how to build poor man hybrid kit?

[MKimagin]

I wonder if it is possible to build hybrid convention kit for existing cars that will use of the shell components.

The basic requirements.
From this what I read the car need around 200W per mile for normal size car (not exally sure what normal size car is in that matter), that mean it will required 12.4kW/h or 16.6hp assuming speed of 62mi/h.

Knowing the minimum requirement for the power let see what the power plant we need.

We need engine that at list will produce 16.6 hp.
16.6 hp engine that really small engine by today standards.
Because we look to build hybrid system I will add another 40-50% more power to be around 25Hp or 18.6KW.

We need high efficiency power generator (dynamo or alternator).
Right now it not uncommon to have more then 90% efficiency generators. so that not out of the reach.

The question is why we have to build our own gasoline or diesel electrical generator system (engine + electrical generator).
This systems are already on the market (specially the low power one). What more they contain all the electrical controls. So that part do not need to be re-develop.

We will need some speed control system that will be able to operate with power close to 30KW.

Do we need transmission ? No. The system should not have a transmission due to fact that it will not make any advantage in terms of efficiency, cost and weight.

We will need electric motor , to be exact 2 electric motors.
The best will be the hub motors in the wheels. However this are not easy to find due to fast that most of them are in experimental stage, and not on the market.

I will propose to use more conventional high efficiency electrical motors in direct drive configuration. Electric motors like that definitely can be found on the market.

Do we need the big battery pack? No. One of the misconception is that it is absolutely necessary to use large battery pack to store recover energy from braking.
The idea is good however, the monetary cost, added weight and system complication make that idea not that grate for such conversion kit.
I will forget that idea utile better, with higher power density and less expensive battery will be develop. In that time we will probably switch to totally electric car any way.

The cost of that conversion kit will have to be below $10k
to be realistic.
I will not be surprise if car retrofit with such hybrid conversion kit will make 100mpg.

Now the main question is is this realistic?
Where to find the necessary components?

Any comments are welcome.

 

[amorrison]

For starters

The units used here make no sense.

200W per mile
12.4kW/h

 

[crysta1c1ear]

I guess what he's saying is the car needs 200 Wh = 0.200 kWh of energy per mile if it uses power at a rate of 12.4 kW
(or 16.6 hp) at a speed of 62 miles per hour.

0.2 Watt hours * 62 miles/hour = 12.4 kW.

If that is what he means, he needs to pay attention to where and when he puts his "h"s for hours.

 

[BrianPetersen]

I don't doubt that some industrious person could build something like this, and it has certainly been done already. It will be what is called a "series hybrid". All the engine power goes through the electrical system to the drive motors. Expect underwhelming powertrain efficiency under motorway cruising conditions ... too many conversions between different forms of energy. It will probably be little different in overall efficiency from a standard powertrain with a conventional manual gearbox and a normally sized engine. 100 mpg ain't gonna happen except in a vehicle that's so small and light that it would do 100 mpg with a conventional powertrain ...

People need to get over the wheel motors thing. If you are going to go all electric drive then fine, but if the original power source is going to be a combustion engine, then the most efficient way to get that power to the wheels is a gear-to-gear transmission. Prius hybrid transmission is arranged such that under motorway cruising conditions, most of the engine's power goes through the mechanical path to avoid the inefficiencies of the electric path.

 

[crysta1c1ear]

I'm drunk and he's got me at it now, sorry ...

I guess what he's saying is the car needs 0.200 kWh of energy per mile if the power is 12.4 kW and the speed is 62 miles per hour.

0.2 kilowatt hours / mile * 62 miles/hour = 12.4 kilowatts.

If this one's wrong, tough - eng-tips should allow people to edit their posts.

 

[ca2sbl]

MKimagin:
It has been done.
Goto

http://www.motherearthnews.com,

click on "article archives", search for "July/August 1979".
Then click on "An Amazing 75 MPG hybrid Electric Car". Follow the trail to January/February 1980, May/June 1980, September/October 1980, June/July 1993.
The plans are still available.
Not quite 100 mpg and before solid state pulse width modulation.

Have fun,
Russ

 

[MKimagin]

Yes, it should be 12.4KW per hour for 62 miles/hour.
BrianPetersen
I will direct you to see the hybrid bus build by e-Traction

http://www.e-traction.com/fuel_consumption_calculator.htm

You can see that conventional system need almost 3 time more energy then the hybrid system shown by e-traction. That 9200kg bus build by e-traction use less fuel them most SUV in US.

http://www.e-traction.com/fuel_savings_in_perspective.htm

There is no way that the mechanical transmission can compete with electrical system. Electrical systems can be build to have efficiency higher the 90% efficiency in almost all condition of operation. That almost impassible with total mechanical system.

In my opinion Pirus design is overkill. Whey too complicated and the fuel efficiency is not better then car with diesel engine for 50% of the cost (look Toyota Yaris diesel - 64mpg!!!)

The serial system is used in diesel electric locomotives for something like 40 years or so , so why we can't start use them in cars?

We have to look out of the conventional approaches, otherwise we never improve any thing.

 

[MKimagin]

ca2sbl
Grate finding.
Now let adopt that idea with component that are available right now. We definitely can do better then 75mpg.

 

[BrianPetersen]

MKimagin, I must point out first of all, that any claims taken directly from the promoter of the technology itself have to be taken with a VERY big grain of salt.

Secondly, I also have to point out that an urban transit vehicle (or urban delivery vehicle or anything of the sort) that operates purely in an urban environment, is an ideal application for electric drive with regeneration, because it can make maximum possible use of the regeneration in theory, and there is not so much aerodynamic or road friction loads. Series hybrid systems work well in that sort of application provided that the regeneration strategy is efficient enough.

The whole story changes when the vehicle goes out on the motorway and can't make use of its regeneration system ...

 

[EdDanzer]

Before you believe the e-traction propaganda, look closely at the data. How can you change the rolling resistance that much for their vehicle? Every hybrid system that exists in operation weighs more than a conventional system. If you plan on staring out on a hill the low speed starting torque will impact the actual efficiency of any electric drive including trains so don’t bet the farm on their 92% claim.

Designing a motor/generator for a vehicle drive is complicated by the shaft speed and torque variations during a drive cycle. The November 22 2006 Machine Design magazine has a good article by Ansoft Corp. highlighting some of the difficulties. One problem area is controlling the magnetic fields at different speeds and loads.