Getting excited about next Gen. Prius Plug-in

[9G-man]

I am beginning to greatly anticipate the next Gen. Prius Plug-in.
The more I consider how it will work, the more excited I get. Because it's gonna do something that the current Plug-in MODIFICATIONS, and the Volt wont do.....
Recharge it's own battery in transit. (If the drive is long enough).
And my drive will be long enough.

It means that with a commute like mine (47 mile one way)
I'm gonna have a fully charged battery on the front end of my drive (by charging at home), and again at the latter end because the ICE will recharge it once the car reverts back to normal hybrid mode during my drive.

So it means that the advertised EV range of the Plug-in prius will actually be double, if the commute is long enough. For example, A PHEV-10 would really give 20 miles ev range, 10 in the beginning and 10 more later in the drive.

And with efficient driving techniques, and glide exploitation, the basic advertised EV range will be easy to exceed anyway.

Using HSD as the foundation for a PHEV is gonna be huge, and I can't wait....

Initally the Prius Plug-in will be criticized for it's limited Ev range, when compared to the VOLT. But the realizations will soon be evident, the VOLT will have the practical limitations . JMHO.

[miscrms]

Originally Posted by 9G-man

I am beginning to greatly anticipate the next Gen. Prius Plug-in.
The more I consider how it will work, the more excited I get. Because it's gonna do something that the current Plug-in MODIFICATIONS, and the Volt wont do.....
Recharge it's own battery in transit. (If the drive is long enough).
And my drive will be long enough.

It means that with a commute like mine (47 mile one way)
I'm gonna have a fully charged battery on the front end of my drive (by charging at home), and again at the latter end because the ICE will recharge it once the car reverts back to normal hybrid mode during my drive.

So it means that the advertised EV range of the Plug-in prius will actually be double, if the commute is long enough. For example, A PHEV-10 would really give 20 miles ev range, 10 in the beginning and 10 more later in the drive.

And with efficient driving techniques, and glide exploitation, the basic advertised EV range will be easy to exceed anyway.

Using HSD as the foundation for a PHEV is gonna be huge, and I can't wait....

Initally the Prius Plug-in will be criticized for it's limited Ev range, when compared to the VOLT. But the realizations will soon be evident, the VOLT will have the practical limitations . JMHO.

Two questions:

1. Why do you assume the PHEV Prius will recharge itself?
2. Why do think that would be a good thing?

The main advantage of a PHEV over a standard HEV is that it can offset gasoline with electricity from the grid. To maximize gasoline offset, you want to match your battery size to your trip length, so that you always finish your trip with a battery that has just reached empty. That way you are not paying for and hauling around more battery than you need, but you also have as much available capacity to store grid electricity as possible. If after reaching the empty battery point you still have to drive more, you want to run the ICE as little as possible and as efficiently as possible until you can recharge the battery. If you use the ICE to recharge the battery you will burn more gas than you needed to on your trip, and have less room in the battery to store grid electricity for offsetting gas on your next trip.

Your thought that this would double the effective EV range doesn't make sense to me. EV range attributed to electricity generated by burning gasoline in the ICE is not really EV range. Its gasoline range, at a lower efficiency than if the ICE was turning the wheels directly. By that logic the Volt would have infinite EV range, because its always being driven purely by the electric motor whether its electricity is being supplied by the battery from the grid or from ICE turning the generator. IMHO that is the true advantage of the HSD over the Volt. Both will be potentially equally efficient while discharging the battery through the motor, as both will run essentially as series hybrids. Once the battery is empty, the HSD will have a significant advantage. The Volt will have to continue to run in a series mode, with its built in efficiency penalty of converting energy from mechanical to electrical and back, while the HSD can transition into a parallel hybrid mode where the ICE drives the wheels directly with no such conversion penalty.

Here is a rough numerical example to try and illustrate. To keep things simple, assume a Prius PHEV 10 gets infinite mpg on battery, 50mpg while just maintaining a depleted battery, and 25mpg while recharging the battery. For the 25mpg, I assume that it will take the same amount of time to charge the battery back up as it did to deplete it. I also assume that the efficiency improvement from more heavily loading the ICE cancels the conversion and storage loses associated with charging the battery. If the IC is putting out twice the power (1x to drive the car, 1x to generate electricity) then fuel use doubles, mpgs gets cut in half. A regular Prius is calculated at 50mpg.

