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Discussion Starter #1
I have had my Bolt for 4 days and love it. (Previous owner of Prius Plug-In). One question. I live at 9500 ft in Colorado and every drive starts with a 750 ft descent. So I love the Hilltop Reserve feature. Does anyone know exactly how it works? Will it charge to the same level each time (appears to be 195 miles, but I am not yet certain of that). I gain 10 on the descent, so this "empty space" of 45 miles is too much, tho not a problem.

And when I charge fully at home, I wonder what will happen when I descend. Will the green lightning bolt that tells me it is charging at, say, 20 kw, still come on. Or will it not come on because there is no space to store it.

I did see one of the Hilltop threads, and it pointed out that it is smart to use this even when not an a hill. But it did not answer my queries above.
 

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Welcome!

With Hilltop Reserve on, it charges to 88% every time. The visible range is just an estimate of how that range translates into miles; we've taken to calling it the "guess-o-meter", so that number could change depending on your recent driving even though the battery is actually at the same level every time.

If you charge completely, yes, regenerative breaking on your way down the hill will be reduced because there is no room to store the generated power.
 

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Discussion Starter #3
Many thanks. So it will be interesting to see when, starting from a full charge, the green lightning bolt comes on on the downhill. I think you are saying NO.

For us the excitement will be going to Denver and shop, etc., and return. Say it's 170 miles for such a a trip. The issue is that there is 8000 ft climb on the return. And the descent from the tunnel adds range (11000 down to 8700') but one must have enough to get to the tunnel on return. We'll see. I am optimistic and studying all the numbers trying to see if I can count on 4 miles/kwH even in very hilly conditions. Right now, it appears so.

We have a huge backlog of kWh because of 8 years of excess solar panel generation. Should be good for 36000 miles, or more. We signed up for the Tesla but (like many?) cancelled our order because of the excessive delays.
 

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Many thanks. So it will be interesting to see when, starting from a full charge, the green lightning bolt comes on on the downhill. I think you are saying NO.
You'll notice the Regen icon will be white when regen is unavailable/reduced. There's actually a little white hair-thin line under the center line that shows how much regen is currently available.
 

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Discussion Starter #5
Another question. A good goal is 4 mi/kWh. The bar chart looks like it might tell you how you are doing. [[The trip odometer gives this exact average, so as long as I never reset that, I will have the lifetime number. Ok.]] But the bar chart seems totally wrong to me -- in a gigantic way (I'm a prof. of mathematics). I attach it here as a photo. To estimate the numbers, for the five 5-mile segments I used
4 3 2 8 76 for the mi/kwH on each segment


4 1.25 kWh (because 5 mi / (4 mi / kwH) = 1.25 kwH used
3 1.67 kWh
2 2.5 kWh
8 0.63 kWh
76 0.065 kWH

So for these 25 miles about 6.1 kwH were used. Makes perfect sense, and the average is about 4, again perfect. But the red line purports to give an average of 19 mi /kWh. Huh? That would indicate that over 100 miles were driven, when only 25 miles were driven. I hope I am making a mistake and GM does not have some horrible programming error here.

I did reset this this a.m. so I could see what is happening from a known starting (elevation). But down hills give gigantic numbers, making the scale unusable.

Oh, I get it: They are taking the average of the 5 numbers 2, 3,4, 8,76. Add and divide by 5 gives 18.6. This is a bonehead error. I must sent this in to a math journal, because this is really a pretty embarrassing mistake -- not understanding how division works. The x-axis scale is miles -- they are treating it as if it were kWh. Aaaargh.
 

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Another question. A good goal is 4 mi/kWh. The bar chart looks like it might tell you how you are doing. [[The trip odometer gives this exact average, so as long as I never reset that, I will have the lifetime number. Ok.]] But the bar chart seems totally wrong to me -- in a gigantic way (I'm a prof. of mathematics). I attach it here as a photo. To estimate the numbers, for the five 5-mile segments I used
4 3 2 8 76 for the mi/kwH on each segment


4 1.25 kWh (because 5 mi / (4 mi / kwH) = 1.25 kwH used
3 1.67 kWh
2 2.5 kWh
8 0.63 kWh
76 0.065 kWH

So for these 25 miles about 6.1 kwH were used. Makes perfect sense, and the average is about 4, again perfect. But the red line purports to give an average of 19 mi /kWh. Huh? That would indicate that over 100 miles were driven, when only 25 miles were driven. I hope I am making a mistake and GM does not have some horrible programming error here.

