25.5 mpg?

10 miles is a long distance to travel with only getting 26.5 mpg. Without riding along with you to see how you are driving...I'm concerned about your low mpg. Even if the temperature was 50 degrees in Anchorage your car should be up to temp by at least mile 3 and the next 7 miles (unless you are driving straight up hill) should be in the 40 mpg at a bare bones minimum.

Try the EBH and grill block and see what that does for you. Take pics of the grill block when you get it done so we can check it out. Take a pic of your MFD on your first trip with both installed (or write down the results by 5 min intervals)...just interested to check them out.

 

ICE is very efficient generating 15hp or more. The HV battery can output 28 hp. If you need to use more than 15hp, it is better to use the ICE. Otherwise, use the HV battery. This will prolong the HV battery life and you should get higher MPG.

In summary, it is best to use the HV battery in situations where ICE is inefficient. Do use more HV battery if it is green (more than 60% SOC).

 

Billinak,

If your commute is short, try this.

Warm up your car before taking off. Start the Prius and let it sit until the gas engine shuts down. This will allow the ICE to shut down more often during your commute, if you come to stops. If you don't have many stops (continuous driving), use EV button to shut down the ICE.

My assumptions are that you travel at speed less than 42MPH.

 

I would not recommend this at all...any idle time with ICE running during initial start up is 0 mpg and worse than you would be doing while moving (at least 25.5 mpg worse). Even if you drive immediately after starting the car and the car is not up to temp and still in ICE when you make your next stop the distance you traveled before your first stop is mileage logged more than 0...and higher mpg than 0.

A big killer of mpg in the Prius is initial start up until you're up to temp (160 degrees) and the best way to get out of initial start up cycle is to get the car up to temp (any miles logged while in start up cycle adds to mpg...more than 0 while idling). The EBH should help you get up to temp quicker...but sitting with ICE running is a definite no-no for max mpg.

 

If you already have energy in the battery, then sure, use it. But you get more efficiency by sending power directly from the engine to the drive wheels, avoiding the generator -> battery -> motor path and its inevitable losses.

(So why have a battery at all? Because it allows using an electric motor to provide low-speed torque, which the efficient Atkinson cycle engine is dismal at, and that in turn allows greatly downsizing the engine. A smaller engine is an enormous improvement in system efficiency, completely overwhelming the conversion losses incurred by using a battery and motors for launch assist. Even so one should use the battery and motors as little as is necessary.

The genius of the Hybrid Synergy Drive is that it combines the strengths of engines and motors using a relatively low-loss mechanical path for much of the motor's contribution. For years people were stuck in the false dichotomy of series vs. parallel architecture. Toyota realized that a mix of both was possible.)

 

I don't disagree with it. However, during the initial start up, ICE will be reluctant to rev above 1,300 RPM (with negative IGN timing). Any non-agressive acceleration will use the HV battery.... draining 1-2 blocks down very quickly. You will end up paying for it later in the trip with gas engine recharging it and consume the HV battery life.

It is best if you start driving during the initial warm up stage BUT take it easy (no arrow from HV battery to wheel). If you must accelerate hard (merging into the road) during the warm up stage, it is better to warm up first then take off.

 

160 miles at 25.5 mpgs, then after ten miles 170 miles at 26.5 mpgs

using those figures - you achieved 71.3mpgs for that 10 mile jaunt

 

What you are saying is correct but directing a person getting 25.5 mpg to start off with 0 mpg over the first 5 minutes while waiting to get up to temp is not good advice. Getting him to 30-35 mpg is the goal before getting into the finer points of driving the Prius (I am assuming he doesn't know about no arrows from HV battery to wheel and what it means at this point or his mpg would be much higher than 25.5). EBH, grill block, moderate acceleration, etc. are baby steps before taking huge leaps.

Just the same, I'm not recommending he do an under belly pan, wheel covers, etc. for extreme physical mods (the grill block and max psi on the tires are good places to start).

 

Note: No standard-issue EV button on the 2009.

 

What's your math on a 1 mpg increase over 10 miles after driving 160 miles at 25.5 mpg avg?

I got 66.67 mpg over 10 miles to increase 1 mpg from 160 miles to 170 miles.

My math:
160 miles on 6.262 gallons = 25.55 mpg
10 miles on .15 gallons = 66.667 mpg
Total 170 miles on 6.412 gallons = 26.5 mpg

 

Quick advice on the grill block install...guessing you bought the foam pipe insulation to use from Home Depot or the like.

