MB Hybird?

Hybridizing a Mercedes is not practical, in my opinion.

Hybrids run off of internal combustion energy (and ONLY internal combustion energy).

They convert this energy to electricity and then use electric batteries to to store excess power for peak use.

The efficiency of a hybrid does not come from the conversion to electric power. This conversion actually WASTES power. The efficiency comes from the special design of the internal combustion engine.

Internal combustion engines have a tight torque curves. This means they produce power effectively in a very narrow RPM range. Car companies get around this in two ways: 1. They put gearboxes in cars which allow drivers to keep the engine speed in a power producing range 2. They grind camshafts to provide a compromise between efficiency and power in order to increase to RPM driveability range.

Hybrid engines run at a single speed, and only when the batteries need charging. They start up when the battery runs low, charge the battery and then shut down when the battery is charged. Since the engine only runs at one speed (or a much narrower range of speed) while the battery is charging there is no need to compromise engine design. The engine components can be designed for optimal efficiency at this single speed, and so the engines are (theoretically) more efficient.

Since the ENGINE makes the difference, it makes no sense to try to hybridize a standard 2.4 Mercedes diesel engine.

Hybrids can recover some energy from braking, and the DC motors have excellent torque characteristics and make a good drive system, but I think any efficiency you would gain in the drive train efficiency would be offset by the extra weight of the batteries, alternator, control system and motors.

That's my take > I have a serious question regarding the possible use of a 240D as a hybrid.

Try querying the Regional Transit District, the public transportation agency in Denver, Colorado. That agency built its own hybrid all-wheel-drive right-hand-drive coaches for its use on 16. Street Mall Shuttle. The motor is 1,6-litre Ford four-cylinder running constantly on compressed gas, turning the generator to provide the electricity for four motors and for batteries. I am sure they can point out the companies that manufacture the software and hardware necessary to make the hybrid system possible. The agency was forced to manufacture its own when no coach builders would accept the design specification for one-off coaches.

Oliver

Ernie Sparks wrote:

Agreed.

This is wrong.

They also use electric motors to move the vehicle.

This is completely wrong. A traditional vehicle dissipates a LOT of energy as heat.

For example, the light turns green, you step on it and accelerate to

50mph. The light ahead of you turns red. Guess what? All the the energy of your moving vehicle is now completely wasted by being turned into heat at your brake rotors.

Hybrid recapture this energy instead.

Interesting, but completely wrong.

What kind of power is wasted in a convential rear-wheel drive by turning it 90 degrees via differential?

Seems I recall that Ferdinand Porsche built a hybrid about 1907-1908. There was in interesting picture in a magazine - popular mechanics or popular science - something like those anyway.....

No it's not!... EVERY watt-hour of energy that propels a hybrid car comes from an internal combustion engine! The engine makes power which is converted to electricity... But the electricity COMES from internal combustion...

This goes without saying...

This is NOT wrong.. Any time you convert energy from one form to another, you waste some.. This is the second law of thermodynamics. In hybrids, energy is lost in converting mechanical energy from the engince to electric energy.. And more energy is lost in converting the electricity to chemical energy and then back to electrical energy...

Hybrids capture SOME of this energy, true.. (They also emply traditional brakes) However, this recapture alone does not account for their efficiency

How so?...

The efficiency of a hybrid comes from using a SMALL engine optimized to run at a single speed... That's all there is to it....

From answers.com:

"A standard combustion engine is required to operate over a range of speed and power, yet its highest efficiency is in a narrow range of operation. Also, an engine designed for a reduced operating range can be more efficient than a standard engine. The battery storage and electric motor allows the engine to operate at its point of maximum efficiency, to be of a higher efficiency design, and to be smaller than non-hybrid applications"

Brake recapture rate is about 30%...

"Regenerative braking is any technology which allows a vehicle to recapture and store part of the kinetic energy that would ordinarily be lost when braking. A simpler technology that can only convert the energy to heat but which uses similar principles is known as dynamic braking. Both are most commonly seen on electric or hybrid vehicles. Braking is accomplished by electrically switching motors to act as generators that convert motion into electricity instead of electricity into motion. Traditional friction-based brakes must also be provided to be used when rapid, powerful braking is required. Estimates currently see 30% efficiency; however, the actual efficiency depends on numerous factors, such as the state of change of the battery, how many wheels are equipped to use the regenerative braking system, and whether the topology used is parallel or series in nature."

