Hybrid Automobiles

Contents: Basics; Concerns;


Hybrid vehicles incorporate an internal combustion engine (ICE), an electric propulsion motor, a battery pack, and an electronic drive system, all integrated into one complete package. Arguably in the same class, are true battery-powered vehicles like Nissan's all-electric Leaf®. It too requires an electronic drive system, to convert battery power to propulsion power. It is this latter device which makes hybrid technology and amateur radio, all but mutually exclusionary!

Nissan LeafThe first modern hybrid was Toyota's Prius®. Its Synergy® drive system has evolved since its introduction in 1997 (in Japan), to its current Generation V, a plug-in version with a larger capacity battery. The Prius®, is a true hybrid. Like other hybrids, either the ICE and/or the electric motor propel the vehicle, depending on driving conditions.

Hybrids share a lot of the same features as plug-ins do. For example, regenerative braking which puts back some of the battery power used to accelerate the vehicle in the first place. Most hybrids use electric motors not only to power the vehicle, but to run water pumps, power steering, and even the HVAC! A few use switching power supplies to power the lighting, radios, navi systems, etc., but others do have 12 volt, standard lead-acid vehicle batteries on board for that purpose.

Propulsion batteries are universally NiMH (nickel-metal-hydride), although Mercedes Benz's model uses a Li-ion (lithium ion), as does the Leaf®. Nominal battery voltages range from 36 volts, to 440 volts. All of this power does generate some concern for both owners, and emergency-responders in case of a vehicle crash (see below).

As noted, all of this electrification requires some sophisticated electronics, as evidenced by this white paper. The main reason is, the propulsion motor (at least) is a three-phase, AC motor. Those electronics are used to generate the requisite three-phase current, but that's not all. The frequency, voltage, current draw, pulse width (in some cases), regeneration, and many more parameters are controlled by digital electronics. Read into this, harmonic-generating, square-wave, switching circuitry!

Unless you live under a rock, you know that RF filtering a nominal 12 volt DC switching power supplies is a mixed bag of tricks. A few don't generate a significant amount of hash, while others sound like white-noise generators! Part of the issue is the amount of current being switched. In a hybrid, not only is the voltage considerably higher, so is the current. Thus, the amount of RFI they generate is rather copious in nature irrespective of the manufacturer's efforts to quell it. We should be protected to some extent by Part 15 of the FCC rules and regulations, however, vehicle manufacturers are exempt (Section 15.103)!

The question remains, just how RF noisy are they? Although the level of RF emitted varies considerably from model to model, none of them are what amateurs would call quiet! In fact, some are so bad, they can be heard from several blocks away, and the year of manufacture has little to do with the level! The next question is, can it be tamed? Yes, but it is a herculean task requiring countless hours, and hundreds of dollars spent reducing the RFI to a level compatible with HF operation. This is on top of the premium price most hybrids demand (≈$4,500 to $6,000).

One interesting sidelight to the cost issue, is the fact that every hybrid vehicle sold, costs more to make and distribute, than their MSRP. This says nothing of their aftermarket recycling costs and/or environmental impact after the fact. They are, by any description, a political medicine ball!



The National Fire Protection Association recently released a report entitled Fire Fighter Safety and Emergency Response for Electric Drive and Hybrid Electric Vehicles. It outlines the procedures for proper emergency response to hybrid vehicle fires, and crashes. It also contains a list of all current (circa 2009), and near future models of alternate-fuel vehicles. These include all electric, hybrid electric, hydrogen, CNG, and the various combinations. Here's an excerpt from the document:

Electric propulsion systems introduce new and possibly unanticipated hazards to emergency responders, although these do not include anything that members of the fire service would consider particularly challenging. For example, EVs and HEVs utilize high voltage power used for propulsion in conjunction with their low voltage electrical systems used for accessory lighting. The cabling for these high voltage systems were voluntarily colored bright orange for easy and consistent identification. In certain recent models cabling has appeared that, although it does not carry high voltage, still presents an appreciable and dangerous shock hazard, and these are identified using blue and yellow to color-code cables. In the meantime, additional shock hazards exist in all vehicles from certain features of the low voltage electrical system, such as, for example, the use of special high intensity discharge headlights.

While the NFPA is concerned with emergency response, potential mobile operators of these vehicles should also be concerned as well. You might want to read this article published on the Tesla Motors web site.

Probably, the most egregious issue is the false impression of the environmental savings associated with hybrid and plug-in vehicles. Plug-in cars like the aforementioned Leaf®, are not as environmentally clean as pundits claim they are. Just ask yourself where the power to charge them up comes from. Here in the US, that's predominately a coal-fed power plant. Oh! But! You can charge them with solar panels! The truth is, the cost of enough solar panels to charge the Leaf® in the same time frame (≈8 hours) as 240 volt mains, would cost almost twice the Leaf's® ≈$40,000 MSLP. Using solar also negates charging the vehicle overnight!

Everyone brags about the mileage they were getting. What they didn't tell you about, is all of the trips back to the dealer to adjust or fix something that quit working. And, if they installed HF amateur radio equipment, they don't tell you they have to pull over, and turn off the engine to use HF radio!

Further, manufacturers of hybrid vehicles go to great lengths to increase the overall mileage. One of the strategies is to employ small diameter, low rolling resistance tires. Since they have to carry a lot of battery weight (up to 1,300 pounds), they require high inflation pressures (≈40 psi). Add in the requisite stiff suspension, and the ride isn't what one could call cushy.

Another strategy to increase fuel mileage is to essentially enclose the bottom of the vehicle in an effort to decrease its Coefficient of friction (CF). It does work by the way, but there is a drawback. Remember, those skinny little tires? Well, they certainly aren't snow tires! So be aware that skidding off into the ditch on a snow-packed street is enough to do great damage to the underside, which typically totals even a brand-new vehicle!

Hybrid vehicles tend to be sub compacts (although some are mid, and some are large sized). Sub compacts typically are four passenger vehicles, with an occasional 5 passenger if you don't mind being squeezed. Add the requisite battery space, and the trunk tends to be minuscule. They are not long-vacation-travel vehicles, unless you have a very good relationship with your travel partner. By the way, if you're a golfer you'll have to put the clubs in the back seat as hybrid vehicle trunks are typically too small—think batteries!

While the hybrid vehicle idea seems like a very smart, environmental-friendly, form of transportation, the fact is, their overall cost to manufacture, distribute, and recycle, far exceeds any real-world benefit they may appear to have. Especially if you're an amateur operator. Caveat Emptor!