CS = Charge Sustain, maintaining the battery at a constant level once discharged
RCH = Recharge, cycling the battery back up to 100% every time it depletes
HEV = Normal Prius

Trip - CS gal - CS MPG - RCH Gal - RCH MPG - HEV Gal - HEV MPG
10 mi -- 0 ------ inf ----- 0 ------ inf ----- 0.2 ----- 50
20 mi - 0.2 ----- 100 ---- 0.4 ------ 50 ----- 0.4 ----- 50
30 mi - 0.4 ------ 75 ---- 0.4 ------ 75 ----- 0.6 ----- 50
40 mi - 0.6 ------ 67 ---- 0.8 ------ 50 ----- 0.8 ----- 50
50 mi - 0.8 ------ 62 ---- 0.8 ------ 62 ----- 1.0 ----- 50
60 mi - 1.0 ------ 60 ---- 1.0 ------ 50 ----- 1.2 ----- 50

I think this shows a couple of interesting things. First, in the best case the recharge mode is as good as charge sustain at 10, 30 and 50 miles, but worse at 20, 40 and 60. Its never better. And this assumes that there is no penalty for charging the battery off the ICE, which I think most current gen Prius drivers already know is not the case. In reality the conversion efficiency loses of converting the ICE output to electricity, storing it as chemical energy in the battery, then converting it back to electrical energy to drive the electric motor will probably keep you from even breaking even at 10, 30 and 50 miles.

The other interesting thing to note is that while a PHEV 10 sounds pretty pathetic, its still reducing fuel consumption by 33% at 3X its range and 20% at 5X its range. With the cost probably being a few $k at most, thats not a bad result.

Rob

[9G-man]

Originally Posted by miscrms

Two questions:

1. Why do you assume the PHEV Prius will recharge itself?
2. Why do think that would be a good thing?

1. Its only gonna have one battery, so HSD will have to recharge that battery in order to continue to function as a hybrid. That feature is a key function of the current HSD, and will have to remain so.

2. Economic and functional advantage. In a big way.

The main advantage of a PHEV over a standard HEV is that it can offset gasoline with electricity from the grid. To maximize gasoline offset, you want to match your battery size to your trip length, so that you always finish your trip with a battery that has just reached empty.

Sounds good, but it's a downright silly statement, isn't it.
How does one determine their "trip length" requirements. That is the #1 limitation of an electric car and the reason most folks will avoid one. My trip length requirements are variable.

Your thought that this would double the effective EV range doesn't make sense to me. EV range attributed to electricity generated by burning gasoline in the ICE is not really EV range.

Don't forget about energy regeneration. That moderately larger battery in the next Gen. Plug-in Prius is going to offer a nice place to absorb more regenerative energy. And that's a gas cost offset anyone can admire.

My trip length is variable, and most folks don't want an expensive vehicle that imposes travel limitations. Or the anxiety of constantly having to calculate the point of no return.
Big batteries cost alot of money.... thus the cost of matching batteries to trip length eliminates the "gasoline offset advantage". It's not like were gonna have a battery size choice.
Your argument is beginning to sound like GM, and other, original nay-saying arguments against the Prius and why it doesn't (mistakenly) make economic sense. The Prius uses gas to recharge it's battery now, and it has proved every nay-sayer wrong.

Your argument also tends to align with the Volt philosophy, and Toyota will be taking a totally different approach with it's plug-in. We'll see which one has the most realistic viability.

With that argument, a Volt's claimed EV range of 40 miles will really only be 20 miles, because you can only go 20 miles before you have to turn around and return home, to recharge to avoid gas use, with that "right size'' choice to "off-set gas use."
With the Prius you'll have double the advertised Ev range with a long enough trip.
And have the choice to use that battery power at the end to further enhance overall gas mileage, when a plug is available, prior to next use, or not if a plug in opportunity is not available.

Think about like this, how many time have current Prius owners said, I wish I had a bigger battery... to absorb more regen, or just further enhance it's glide and EV abilities. We're gonna get that and the ability to plug it in too.

A low priced Prius with a small battery that can be plugged in and recharged in transit, is much more valuable than a big expensive battery that can't.
If we're talking about an everyday vehicle that can be used without travel limitations.

[PeakOilGarage]

From everything I have read about the factory Toyota Plug-In, they are only aiming for 8-10 miles of EV range. That is less than 1/2 of what the Hymotion system is providing today.

Of course, the Toyota Plug-In will also likely be cheaper than the $10,000 premium of the Hymotion system.

After driving the Hymotion plug-in for the past few weeks, I can say that 20-40 miles is the minimum necessary for this type of system. Most days it is enough for me because I either drive less than that, or I have the opportunity to recharge a few hours during the day while parked at work or at various locations where I am during my daily driving. Only 3 times in the past 3 weeks have I actually emptied the Hymotion battery and been forced to run in stock Prius mode.

If Toyota is only aiming for 8-10 miles, that is gone in a heartbeat. Why even bother?
I would use that up quickly every single day and be driving many miles without the electric boost of a Plug-In battery.

So frankly I think there will always be an aftermarket to boost the power of these Plug-Ins with additional range. I encourage Toyota to improve on the Prius. But their current goal of 8-10 miles is not even close to being sufficient.

[9G-man]

Originally Posted by PeakOilGarage

From everything I have read about the factory Toyota Plug-In, they are only aiming for 8-10 miles of EV range. That is less than 1/2 of what the Hymotion system is providing today.

