Terrain Mapping for Best MPG Route - 2019 Honda Insight Forum
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post #1 of 12 (permalink) Old 01-20-2020, 11:40 AM Thread Starter
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Terrain Mapping for Best MPG Route

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Originally Posted by pasei View Post
Nice. No drop in elevation? Were you in a heated garage? My section of 93 feels overall flat but I see a huge difference in traveling North or South ;-)
Attached is a rough terrain map of I-93 by city, from Lawrence to Quincy. It looks like traveling north of Winchester is 'uphill' and traveling south from Andover is generall 'downhill.'
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post #2 of 12 (permalink) Old 01-20-2020, 11:49 AM
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Attached is a rough terrain map of I-93 by city, from Lawrence to Quincy. It looks like traveling north of Winchester is 'uphill' and traveling south from Andover is generall 'downhill.'
Wait how do you get the elevation of highways? You're using google maps cycling tool right? I can't go on highway when I try.
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post #3 of 12 (permalink) Old 01-20-2020, 11:53 AM Thread Starter
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Wait how do you get the elevation of highways? You're using google maps cycling tool right? I can't go on highway when I try.
Yes, cycling route was the closest path, thus the mention of 'rough' terrain estimate. You can try dragging/dropping points to see if it will adjust the path, but the graph was the closest I could get. Unless there are major hill spikes in a small space, the rough estimate should approximate the area.
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post #4 of 12 (permalink) Old 01-20-2020, 02:50 PM
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Yes, cycling route was the closest path, thus the mention of 'rough' terrain estimate. You can try dragging/dropping points to see if it will adjust the path, but the graph was the closest I could get. Unless there are major hill spikes in a small space, the rough estimate should approximate the area.
Found the way to do it... Google Earth Pro (desktop version, free!)
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post #5 of 12 (permalink) Old 01-20-2020, 04:12 PM Thread Starter
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I look up new/unfamiliar routes to determine what type of terrain to expect... but never did so with conventional cars that climb hills more easily. (i.e. huge contrast between Insight versus a Civic LX rental that took super-steep hills in stride)

For the Insight, I pre-identify routes with alternate terrain that might be an 'easier' drive even if a little further drive distance. It also helps me decide whether to switch to Sport mode and build up battery ahead of time and/or brace myself for engine roar.
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post #6 of 12 (permalink) Old 01-22-2020, 03:28 PM
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I look up new/unfamiliar routes to determine what type of terrain to expect... but never did so with conventional cars that climb hills more easily. (i.e. huge contrast between Insight versus a Civic LX rental that took super-steep hills in stride)

For the Insight, I pre-identify routes with alternate terrain that might be an 'easier' drive even if a little further drive distance. It also helps me decide whether to switch to Sport mode and build up battery ahead of time and/or brace myself for engine roar.
I suppose a long downhill is preferred to a steep downhill. But what about for uphill? For better mpg, would we want a short but steep hill or a very slight incline hill (for a longer distance), or something in between? Assuming all the hills have the same change of elevation and the same downhill past the crest.
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post #7 of 12 (permalink) Old 01-22-2020, 04:05 PM Thread Starter
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I suppose a long downhill is preferred to a steep downhill. But what about for uphill? For better mpg, would we want a short but steep hill or a very slight incline hill (for a longer distance), or something in between? Assuming all the hills have the same change of elevation and the same downhill past the crest.
I find 'rolling' terrain the best for energy management (short uphills, short downhills), and choose it when I have the chance. There's some/minor energy output to climb the short hill, but I just as quickly/easily rebuild charge on the downhill portion. If I know there's a steeper hill in my future, I try to pre-build battery charge in Sport mode.

