Hello all! I just purchased my 2011 Prius IV last Thursday and have been enjoying it a lot so far. I believe I have a pretty good understanding of how the HSI works, but for some reason I feel like my car has been reacting differently. As I understand it, the left half of the HSI will cause the electric motor to operate without the ICE (assuming there is enough charge in your battery and you aren't running A/C etc). When driving in town I usually accelerate at about 75% of the HSI, then reduce the left half when I've reached 30-35 mph. When driving today, when I reached the desired MPH and dropped to the left half the ICE would not shut off so I could run on battery. In order to get the ICE to stop powering the wheels I had to drop the HSI to 0-20% approx. From there i could use the whole left side of the HSI without the ICE turning on (my battery was 6 and even 7 bars this whole time). But as soon as I moved even a little into the right half of the HSI the ICE would kick back on and not come off until i dropped acceleration all the way down. Is this normal? I feel like this just started happening today, that previously I would be able to just enter the left half of the HSI and the ICE would come off without having to take my foot off the pedal all the way. Thanks for the help, this site has been very helpful in my decision to get my Prius, so thanks ahead of time!
Another note. I felt like when accelerating from a stop today the car was much more sluggish, and seemed to be getting less MPG when accelerating. The Energy Monitor was showing that the battery was being charged while accelerating, when it should be helping acceleration. I know this isn't always true, but my battery was also at 7 bars, and the ICE was still charging it during acceleration and would not stop until i took my foot fully off the gas, which would move the HSI all the way to 0%. On one hand, I don't believe it was running like this previously, but on the other hand i feel like I may be too worried about it and watching the HSI too closely.
Welcome aboard sunday! There are situations that will cause the ICE to run no matter what. Mainly during warmup. Other times... when you use defrost or calling for heat and the coolant temp cool. Remember, running on electric only is rarely a good idea, FE-wise
Just getting the bar to the left of centre does not automatically switch to electric mode. Check the Owners Manual, suggestions on improving fuel economy. It suggests to lift your foot completely off the gas, then gently re-apply. As long as other parameters are met (decent charge, engine warm, etc, not going too fast) this will virtually always put you into electric mode. Then, as long as you keep the bar to left of centre it should stay electric only. Under some conditions I believe I've had the bar a bit to right of centre and still was electric only. Not sure, could have misread. One thing, driving electric mode with the bar almost to centre is a really efficient way to deplete your battery charge. Best used sparingly. If I see that condition I'll often purposely step harder on the gas, to kick the engine back on, then either glide, or try to back off the gas to keep the engine running, but very efficiently. Also, not sure, but I suspect the in-dash indication of fuel consumption, which also is the tip-off of engine running or not, might be fibbing sometime. I've had a scangauge hooked up off-and-on for a few weeks now. Sometimes the fuel consumption indicator in-dash says zero, but scangauge indicates rpm, around 900 or more, and instant mileage somewhere around 1~3 liters/100km. I know scangauge has around 2 second lag, but this is persistant. Usually at freeway speeds. Funny though, it feels like the engine is off, so like I say, not sure.
Welcome! Try to drive as smoothly as possible, avoid sudden braking when possible, don't rush to the next traffic light when it is already red, and accelerate as fast as you wish as long as the ECO light is on (I.e. The HSI bar is not in the PWR area) from a stop. If you drive like this you will get good mpg without the need of worrying where the bar is. It is ok for the ICE to be on when the bar is left of centre (actually in that case it will consume very little fuel), and yes, you can have the car be pushed electrically only when the bar is a tad right of centre (the only condition is that the battery needs to be properly charged, at least 6 bars, otherwise the ICE will kick in). Focus on the smooth driving and the Prius will prize you with the best possible mpg for your driving style. PS: if you drive smoothly, especially in city traffic, you will eventually be doing some kind of "mini" pulse&glide without you even noticing it and this will increase your fuel efficiency..
PS2: if check out my blog in the signature below there are a couple of articles about what you asked and on the PriusWiki additional information on the Prius
The car seems to have a mind of its own re when the iCE is on while using electric drive. Clearly when the engine is cold, when your are going over 46 mph, when the defroster is on, when there are 2 bars on battery left or less, when the battery is full and you are still regenerating , when the heater is on and the engine not up to temp yet, AND OTHER TIMES WHEN IT MAKE NO SENSE to be on ! Very frustrating . Sometimes the scanguage will show 992 rpms with no hp being generated i.e. no fuel being used.- this is good - spinning a motor to limit other spinning going on. Other times, when there is no need for the ICE to be on , it will be on and using fuel - generating 3-5 hp. The MFD does not show these differences in MPG - its pegged at 99 mpg, but they are there and frustrating to eliminate. The only thing that seems to work is to stop the car - the ICE will turn off and stay off, as long as you stay in the lefthand half of the HSI.
