Hybrid Diesel Engine International School Bus

We have an International Hybrid School Bus that is powered by a 6 Liter MaxxForce Diesel Engine. I just wanted to go through some of the components in this system that will increase fuel economy when applied under the right driving conditions.

The generator is inline with the driveline and acts as an electric retarder. The generator also provides more horsepower defined in Kilowatts to help the diesel engine with added torque up to 30 mph.

The Computerized Control Unit (CEU) monitors the loads and speeds and sends amperage to the generator from the battery pack to provide braking then allows the generator to recharge the battery pack when the bus is going downhill in the coast mode. Light braking also helps charge the battery pack.

The generator is water cooled (long life antifreeze) and has a coolant pump to circulate the coolant through the generator body then it returns to the radiator which is specifically for the hybrid system.

The radiator is mounted below the driver's area and has an electric fan that is controlled by the CEU. The coolant pump is also monitored and operated from the computer. The more stop and go driving creates more heat in the generator but creates maximum torque/Horsepower/Kilowatts out of the hybrid system.

The battery pack has a main switch that must be turned off when working on the system. The batteries are lithium Ion and weigh far less than previous hybrid systems. They were manufactured in Korea and ENOVA (the developer of this hybrid system) reported very positive testing results with these batteries. The orange covering on the cables indicate high voltage and should be handled with care and properly insulated gloves.

Previously the battery pack used to be liquid cooled. This caused some minor problems with leaks and maintenance. Now ENOVA has developed an air cooled system that has a standard paper type filter with a high output blower inside the battery case that is funneled throughout the battery pack and exits out the rear of the aluminum encasement (towards the frame).

This has been a short over-view of the International School Bus Hybrid Diesel Engine. Please feel free to make any comments & thanks for stopping by...

Diesel Engine Oil - Switching to CJ-4 For 2007

To meet 2007 EPA standards low emission engines must use CJ-4 engine oil formulated especially for diesel engines using exhaust aftertreatment systems. New EPA standards are a 50% reduction in oxides of Nitrogen and 90% reduction in particulate matter. CJ-4 is a low ash diesel engine oil that can be used in older engines but comes at a higher price. The warranty becomes invalid if regular CL-4 oil is used in '07 diesel engines but the 10 to 30% increase in price is significant when it comes to a fleet operation.

You could stock both oils but there is a risk of operators who normally add oil to there assigned unit could inadvertently grab the wrong oil and mix the two. Mind you one litre of the wrong oil would not be detrimental to the life of the 2007 diesel engines but over time it would make a difference. The possibility of an engine oil test after a failure could happen.


Our fleet operation only stocks the CJ-4 so there is no confusion and zero risk to jeopardizing the integrity of the DPF [Diesel Particulate Filter]. The DPF has a regenerating cycle when a difference in input and output exhaust gases in the DPF [muffler] are picked up by the engine ECM [electronic control module]. The DPF literally cooks out the carbon build up and it gets kicked out the exhaust pipe which creates extremely high temperatures.


EPA standards are here to stay, with vehicle emission standards being on top of the heap when it comes to environmental concerns. Our School Bus Fleet will be receiving a Hybrid International School Bus next September. This will be an interesting technology to experience and another brand new learning curve to grasp.

DC Generators Fundamentals

Looking at DC Generators Fundamentals you can easily relate to Hybrid Automobiles which are powered by a fuel driven engine to create DC current that charges the batteries that drive the electric motors that drive the wheels.

Diesel locomotives are, for example, an example of a hybrid drive train, as the diesel engine does not cause the wheels to spin, but instead generates electricity that turns electric motors that then cause the wheels to spin.

There are two kinds of hybrid drive trains:

* Serial hybrid: The thing which turns the wheel is an electric motor, and the gasoline engine is used purely to generate electricity.

* Parallel hybrid: Both the electric motor and gasoline engine can cause the wheels to turn.

These "new" hybrid cars are all of the parallel design pattern. Not a one, so far, is of the serial design pattern even though that would be a much simpler vehicle to design and build. A simple-and-obvious-to-construct serial hybrid vehicle would be an otherwise pure electric car, and carry a portable generator.

When the batteries run low, fire up the portable generator and make some electricity. You could recharge the battery pack from the power grid, or from the generator, your choice. This could turn a limited range electric vehicle into one that could drive long distances.

However there are several steps of converting power (e.g. mechanical to electrical, and AC to DC). Each conversion step involves some lossage, and maybe this isn't the most efficient use of fuel.

The automakers are also working with a third type of hybrid, that they call "mild hybrid". [No information available yet]

It's not electric unless you can plug it in.

That is, many people seem to think the hybrid-electric vehicles on the market now are electric. Well, honestly, are they? None of them let you plug the car in to charge the batteries, none of them drive for any significant distance on pure electric, so how can one honestly think of them as an electric vehicle?

The electricity used in the electric motor, in all of these vehicles, comes from gasoline burned in the gas or diesel engine. These are not electric vehicles, despite the presence of that electric motor.

One day there will be 100% electric vehicles but technology will have to come up with a super/cost effective deep cell battery that will absorb and retain an amazing amount of amperage.

Here is a Youtube Video on a very old DC Generator that was steam engine driven back in 1917. It's a great example on how a driven DC Generator can be used to charge the battery pack [i.e. hybrid vehicle] or supply an amperage to a load. In this video the load is obviously the light being held for the demo...




DC Generators Fundamentals