Cut the tub in half so you have two "C's". Fold the C into a V shape and insert/stuff into each grill slot (the top grill will fit perfectly for length and size...the bottom grill slots are a little smaller and longer so some shaving may be necessary). This will give you a wavy effect on the grill because of the vertical plastic pieces in the grill that get in your way while inserting the material. You can cut slits in the material to fit the grill perfectly and it will get rid of the wavy effect but if you look at the pic I posted of my grill block you can barely even see it (I didn't think the slits were necessary).

I should note I started with just an upper block and after monitoring my temps I added 3 slots to the bottom grill (my temps have not gone over 195 degrees in any ambient temperature). But...and a big but...it's a risk running the grill block at higher temps as you need to keep in mind the inverter temp not getting too high. For me, any days over 75 degrees and I pull the block (a 1 minute procedure) and then re-insert when temps are cooler.

 

160 miles at 25.5 mpg = 6.27451 gallons
170 miles at 26.5 mpg = 6.4151 gallons

gas used = .1406 gallons to go ten miles

10 miles/.1406 gallons = 71.124 miles per gallon

some rounding but also you used 25.55 and i used 25.5 as stated in the problem

 

New thread here:

http://priuschat.com/forums/fuel-ec...ss-use-not-use-ice-dead-stop.html#post858532:)

 

The warm up cycle takes 20-30 seconds only, not 5 minutes. My suggestion was to avoid battery drainage or fuel enrichment followed by a huge MPG hit to recharge it. The remaining details were in my reply to you.

EBH will only warm up the engine block but not the Catalytic converter. Prius needs to warm up both before entering Stage 2 operation. EBH benefits is also limited in the summer.

Blocking the grill in the summer is not good for the radiator fan (constantly on/off). Evan recommends removing it at any temp above 70 deg F.

Moderate acceleration suggest is good as long as Prius is properly warmed up. It is bad during the warm up stage (S1). A properly warmed up Prius will manage to get better MPG. Driving in the S1 can take a huge MPG hit if the driver is not cautious or aware.

During S1, the gas engine runs at negative ignition timing. I estimate the power output is about 10hp. It was done to carefully bring the Catalytic converter up to the operating temp along with the coolant temperature quick as possible. If you accelerate in S1, the HV battery is used aggressively. If you accelerate even harder (above maximum HV battery power), the ICE will get out of the warm up mode and rev at higher RPM. The exhaust temp would damage the Catalytic converter so additional gasoline is sprayed to cool the exhaust gas. We want to avoid HV battery drainage and extra fuel consumed out the exhaust pipe. Therefore, 1) either warm up first or 2) drive easily and carefully (if traffic allows) for the first 20-30 seconds.

#1 is the best suggestion for the OP.

[Added]: My guess is that 2010 Prius ICE will not run in negative IGN timing because it has Exhaust Heat Recovery system. The extra heat in the exhaust will be recycled to warm up the coolant before reaching the Catalytic converter. It would be great if a 2010 Prius owner with ODBII owner can verify it!

 

Yes, but those are minor issues and the computer manages / balances it well when you accelerate. There is little you can do because if you adjust your foot on the accelerator, the computer would re-adjust per the programming.

You just need to avoid big issues during the warm up stage. If you can not or don't want to, just let it sit and complete the warm up stage before driving off.

 

Are you telling me that in 20-30 seconds the Prius is up to temp and EV mode available? That was the idle time I was warning against for the OP...to get into EV mode. Still, idling a car in ICE does nothing positive for mpg...it only limits it.

And when you say "huge MPG hit" that seems a bit much...can you quantify with actual data?

 

Yes, once the coolant temp reaches 104 deg F (40 deg C), ICE will shutdown by itself. After that you can shutdown ICE on demand with the EV button.

See this thread for more detail: http://priuschat.com/forums/knowled...perating-mode-availability-reference-aid.html

The positive side of the "standby" warm up is to recharge the HV battery. The MPG hit can be made up toward the end of your trip (before you get to home/work) by using EV mode.

Sorry, I do not have scientific data to quantify it. I have tried both ways in my normal route and the difference for the first 5 mins can vary up to twice the MPG.

I recorded a video below about the thermo coolant bottle. I let the car warm up and took off in near freezing temp. My first 5 minutes was 40+ MPG. It was with the grills blocked during winter.