I did reset this this a.m. so I could see what is happening from a known starting (elevation). But down hills give gigantic numbers, making the scale unusable.

Oh, I get it: They are taking the average of the 5 numbers 2, 3,4, 8,76. Add and divide by 5 gives 18.6. This is a bonehead error. I must sent this in to a math journal, because this is really a pretty embarrassing mistake -- not understanding how division works. The x-axis scale is miles -- they are treating it as if it were kWh. Aaaargh.
Wow!! That's the kind of question you would find on a grade 5 test.
 

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I don't understand the bar chart. It annoys me, I never look at it. Otherwise I can see or figure out anything I think I need to know.

Maybe it's because I failed grade 5. ;)
 

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The x-axis scale is miles -- they are treating it as if it were kWh. Aaaargh.
Thank you so much for clearing this up. This was driving me crazy. I zero out the trip reading on the dash, and the the efficiency history on the infotainment screen, each time I go for a drive. As you found, the red bar goes nuts. But I still have a question, because after a while the red bar seems to jive with the Mi/kWh indicated on the trip reading. How does it correct itself?

Never mind. I think I just figured it out. If every 5 mile segment were exactly the same, both calculations would give the same answer. But a long uphill, or downhill will give you some 5 mile segments that are way off from the average. But the longer you drive the less those few outliers will affect the average. How did I do, teacher?

Oh! And I know they are doing two separate calculations for the dash, and the infotainment screen, because for the infotainment screen they aren't counting the 5 mile segment you are building currently. The dash is doing a running average counting every mile, as near as I can tell.
 

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Each bar is a 5 mile segment. The x axis is just confusingly/incorrectly labeled. It’s your last 5 miles on the right, the previous 5 miles next, etc. ( I’ve watched it and confirmed this with the trip odometer ). So averaging the bars is the correct way to get overall average kWh.
 

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Discussion Starter #10
Thanks all for comments.

Nautilus: The x-axis looks fine. 50 on the left, 5 on the right, and its says MILES. All perfectly correct. It is working in 5 mile increments. Fine.

But I fear you are wrong re. the average. Imagine each of 9 bars went up to 5 except the tenth went up to 200 because of a downhill. For each 5 mile segment you would have used 1 kWh (5 miles per kwH for 5 miles = 1 kWh). For the down segment you would have used almost 0. So you would have used 9 kWh for 50 miles for an average close to 4.5 mi/kwh. But the red line will do the stupid thing of averaging the numbers 5 5 5 5 5 5 5 5 5 200 = 245, which divided by 10 is 24.5 miles/kwh. It is off by a ridiculous amount from the correct (and useful) answer of 4.5.

There are some tricky things here, in that if one goes 5 miles downhill the actual kWh used is negative, so the bar for that 5 miles should be a negative number. Clearly, they didn't want to do that. But they could have made the red line be the proper average (in almost all cases).

This is all somewhat important since when I go on a long trip I would like to know that I can get 4 mi / kWh. The bar chart could be helpful as I learn. It is not.

Also because there is only the one trip odometer, I feel I should never zero that out because I would like to know the lifetime mi/kwH.

Strange thing just learned today: I am charging on regular outlet. But I chose the 12 amp option. On every restart that resets to the 8 amp option. So I must set this every time I charge. Ok. But annoying.

Clearly this car was designed with very aggressive energy recapturing. Dealer says I should use "L" all the time. I tend to think using neutral once in a while is better than L (I know it is frowned upon), because I hate using any energy at all when coming down from the tunnel (11000 ft) to town (8700). If I use L or D it would often go too slowly. So my gut feeling is that efficiency is gained by bouncing between N and D, but I would need to do some experiments.

Jetson: Yes, if you have no big hills then that bar chart will be somewhat useful. Each particular bar will be 100% accurate. But all driving here is very hilly. I do find the other chart useful: the one that gives kwH used and miles traveled since last full charge. Now, since I am using Hilltop Reserve, this might not reset for a long time. But simply multiplying the kWh by 4 and comparing to the mileage shows if one is beating 4.

Question: Are you all beating 4? Can one get 5 mi/kwH in good conditions (flat, warm)?
 

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Thanks all for comments.

