Electric & Alt Fuel Vehicles, Part 3

[gadget_lover]

Yes, like John1701a says, it activates a mode to simulate engine braking. It first uses regen braking, and then engine braking if needed. If the hill is long enough to switch into 'B' then the battery will probably be topped off before I hit the bottom.

The B mode only delivers poorer milage (wastes power) if you are in a situation where you could have coasted without touching your brakes. I find going 80mph down-hill in the mountains a bit too scary.

I use D all the time except when going down long grades of more than 3% or so. There are some long downhill runs driving into California from Nevada and Oregon. Some of the grades are many miles long. I set to 'B' and then set the cruise for the speed limit and forget about it.

As Darell says, coasting is a beautiful thing. Regen braking catches SOME of the energy used to accelerate, but not all. Coasting does not waste any extra energy.

Using B in normal driving is kind of jerky (especially in comparison to the normal Prius drive), as the car will try to slow every time you take your foot off the gas.

Brock; if you have 20 miles at 42 mph you'd love the Prius, I understand that's about THE sweet spot for fuel economy in the 2001-2003 models. You may be suprised at your milage if you can borrow a car.

My milage is killed by the fact that my normal drive always starts with 1 mile of city streets (with 3 stop signs) followed by 5 minutes at the coffee hut drive through. If I killed my coffe habit my milage would skyrocket.
/ubbthreads/images/graemlins/smile.gif

Daniel

 

[Bright Scouter]

OK,

I know this will go a little off topic, but no so far that I think you guys will mind. We have an RV. I would very much like to start working toward using either solar and wind power to help us charge the batteries. Any idea which is more cost effective on a small scale? Michigan is not a good place for sun. But we have enough hills and trees that it is not overly windy either. I have seen ads for wind generators in the under $1000 range. Any thoughts on that versus a solar system?

Thanks,

 

[MJRMetalworks]

What are the major challenges with building a serial, gas optional, HEV? I'm dreaming of making an offroad "fun" vehicle that is basically a BEV with a small onboard 'emergency/backup' generator. In this type of application can the vehicle be in operation while the generator is running?
If this question has already been answered, forgive me and point me to it.

Thanks. And thanks everyone for the very eye-opening discussions on Alt Fuel vehicles!

 

[mattheww50]

I think generally wind is less expensive per installed KW than solar, and while wind has moving parts,most the units these days are self managed, and will even effectively feather in high winds. I know a couple years ago when I looked into power for a sail boat, wind was much more attractive. The guy spent about $300K on the sail boat, and it had a thermoelectric fridge, which could simply eat battery. A modest 300 watt wind unit on the back end of the boat worked wonders. Just make the unit can put up with outdoor temp range. The 300 watt unit lives in Sydney Australia, where temp is never a problm.

 

[gadget_lover]

The question posed by MJR Metalworks is a good one. It all depends on what your design objectives are.

There is a lot of information on building a small BEV. An offroad fun vehicle (an OFV for short) would have a fairly small range, no? So that would call for a fairly small battery pack.

The addition of an ICE would add a bit of weight as well as size. How quickly would the genset need to charge the battery? If it needs to be able to power the OFV when the battery is dead (at full power), it will need to be pretty big. If you just want to limp back to camp and charge the battery overnight it can be a lot smaller.

The genset should be able to feed the battery as the battery is feeding the motor. What really happens is the power produced by the genset goes to the motor, with any extra going into the battery or any deficit is made up by the battery.

Serial hybrid is really the easiest to make. It can be as simple as a BEV with a circuit that starts up the genset when the battery discharges to a set point. The hard part comes in designing it so that everything is exactly the size needed, no more and no less.

Daniel

 

[Brock]

[ QUOTE ]
Brock; if you have 20 miles at 42 mph you'd love the Prius; I understand that's about THE sweet spot for fuel economy in the 2001-2003 models. You may be surprised at your mileage if you can borrow a car.

