Accelerating from a red light

Personally, I think 'brisk' is a pretty useless term. (I actually had it described to me as between a crawl and flooring it.)

If you watch the recent video from Wayne, it will show him advising, keeping it in EV mode below 16 mph, and then admonishing the driver to accelerate to the 3/4 point, IIRC, on the HSI.

People who want to think of hypermiling as slow will quote the first part, while those who want hypermiling approval for fast acceleration will use the brisk part. Wayne actually has NUMBERS for both of those behaviors.

 

i think you've summed it up nicely...... this seems to be the way to go

up to now i was not doing the ev mode to 16mph...now i am ..i will see if improvement


by the way what is IIRC??

 

"If I Recall Correctly"

 

doooo as bart would say

 

No, it's doh! As Homer would say...

 

oh yea i don't really watch it anyway...

i watch my hsi more

 

I guess I would like 2 optimized acceleration scenarios in the 10 to 60 mph range where there are several red light junctions as part of the trip, that can be described visually in term of the HSI indicator. I feel keeping the indicator at a fixed location in the HSI from 15 to 60 mph is more like a simple/slow rule of thumb as opposed to achieving the most useful/economic in typical red light to green situations. I welcome refinements.
Scenario 1: Compromise Rapid/MPG weighted acceleration in rush hour traffic (within ~10% of optimum BSFC)
10 to 20 mph: right side of the PWR band
20 to 25 mph: middle of PWR band
25 to 30 mph: left side of PWR band
30 to 35 mph: right edge of ICE ECO band
35 to 45 mph: right edge of ICE ECO band
45 to 60 mph: between left and right quadrants of ICE ECO band as necessary

Scenario 2: Within ~5% of Absolute optimum BSFC acceleration in light/no traffic
10 to 20 mph: right edge of ICE ECO band
20 to 30 mph: 3rd quadrant of ICE ECO band
30 to 60 mph: between left and right quadrants of ICE ECO band as necessary

I feel trying to calculate iMPG =iMPH/2 could be distracting/dangerous and something like above would be much easier for more drivers to follow.

I wonder what the BSFC is from the left to the right of the PWR band when the car is at 20, 30, 40, and 50 mph. Or is it completely independent of speed due to CVT?

 

i like your theory....
the middle 50% to left/50% right seems to be in the most inefficieent area...and obviously to long in the pwr area would be to
and thats what scanguage indicates to

 

That's the sort of term you get when there are no useful metrics. The "brisk" term comes from the Gen II, where we don't have the power indicator. I've always described it as relatively fast acceleration, but short of WOT.

Tom

 

What about using the "LOD" gauge on the Scangauge? This is what people do in other cars, but maybe it isn't a good metric for the Prius??

 

I don't know about your Prius, but when I bought mine a Scangauge wasn't included. If we want to talk about adding equipment, then the skies the limit when it comes to metrics.

Tom

 

No need to be snarky. I was just asking if the LOD gauge was useful or not.

 

when using lod......best eficiency is at about 85% when ice is running..that's my understanding

 

Fair enough. I interpreted your comment as questioning why Gen II owners don't use the LOD gauge, which of course isn't standard.

As for your real question, certainly LOD is a useful metric. Atkinson cycle engines are most efficient at fairly heavy LOD levels, generally around 90%.

Keep in mind, of course, that ICE efficiency is only one factor in overall efficiency.

Tom

 

It's an abbreviation for LOAD, which I think means load on the ICE not the total load ICE+MG load???

 

Thanks Tom. I DO find the SG VERY useful for my Prius. HSD is a complex system and it helps me figure out what is going on. I wish the HSI display included something that showed me whether the ICE is on or off (it's SO quiet when it's on) and gave me a number rather than a bar graph for the iMPG.

 

From a dead stop at a red traffic light

I. Traffic/distance you can travel before stopping is very important

if the Prius must stop ( because of traffic, stopsign, pedestrian, furry creature crossing the road) soon after starting from a green light then the maximum speed the Prius accelerates is the most significant factor in fuel efficiency. The Prius max speed must be no faster than the top speed needed for the Prius to slowdown to 10 mph while coasting (no braking, no regen braking) to the stopping location. For example, the most fuel efficient way to move a short distance on a Prius is to push the accelerator past the HSI mid point and engage the gas engine to a target speed then let go of the accelerator so the gasoline engine is turned off and the electric motors are barely if not running ( and no regenerating electricity) . The Prius is allowed to glide until it reaches about 10mph to 5 mph - at which point the driver applies the hydraulic brakes and does a full stop. As long as the target speed is under 40 mph - loss from wind resistance/aerodynamic drag should be mimimal.



II. The terrain is very important

1) if the Prius will go uphill within the first 20 feet
then set the Prius to PWR mode,
accelerate up to 7 mph using electric then switch to gas
push the accelerator pass the 3/4 point of the HSI ECO bar but not yet to the PWR bar
hold this position until the target speed is acquired - (PWR bar levels maybe required if going
up a mountain road)
scangaugeII only: iMPG =MPH or (> 1.20Gph, 1088-1800RPM)

2) if the Prius will drive flat road
then set the Prius to Normal mode
accelerate up to 15 mph using electric then switch to gas
push the accelerator between 3/8- 5/8 point of the HSI ECO bar until target speed is acquired
scangaugeII only: iMPG =2/3 *MPH or (.7-1.1Gph, 1088-1344RPM)
under 40 mph do a pulse & glide
from 40-55mph do a super highway mode
slowly release the accelerator 1/10- 2/3 point of the HSI ECO bar until target speed is acquired

3) if the Prius will go downhill within the first 20 feet
then set the Prius to ECO mode
accelerate up to 25 mph using electric then switch to gas
push the accelerator between 1/2- 5/8 point of the HSI ECO bar until target speed is acquired

a. small downhill grade - with no uphill grade in sight
under 38 mph - foot off brake once target speed acquire, recharge batteries
under 45 mph - switch to Pulse & glide
over 45mph - switch to superhighway mode

b.medium or steep downhill grade - with no uphill grade in sight
glide - foot off the brakes,
if over target speed use regen brakes to recharge batteries
when SOC =8 bars(>77%soc) switch transmission from D to B

c. medium or steep downhill grade with uphill grade coming up
glide - foot off the brakes,
if over target speed use regen brakes to recharge batteries
when SOC =8 bars(>77%soc) switch transmission from D to B
at last part/section of downhill accelerate 10 mph to 15 mph over target speed for
top of the upcoming uphill grade before geting to the foot of the uphill climb - driving with load