Help with dead band on Prius II

[Dan]

Hi all. I've been reading up on the finer points of Prius P&G and had one of the more common questions. How do I hit dead band?. I can get it from time to time, and when I'm lucky I can get it from 0-40, but my success rate from 30-40 is only about 50% of the time. When I'm not in dead band, yellow pack arrow looks schizophrenic (to pack, from pack, off, from pack, to pack).

From what I've read here's what I've gathered.

A) Your best FE on a pulse is somewhere over 1500 rpm.

B) If your SoC is not 6, dead band becomes harder to maintain.

So my blanks so to speak are this:

1) Is dead band a factor of rpm? For example "Just maintain 1726.5 rpm and dead band is guaranteed", or is it more abstract like "from 0-20mph 1500-2000 rpm is dead band; from 20-30mph 2000-2200 is dead band".

2) If rpm is the gating factor, does it vary with speed? What I find, is if I stay on the same spot on the accelerator from 0-20 I'm DB, then around 20, I have to adjust a bit to get back into it, same thing around 35.

3) What SoC makes DB easiest? 6, 7 , 8?

4) What instrumentation is advisable for finding DB? Scanguage? MG1/2 audio sampler?

5) Once in DB there seems to be some room to move. Is a lower or higher impg better in DB for a P&G attempt?

Thanks guys... guess I better write my intro after peppering ya' with questions.

[xcel]

Hi Dan:

___You are mixing some items up here. DB was a mode the early Prius II drivers were searching to achieve when the answer all along was in the Glide. I am glad I was weaned off of it by the second time behind the wheel. Forget about dead band on a pulse. You want to see the ICE-On, arrows from the ICE to the wheels and to the pack during a pulse. Nothing else matters or is particularly useful.

P&G plus Warp Stealth in the Prius II for maximum FE …

___A new driver with a brand new Prius II in colder temps may have some problems with the perfect Glide which is where you want to see nothing but a blank screen other then the ICE, Wheels, MGSet, and Pack mimics (no arrows).

A) I have never driven a Prius II with a tach via SG-II, CANView, and analog tach (that I was watching anyway) so I can’t answer that one for you … I can tell you that 105 + is available from a 50 + mpg pulse, a 16 - 20 mpg pulse and everything between if you have the opportunity to take the Glides out the proper distance. When it warms up, the Prius II starts working like a knife through warm butter and you will quickly become an expert to its particular brand of a natural P&G.

B) The best Prius II FE I have received came about running the SoC at 2 to 3 Blue bars max in temps from 65 - 78 degrees F. Running a high SoC can be a waste of effort and heat other then for heavy stop and crawl traffic conditions where a lot of EV would be involved.

1) Forget about Dead Band on a pulse.

2) This is an area where I think many lose what is available from their Prius II’s. Once you begin a pulse, keep accelerating to maintain your iFCD in a given but tight range. I have seen far to many times where a driver seems to let off while the iFCD climbs and carry a pulse for far too long. Once you have begun your pulse at your own predetermined rate to match traffic conditions, recognize it for what its worth and don’t let off.

3) Where are you reading this discussion on dead band?

4) Your built in Energy Monitor screen.

5) Forget about DB on a pulse. Concern yourself with quick transitions to glide in traffic and without + judging traffic and such to extend your glides when and where appropriate.

___Read the linked article above as it should give you everything you need to begin.

___Good Luck

___Wayne

[brick]

Heh. I think Wayne pretty much covered that. Lately the only things I have been watching under acceleration are the road ahead and my tachometer (added a couple weeks ago) in that order. My goals in doing so are a) don't over-accelerate for the conditions, resulting braking later and b) keep the engine under ~2300RPM per some information that we were kicking around here last month. (2300-2400RPM appears to be a cut-off point for maximum ICE efficiency, and ~1700RPM has been targeted as a "sweet spot".)

Since you don't have a tach, I can tell you that it isn't tough at all to keep the engine turning below that mark when travelling below 40mph. Any pulse rate over 20mpg or perhaps even a bit lower will get you there. (Obviously you aren't going to reach that mark until the car gains a little speed, so don't try to crawl off the line!) Climbing steep hills will put you outside that range as will shallower hills at higher speeds (50mph+) and the only way to combat that is a heavy DWL routine which may or may not be appropriate for the conditions.

[Dan]

Wow... thanks. Looks like I was off base a bit.

For the sake of discussion, here's a key. There are distinct arrows on the MFD, so i'll name them.

E2W - Orange arrows from the Engine to the wheels.
E2G - Orange arrows from Engine to the generator.
G2W - Yellow arrows from Generator to the wheels.
G2P - Yellow arrows from Generator to the pack.
P2G - Yellow arrows from Pack to the generator.
W2G - Blue regen arrows from wheels to the generator.
R2P - Blue regen arrows from the generator to the pack.

DB - Dead Band = E2W + E2G + G2W
DBC - Dead Band charge = E2W + E2G + G2W + G2P
DBA - Dead Band assist = E2W + E2G + G2W + P2G
LBC - Low Band charge = E2W + E2G + G2P
EV - G2W + P2G

The assumptions on high SoC was related to two points. I'd heard the ECU works to keep the SoC close to 6 (don't know if it's true). Also heard that SoC effects impg in a pulse (again don't know if it's true).

As far as the pursuit on DB, I'll worry less about that as well. I was getting fair mileage when I would pulse with LPC. Is the point simply to avoid P2G?

Sounds like the big part here is really getting a full pulse, knowing your impg, and maintaining your glide.

Is iFCD current Fuel Consumption Display?

[hobbit]

General agreement -- forget about this supposed "deadband".
Which way energy flows in/out of the battery is ENTIRELY dependent
on the state of charge, and as it floats up and down the point
of zero current flow is going to also float all over. So just
try to get north of 1500 RPM on most pulses, knowing that you're
up into the high part of the efficiency curve, and don't let
things drift back down or let it go on too long.
.
Yes, there are times when even 1500 rpm is too aggressive an
acceleration rate -- do what you can; sometimes waiting for an
extra second or two for things to clear in front is all you
need to then get a "good burn".
.
_H*