Trip meter failing to factor in regen energy

[johnr]

Hi! I just purchased my truck last month, and there was this one issue I noticed during a long descent - the trip energy meter was failing to account for energy recovered due to regen braking, and instead erroneously counted that energy as a loss due to "temperature". This has been happening all the time, every time I slow down and energy is put back into the vehicle, the trip meter incorrectly counts this as a "temperature" loss.

Here's a picture showing just how stupid this looks!

I took the vehicle to the dealership and they updated the software but it did not solve the issue. Before taking it back to the dealership, I wanted to check how your experiences have been relating to the trip meter and energy meter when using regen on long downhills. How does your trip meter indicate regen energy?

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[RST]

I wouldn't say it didn't factor in the regen. You averaged 12.4 miles per kWh, on your 15.9 mile ride. That's about 5 times better than you'll get on flat road driving.

 

[Amps]

The screenshot shows, "Where did my energy go?"

A: 85% of the minuscule total amount of energy that was expended from the HVB on the trip (15.9/12.4=1.28 kWh) went to tasks dealing with the exterior temperature; 15% to accessories.

The regen is reflected in the consumption efficiency of 12.4 mi/kWh. You could approximate it by dividing the distance by your average consumption and subtracting the net 1.28 kWh you actually consumed. ex: If your average is 2.0 mi/kWh, your net regen was about 6.67 kWh restored to the battery when compared to an average trip. (15.9/2.0)-1.28

 

[Heliian]

There is nothing wrong with your screen.

You barely used any for driving. The majority of your electrical usage went elsewhere.

The inverse will happen going uphill.

 

[TaxmanHog]

What was your SOC at the start of the trip down the mountain, assuming you had plenty of buffer to store all of the 6.7 KWH you generated.

If you started at 100%, some or most of the energy might have been wasted through the PTC to consume the extra KWH and CHILLER to export that heat to the condenser up front with fans blowing hard.

 

[snowy_91]

the software is simply not capable of showing negative energy loss from driving.

 

[Piquette]

In my ‘22 Lightning Lariat ER coasting down a long hill (only occasionally using the brake) the left hand meter on the control panel shows green and what appears to be a fair amount of charging. Still, at the bottom of the hill the range meter (aka Guess o Meter or GOM) shows very little gain in range before empty.

I suggest you watch your Mi/kWh as others have, and if you want long range drive so the Mi/kWh value is as high as possible. Drive the terrain, and plan ahead for braking to a stop and starting moving again. The GOM does not respond immediately after charging/coasting down a hill, but over a span of 3-5 miles traveled you should see the decline in the GOM to empty much more more slowly.

You will see the benefits of your careful driving the next time you charge the battery to 100%. The total range will increase over time as the truck learns how you drive.

 

[Grease Lightning]

Hi! I just purchased my truck last month, and there was this one issue I noticed during a long descent - the trip energy meter was failing to account for energy recovered due to regen braking, and instead erroneously counted that energy as a loss due to "temperature". This has been happening all the time, every time I slow down and energy is put back into the vehicle, the trip meter incorrectly counts this as a "temperature" loss.

Here's a picture showing just how stupid this looks!

I took the vehicle to the dealership and they updated the software but it did not solve the issue. Before taking it back to the dealership, I wanted to check how your experiences have been relating to the trip meter and energy meter when using regen on long downhills. How does your trip meter indicate regen energy?

As others have asked, we need to know you SOC at the start and stop to better assist in your question.

Your display shows you only used approximately 1.28 kW on that trip and all was given to other elements. Around 0.20 kW to your accessories and 1.08 kW to your trucks cooling/heating system for the drivetrain.

In your case the regen was the difference between your normal coasting energy used by the aforementioned systems and the amount used on this trip.

So the big question was how much energy would the Lightning have used to roll 15.9 miles without spinning up the motor or regenerating energy

 

[johnr]

This was after a 15-mile non-stop descent. There were only a couple of very short level sections which is where the 12.4mi/kwh comes in - the rest (14 miles of the 15) was all downhill, regening the entire way. I should have written down the state of charges at the top and bottom, but I didn't. I think it was somewhere around 35% at the top and around 38% or so at the bottom. There was definitely a significant net increase in energy resulting from the downhill.

In my opinion, the meter should show the driving energy in negative if it is negative as was the case this time. Then it would make sense. The temperature was 70F and the battery was not cold, so ordinarily no energy should go toward "temperature", and in level driving the "temperature" energy has always been displayed as zero. I hope this helps.

 

[johnr]

I did some more tests last weekend and took several photos to share with you here.

