155 miles remaining on 50% charge!

[WattsUp]

Yup, with the new larger battery pack I just had installed, after driving for a few hours today, I still had plenty of range left:



























Hehe... okay, just kidding. :lol: I still have the normal battery pack. Actually, I went for a long mountainous drive today and, apparently, doing a lot of regen (down hills) really wreaks havoc with the FFE's range meter! It ends up very confused and estimates crazy big ranges.

For those of you familiar with a SF Bay Area, I drove my FFE along Skyline Blvd in the peninsula hills, following this route:



As you can see, there are many winding roads and, as you might surmise, significant elevation changes. At the beginning, after a bit of freeway and suburban driving, the initial climb is very windy. Then, Skyline Blvd (going basically south-east) rides along the tops of the hills and is (comparatively) flat with gentle curves. At the end, more windy roads (to descend) and then finally a trip (all down hill) on Hwy 17 back into Los Gatos.

I started the trip with a full charge and a range estimate of 97 miles (high, but not uncommon for me). After the initial climb, reaching Skyline Blvd, my status was down -30 (!) and the navi said I would have a surplus of only +16 miles upon reaching Hwy 17 (which I knew, if I could reach without dying, regen would get me home). I was a little nervous (having never driven this route in my FFE before) but decided to go for it! My nerves calmed after the bulk of the drive along Skyway, at which point I was still showing a +12 surplus.

But then... with all the descending windy roads near the end of Skyline and then on Summit Road, I did a lot of "one-footed" driving in L, using regen as a form of braking in the curves (fun!). Speeds were 20-30 mph. After several miles of this, the surplus started climbing nicely... I hadn't looked at it for about 10 minutes when, lo and behold, I glanced down and it said something like +50. Whoa! I knew this was not accurate, but at least I was assured that regen was really kicking in and that I would make it to Hwy 17. Which I did.

Finally, after coming down Hwy 17 into Los Gatos, at freeways speeds (50-60 mph) doing heavy regen in L, the range meter said this:



Strangely, after driving on level ground back in the valley for a mile or so at 34-45 mph, the range meter climbed even higher! (Predicting the awesomely crazy 155 miles of range on a 50% charge that I showed an image of at the beginning of this post.)

After another few miles of similar suburban driving, the surplus finally started to decrease, but it was still crazy high:



Out of curiosity, I parked and turned the car off and then back on, to see if the estimated range would persist. It did:



*sigh* If only this were true!

I actually drove around some more, some street and freeway, all on level ground, taking the battery down to about 10%, at which point the range estimate became somewhat more realistic (15 miles). And, as my FFE sits charging now, the predicted range for the full charge stands at 105 miles. So... while I think my FFE is probably still feeling a little giddy from all the regen today, it is done being crazy.

The trip was just for fun... plus, it has been HOT around here this weekend and at the higher elevations of Skyway Blvd it was a bit cooler... and great to drive along with the windows down. Anyway, I'd heard that driving a lot of hills make the range meter go crazy, and apparently it's true!

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Edit: I suppose the thing that really stuck me about this drive was the fact that I had 50% charge upon reaching Los Gatos! At that point, I'd done about 50 miles. Starting out on the 60-mile route, I thought my FFE would probably make it, but that it might be close, given all the climbing. It wasn't close at all. Well at least the next time I do the same drive, I will be able to be much more relaxed.

Btw, while cruising through the hills, I saw a Model S and a Leaf out for a similar drive. I wonder if they recognized me as an EV.

 

[Jasper7821]

I attempted a mountain drive yesterday.
I'm in Tucson at 2,400ft and Mt Lemmon is a little over 9,000ft and 38 miles away.
I made it 5 miles from the little town with 3 miles left on the battery. I
had to turn around, I was so close. It was 110 degrees outside and we had the AC on the whole time.
When I got home my range said 186 miles but the battery gauge looked almost empty.
We went to dinner an hour later (didnt plug in) and it said range was 10 miles and had 7 when we got back

Later in the year when it cools down I know I can make the trip.