[/ QUOTE ]

In the TDI I got 59.4 on one tank that was mostly that run. I don't know what it would be if that was all I did. I would think 60+ for sure.

I guess the if the "B" does just engine brake there isn't a "battery" advantage it wouldn't make since. I was thinking it would be say 100% generator or battery charging breaking, which was be about al I need. I can drive to work without using the brakes, coasting for a while and at the turns using a bit of engine braking. Really it is the stop at the end I need the brakes for.

 

[Brock]

[ QUOTE ]
Bright Scouter said:
OK,

I know this will go a little off topic, but no so far that I think you guys will mind. We have an RV. I would very much like to start working toward using either solar and wind power to help us charge the batteries. Any idea which is more cost effective on a small scale? Michigan is not a good place for sun. But we have enough hills and trees that it is not overly windy either. I have seen ads for wind generators in the under $1000 range. Any thoughts on that versus a solar system?

[/ QUOTE ]

You so need to go to my other stomping grounds Wind & Sun There is at least one long thread about it a month. There is at least one other camper that is also from MI on the list.

 

[Brock]

Daniel, I could be wrong but I thought the TDI used about 12HP to run 60 mph on a flat road. The reason I am mentioning this is because my dream car has a BEV, with enough battery to run 40 miles and a 20hp diesel backup generator that did nothing but charge the battery bank. With that setup you could run directly from the genset for long cruising at 70mph and accelerate quickly via the power stored battery bank.

Does the Prius tell you HP out as your driving? If you just floored it forever and the battery bank was depleted what would it run at? What I am getting at is that you would need to size the genset for flat out highway running at maybe 85 or ???

Hey maybe that would be the thing, you buy the car and then choose a "power plant" sized to a max continuous speed. You could also have 120/240vac plugs on the car to act as backup for whatever you need.

 

[jtr1962]

I was always under the impressive that under regenerative braking the car coasts unless you hit the brake pedal, and once you brake the car goes into regenerative mode unless either the battery pack is full and/or you need to stop faster than the regenerative mode is capable of (in which case the friction brakes apply enough to make up the difference). Is this what the Prius does when not in "B", and thus the purpose of "B" is just to provide a constant braking force for downhill situations and the like? Maybe I'm missing something here. If regen braking is touted as a feature, then it should be in operation whenever you hit the brake pedal, and only then unless there is a setting to do something else. Having the car decelerate sharply whenever you lift off the gas would be annoying to say the least. And it negates the advantage of a low-rolling resistance, aerodynamically slippery design which can coast for a few miles from highway speeds if need be.

Regarding coasting, I do it all the time on my bike when approaching situations which require me to slow or stop. If I time it right, I almost never need to hit my brakes. Often, I'll hit a red light just turning green at maybe 10 mph after coasting down for a few blocks.

 

[jtr1962]

[ QUOTE ]
Brock said:
Does the Prius tell you HP out as your driving? If you just floored it forever and the battery bank was depleted what would it run at? What I am getting at is that you would need to size the genset for flat out highway running at maybe 85 or ???


[/ QUOTE ]
I read somewhere that the Prius was governed to 99 mph. Just doing some quick calculations (frontal area=25 ft², Cd=0.26, weight=3300 pounds with two passengers, LRR tires) I get a cruising HP of 53 at 99 mph, more than enough for the ICE to manage. In fact, I've noticed that quite a few very slippery cars, especially those with large engines, have governers to limit the top speed which would otherwise be in the stratosphere. My brother's Mark VIII is governed to 128 mph but replacing one of the chips lets the car reach its power-limited top speed of well over 150 mph. I imagine something like the EV1 could do close to 150 mph with the stock electric motor and proper gearing (stock was governed to 80 mph IIRC but could likely go over 100 mph despite still being limited by gear ratio).

