a certain amount of power to run things while charging. At L1 that's a significant percentage of the power coming from the wall, while at L2 it's a lot smaller percentage which makes the L2 charging more efficient than L1

 

[ksoul2084]

If you are charging with L1 at 120V then yes, it is quite inefficient.

The problem is that the car takes a certain amount of power to run things while charging. At L1 that's a significant percentage of the power coming from the wall, while at L2 it's a lot smaller percentage which makes the L2 charging more efficient than L1

With my 2016 I have calculated the following approx. charging rates using L1 (120v) charging during "normal" temps and very cold outside temps:

Normal: +1.82 kWh per hour
-29c: +0.54 kWh per hour

So you can see that the car uses and additional 1.28 kWh equiv. every hour to heat the battery pack when it is very cold.

 

[notfred]

1.82kW at 120V is just over 15A. The cable that comes with the car only signals the car to charge at 12A in accordance with the continuous load requirements in the electric code. The 2016 also derates what the EVSE tells it at 120V for further fire safety - I think it ends up only drawing somewhere around 10A. Are you using a different EVSE cable on a higher current circuit?

Rather than the battery heater, I was referring to the power consumed by the electronics when the car is on - I think people worked out it's about 300W. So with the standard EVSE cable the car would draw 1.2kW from the wall but only 900W of that goes in to the battery i.e. 75% charging efficiency. If you are charging at L2 with 7.2kW then you get 96% in to the battery.

 

[ksoul2084]

1.82kW at 120V is just over 15A. The cable that comes with the car only signals the car to charge at 12A in accordance with the continuous load requirements in the electric code. The 2016 also derates what the EVSE tells it at 120V for further fire safety - I think it ends up only drawing somewhere around 10A. Are you using a different EVSE cable on a higher current circuit?

Rather than the battery heater, I was referring to the power consumed by the electronics when the car is on - I think people worked out it's about 300W. So with the standard EVSE cable the car would draw 1.2kW from the wall but only 900W of that goes in to the battery i.e. 75% charging efficiency. If you are charging at L2 with 7.2kW then you get 96% in to the battery.

I am using this cable: https://www.amazon.ca/gp/product/B07CYQV2VL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1&fpw=alm

It is an approx. number for sure, but the difference between the two are using the same plugin and charger, etc.

I think that there would be a percentage of total power during charging that will be lost to heat, so it's not as simple as saying 300w baseline to run the electronics, there are also heat/resistance related losses that may or may not favour level 1 vs level 2 in terms of overall efficiency.

 

[notfred]

That cable is scary, I hope you have a proper 20A circuit that it's plugged in to. If you have that plugged in to a normal 15A socket via the adapter that it comes with, you are asking for an electrical fire!

Yes, the losses will vary, including whether the water pump, radiator fan and battery fan need to run. I just wanted to highlight that with lower power comes significantly lower efficiency.

 

[spencerledlow]

If I were a heavy user I would probably now switch to L2 but just using ~100KWH a month I could never recover the investment. I do appreciate finding out where the extra watts went. In Austin I don't see the cold weather. My indicated and measured miles/KWH don't vary much over the year.

 

[ksoul2084]

That cable is scary, I hope you have a proper 20A circuit that it's plugged in to. If you have that plugged in to a normal 15A socket via the adapter that it comes with, you are asking for an electrical fire!

Why is that? I use it with regular 120v circuits, and have been for over a year without so much as blowing a breaker.

The description states "Perfect replacement for manufacturer's original level 1 charger by using the provided 110V adapter, which connects to a 110V regular home outlets(charging speed is capped at 13 Amp to prevent circuit overheating)."

 

[EVDee]

From my own experience: when I first got mine I was charging from an outside 120V outlet that we had. Thankfully I kept checking the cable and it became apparent that there was an issue when I noticed the plug was discoloring. I took a proper look at the electrical box and noticed we only had a 15amp breaker/circuit. Replaced it with both a 20amp breaker, and had it rewired for 240V - been smooth sailing since.

I was really lucky that I knew where to check for issues, and that the plug-end I used made it easy to tell there was an on-going issue. It took several months, but it happened, and I worry what may have happened had I not noticed.

 

[notfred]

1) It should be 12A not 13A at 120V. The 15A circuit is good for 12A continuous load.

2) You are reporting it charging at 1.82kW which is 15.1A. I don't believe it is dropping to the 13A it claims and is just signalling the car at 16A. That's OK if you plug it in to a 20A circuit, but you aren't.

3) Reviews point out it isn't CSA certified. Reviews also mention melting of the adaptor, another sign that it is drawing too much current.

 

[ksoul2084]

1) It should be 12A not 13A at 120V. The 15A circuit is good for 12A continuous load.

2) You are reporting it charging at 1.82kW which is 15.1A. I don't believe it is dropping to the 13A it claims and is just signalling the car at 16A. That's OK if you plug it in to a 20A circuit, but you aren't.

3) Reviews point out it isn't CSA certified. Reviews also mention melting of the adaptor, another sign that it is drawing too much current.

Interesting. Well on the upside, it's "turbo" charging my car for me!

Wouldn't the 15A breaker flip long before the wires got hot enough to start a fire?

 

[notfred]

In theory it should trip after 3 hours. In practice it almost certainly will not.

The breaker is measuring the current, it can't tell how hot any of the rest of the parts of the circuit is getting, If you have a brand new good quality socket with good contacts and good connections to it, you'll probably be OK. But any poor contacts any where on that circuit and it can cause a fire.

 

[ksoul2084]

In theory it should trip after 3 hours. In practice it almost certainly will not.

The breaker is measuring the current, it can't tell how hot any of the rest of the parts of the circuit is getting, If you have a brand new good quality socket with good contacts and good connections to it, you'll probably be OK. But any poor contacts any where on that circuit and it can cause a fire.

Okay, I will run some tests and check the wiring and plug.

Thanks for the heads-up.