Above 70mph power flow is odd

[prius2go]

Above 70mph power flow appears to be reversed - the screen with the wheels and arrows
Holding speed at say 75mph the ICE drives the wheels and supplies power through the motor to the battery
even though the battery has all bars green except for top blank one.

Ease off the gas (accelerator) slightly and the ICE and motor drive the wheels with some power coming from the battery

Ease on the gas and again the ICE drives the wheels and charge the battery

There appears to be no sweet spot avoiding charging or discarging the battery

Isnt this the wrong way around
shouldnt easing off the gas cause it to slightly charge the battery?

2004

[john1701a]

<div class='quotetop'>QUOTE(prius2go @ Nov 29 2007, 06:00 AM) [snapback]545596[/snapback]</div>

shouldnt easing off the gas cause it to slightly charge the battery?[/b]

Nope, engine-speed relation to travel-speed isn't as straight forward as you would think.

It's like when you accelerate while climbing up hill. You'd think the battery would always kick into heavy use. Instead, that only happens up to moderate power. When the need is high, just the opposite happens. The engine contributes heavily, resulting in the battery getting recharged instead of being drawn from.

After awhile, the behavior becomes second-nature. But initially, it will leave you scratching your head. That's why so many attempting to compare hybrid designs guess incorrectly. What happens under the hood is not obvious.

[bwilson4web]

Hi,
<div class='quotetop'>QUOTE(prius2go @ Nov 29 2007, 06:00 AM) [snapback]545596[/snapback]</div>

Above 70mph power flow appears to be reversed - the screen with the wheels and arrows
Holding speed at say 75mph the ICE drives the wheels and supplies power through the motor to the battery
even though the battery has all bars green except for top blank one.

Ease off the gas (accelerator) slightly and the ICE and motor drive the wheels with some power coming from the battery

Ease on the gas and again the ICE drives the wheels and charge the battery

There appears to be no sweet spot avoiding charging or discarging the battery

Isnt this the wrong way around
shouldnt easing off the gas cause it to slightly charge the battery?
[/b]

One of the problems with the multifunction display MFD is it shows 'arrows' but not 'quantities.' So whether you are getting 1 to 70 kW, you only get the 'arrows.' I have the older version, 2003 Prius, with a Graham scanner and can read the energy flows. Sad to say, one of the most important energy flows, between MG1 and MG2, isn't even shown on the MFD. For me, it is nearly useless but instead use the consumption display that has a coarse metric of vehicle performance.

Good Prius friend Hobbit may have some techniques that work for achieving 'no arrow' state on the MFD. In my case, I go by ICE rpm, a good indication of requested power. If the ICE is spinning above 2,600 rpm, I become alert and start looking for slower speed opportunities. If it spins faster than 3,200 rpm, I get serious about looking for ways to slack off the power.

You might consider getting an OBD scanner that can read out ICE rpm and other parameters. This would give you a much better indication of what is going on and the ability to 'load drive.' By 'load drive,' we mean driving so your engine stays in a maximum efficiency, rpm range. The speed will follow but having accurate, quantitative data gives you a lot more control than the coarse 'arrows.'

GOOD LUCK!
Bob Wilson

[prius2go]

youre right
I thought when going uphill that the motor would supplement the ICE

instead the ICE rpm steps up
and the ICE drives the wheels and charges the battery


I'd have thought that it would have discharged battery going uphill and charged it going down the other side

I guess the losses in the charging/dischrging process must be greater than increasing the ICE rpm

Must read the MIMA site again to see what Insight owners do

[hobbit]

F'geddaboudit. At highway speeds like that you're almost entirely
on the engine and battery currents in and out are *very* small [but
still shown on the MFD]. There's no sweet spot in terms of that,
it doesn't matter. The system will simply seek 60% SOC and that's
the end of it. Where you want to worry about sweet spots in that
scenario is for the *engine*, and that's where you need a tach.
.
_H*

[John in LB]

<div class='quotetop'>QUOTE(hobbit @ Nov 29 2007, 06:41 AM) [snapback]545614[/snapback]</div>

F'geddaboudit. At highway speeds like that you're almost entirely
on the engine and battery currents in and out are *very* small [but
still shown on the MFD]. There's no sweet spot in terms of that,
it doesn't matter. The system will simply seek 60% SOC and that's
the end of it. Where you want to worry about sweet spots in that
scenario is for the *engine*, and that's where you need a tach.
.
_H*
[/b]

I regularly drive my Prius at 145 mph. And get 85 MPG by using HBS techniques. Most importantly, the rear view camera is on all of the time - forget about the damn arrows on the display....

One thing that makes a big difference is the size of the hill - It has to be BIG... and it's got to be going downwards! Otherwise, not even HBS techniques will work (only a Hail Mary will help you here....)

Using HBS techniques, I can even get the ICE to completely cut out and only use battery power; however, at the end of the 100 mile run the battery pack is smoking. For this reason, I have to keep the windows open to blow toxic fumes out. One question I have is: Should the AC be on or not? And should I use the recirculation button?

At these speeds, I found the AC drops my FE down to 84.8 MPG... Boy, do I hate that. When this happens, I usually get pissed and then speed up to 148 MPH - at this point, the ICE just backfires and smoke billow out the rear end... But no worries, I use Mobil 1.

At the end of the run, I did notice that my tires are a little warm and the pressure is usually 95/97 PSI... I guess, I will use Helium next time instead of damn cheap Nitrogen.

I think of selling the car - it is in pristine condition and DEFINITELY broken in... anybody want to buy it? It comes with a lifetime tow package (that is, a membership to AAA...)

Please let me know soonest - I am in a bit of a hurry!

[Proco]

<div class='quotetop'>QUOTE(John in LB @ Nov 29 2007, 09:16 AM) [snapback]545625[/snapback]</div>

I regularly drive my Prius at 145 mph. And get 85 MPG by using HBS techniques. Most importantly, the rear view camera is on all of the time - forget about the damn arrows on the display....

One thing that makes a big difference is the size of the hill - It has to be BIG... and it's got to be going downwards! Otherwise, not even HBS techniques will work (only a Hail Mary will help you here....)

Using HBS techniques, I can even get the ICE to completely cut out and only use battery power; however, at the end of the 100 mile run the battery pack is smoking. For this reason, I have to keep the windows open to blow toxic fumes out. One question I have is: Should the AC be on or not? And should I use the recirculation button?

At these speeds, I found the AC drops my FE down to 84.8 MPG... Boy, do I hate that. When this happens, I usually get pissed and then speed up to 148 MPH - at this point, the ICE just backfires and smoke billow out the rear end... But no worries, I use Mobil 1.

At the end of the run, I did notice that my tires are a little warm and the pressure is usually 95/97 PSI... I guess, I will use Helium next time instead of damn cheap Nitrogen.

I think of selling the car - it is in pristine condition and DEFINITELY broken in... anybody want to buy it? It comes with a lifetime tow package (that is, a membership to AAA...)

Please let me know soonest - I am in a bit of a hurry!
[/b]

[prius2go]

[statultra]

word of advice to new owners, the car will take car of itself