ALL-Electric Prius

[nimblemotors]

There are other limits than just the battery!
On the surface it seems if you just add a lot of battery, the Prius can operate as an EV and not generate Co2. This is not the case.
The first is that the motor controller is limited in its power, it depends on the gas engine for additional power.
The Prius HV Controller will run the gas engine under most commonly occurring conditions, it MUST over 52mph. Killing the fuel to the motor and have it spun by the electric motors is highly inefficient. And I would not discount the "bit" of reduction in weight by removing the gasoline components. It is probably 300lbs. That means you can add 300lbs of batteries instead.
As the video shows, just removing the gas components, the system throws codes and will not operate normally, it is going to take some engineering to make it work correctly.

Now if you don't mind your car generating Co2 and need to travel longer distances, then you want to keep the gas engine.

Originally Posted by sub3marathonman

It probably hasn't been done much because it isn't a great idea. I think before the engine is removed just run the car out of gas and see what the situation is.

Because really the limiting factor as far as I know isn't the Prius electric motors, it is the batteries. So unless you're putting more batteries in, there isn't a benefit, but if you do put more batteries in you might as well keep the engine and either do the "52 mph hack" or else do as was done in the video and remove the engine components and leave a bare block, which to me the only benefit there is a bit of weight reduction. The PICC conversion has already accomplished 70 mph in EV only mode, but unfortunately they won't market just that part of their kit, so hopefully pEEf or somebody else will come along and figure it out too. Obviously it can be done, which is the first hurdle to any project.

It will always come back to the range of the batteries, not the speed of the car. And unfortunately, as the speed of the car increases, the range of the battery drops quickly.

[pEEf]

Originally Posted by sub3marathonman

It probably hasn't been done much because it isn't a great idea. I think before the engine is removed just run the car out of gas and see what the situation is.

Because really the limiting factor as far as I know isn't the Prius electric motors, it is the batteries. So unless you're putting more batteries in, there isn't a benefit, but if you do put more batteries in you might as well keep the engine and either do the "52 mph hack" or else do as was done in the video and remove the engine components and leave a bare block, which to me the only benefit there is a bit of weight reduction. The PICC conversion has already accomplished 70 mph in EV only mode, but unfortunately they won't market just that part of their kit, so hopefully pEEf or somebody else will come along and figure it out too. Obviously it can be done, which is the first hurdle to any project.

It will always come back to the range of the batteries, not the speed of the car. And unfortunately, as the speed of the car increases, the range of the battery drops quickly.

The biggest limit to EV power is actually the boost converter. It takes the battery voltage (201.6v nom) and boosts it up to whatever is needed at the time. This is needed because the Prius uses permanent-magnet based brushless DC motors (DC is a misnomer, as it's actually 3-phase AC). As these motors spin faster, the develop more back EMF (the voltage raises). To keep the motor delivering high power, you must have a high voltage, as back EMF is a function of RPM. Here's ORNL's table:



MG2 is rated at 50kw according to ORNL, but the boost converter is only rated for a little more than 20kw. This means in battery mode you can't really get more than that total unless you do some serious hacking. Normally the ICE is spinning MG1 which is producing power that's put back into the invert high-voltage bus, so that's how the Prius can come up with 50kw for MG2. (~30kw from MG1, ~20kw from the battery via the boost converter)

So really, the Prius just isn't made to be an EV, you are much better off just putting a new motor with lower voltage windings, coupled to a simple transmission. Yeah, you can hack all kinds of things, but by the time you do all that you are going to have WAY too many hours into it.

Now as long as you have the ICE for power when you need it, the ~20kw or so that EV mode can provide is just about enough to sustain the car at speed on a flat surface. So if you have an upgraded battery, can can make good use of it and just keep the ICE for rapid acceleration and long trips. This way you only need 1 car for all your trips.

I currently own 2 EVs in addition to my Prius, and they are fine for city driving. Until we have charging stations available on our highways and packs that can do less than a 10 minute fast-charge, we are stuck using the ICE I'm afraid.

I'm doing what I can within my means to reduce the petroleum I use and trying to limit my emissions. My goal is to get the Prius so it can serve both purposes and give one the EVs to someone who can benefit more from it. (it's for sale BTW)

[sub3marathonman]

Originally Posted by nimblemotors

There are other limits than just the battery!
On the surface it seems if you just add a lot of battery, the Prius can operate as an EV and not generate Co2. This is not the case.
The first is that the motor controller is limited in its power, it depends on the gas engine for additional power.
The Prius HV Controller will run the gas engine under most commonly occurring conditions, it MUST over 52mph. Killing the fuel to the motor and have it spun by the electric motors is highly inefficient. And I would not discount the "bit" of reduction in weight by removing the gasoline components. It is probably 300lbs. That means you can add 300lbs of batteries instead.
As the video shows, just removing the gas components, the system throws codes and will not operate normally, it is going to take some engineering to make it work correctly.

