Prius-II OEM PHEV-6 caught in the wild

I should clarify: When I said "battery" I really meant "plug-in battery." I'd like to keep the battery that's already there.

 

My thoughts were the same as Brick's initially. Just give me that glide. But then I started thinking about all of those Prius purchasers who get on Priuschat and say "I only get 35mpg, and yes all my driving is short trips". A mere PHEV-6 might not end gas entirely for most commutes, but boy will it help the short trip syndrome a lot.

My guess is that highway EPA would be better at all speeds, and not worse at any. If I were designing the thing, I would leave the "mimic" exactly where it is (around 65% SOC currently, much lower with two packs), and program the computer to bleed (assist) any excess charge until that mimic level is reached. What that means in practical terms is that you'd have two full packs in the morning, you'd get on the highway, and you'd have 6 miles of grid-generated pack assist of the ICE on the highway, which would get you iMPG in Insight territory for a while.

When you reached the current mimic level, assist would end and the computer would maintain that level on the highway (65% SOC) with the arrows flashing back and forth between assist and powering up the pack. Then iMPG would fall back down to more Prius like levels.

If you didn't keep the mimic where it currently is, then a long highway trip without an overnight grid charge would fill, and fill, and fill, and fill up that pack. And that's no good. I don't want gas filling up two packs. I'd rather fill it up from the grid when I get to my destination.

If this doesn't make a lick of sense, let me know and I'll take another stab at it.

 

Thanks mparrish.

Won't the EPA conduct it's tests such that SoC is the same at beginning and end? If so, where does the mpg bump come from in steady mph above 62? Or even steady mph below 62? I know the folks here will drive smarter, but where will the EPA get better highway results? We know the extra weight pulls it down, but where is the offset for them? Certainly they get some back from regen at exits and stops, but I'm thinking that can't offset the extra weight in longer trips.

Also, wouldn't you want to have the pack just get enough recharge to assist on climbs and to run AC and other accessories in steady state highway driving? (I'm ignoring the initial 6-10 miles of pack benefit from charging in the garage, like I'm starting from the hotel parking lot on vacation.) I'd think you want the gas going straight to the highway to minimize conversion losses.

I just think the world at large may yawn because it cannot beat the P-II under highway cruise control. (I'll buy mine before they "get it.") But man, in town and stop and go this thing ought to be spectacular.

 

ksstathead, these are great questions. And the most important thing for me to point out is that I don't know the answers . I honestly don't know much about the details of the EPA tests themselves. I bet others here do. But it's worthwhile and fun to talk them out.

You are most likely right. If you bought this plug-in Prius and never plugged it in, your highway MPG at any speed would be slightly lower because of additional weight. It leads to all kinda of interesting questions. How does the EPA account for a second, additional fuel source that is both cheaper and optional? Do they publish two sets of ratings? One assuming no use of the optional source, and one assuming daily use? That seems like a good "truth in advertising" solution to me. So maybe the Prius on the highway goes from 45mpg to 43mpg (no charge) / 60mpg (daily charge) assuming a fixed number of highway miles driven. Also, charging ain't free. Should daily use kWh be converted into a mpg-equivalent? I'd say yes. Either that, or your new EPA ratings are 43mpg/0mpkWh (no charge) / 43mpg/17mpkWh or something. Now my head hurts. Those EPA ratings are completely unhelpful to the typical consumer.

Yes. Once the initial 6-10 miles of grid charging is exhausted, I'm assuming the plug-in would operate just as any Prius today...maintaining (bleeding & charging) a steady SOC as needed for climbs and electronics and such.

I think in the end the EPA has to at least publicize a likely improvement in "miles per fuel cost" in some easy to understand manner assuming one plug-in per day and a typical number of highway miles driven. That may not be all that should be publicized, and I bet there's a lot of debate how it's done. But I kinda like converting kWh to an mpg-equivalent and then advertising "60mpg-equivalent highway assuming one full daily charge". For the EPA to not take it into account seems almost deceitful.

Yeah, she would be absolutely awesome in the city. At the same time though, as a hypermiler it's the highway that has me excited about these developments. Gliding up to 62mph will of course kick butt. But in addition to that most of us have our 10 mile highway trips from time to time and like many I know I can stretch that 6 miles of charge out to maintain Insight-like highway performance for most of my highway driving needs within the city.

 

My thought would be you would change the 40-80% range to the lower bound of the 2 pack SoC range + 20% when the pack is depleted.

So if the double pack SoC range is 10-90%, once the pack reached 10% it goes into normal operation between 10-30%, trying to hold ~22% until you plug in. Or have it go into normal at 22%. I think we're saying the same thing, but I'm thinking a lower mimic level with a smaller range.

 

Wayne,

Thanks for the update. So what does the 2009 Prius-III add? The extra MFD displays? An EV button? (It's not PHEV and has the same pack...) EDIT: AHHH! HIGH SPEED GLIDE, now I get it...

thx,
ksstathead

 

Wayne,

Any ideas on how I could "volunteer" to be one of the 400 testers?

 

What Skwyre7 said!

So these 09 Prii would be out this fall as an 09 model?

 

I'd be thrilled to be one of the 400 testers, but I'd bet Toyota would prefer a more typical "end user". When Tom Brady is testing a new football, and the public begins to believe that the new football allows ANYONE to throw like Tom Brady, then it's best not to let Tom Brady test it.

Not that I'm Tom Brady. That's Jerad. I'm more like Eli.