Nautilus: The x-axis looks fine. 50 on the left, 5 on the right, and its says MILES. All perfectly correct. It is working in 5 mile increments. Fine.

But I fear you are wrong re. the average. Imagine each of 9 bars went up to 5 except the tenth went up to 200 because of a downhill. For each 5 mile segment you would have used 1 kWh (5 miles per kwH for 5 miles = 1 kWh).
edit: I see what you are saying now. They are showing the average m/kWh per 5 mile period, not the overall average m/kWh.

Over the last 7,000 miles I have exactly 4.0 m/kWh.
 

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stanwagon,

"I tend to think using neutral once in awhile is better than L (I know it is frowned upon),"

The ATF pump does not work in Neutral. If you persist in using Neutral, we will find out how long it takes to ruin the bearings. :-(

"If I use L or D it would often go too slowly."

If you put it in cruise control, it will go exactly as fast as you want it to, and you will regain some lost energy.

"Question: Are you all beating 4? Can one get 5 mi/kwH in good conditions (flat, warm)?"

Yes. In summer it was easy to do 5 mi/kWh off the interstate. Since fall, we rarely see over 3.7 mi/kWh, using the resistance heater.
 

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Discussion Starter #13
Again, thanks all. There are of course other minor frustrations with numbers.

I just went downhill 2 miles to store then back up. I started with 147.5 kwH used since full charge. This went down on descent, and climbed on ascent, and back home it was 148.4 or so. Fine; makes sense. But the mileage number in the battery capacity was the same value it was when I left! Impossible, except that, as one of you said, this is just some sort of estimate and mustn't be take too seriously. Hence the interest in understanding as exactly as I can the mile/kwH thing.
 

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...the mileage number in the battery capacity was the same value it was when I left! Impossible, except that, as one of you said, this is just some sort of estimate and mustn't be take too seriously.
Exactly. A common mistake that people make is to drive up a long mountain pass and then back down the other side, and exclaim that they have more range at the end than they did at the start. That's because the range estimate weighs recent driving conditions more heavily, and having just gone down a long hill makes it overly optimistic. That may give them a higher estimated range, but a check of the energy display will show that they've used up some of the kWh in the battery and therefore they have less charge than they started with.
 

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Discussion Starter #17
Yes, I can see that the energy display for kwH used is key. It appears that:

1. When charging to 90% with hilltop reserve on, that is not considered a full charge. The display does not reset (a good thing). The green lights flash 4 times to indicate it is only at 90%, not full. But charging has stopped.

2. This a.m. it showed 90% full and a 224 reading, which of course means about 224+22 when full, or 246. So this is just confirming that it is taking my recent calm driving as a guide and would, for now, be well above the nominal 238 if I let it go to 100%. So if one drove somewhat slowly for 1000 miles and average 5 mi/kwh, I guess the virtual tank would read 300 when full. The Prius did the same think, but it only went to between 9 and 12 miles for capacity indication, and we basically ignored that as it was meaningless since past driving does not predict future on a particular day (snow, hills, cold) etc.

3. I will be sending in the erroneous average line at start of thread to a math journal for its educational value, and will probably find a way to send it to GM as well. If anyone has an idea of to whom I might send that, do tell. The fix is easy, and they do upgrade the software once in a while.
 

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1. When charging to 90% with hilltop reserve on, that is not considered a full charge. The display does not reset (a good thing). The green lights flash 4 times to indicate it is only at 90%, not full. But charging has stopped.
That's not how my Bolt behaves. With hilltop reserve turned on the dash indicator goes to solid green once the charge is complete, and the energy usage display (the one with the circle/pie chart braking down usage between driving, HVAC and battery conditioning) resets to 0kWh used.
 

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Discussion Starter #19
OK. Thanks. I suspect I was just premature in disconnecting, as I had a morning errand to run.

What will happen to the bar chart if I reset it at 11000 feet and drive down to 8500 (with no uphill). I guess I should reset the kwH-used screen as well (if I can set that manually; not certain; as it says "since last full charge). Both should be negative after the 7 miles. It will be interesting to see if it is so.
 

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Where does this information come from?
"The lubrication system uses an electric auxiliary fluid pump motor assembly located outside of the transmission for lubrication of rotating components. The transmission fluid pump operates under low pressure and will only run when out of Park or Neutral and vehicle speed is detected."

http://sandyblogs.com/techlink/?p=7070
 
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