Now if you don't mind your car generating Co2 and need to travel longer distances, then you want to keep the gas engine.

It is simply a matter of physics, not beliefs. Now, it is true what pEEf says about power, but that is comparing apples to oranges, because (almost) everything is about range in my opinion. Yes, you can't take 30 minutes to get it up to 30mph, but it doesn't need to go 80 mph either (not that pEEf said that).

As far as I know, the PICC uses strictly battery power, with absolutely no input from the engine, and can (no matter how long it takes or how inefficient it supposedly is) get the Prius up to 70 mph. But what is the range at that speed? It obviously is much lower than doing 30 mph.

Now, I actually don't want my car generating CO2 any more than absolutely necessary, but there is a limit to what is practical to do with the Prius as it was manufactured. And, although I'm not to the level of pEEf or mrbigh or others, I have done what is practical for myself at the present time and put in the Hymotion kit. The last tank went over 1100 miles, at about 125 mpg. I think by following a few tips from The Force, I could easily double the mpg. But that is for my situation and the relatively short commutes I'm making in the car. For a longer trips, no matter what, it would need the gasoline engine. There is no battery pack that would give 200 or 300 miles of range, and can be recharged in less than an hour while you stop for lunch. And by removing the gasoline engine, you cut that aspect of the Prius out of the equation and thus require another car. This is essentially what pEEf said too.

But actually, I did speak a bit too soon, and there is one possibility when such an idea would be possible. If there was an otherwise pristine Prius with a blown engine, then such a project might make sense. But still, I don't think you'll be saving 300 lbs. because you've got to leave the engine block and the crankshaft. Just running the tank dry saves about 88 lbs, so you're more than 1/4th the way there just doing that and nothing else, which is MUCH easier. And, at some point, you can return to as manufactured condition just by putting gasoline in the tank and clearing the codes. And no matter what, with such a project you will never have a "normal working" Prius. The video showed that during the first minute or so.

[pEEf]

Originally Posted by sub3marathonman

It is simply a matter of physics, not beliefs. Now, it is true what pEEf says about power, but that is comparing apples to oranges, because (almost) everything is about range in my opinion. Yes, you can't take 30 minutes to get it up to 30mph, but it doesn't need to go 80 mph either (not that pEEf said that).

Yes, as the Ewerts have shown, the car will do 70 on a flat surface even with the transaxle and ICE spin losses. That's pretty much the upper limit of the boost converter, as it's going to be pulling about 100 amps to give you the ~20kw. Now if your ICE is warmed up, there's little wrong with using some of it's power to get you to that speed. That way you get up to speed in a reasonable amount of time without pissing everyone on the road off and/or creating a safety hazard.

Originally Posted by sub3marathonman

As far as I know, the PICC uses strictly battery power, with absolutely no input from the engine, and can (no matter how long it takes or how inefficient it supposedly is) get the Prius up to 70 mph. But what is the range at that speed? It obviously is much lower than doing 30 mph.

You can calculate it. It's pulling around 20kw from the batteries. If you have a 20kwh usable capacity pack, you can't expect more than an hour or 60ish miles. 5kwh? About 15 minutes/15 miles. I'm putting in a 7kwh (usable) pack which I believe is a good compromise. It weighs 170 pounds with all it's goo installed, but I'll be removing the stock pack, so that's a net gain of around 100lbs.

Originally Posted by sub3marathonman

Now, I actually don't want my car generating CO2 any more than absolutely necessary, but there is a limit to what is practical to do with the Prius as it was manufactured. And, although I'm not to the level of pEEf or mrbigh or others, I have done what is practical for myself at the present time and put in the Hymotion kit. The last tank went over 1100 miles, at about 125 mpg. I think by following a few tips from The Force, I could easily double the mpg. But that is for my situation and the relatively short commutes I'm making in the car. For a longer trips, no matter what, it would need the gasoline engine. There is no battery pack that would give 200 or 300 miles of range, and can be recharged in less than an hour while you stop for lunch. And by removing the gasoline engine, you cut that aspect of the Prius out of the equation and thus require another car. This is essentially what pEEf said too.

Thanks for the Compliments!

The PHEV modifications for me will cover most of my in-town needs. I probably won't have to visit the pumps even as often as once a month! But I like to take trips, and then I don't need a separate car.

Kind of OT, But I've made a piece of plywood that goes in the back to span the gap when you fold down the seats. Slide the front seats all the way forward and drop the plywood in. Then unroll a foam mattress and I've got some of that mylar-coated bubble wrap cut to fit all the windows. Presto! Mini camp-anywhere Prius for 2! If it's hot outside I can even leave the car in ready mode and run the A/C. The PHEV pack can run the A/C for about 10 hours if it's fully charged. This is amazingly comfortable and works well. I don't need to bother with Hotels. If I can find a place to plug in I can even run my A/C indefinitely from a 120v outlet!