With regard to downhill stretches, it's about momentum and battery SOC (related to what you can store). You'd want a low enough battery level before a downhill stretch to maximize how much energy can be captured/stored, whether it's a long downhill or steep downhill. Regeneration is happening in both cases, but the battery can only hold so much before full.
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post #8 of 12 (permalink) Old 01-22-2020, 04:40 PM
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Quote:
Originally Posted by pasei View Post
I suppose a long downhill is preferred to a steep downhill. But what about for uphill? For better mpg, would we want a short but steep hill or a very slight incline hill (for a longer distance), or something in between? Assuming all the hills have the same change of elevation and the same downhill past the crest.
I tend to prefer steep hills, especially if you are proactive about building a charge (sport mode). Too long of a descent and you will be engine braking. Trust me, coming through the Berkshires, it's LOUD, it smells, and there is absolutely no escape.

From an efficiency standpoint, the shallower longer climb should be more efficient than a steeper, shorter climb: Say I A) climb 1000 meters over 5 minutes vs B) 1000 meters over 10 minutes.

P= W x (h/t)
Watts = Weight(Newtons) x (height (meters) /time (seconds)).

For this example we will assume the Weight of the car to be 15,000 Newtons
P=
A) 49,950
B) 24,900

The thing physics doesn't cover is ICE runtime; at a certain nexus it's better to run 100% load at time x, than 80% at time z.

There is definitely an ideal number for any grade/distance. My goal is to carry as much force into a climb as possible, and not to descend longer than I can regenerate energy.

2019 Insight EX, Aegean Blue (Owned by my someday wife)
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post #9 of 12 (permalink) Old 01-22-2020, 05:09 PM
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Originally Posted by Wifey'sInsight View Post
I tend to prefer steep hills, especially if you are proactive about building a charge (sport mode). Too long of a descent and you will be engine braking. Trust me, coming through the Berkshires, it's LOUD, it smells, and there is absolutely no escape.

From an efficiency standpoint, the shallower longer climb should be more efficient than a steeper, shorter climb: Say I A) climb 1000 meters over 5 minutes vs B) 1000 meters over 10 minutes.

P= W x (h/t)
Watts = Weight(Newtons) x (height (meters) /time (seconds)).

For this example we will assume the Weight of the car to be 15,000 Newtons
P=
A) 49,950
B) 24,900

The thing physics doesn't cover is ICE runtime; at a certain nexus it's better to run 100% load at time x, than 80% at time z.

There is definitely an ideal number for any grade/distance. My goal is to carry as much force into a climb as possible, and not to descend longer than I can regenerate energy.
You're looking at the potential energy which is overly simplified for a car. The MPG is highly non-linear with slope especially with our hybrid cars. You wouldn't want to climb 1000m over 100km or you'd be wasting fuel. But you wouldn't want to climb 1000m over 100m either because the engine probably doesn't have the power to do it. So I imagine there is a happy medium grade (speed dependent)?

Also, which smell are you talking about re: engine breaking? Can you cruise down in neutral or is it non advised (besides the legality of it)?

Last edited by pasei; 01-22-2020 at 05:12 PM.
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post #10 of 12 (permalink) Old 01-22-2020, 05:52 PM
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Originally Posted by pasei View Post
You're looking at the potential energy which is overly simplified for a car. The MPG is highly non-linear with slope especially with our hybrid cars. You wouldn't want to climb 1000m over 100km or you'd be wasting fuel. But you wouldn't want to climb 1000m over 100m either because the engine probably doesn't have the power to do it. So I imagine there is a happy medium grade (speed dependent)?

Also, which smell are you talking about re: engine breaking? Can you cruise down in neutral or is it non advised (besides the legality of it)?
I know I over simplified it, frankly I just didn't feel like even trying to do all of the math to get a "real world estimate".

The smell from engine braking is probably mostly hot brakes. When you are descending for 10+ minutes and engine braking is active, you are still riding the brakes pretty heavy. I know according to the owners manual, descending in neutral is not advised, I honestly don't even know if the car would allow it.

The simplest answer is the perfect hill is one that you can crest at as close to the lowest remaining state of charge before the engine is providing 100% of the power. Unfortunately we only regain ~80%, so the subsequent hills would have to be further apart, or smaller for an ideal situation.

I just realized that I had deleted the part about "I'd rather climb shorter, steeper in most situations, as the engine can only burn so much fuel x time"

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Last edited by Wifey'sInsight; 01-22-2020 at 05:54 PM.
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