 

[FlufferMew]

So I'm confused now. How good is the regeneration then? How does it work/what is it based off of? I've had similar experiences driving up and down hills on the highway heading out towards Ventura County. I see sometimes +20, +30 miles regenerated, but no actual battery percentage is getting regenerated. The percentage doesn't budge. I might gain 1% going down a hill. It just makes it seem like the system of having a Guess-o-meter pointless and flawed to me.

 

[WattsUp]

A positive status does NOT indicate regen. This is a very common misconception.

Now, regen can certainly contribute to having a positive status, but remember that the "status number" in the FFE display is simply the difference between what the original range estimate was (when you turned the car on) and what the current range estimate is (now that the car has been driving along for a while). That's it. It's just a subtraction, and it is constantly varying as you drive, depending on how you drive.

Your driving style and the current driving conditions are the primary inputs that affect the status, not regeneration. A big status number doesn't necessarily indicate that a lot of regen has occurred.

Consider this: If you were to drive perfectly steady on level ground, but very slowly (which uses much less energy per mile than driving fast) your status will start to go up, and possibly positive. Conversely, if you were to start driving very fast, or drive up hill (which uses much more energy per mile than driving slowly) your status will start to go down, and possibly negative.

On my mountain trip documented above, I covered so many miles (doing down hill) near the end of my trip where a very small amount of net energy was being used per mile (because so much of my energy usage was being offset by regen) that the algorithm correctly started estimating that I could continue for another 155 miles under those conditions. I say "correct" because the algorithm is "stupidly" logical. If there were another 155 miles of the same downhill driving, I'm sure that I could have, in fact, traveled that far.

In my case, yes, regen was an important factor in the crazy big range estimates I got, but only in that the plentiful downhill regen significantly changed the net energy used per mile, causing the range estimate to change drastically. Something similar is probably happening to you on your Ventura commute.

So, the "guess-o-meter" behavior can be confusing, misleading, mysterious, etc.. But, once you know how it works (it's just math) it is a little easier to cope with. Obviously, the "real" number to go by is the percentage of charge. That, combined with driver experience (i.e., "getting to know" what the FFE can do with that charge).

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Btw, you can also see the actual miles regenerated in the "trip summary" displayed on the left-hand dash area whenever you turn the car off. It will often be a surprisingly small number (and usually have very little to do with the status).

 

[FlufferMew]

A positive status does NOT indicate regen. This is a very common misconception.

Now, regen can certainly contribute to having a positive status, but remember that the "status number" in the FFE display is simply the difference between what the original range estimate was (when you turned the car on) and what the current range estimate is (now that the car has been driving along for a while). That's it. It's just a subtraction, and it is constantly varying as you drive, depending on how you drive.

Your driving style and the current driving conditions are the primary inputs that affect the status, not regeneration. A big status number doesn't necessarily indicate that a lot of regen has occurred.

Consider this: If you were to drive perfectly steady on level ground, but very slowly (which uses much less energy per mile than driving fast) your status will start to go up, and possibly positive. Conversely, if you were to start driving very fast, or drive up hill (which uses much more energy per mile than driving slowly) your status will start to go down, and possibly negative.

On my mountain trip documented above, I covered so many miles (doing down hill) near the end of my trip where a very small amount of net energy was being used per mile (because so much of my energy usage was being offset by regen) that the algorithm correctly started estimating that I could continue for another 155 miles under those conditions. I say "correct" because the algorithm is "stupidly" logical. If there were another 155 miles of the same downhill driving, I'm sure that I could have, in fact, traveled that far.

In my case, yes, regen was an important factor in the crazy big range estimates I got, but only in that the plentiful downhill regen significantly changed the net energy used per mile, causing the range estimate to change drastically. Something similar is probably happening to you on your Ventura commute.

So, the "guess-o-meter" behavior can be confusing, misleading, mysterious, etc.. But, once you know how it works (it's just math) it is a little easier to cope with. Obviously, the "real" number to go by is the percentage of charge. That, combined with driver experience (i.e., "getting to know" what the FFE can do with that charge).

