Steep ramps and gently slopes

Better steep or gently?

To answer, we'd need 2 roads that start and finish in the same place, while passing the same peak.
Pretty hard to find.
We may try to find an approximate answer with an asymmetric trip: the outward leg has a gentler slope than the return one.
The altimetric profile shows an highway section, so we are talking about higher than usual speed here.

We can't use the full trip, because the starting and ending point are at different altitude.
We need to fix a fictional "zero level" from which we'll start from one side of the mountain and end on the other side.
By picking up 2 point of equal altitude, we'll have equal potential energy; we also need to account for differences of cinetic energy (we're not standing still in those points) and electric energy (SOC level).

Let's choose the 150 m quote that crosses the profile first after 6 km and then again on the downward slope at nearly 63 km.
Using GPS coordinates, we can find the same point on the return trip log.

Here's the start:
Row: 612
Longitudine: 8.57436894
Latitudine: 44.87122654
Speed: 84
SOC: 56.47058868

And the finish line:
Row: 2066
Longitudine: 8.73766059
Latitudine: 44.4367162
Speed: 98
SOC: 69.41176605

We need to delete from the log all rows not belonging to the above range.

Then, we should rewrite columns
Trip Distance(km)
Fuel used (trip)(l)

by subtracting the value of the starting point to all other values.

Now, by running the analyzer, we'll have the stats only for the selected range.

Moving on to the return trip log, we search for the same points used as start and finish, this time in reverse order tough.

Start

Row: 1009
Speed: 68
SOC: 63.52941132

Finish

Row: 2502
Speed: 81
SOC: 60.7843132

Another analyzer run will gather the stats for this trip also.

Let's focus immediately on the main parameter:

Gently slope:

Fuel used

3.01

litres, as reported by Torque

Steep slope:

Fuel used

3.12

litres, as reported by Torque

Driving the gently slope, we save 0.11 liters.

Do boundary conditions justify this difference?

On the gently slope we finish with 12% more SOC, another energy credit.

On the steep slope we finish with 2% less SOC, so we lost energy.

On the gently slope we finish with 14km/h more.

On the steep slope we finish with 13km/h more.

It seems the same, but cinetic energy is related to the speed squared and the greater exit speed is the one of the gently slope (98 vs 81).

So, consumption in the case of the gently slope is potentially even lower, because we spare some energy to use on the road ahead.

Let's see some other interesting parameter:

Battery Stress

8.37

Quadratic average of battery current flow

vs

Battery Stress

7.82

Quadratic average of battery current flow

The steep slope puts less stress on the battery, mainly because we recover less SOC.

HSI:

HSI PWR %	0.00	Hybrid System Indicator % time in Power zone
HSI Upper ECO %	89.75	Hybrid System Indicator % time in the upper half of ECO zone
HSI Lower ECO %	3.39	Hybrid System Indicator % time in the lower half of ECO zone
HSI CHG %	6.86	Hybrid System Indicator % time in Charge zone

vs

HSI PWR %	4.42	Hybrid System Indicator % time in Power zone
HSI Upper ECO %	91.10	Hybrid System Indicator % time in the upper half of ECO zone
HSI Lower ECO %	1.74	Hybrid System Indicator % time in the lower half of ECO zone
HSI CHG %	2.74	Hybrid System Indicator % time in Charge zone

on the steep road we have to venture in the PWR zone and spend less time in CHG.

Engine load:

Average Engine Load	83.68	Mean value considering only non-zero values
Min Engine Load	30.20	Excluding zero values
Max Engine Load	92.94	Maximum value

vs

Average Engine Load	86.38	Mean value considering only non-zero values
Min Engine Load	33.73	Excluding zero values
Max Engine Load	92.16	Maximum value

no significant differences exists.