The idea is go to EV at the top of a hill to shut the ICE off on the way down and then go back to HV at the bottom, all while on cruise control. Harmful to any of the systems?
I do that but not while the CC is on. I have seen no ill effects from this and I have not found anything in the owners manual stating to avoid doing this.
If it was harmful, it probably wouldn't be allowed in software. We can always speculate though. I haven't jabbed that button repeatedly but I've noticed it is always quick to switch to HV mode. Sometimes, there is a significant delay to switch to EV mode even if I am we'll under 62 mph. ICE is already warm.
Not harmful. PiP is designed for it. ICE start up and shutdowns at higher speed is actually smoother than regular Prius at lower speed. Take advantage of it but don't abuse it.
What would be abusing it be? Trying to use it even on small hills? Toggling it less than 20 seconds apart?
Added wear on the switch but not near as much as an active cruse control user does to those switches. Toyota/Lexus hybrids have been doing this toggle by design automatically for 15 years now. Not a problem. Do play with it as you cross the PA. mountains on your way home. Lots of steep hills on I 80 and I 76/70 to play with technique. Curious to see your results.
I believe what you are doing is called "stacking" and it is a way to get the most battery charge out of all the ups and downs. In the HV Mode the computer tends to keep the SOC close to what it was at when you switched to HV. If you have a long downhill you need to "stack" (switch into EV then back to HV) or you won't get full advantage of the regeneration. By switching to the EV mode you can fully charge the battery if the downhill is long enough. I have done this descending from Donner Pass to the Sacramento valley. I switch to HV for the few flat and uphill areas so as not to use up the SOC. There is, however, a hitch. If the SOC is above about 75% switching to HV to go uphill will deplete the SOC back to the 70% to 75% region. In that case you just as well stay in EV down to the same SOC. So I use the good long downhill (through Auburn and Newcastle) just before getting to the valley floor in order to pretty much top off the SOC. I don't use CC because I want to determine the amount of accelerator pedal, not the computer. Often (depending on the speed limit and flow of traffic) its better to build momentum for the next uphill rather than have the CC computer slow you down even if it is adding to the battery charge.
I am a bit confused here. I thought that when going downhill, it didn't matter whether you set EV or HV; as long as you were on a steep enough downhill to be in regeneration mode, all of the regeneration goes into the battery regardless of mode. But when you go uphill, you want to be in HV mode to use the ICE rather than the battery. I an not sure what a "stacker" wants to do on level road or a downhill that is shallow enough that some power needed. When do you WANT to use the battery charge?
When you hit the city streets or when traffic slows such that you can go into full EV mode and typical hypermiling would be difficult. Or If it is windy and you have a section of highway that turns you into the wind and you have no other use for the charge.
Yes it is confusing. These threads quoted in the Plug-in FAQ may help. Wow - suddenly got back 0.9mi EV after being out for a couple miles | PriusChat EV miles can be regenerated by PIP after EV depletion | PriusChat Yes, you can charge the battery while driving: my plug-in experience | PriusChat
Mark, I tend to stack when I am in traffic situations that make long glides impractical and I must come to a stop much faster than I normally would. This regenerates a lot of energy so as soon as I stop I hit the EV button (on) then hit it again (off). If this is what you mean by "within 20 seconds" then I don't see a problem doing so.
You want to use the battery when ICE is not efficient. It is the same idea as a regular Prius but PHV enables more things we can do that a regular hybrid cannot. 2010 Prius 2ZR-FXE engine efficiency map | PriusChat BSFC graph shows ICE cannot be at ideal efficiency (220h/kWh) at below 12kW (16hp). If you are going downhill, you won't need 12kW a lot of time, if not all the time. Using the plugin charge would be preferable. We can keep the ICE off below 65 mph downhill. Another reason is to avoid ICE from spinning. If I recall correctly, it takes about 300 Watts to keep the ICE idling (995 rpm) without using gasoline. That's about 6 headlight bulbs draining. I use EV mode in city traffic with stop signs and red lights. Prius can get great MPG in HV mode if you know how to pulse and glide. However, using EV miles is more suitable because I like to avoid constant ICE turning from stop to stop. It is also the best driving situation for EV portion of PiP as it was designed to be EV for local short trips and 50 MPG hybrid for long trips.
Hmm.. That's right. When in HV mode, the ICE will be on and at least idling when above, what, about 35mph? When in EV mode, you can get up to about 62mph without the ICE coming on. So if you are in that 35-62mph range, being in EV mode saves that 300W to idle the ICE. Sometimes I actually like it when there is a bit of freeway traffic slowdown so I can go 55mph or so without being a "road boulder" (as the local newspaper traffic reporter calls it), and get around 58mpg in HV (depleted battery).
Here is my blended mode trip today. I left the gas station with 11.0 EV range and 0 miles on the Trip B. I went about .7 miles before hitting the freeway. I entered the freeway and hit CC at 65mph (66mph displayed) with about 8.7miles EV range displayed. I was kicked out of EV Blended Mode at 12.5 miles total. I took the picture before being kicked out.
The crappy part is in blended mode with a cold engine, the iMPG drops to around 38-44mpg while the engine warms up from about 100F to about 130F. Then it jumps up to 98-110mpg or so until it hits 193F at which point it does another cycle check and iMPG drops to 55-60mpg then jumps back up to 98-110mpg until EV range runs out.