The first is 1.8 miles of mostly downhill. As you can see, the meter is claiming that a whopping half of my energy went to "temperature" despite the fact that it was 76 degrees outside. Clearly, "temperature" is being used as a catch-all for when the numbers don't add up because the computer fails to consider regen in the calculations. The picture is below:

The second test is 16 miles of all downhill. The trip meter correctly shows that no energy went to driving, as this was ALL downhill. However, it really should show a negative number for driving, due to regen, but it doesn't. Instead, since it fails to consider regen, the numbers don't add up so it incorrectly assigns an absurd amount to "temperature", in this case a whopping 80%. It also incorrectly shows 12.4 mi/kwh despite the fact that absolutely no energy was used for driving, and in fact a lot of energy was generated in regen. Here's that image:

At this point, I turned the vehicle off and back on to reset the trip meter. Here are the screens at the time the meter was reset. It's showing 99 miles of indicated range and the energy gauge is slightly below the halfway point so it looks to be about 48%. Temperature outside is 62 degrees. Here is that photo:

After 8 miles of all downhill, it's showing 118 miles of indicated range, and the energy meter is just slightly over halfway mark, looks to be about 51%, showing a net increase in energy in the battery. The energy meter incorrectly indicates 7.8 mi/kwh despite the fact that no energy was used for driving, and the meter shows 90% for "temperature" although it's 74 degrees outside.

A couple more miles later, after 10 miles of all downhill, it's now showing 122 miles of indicated range, and the energy meter is showing another slight increase, looks to be about 52%, showing a net increase in energy in the battery. The energy meter incorrectly indicates 8.9 mi/kwh despite the fact that no energy was used for driving, and the meter shows 92% for "temperature" although it's 76 degrees outside.

After 33 miles (the first 13 miles were ALL downhill, and the rest were mostly down with some up and some level), it's now showing 144 miles of indicated range, and the energy meter looks like it's right at halfway mark now, showing a net usage of energy since the previous reading, but a net increase since the beginning of the trip. The energy meter incorrectly indicates 15.5 mi/kwh and it claims that no energy was used for driving, and the meter shows 84% for "temperature" although it's 79 degrees outside.

At the end of the trip, 41 miles in total, the energy meter has gown down to just under halfway, it looks like about 48% now, and it indicates 140 miles of range now. Between the last reading and now, it has been all level going at highway speed. The meter is showing 20.7 kwh/mi now, which is more than the last reading, even though the vehicle has actually been consuming energy at a much greater rate after the last reading due to driving faster and on level ground instead of a net downhill, so that's really weird. I think it's factoring in the energy usage for the whole trip only when energy was used, not when regen was used, and as such the previous stretches despite being more downhill were considered to be using more energy because the downhill parts were not counted.

Here are those four images for your reference, first after 10 miles of all downhill, second after 13 miles of all downhill, and the last two after 33 miles and after 41 miles of mixed driving (the first 13 miles of this trip were all downhill, the next 18 were up and down but mostly down, and the last 10 were all level).

8 mi:

10 mi:

33 mi:

41 mi:

I hope this additional data is helpful. Would like to hear your feedback.

 

[TaxmanHog]

What were your SOC's at the start and end of the test session?

 

[johnr]

During the main downhill section, the beginning SOC was 48% and ending SOC was 52%. I did a similar test just the other day too, with ending SOC significantly more than beginning, and again the trip computer didn't know what to make of that. I'm surprised at the lack of comments here - either nobody else is experiencing this issue, or nobody else is bothered by it, I guess. To me, this is a big problem.

 

[Webbo85]

Hi John,
I actually think it's working correctly. It breaks down how the energy is used in percentage form which can be confusing. So you went 8.1 miles downhill essentially. The car was getting 7.8 mi/kwh, so essentially that's telling you that it took 1.04kw of energy to travel those 8.1 miles. You're going downhill so you gained more energy from Regen than from the motors working (0%). You didn't have cabin heat on (0%). Guessing you had your phone plugged in (10% of that 1.04kw). Rest of the energy, .9kw was used through "External Temperature". My guess is that 'External Temperature' is probably heating or cooling of the battery pack and running any of the systems to maintain the batteries, others may know more.

In the 41 miles you were getting an efficiency of 20.7 mi/kwh, essentially using 1.98 kw. And where those 2 kw were used is broken down in percentages. I don't see anything wrong if you're actually driving downhill for that long. As soon you would drive on flat or uphill and use more energy, your percentages would shift rather quickly.

 

[TaxmanHog]

There have been other threads discussing the impact regen energy recovery, none as drastic as your example.

The bar chart is designed for net consumption, you had no net consumption for driving so the amount of energy to moderate the pack temperatures and accesories is exaggerated.

 

[johnr]

I see. That makes sense.

BTW I also sometimes notice this even in around-town driving (stop-and-go) - whenever regen braking is used, that energy gain is not accounted for as the chart only shows consumption, so the "temperature loss" part of the display gradually begins to increase to fill the gap, and the mi/kwh figure is not accounting for these bursts of regen, so the displayed mi/kwh figure keeps dropping although I know I'm getting more mi/kwh than on the highway.

I wish Ford would update the software to factor in regen data in the mi/kwh figure, although they would probably have to change it to kwh/mi to avoid a potential infinity divide by zero situation. At the very least, show the kwh consumed/generated since last charge. As it is, we're getting terribly inaccurate data whenever there is a significant amount of regen used in a trip.

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