 

[Brock]

Right, I was just wondering how many HP it takes to push it at 60mph, or my TDI (29ft, cd32, and 3100lbs and Michelin energy's) or even Darell's RAV4. Actually Darell you should know how many KW's it pulls at any given speed, so you could calculate it out.

 

[Darell]

[ QUOTE ]
gadget_lover said:
Yes, like John1701a says, it activates a mode to simulate engine braking. It first uses regen braking, and then engine braking if needed.

[/ QUOTE ]
OK, I'm not gonna eat my shorts until we have a concensus here. The fist quote says there is NO regen, but Daniels says it is regen first, and then engine braking. That latter is what I'd assume. After the battery is full (though the Prius never lets the battery get remotely close to what EV folks call full!) then engine braking would need to be employed. But if engine braking is ALL that happens, I'll still be upset (and over more than just the shorts-induced indigestion).

 

[Darell]

[ QUOTE ]
jtr1962 said:
Regarding coasting, I do it all the time on my bike when approaching situations which require me to slow or stop. If I time it right, I almost never need to hit my brakes. Often, I'll hit a red light just turning green at maybe 10 mph after coasting down for a few blocks.

[/ QUOTE ]
I call this "driving ahead." Meaning you look way farther ahead than most drivers do - which is typically one car. If everybody drove like this - anticipating the next move well before it happened, our average fuel economy would significantly increase. But we are a nation of "floor it and stop it," I'm afraid.

Once you get an EV up to speed, you can fine-tune your speed so precisely because there is no engine drag when you lift your foot from the go pedal. Once you're used to it, driving an ICE is just the strangest feeling since it slows down so damn fast when you lift your foot.

 

[Darell]

[ QUOTE ]
jtr1962 said:
I imagine something like the EV1 could do close to 150 mph with the stock electric motor and proper gearing (stock was governed to 80 mph IIRC but could likely go over 100 mph despite still being limited by gear ratio).

[/ QUOTE ]
The Impact did 183mph in 1994. Only addition was four more batteries, taller gearing, and smooth hub caps. This is the very vehicle. Held the electric land speed record for that year.

 

[Darell]

[ QUOTE ]
Bright Scouter said:
I know this will go a little off topic, but no so far that I think you guys will mind. We have an RV. I would very much like to start working toward using either solar and wind power to help us charge the batteries. Any idea which is more cost effective on a small scale? Michigan is not a good place for sun. But we have enough hills and trees that it is not overly windy either. I have seen ads for wind generators in the under $1000 range. Any thoughts on that versus a solar system?


[/ QUOTE ]
One thing to consider os that a solar system can be employed while driving - a wind system can't/shouldn't be. I assume this is for use ON the RV, right? I would personally go with solar because there is nothing bulky to store or deploy (you'd have to run the generator up a mast somewhere - the solar panels just sit on the roof and do their thing whenever they can.

 

[Darell]

[ QUOTE ]
MJRMetalworks said:
What are the major challenges with building a serial, gas optional, HEV? I'm dreaming of making an offroad "fun" vehicle that is basically a BEV with a small onboard 'emergency/backup' generator. In this type of application can the vehicle be in operation while the generator is running?

[/ QUOTE ]
There really are no show-stoppers. This is what the UC Davis "Future Truck" deal was all about. If I threw a Honda generator in the back of the Rav, I could run it and drive all day. In fact, there was a tow-behind generator commissioned by Toyota and built by ACP to do just that. The Rav could drive at 70 mph until the tank ran dry. In this configuration, about 30mpg was achieved. No problem at all to charge while driving. The generated power just goes directly to the traction motor - unless it isn't all needed at the time, and then it would go the the batteries for use later. A Series hybrid is considered to be the most simple since the electric motor just provides traction, and the ICE just runs the generator. No complicated (though sexy in the case of the Prius) coupling/transmission.

 

[gadget_lover]

Brock, I don't know what the HP output is at any particular moment. It's designed to be totally transparent to the driver unless you turn on the display that graphically shows the power routing and source. There's not much info there.

