HCH II-Specific Discussions Model Years 2006-2011

Neutral Coasting?

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  #21  
Old 07-17-2006, 04:22 AM
PCK's Avatar
PCK
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Default Re: Neutral Coasting?

Spent a little time trying out the FAS technique over the weekend and on this
Mornings commute to work.

This Morning I tried it 5 times over my first 10 miles of driving,
2 times on flat and 3 times on a downhill segment. It felt to me that speed decreased too rapidly and didn't produce any better results than my normal driving techniques.

A real annoyance is if you have the NAV, everytime you do this it reboots. Also you have
to keep an eye on your SOC, because my short weekend test I also experianced a
forced regen for the first time (4 bars).

Perhaps someone who has performed this on the HCHI should try this out on an HCHII and make a comparison. For myself I am pretty sure I can do better without
the FAS.
 

Last edited by PCK; 07-17-2006 at 04:24 AM.
  #22  
Old 07-18-2006, 04:13 PM
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Default Re: Neutral Coasting?

Originally Posted by PCK
It felt to me that speed decreased too rapidly .
This does not make sense to me. All other methods for going downhill add more drag than the FAS.
 
  #23  
Old 07-19-2006, 03:25 AM
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04 prius 350,000km
Join Date: Sep 2005
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Default Re: Neutral Coasting?

can you explain how you did a fas in your hchII?

hm you should have a test.... get up to 40 mph and then coast wtih gas pedal (no regen/ev bars) and then time how long it takes you to get down to 20 mph

same test again but fas and then time it!
 
  #24  
Old 07-19-2006, 04:44 AM
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Default Re: Neutral Coasting?

This is the way I understood FAS:
1. Drive till you acheive a desired top speed
2. Shift into Neutral then turn off car with key
3. Wait two or three seconds then turn key on to middle position
so electronics is on but not ICE. This allows the car to measure
the mileage and estimate the MPG (the max the HCHII can read on
trip is 150mpg).
4. When you reach your desired low speed turn key to on position till
the ICE starts, depress accelerator slightly to increase revs and shift
into drive.

As far as coasting resistance I can only compare to a Nissan Altima that
I tried coasting in Neutral a few times and it would drop speed very slowly
in comparison. That's why we need an experianced FAS driver to try it
out in the HCHII for a comparison.

Also one of my issues with FAS once you end a segment you then have to
accelerate back to a desired driving speed again which drops your mpg during
the process. I basically like to get to a desired speed then backoff on the gas
pedal as much as possible without dropping speed, then I can cruise at
70 mpg and higher for as long as traffic does not interfere. I do use P&G
alot but only with hills and stop & go traffic, I don't go looking for a P&G
opportunity they just show up as part of my traffic conditions.
 
  #25  
Old 07-19-2006, 05:34 AM
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Location: Melbourne, Australia
Posts: 148
Default Re: Neutral Coasting?

OK. So what I'm doing now is...if the batteries are a bit low (say coming off a freeway) I'll allow regen to come on and slow down that way. If the batteries are full I'll coast with zero assist/regen (what does FAS stand for anyway?), right up to the last hundred feet and then brake.

There seems to be no point in slowing the car down using regen if it's not going to be used.

I just came back from a 375 mile vacation (round trip) and averaged 50mpg (my best so far) - 4.7L/100klm. The HCH-II is rated at 4.6L/100klm combined here, so I', pretty pleased with that...and...it was raining the whole trip!
 
  #26  
Old 07-19-2006, 12:07 PM
philmcneal's Avatar
04 prius 350,000km
Join Date: Sep 2005
Posts: 517
Default Re: Neutral Coasting?

fas stands for "forced auto stop" basically engaging auto stop earlier than when the car comes to a complete stop.

the theory behind it is, the engine is killed and is not spinning therefore elminating coasting drag. They say the HCHII engine is designed so that it can seal its valves and then coast as good as a FAS however there hasn't been enough facts to back this up. Like PCK said a true FASER is needed to see if its truly useful on the hchII or not.

personally i use fas when i know i can maintain speed or bleed it off slowly for a long time, OR when i predict a traffic light is going to turn red on me. The theory behind it is, if you can coast up to a light and then by the time your required to stop, you only have maybe 10 mph or less in speed left which in theory is USELESS FOR REGEN. But the energy SPENT to get to that light is greatly reduced as compared to someone approaching the light at 30 mph and then using regen to slow down.

look at my tanks, it will speak what FAS is capable of, but i have a 5spd so i can turn on my engine with the clutch... the same way your electric motors give torque to your engines to turn it on.
 
  #27  
Old 07-19-2006, 05:26 PM
Aussie's Avatar
The Devil's in the detail
Thread Starter
Join Date: Jun 2006
Location: Melbourne, Australia
Posts: 148
Default Re: Neutral Coasting?

Thanks Phil.


I had noticed that the ICE cuts out at about 12kph. If I'm driving downhill I can then coast (providing traffic conditions allow) for a few hundred metres at a time. So it looks like is was already "FAS'ing".

I'm not too keen on actually turning the ignition off altogether in neutral to test this further however.

All of these methods assume that you have an open road with no other traffic around. A situation which is sadly impossible where I live.
 
  #28  
Old 07-19-2006, 05:49 PM
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Posts: 1,672
Default Re: Neutral Coasting?

Originally Posted by PCK
This is the way I understood FAS:
1. Drive till you acheive a desired top speed
2. Shift into Neutral then turn off car with key
3. Wait two or three seconds then turn key on to middle position
so electronics is on but not ICE. This allows the car to measure
the mileage and estimate the MPG (the max the HCHII can read on
trip is 150mpg).
4. When you reach your desired low speed turn key to on position till
the ICE starts, depress accelerator slightly to increase revs and shift
into drive.

As far as coasting resistance I can only compare to a Nissan Altima that
I tried coasting in Neutral a few times and it would drop speed very slowly
in comparison. That's why we need an experianced FAS driver to try it
out in the HCHII for a comparison.

Also one of my issues with FAS once you end a segment you then have to
accelerate back to a desired driving speed again which drops your mpg during
the process. I basically like to get to a desired speed then backoff on the gas
pedal as much as possible without dropping speed, then I can cruise at
70 mpg and higher for as long as traffic does not interfere. I do use P&G
alot but only with hills and stop & go traffic, I don't go looking for a P&G
opportunity they just show up as part of my traffic conditions.
What you are talking about is P&G (which I generally do not use). True you do FAS whild P&Ging but what I call a FAS is when you do the same thing as a regular AutoStop (while stopping) just a lot sooner than the car would. I guess I also call it a FAS when you kill the ICE near the top of a hill and let the downhill maintain your speed. P&G is the same thing except on the flat when you are not thinking of stopping. I might not be useing the terms correctly but I don't FAS on flat land unless I need to slow down or stop anyway. I FAS all the time on downhills or when coming to a stop.

If someone knows more precise terms please post em.
 
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