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Test Google Phote

09-21-2009 03:51 PM

Tested at: 2:51 PM 9/21/2009

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MediaFire test at 3:29 PM 9/21/2009

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Prius Throttle TImer

09-13-2009 12:25 PM

http://www.cleanmpg.com/photos/data/500/heretical.png

Here are some doodles from my notes on the throttle timer behavior I've been fooling around with. It doesn't provide any efficiency improvements to known tools, but it helps me understand how the car is put together.

Basically it goes like this..

If you have your throttle low (around 16-20%) you seem to set off some type of throttle timer. If you can manage to hold the throttle unchanged (+ or - 1% throttle) for a set duration of time the timer will expire. Once the timer expires you can get a boost you can possibly fall into two kind of interesting states.

One is Heretical Balance (aka SHM). In this state RPM is low, speed is high, MG1 spins backwards and the net power going into or out of the pack is very low. You are effectively driving in high speed, low gear with very little use of the battery in any way.

The other interesting state is a Heretical Assist. This is an interesting state for the PHEV folks since it runs the ICE at a very low RPM and draws 10+ Amps to maintain highway cruising speed. Heretical Assist can yield some of the 120+ MPG highway numbers that the PHEV folks are after without chewing up too much charge from what I've seen.

The interesting thing I noticed on both of these is that you seem to have to make it through a throttle timer before you fall into them. The "seven second hold" to enter SHM is one of these timer transitions. Warp Stealth is another way you can see the timer happen. Normally to enter WS you need to take your throttle all the way to 0.0% then re-apply just a touch. But if you hold your throttle low at about 45 mph with a high SOC you will "naturally" fall into WS after about 10 seconds, all without bouncing the throttle. You can do the same thing under 45 and transition "naturally" into a glide after about 10 seconds.

Now this is interesting from an academic point of view, but it doesn't give you any new MPG tools. It is interesting to think that the engineers designed some type of timer in the control logic as a sort of hysteresis to keep the the engine from coming on and off at any variation of throttle. Basically you have to hold throttle low, or take it to zero for an instant before the engine or injectors will cut out. This prevents a bouncing throttle from sending back to back START-STOP-START-STOP engine commands.

Again, nothing new but it does piece together why throttle variation is such a bad idea in the Prius. Any significant movement in throttle will reset the timer and make it even harder to fall into an efficient state.

One final note is a sort of special case that I found and Dan K has confirmed. If you enter into a low speed Heretical Charge condition you can hit the "special case" clause in my flowchart. Basically a "I don't know why" bucket. If you hit the special case, you can charge you pack all the way up to 75% before you will get kicked out of the Heretical Charge. This may be pretty useful to Gen III owners or TCH owners since it provides an alternate force charge method to top off your battery for whatever reason you might have. Force Charging is rarely a good thing to do to your pack, but it is fun to know how to do it.

Again, very very rough draft so, hopefully I can clean it up enough to post later.

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Speed Test

10-08-2008 08:10 AM

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