----

Btw, you can also see the actual miles regenerated in the "trip summary" displayed on the left-hand dash area whenever you turn the car off. It will often be a surprisingly small number (and usually have very little to do with the status).

I see. It makes me hope that they'll provide a better method for monitoring how much energy I'm using and have left for a trip. I know the FFE estimated to have about a 72 mile range. However the budget always says I have about 90-100 miles of range, which of course I know may or may not be accurate. I make a 61 mile trip every weekend from San Bernadino County to Ventura County. And once I get to my destination, I typically have about 20% battery left, which I found I can usually squeeze about 20-25 miles out of depending on driving conditions. But like I said before, I pretty much ignore the miles and focus on the battery percentage. I wish that was more the main focus I guess. XD

 

[dmen]

Fluff, just keep in mind that the displayed battery percentage isn't particularly accurate either, at least until it gets down to ~25%. It's certainly better than the range estimate anyway.

By the way, your Focus *does* offer a display that shows you how much actual energy you've used. Select the Trip display and select enhanced view in the settings. When you start on your trip to the coast with a full battery, reset the trip recorder. Your energy used will display along with the trip's efficiency, time, and miles driven. As long as you know your available capacity (~19.5 kWh when new), you can know how much you've got left. This is my default screen and I find it much more helpful than the range display or the battery gauge.
I plan to take my battery to empty every 10k miles or so to track capacity loss, so that will keep my capacity accurate.

 

[WattsUp]

Another way to think of the status number...

As I described above, the status is simply a difference. It is the difference between two "parallel" estimates... what I think of as the "fixed budget" and the "running budget".

When you start the car, "some algorithm" (let's not care what the algorithm is right now) computes a range estimate based on the battery SOC. This first estimate is called the "fixed budget", and appears in the FFE display (labeled "Budget"). It is conceptually a fixed estimate (computed only once) but it does decrease in real miles traveled as you drive, like a reverse odometer.

The second range estimate is actually constantly re-computed. Again, "some algorithm" uses the current battery SOC and rate of consumption (Wh/mi) to compute this range as you drive. This second estimate (let's call it the "running budget") is displayed on the battery graphic, and you can also see its value reflected in the form of the "status number".

status number = running budget - fixed budget

If you think about how these numbers will all interact as you drive, you realize that the status number basically shows how much "debt" or "credit" you currently have against the original fixed budget. Drive "spending" lots more energy than was budgeted for, and you will see a deficit (decreasing and/or negative status). Drive "saving" (or sometimes "making", in the form of regen) lots of energy, and you will see a credit (increasing and/or positive status).

Note that regen is not required to have a positive status, nor vice versa, through regen can certainly help increase status, sometimes significantly. But, there is no direct correlation between the amount of regen and the status number.

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The status number approach may also make more sense when you engage the navigation system. When engaged, the status number becomes the "surplus number". It's called the surplus because it represents how much "extra" range the car can travel beyond the programmed destination. The whole system basically works the same way, but with slightly different variables.

In navigation mode, the "running budget" is computed just the same, but the "fixed budget" is not based on the battery SOC. Instead, it it simply the distance to your destination. And, obviously, the distance to your destination will decrease in real miles traveled as you drive (just like the fixed budget decreases).

Note that it is entirely possible to enter a destination that will instantly give you a large negative surplus. For example, to some far point outside your current "running budget". Or, you can enter a destination that will instantly give a large positive surplus. For example, some point just a couple miles away.

(And again, note that a large positive surplus number might have nothing to do with regen.)

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Finally, once you understand what the status and surplus numbers mean, you can understand the blue "cup" at the bottom of the energy meter. The cup is designed to help you "stay within budget". If you drive such that the energy meter stays "within the cup", your running budget will always closely match the fixed budget. In other words, staying within the cup means that you should be able to travel the budgeted distance (when not using the navi) or travel the distance to your destination (when using the navi).