If you floored it forever you'd be going so fast the battery would be the least of your problems. Actually, it has a governor that acts around 100mph. I think it's actually 105 for the 2002, but I'll never go that fast so it does not matter. If you manage to deplete the battery 100%, it would keep going on the ICE, with "reduced performance". There is an idiot light on the dash to let you know if you ever get in this state. The idiot light is in the shape of a turtle.

It's very, very, very hard to deplete the battery on the Prius. I've not managed to come even close in almost 3 years. I routinely drive 4 or 500 miles and over mile high mountains.

JTR, you are correct, the 'B' is only for down hill stretches where you might downshift a manual tranny to get better engine braking. When in 'B' it most definitely uses regen braking in addition to the compression braking.

The Prius uses regen any time you touch the brakes. The brake pads are used if you need to stop quicker than the generator drag can stop you.

Darell, you needn't eat your shorts. The regen is used in 'B' mode to slow the car. Regen will only exert so much force based (I think) on how fast energy can be pumped into the battery. The engine braking is used if the downhill force is greater than the regen can handle.

When building a serial hybrid like Brock wants, the problem is making sure that you'll have power when you want it. I don't think a 20 HP genset will do the job unless you are absolutely sure the road is level and there is no wind. A long gentle grade (miles long) is a killer if it puts your serial into a negative charge situation. You may find yourself in a position were a small battery pack is depleted.

In the quoted situation a 20 HP genset is providing the cruising power and the battery is used for quick acceleration such as passing, climbing hills, accerating from a stop, etc. The Honda system is sort of like that, but they use the ICE to drive the wheels directly. Popular Mechanics drove a Honda hybrid from NY to LA. Somewhere in the great plains they depleted the battery due to the gentle slope of the land. They were not able to drive the speed limit for a hundred miles or so.

Please don't mis-understand. I think a pluggable serial hybrid is way better than a straight ICE and may allow people to rationalize buying into a BEV. I think it would be cool to have one too, especially if you can only have one car.

Daniel

 

[ikendu]

[ QUOTE ]
Orion said:I wish we would quit relying on foreign oil [heck, even domestic oil] and start using more environmentally friendly means to power things.

[/ QUOTE ]

Actually...for those that want to, we can do that today.

For the last two years I've done my commuting (38 miles round trip) in a vehicle powered by renewable energy...biodiesel. I've had to blend in petroleum diesel in the winter, but overall, I've cut my use of petroleum by 75%. Since we "only" import 60% of our oil...I figure the little petroleum I do use is all domestic.

So...come on in! /ubbthreads/images/graemlins/smile.gif The renewable energy water is fine!

Off-the-lot, unmodified 2003 VW Golf TDI getting 44 mpg on all American biodiesel...make your own for 45 cents/gal.

 

[ikendu]

[ QUOTE ]
jtr1962 said: Actually, we'll probably have to travel long distances like this [trains under the sea] once the oil runs low for the simple reason that planes have no alternative to fossil fuel...

[/ QUOTE ]

Actually, there's no reason that jet fuel couldn't be made renewably. There are diesel engines in planes now that can run on biodiesel. Diesel fuel is not so terribly different than jet fuel.

 

[ikendu]

[ QUOTE ]
Bright Scouter said:
OK,

I know this will go a little off topic, but no so far that I think you guys will mind. We have an RV. I would very much like to start working toward using either solar and wind power to help us charge the batteries. Any idea which is more cost effective on a small scale? Michigan is not a good place for sun. But we have enough hills and trees that it is not overly windy either. I have seen ads for wind generators in the under $1000 range. Any thoughts on that versus a solar system?

Thanks,

[/ QUOTE ]

Solar is best as near as I know.

I asked a guy who lives off the grid who has both wind and solar. If he had to do it all over again, he'd just buy all solar.