I don't know, but hybrids would lose similar amounts of power through their gearsets too...

The way hybrids attain greater efficiency is by having a small, optimized engine which is designed to be the size of the AVERAGE power used in the car.. Which is MUCH lower than the PEAK power used... Rather than run a big engine at a bunch of different speeds, hybrids run a smaller engine much more contimuously at a constant speed.

Porsche did build a prototype hybrid, but it was much later than this, I believe...

Not awfully lot.

All this power loss is turned into heat of the differential. You can feel it by touching the differential after a long drive.

Terv: Harri

I think all the answers/debates on the efficiency of a hybrid are very interesting but I think that any serious, expensive work on a car of the age of yours is very unlikely to pay for itself.

Why would you want to undertake the work? Hobby? Learning experience?

DAS

For direct contact replace nospam with schmetterling

The engines in both hybrids I have driven (Toyota Prius and Honda insight) do not run at a single speed. They may operate in a much narrower band of RPM. Still NOT a single speed.

I see your point regarding all the energy being created by the internal combustion engine, but although seems a good point, it's also not completely right.

Imagine rolling down a big hill and stepping on the brake. You are now getting energy via your scavenging brakes, that isn't (directly at least) created by the internal combustion engine. Of course you can make the argument that the IC engine got you up the hill (which is probably true :~)

Still your dismissal of the energy scavenging system via brakes and suspension of hybrid vehicles is a mistake. these are energies that are 100% discarded as heat in a traditional vehicle and are llkely to continue improving in hybrids.

It is true the in the case of current designs, the energy recovered isn't a great % of total needed. Still it is significant and likely to improve.

in a nut shell why does the TOYTA not get 100 MPG?

the case, minus a few cans!

My main purpose would be to sort of prove a point concerning the use of a small diesel to turn an altenator to charge the batteries. A friend of mine put a 190 diesel in his sail boat and went off into the sunset. That engine would run at about 1,500 rpm forever (it seemed) on a gallon of diesel. The method pure electric cars use is to drive the vehicle into the garage at night and recharge the batteries. The electricity to do so is produced by a power plant many miles away, using coal, natural gas, diesel, etc. This is a rather complicated way to turn the rear (and maybe front) wheels of a vehicle to propel it forward. All I'm suggesting is that the power plant used to produce the electricity be located in the vehicle itself and turning, perhaps, at idle speed. A 240D engine can produce a lot of torque even at idle. This is especially true if you don't have to use any of that energy to drive the rear wheels. Imagine a 200 amp altenator being turned at three times idle speed via a large drive pulley, perhaps one with two V belts instead of one. This would produce a lot of juice to charge the batteries. One could even keep the original altenator to charge a small

12-volt battery for lights, radio, etc., while a 24 or 36 volt altenator could be used to charge a battery bank for the electric motors. Incidentally, electric motors can produce a lot more torque than a similar sized gas and/or diesel. Anyway, there was apparently one company that tried something like this and used a suitcase-sized diesel which burned very little fuel to generate electricity for a battery bank. Wow. I'm impressed by the input on this topic. Good job guys. Keep it up.

I'd love to see you do it and offer plans. I've got my $29.95 ready. The real problem with today's hybrids is that they are a bloodly mess to service. In a few years, we'll start hearing horror stories from consumers who had to have megabuck repairs of current units. There's absolutely no reason these vehicles could not be made with "modular" mechanicals (think original VW bugs). The 240 has enough space that should accomidate a good sevicable design.

Ron

Check out the pre-1907 Lohner-Porsche hybrids.

Because that is an arbitrary number you made up.

An idling mercedes diesel won't lst long idling because it'll coke up.

not me Ernie made up the 100MPG

the case, minus a few cans!

Then I'll just switch to Pepsi. Problem solved!