Monday, November 20, 2006

Serial Hybrids Are Here!

Just six months after Tesla Motors announced the return of a 100% battery car, the Tesla Roadster, we have another great leap forward.  As reported in the Los Angeles Times in a story entitled “GM To Present A Modified Electric Car“ ( on November 10th, General Motors has announced a serial hybrid car.  Early next year they will present a prototype of the vehicle.

If you are wondering just exactly what “serial hybrid” car means, you’re not alone.  But this is a car that will take the market by storm.  A serial hybrid means that the car has two engines, hence it is a hybrid, but only one engine is connected directly to the drive train, hence it is a “serial” hybrid.  By this logic, your Prius is a parallel hybrid, or just a hybrid.  For a detailed explanation of a serial hybrid car, including diagrams and energy conversion charts, read our feature from October 2005 entitled “The Case for the Serial Hybrid Car.”

The advantages of a serial hybrid car are huge.  They are far, far less complex than conventional hybrid cars, because only the electric motor, with its huge range of usable RPM, is connected to the drivetrain.  Another huge advantage is that serial hybrid cars have their second motor, a small, ultra-low-emission gas or diesel engine, connected to a generator to recharge the battery pack while the car is being driven.  By doing this, a cheaper and more reliable battery pack can be used, and there is no need for a complex heat management system that is still necessary for the lithium ion batteries.

It is well and good to criticize General Motors for discontinuing the EV-1.  But they are back with another green car which is as ahead of its time as the EV-1 once was, and this car is going to attract a much bigger market.

Critics may claim the EV-1 was a zero-emission vehicle, while a serial hybrid car has a small, ultra-low emission onboard motor, and therefore it isn’t as green as the EV-1, or the Tesla Roadster, or any 100% battery powered car.  Someday, when all electricity generated everywhere is done so with no combustion or other form of environmental degradation, this concern may be valid, but until that time, this is pure poppycock.

A detail of some interest regarding GM’s bold and groundbreaking new green car initiative are some performance specifications as reported in the Los Angeles Times story.  “The new car, if developed as a production model, would be recharged daily by owners and probably would deliver sufficient power from the batteries to cover the typical daily commute of 20 to 30 miles before depleting the battery charge and switching to electricity generated onboard.”

If these figures are true, GM’s planned serial hybrid car could be dirt cheap.  Theoretically, a car like this could run on lead-acid batteries.  Remember, a serial-hybrid car would only need a two-speed transmission, if that, for the electric motor that provides traction, and no transmission at all for the small gas (or diesel) engine that powers the onboard generator.  Maintenance would be negligible.  If GM used a nickel-metal hydride battery pack, it is likely that their serial-hybrid car will go much further than “20-30 miles” just on previously stored battery power, and the onboard generator engine could be smaller.  The people’s car is here.

However General Motors designs their serial hybrid car, it will be carefully calibrated to create a car with so much value for money that we all want to buy one, and don’t be surprised if they call it the EV-2.  Redemption is a sweet thing.

Original article