Of course, the Toyota Plug-In will also likely be cheaper than the $10,000 premium of the Hymotion system.

After driving the Hymotion plug-in for the past few weeks, I can say that 20-40 miles is the minimum necessary for this type of system. Most days it is enough for me because I either drive less than that, or I have the opportunity to recharge a few hours during the day while parked at work or at various locations where I am during my daily driving. Only 3 times in the past 3 weeks have I actually emptied the Hymotion battery and been forced to run in stock Prius mode.

If Toyota is only aiming for 8-10 miles, that is gone in a heartbeat. Why even bother?
I would use that up quickly every single day and be driving many miles without the electric boost of a Plug-In battery.

So frankly I think there will always be an aftermarket to boost the power of these Plug-Ins with additional range. I encourage Toyota to improve on the Prius. But their current goal of 8-10 miles is not even close to being sufficient.

With that argument, then the current stock Prius is useless. But of course, even with a 1 mile range the current Prius is the most fuel efficient car on the road. It's not useless.
That economical, next gen., 8-10 mile EV range on the front end (via plug-in) is also going to be available on the back end (transit charge), becoming a 16-20 mile EV range. And all of a sudden, it's now getting within range of what Hymotion offers, simply because it can be recharged in transit.
And most importantly, without a 10K premium, it actually becomes cost effective.

And the overall emphasis is to further enhance what the Prius can already do, not be an electric car.

[john1701a]

Originally Posted by miscrms

To keep things simple, assume a Prius PHEV 10 gets infinite mpg on battery, 50mpg while just maintaining a depleted battery, and 25mpg while recharging the battery...

The system wouldn't force such aggressive recharging.

Taking advantage of electricity available from a plug at home is the point.

.

[PeakOilGarage]

9G-man, I agree that the Prius with 8-10 miles of EV range is a huge improvement over the current Prius. It will be wonderful. But I doubt that will be the standard Prius. It will likely be a premium option similar to the "Touring" option now. Maybe 5% of the Prius vehicles will come that way.

My argument is that the people who want that type of performance actually want much more than 8-10 miles of EV action. Recharging from the gas engine is nice, but also very inefficient. The most efficient electricity in the system is from the outlet where you plug in. A small ICE can never compete with large utility scale turbines in the creation of electricity.

The goal is to minimize gasoline consumption and shift the balance of power to the electric grid, which can be produced from zero carbon sources like wind, solar, nuclear, geothermal, etc.

The Hymotion system still allows regen into the stock Prius NiMH battery, so that energy savings is already present. The Hymotion Prius is using both batteries at the same time. The stock NiMH battery never falls below 6/8 while Hymotion is engaged, but it is still providing energy to the overall system and recapturing energy via regen.

My only opinion on the Toyota Plug-In of 8-10 miles is that it will be gone very quickly based on my experience. I use most of the 30-40 mile range of the Hymotion every day. It is right at the limit of my average day and likely the average day of most Americans. I actively try to plug in everywhere that I park for "opportunity charging" in order to extend my daily Hymotion range. It is a new method of thinking and operating. But this is the future.

There is a reason the Volt is aiming for 40 miles. That is the sweet spot of being functional.

[Fibb222]

I agree with miscrms. There might be improved regen, and better overall efficiency but you can't say that the effective EV range of the plug-in prius is doubled because of "transit charging".

If there is only one battery, it will be interesting to know what SOC the system will try to maintain while in normal prius mode after the 10 mile range is surpassed. The OP appears to think it will shoot for over 90%.

It may be relatively low (under 25%?) (<25% SOC of this new battery equaling something above 60% in the current Prius battery in terms of Joules?).

Going higher would lead to more conversion losses. But can this battery be kept healthy at a low SOC? If not, Toyota engineers might have a problem on their hands.

[9G-man]

Good stuff, I appreciate all the responses. I haven't seen a discussion yet on the potential merits of the next Gen. Prius Plug-in and how it will work.

I made a post a while back about how "gliding" will still be an important technique in efficient Plug-in operation. Seems like many folks disagreed with that too.

I agree, the more EV potential the better. Where does the battery cost equation balance?

[bruceha_2000]

Originally Posted by 9G-man

Good stuff, I appreciate all the responses. I haven't seen a discussion yet on the potential merits of the next Gen. Prius Plug-in and how it will work.

I made a post a while back about how "gliding" will still be an important technique in efficient Plug-in operation. Seems like many folks disagreed with that too.

I agree, the more EV potential the better. Where does the battery cost equation balance?

I am hoping there will be a facility where the driver can let the car know whether or not it should specifically degrade mileage to charge the battery. *I* will know if I am going farther than the EV range before I can plug back in, AND whether or nor I'll be able to plug in when I stop, or if it will have to wait until I return. No reason for the car to set a minimum SOC other than battery protection. However, if I'm doing a 200 mile trip, I hope the car can function as it does now, again with me having the ability to end up at my plug in point with little SOC to spare.