I need to make a hack which will let me run the electric heating strips without causing the Prius to start the ICE, then I can have a little heat as well! I suppose I could also just order a small EU-spec space heater (240v) and modify it to run on DC pack voltage.

Originally Posted by sub3marathonman

But actually, I did speak a bit too soon, and there is one possibility when such an idea would be possible. If there was an otherwise pristine Prius with a blown engine, then such a project might make sense. But still, I don't think you'll be saving 300 lbs. because you've got to leave the engine block and the crankshaft. Just running the tank dry saves about 88 lbs, so you're more than 1/4th the way there just doing that and nothing else, which is MUCH easier. And, at some point, you can return to as manufactured condition just by putting gasoline in the tank and clearing the codes. And no matter what, with such a project you will never have a "normal working" Prius. The video showed that during the first minute or so.

You don't need the crank. Steve Woodruff's "conversion" (the one in the video) left the empty aluminum engine block in black mainly as a mounting support. It looks like it only weighs about 34lbs:



I bet you could either fabricate a new mount or at least cut away most of the metal in the block if you wanted to go that route.

Then go into the transaxle and remove MG1, the PSD, etc. Leave only MG2 as it's really all you can use anyway. That would give you a 20kw EV.

To summarize: There is no amount of mechanical fiddling with the PSD, MG2/MG1, gear ratios, etc. that will give you more than 20kw power unless you do a lot of electrical work to somehow deliver more than 40A @ 500V to the transaxle!

If you were to hack the inverter and improve the boost converter, that will give you 50kw. (you could install a 500v pack instead and bypass it) 50kw would be a tolerable EV, and it would get you to highway speeds. That's probably the best you could hope for keeping the Prius transaxle.

If someone wants to send me a wrecked Prius, I'll be happy to figure out all the technical details and (probably need to) come up with a replacement for the HV ECU to make it work well. If you beefed up the boost converter or added a 500v pack, you'd have no choice.

[donee]

Hi All,

I did not take the time to read through all this. But, it seems, the way to do this is to get three standard prius packs, put them in series, and feed that to a third-party three phase VFD (Variable Frequency Drive)....hmmm three stock Gen 1 inverters in series too?

[pEEf]

Originally Posted by donee

Hi All,

I did not take the time to read through all this. But, it seems, the way to do this is to get three standard prius packs, put them in series, and feed that to a third-party three phase VFD (Variable Frequency Drive)....hmmm three stock Gen 1 inverters in series too?

Several problems, one is 3 Prius packs will give you about 3kwh of usable energy. That's enough to only go about 3 miles on the highway!

Secondly, you are going to have considerable trouble locating an affordable 50kw (67hp) VFD that can handle a BLDC-type motor. Pretty much all industrial VFD's are built to run AC induction motors. While the drive algorithms are similar, they will need to be different to run the Prius BLDC motor properly. They also don't build big VFD's like that to be either small or light-weight.

You'd be better off building a 500v Thundersky Lithium pack. If you use the 40ah blocks, that will get you about 20kwh which is more reasonable for a small EV. Then, just run this into the boost bus inside the stock inverter, and buy a motor control development kit from any of the big-name microcontroller manufacturers and connect it to the Prius inverter. You'll have to also interface the encoder, Accel pedal, and do some amount of hacking on the brake system, along with some decent amount of software work. But then you should end up with a decent small EV!

[pEEf]

Bottom line is, unless you happen to have old Prii laying around like Steve Woodruff, you'd be better off selling your Prius and buying a Nissan Leaf.

You'll be much more happy! (and probably end up spending less!)

There are just too many little details and stumbling blocks here. Has anyone asked Steve to see what became of his Prius EV project?!

[kiettyyyy]

Originally Posted by pEEf

Bottom line is, unless you happen to have old Prii laying around like Steve Woodruff, you'd be better off selling your Prius and buying a Nissan Leaf.

You'll be much more happy! (and probably end up spending less!)

There are just too many little details and stumbling blocks here. Has anyone asked Steve to see what became of his Prius EV project?!

From what I recall, It never came to be

There were too many problems with the BMS that they were using(a prototype made by Plug-In Supply and the Ewerts)

The car was eventually sold I think...

[Swanny]

I think you'd be far better off converting a Geo Metro into an EV, the Prius is so complicated to begin with....

[nimblemotors]

Originally Posted by sub3marathonman

...I have done what is practical for myself at the present time and put in the Hymotion kit.

That is great! The first step was a hybrid, the second was a plug-in hybrid, the next is a full EV.
Lithium batteries are finally available at reasonable cost to deliver enough range. Practically speaking today, only a short-range EV is possible. In the future, we expect to see fast charging everywhere and even better batteries. We hope it happens in 3-5 years, not 1 0-20, but for today, an EV will be only a short range car.

Jack Murray