Making Arrows Vanish

After the SOC is sufficient on the HV Battery you may let your foot off the accelerator and then very gently just touch the accelerator pedal until you get a no arrow condition. Simple right? However sufficient SOC is variable and generally requires at least 10-15 minutes warm-up. This no arrow or free wheeling so to speak will only occur with a green or purple battery state, signifying a proper state of charge. During a nice Sunday drive this is easy to obtain especially with nice downhill sections. If you bring the Prius up to a coast and then throw it into neutral you will duplicate the no arrow condition. In doing this, for some reason does not seem to appreciably add to MPG. I'm convinced its detrimental to MPG ( by coasting in neutral) Why this is so has not been addressed by our experts. The consensus is however that putting the car in neutral will not hurt it, niether will returning the car to drive.

 

It is not easy. If it was everyone would pump their tires to 60 psi throw out the spare and rear seat and get > 100 mpg. First try this, after the car is warmed up (easy in your neck of the woods) hit the B mode. You will see no arrows. Go to drive. Accelerate to the speed limit or if you dare 3-5 over and take your foot off the gas. You get the green arrows. Let that go for 2-5 seconds. It needs a bit of time. Slowly and gently (you have a raw rotten egg between your foot and the accelerator if you crack that egg your car will be unusable for 5 years ). If you get yellow arrows to MG2 back off just a bit. No arrows you are gliding. The car must be warmed up to above 70 C. The next part is harder much harder. I am still working on this. When you accelerate press on the gas until there is power to the wheels from the ICE with or with out power from MG1 to MG2. Nothing to or from the battery. If you are getting flickers to and from the battery that is OK to start with. I try to stay away from sustained (several seconds) of battery to MG2 and am willing to accept some charging. Dead banding is really tough. Work on it. You can get a ScanGage or CAN View to help you get a handle on when the ICE is running and when the ICE is up to temperature. Fun, Fun, Fun.

 

The Dr beat me to it, thanks Evan

 

Every one is chiming in. The slight down hill is a good addition to start with.

 

But not found in Alameda!

 

You live in SF so it will be difficult to get "no arrows" in the city. Going downhill will still get you recharge arrows. If there is a more level area that you drive try it there. You really have to get a light foot and even then the arrows will not last for more than 20-30 seconds at a time (unless you are on some very level but very slightly declining road (which does not exist in your area!)

 

I would also say that you're probably going to find "deadbanding" to be difficult there as well. Deadbanding is pretty easy to achieve on flat ground as long as you don't try to accelerate to briskly. Frankly I wonder how effective it really is, particularly if you're going to encounter situations where regenerative braking can help replenish the HV energy you consume by demanding a little more power from the car. It seems to me that if deadbanding is going to get you up to cruising speed at a somewhat slower pace than moderate acceleration w/battery assistance then overall you're not going to see an increase in MPG. In fact, if the discrepancy is big enough, you'll see a drop in MPG. Not that deadbanding is to be avoided at all costs either. There are times when it makes sense.

 

The easiest way to experience the no arrow state is to:

1) Make sure your engine is fully warmed up. After 10 minutes of driving this should be enough.
2) Make sure you have no red bars on your battery.
3) Find an area where the speed limit is 45 mph or less and your in a slight downhill. The steeper the downhill the easier.
4) Get your speed so that it is no more than 40 mph and it is safe to do so.
5) Lift off the gas and allow your car to coast with green arrows going to the battery. This is coasting like a conventional car as your Prius will tend to slow down with engine braking.
6) Now press the gas down just slightly until you see the green arrows go away.
7) You should either see no arrows or possibly a momentary appearance of yellow arrows from the battery to the electric motor.
8) If you see the yellow arrows, wait about 2 seconds to see if they go away. If not just back off the gas pedal just enough to make the yellow arrows go away.

The no arrow state is the tiny sweet spot in between having the green arrows appear and the yellow arrows appear. When you drive 40 mph on level road or downhill it's easiest to achieve.

 

It takes a bit of practice: I too have a late 2005 and I tried this technique after reading it on the board. It does work but it needs a very light touch on the accelerator - very light. I can do it - esp if I've got a good speed and I want to glide. For me, the key is to get it up to speed and then lightly touch the accelerator pedal until the arrows disappear .. use if often on a slight downgrade coming home from work.

Keep trying ... it's neat! and yes, the 'no arrows' will show up on your monitor.

 

a long extended stretch of flat (or, i suppose, a slight downhill - steep just seems to make the batteries charge) seems to be ideal to figure out that point that you need to find. You'll be able to do it better on less ideal surfaces if you can get in some practice somewhere perfect. It's been described many times, but heres a new Prius Driver observations:

First, get to the speed you want to coast down from - around here, the speed limit is about 40, so I go up to about 45. It's pretty difficult to get it to work above 40ish, but I always try. I take my foot off the gas as far as I need to to get into regen - green arrows from the wheels to the motor to the battery. Then I apply a tiny bit more gas - just until the arrows change, and very slowly. Sometimes I've gotten it in just fine, and the arrows all disappear. The car slows down kind of quickly in regen, but the car maintains it's speed much better with no arrows - even later when you can get it to do it up a hill. Most times, though, I apply just a bit too much gas, and the regen arrows switch directions and turn yellow - I'm using the battery to power the motor sending power to the wheels. If you hit yellow, don't worry - just lift up a tiny bit, very slowly - the arrows should disappear. You may 'overshoot' it again - just keep going to green, then yellow, and back - try each time to be a little bit slower.

You get pretty good at this pretty quickly - learning on good flat ground means you get good at it, and then can use it on the hillier portions. Good luck!

 

With regard to the suggestion that deadbanding doesn't help MPG.

Consider that changing energy from one form to another has inheritant losses, usually in the form of heat. So if you are going to stop, if you can glide without regen as much as possible, you lose less to regen.
So, if because of friction and drag you could slow down from 50 to 20 in 1000 feet, start deadbanding 1000 feet from the stop.

As for deadbanding for acceleration, I don't see that possible, even if by deadbanding you mean accelerating with ICE only. MG1 has to either give or take a force in order to get ICE's power to the wheels, and usually it would act as a generator to do so. That generated energy is best going completely to MG2 rather than going to the battery.

By the way, I know this may sound counter intuitive but it has been determined using the miniscanner on a classic that at cruising, the car actually takes power from MG2 and sends it to MG1 to emmulate overdrive.

 

I want a "Glide" button on the steering wheel that would force gliding without the hassle and restore "D" gear when released.

Or, better yet, allow me to set an option where there is no regen unless braking or in "B" gear so I can easily choose when to regen.

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Edit: Changed "Coast" to "Glide" and "deadbanding" to "gliding"