There are several types of hybrid systems and one receiving much behind-the-scenes attention by automakers and top-tier suppliers that’s projected to begin proliferating en masse within a few years is the “micro hybrid” system.

This is a cost-effective means of electrification that augments a given internal combustion powertrain. It utilizes a lithium-ion battery rated under 60 volts to power a motor/generator and to help shift the electrical system load away from the 12-volt battery also on board. Micro hybridization has been shown to offer a 15-20-percent improvement in fuel economy, or about the same benefits as a more-expensive mild hybrid such as General Motors’ eAssist system.

You may have already seen reports from a couple of years ago saying micro hybrids were poised to come on strong by 2015. While micro hybridization adoption has been taking longer than some projected, it is still being touted in close to the same time frame as “the next big thing,” with “all” automakers now working on them.

This description of the present state of affairs comes via Mary Ann Wright, vice president Technology and Innovation for Johnson Controls Power Solutions. Her company does stand to benefit as a supplier, but her words fit with other reports, and today we spoke with the highly experienced and well-connected engineer who explained why micro hybrids will make sense for automakers and consumers.

Mary Ann Wright

Wright has also served as a executive vice president for JCI’s hybrid systems business. Prior to that she was executive vice president Engineering, Product Development, Commercial and Program Management for Collins & Aikman Corporation, and before that she spent much of her career at Ford Motor Co. There she rose to director, Sustainable Mobility Technologies and Hybrid Vehicle Programs. She was the chief engineer for the 2005 Ford Escape Hybrid and involved also in Ford’s fuel cell research and development.

Micro Hybrid Defined

The term “micro hybrid” may conjure images of a tiny runabout like a Smart car, but it has nothing to do with the size of the vehicle. The system could be put in a Chevy Suburban, Mercedes S-Class, you name it.

Rather, it refers to a sub-60 volt lithium-ion battery based system – current prototypes are nominally 48 volts. In addition to a Li-ion battery, a conventional 12-volt lead-acid battery system is also on board. The lead-acid battery could start the car and handle some duties, and the 48-volt could power an 8-12-kilowatt motor/generator utilizing start-stop and regenerative braking.


At the same time, a manufacturer would gain flexibility to shift the electrical load of power-intensive accessories such as power steering, HVAC, power brakes, and so forth to the 48-volt system which could better handle it.

Also luxury features like instant heat and heated windshields, such as some German automakers and others are contemplating, could be no problem for the 48-volt system.

Insulated traditional hybrid system.

Insulated traditional hybrid system.

A critical advantage perceived with sub-60-volt systems is that they are safer as they do not pose an electrocution risk, says Wright. Thus, unlike a 110-plus-volt mild hybrid, or approximately 330-volt full hybrid, you won’t see all the precautions under the hood like the orange insulation needed to keep all that power under wraps. Nor, says Wright, is a thermal management system needed for a micro hybrid. Further, at the dealership service level, less safety training and personal protection needed by technicians will be another plus.

“This is what I call a lithium-ion sweet spot,” says Wright. “It picks up where the traditional stop-start loses its potential in terms of delivering fuel economy.”

A stop-start system is good for up to 10-percent fuel efficiency gain, and the micro hybrid can offer up to double this along with the other benefits and cost savings mentioned.

Advantageous For All

One of the reasons GM’s mild hybrids have received only mild market reception is they offer a questionable value for the dollar compared to full hybrids. A Chevrolet Malibu Eco, for example, offers 29 mpg combined according to the EPA versus a competitively priced Toyota Camry Hybrid that scores 41 mpg.

Instead of necessarily trying to beat Toyota at its own game, like Ford is now attempting with cars like its C-Max, Fusion, and Lincoln MKZ hybrids, manufacturers are also looking at an easier route to cost-effective solutions that offer value to them and consumers.


In short, goes the reasoning, what if an automaker could slash production costs to only several hundred dollars more than a conventional gasoline-powered car with micro hybrid architecture, while delivering the same mpg as a mild hybrid? The automaker could then cut the price or offer more features at a competitive price. At the least, consumers would not feel like they had to pay an outsized premium just to eek out a little better economy.

What’s more, Wright points out, 15-20 percent gains in fuel economy are considered significant. Automakers have been bringing out all the technological tricks they can to even see a single percent or more gain, and to lop off so much for the costs involved with micro hybridization is seen as a compelling “opportunity.”

Further, from an engineering standpoint, Wright says manufacturers are coming to the end of the road in what is possible given all the energy requirements they are adding to existing 12-volt systems.

“So where do we go [from here]?” she rhetorically asked characterizing a dilemma automakers are facing as they add 4-6 amps each year to their vehicles’ “power net.”

So it’s not just about fuel economy, says Wright. It’s also about a more effective approach to automotive engineering, and this is appealing to automakers.

We have no photos of cars to show you, but Johnson Controls has built a running demonstration prototype to prove the concept, and reportedly automakers are working behind the scenes with projects of their own.


Wright says micro hybrid proliferation may begin in Europe where fuel costs more, and regulations are putting a pinch on automakers. It has been projected the technology will follow in the U.S.

Among German automakers, Audi has been seriously looking at micro hybrids, and has had technical conferences with the Society of Automotive Engineers to help flesh out its implementation.

By 2017-2018 – the same years the new Corporate Average Fuel Economy regulations come into play in the U.S., and start escalating requirements year by year – expect to see micro hybrids start taking off, says Wright.

Johnson Controls has said by 2020 micro hybrids will be a fully entrenched technology, in among what ever else manufacturers do to reduce fuel consumption and reduce emissions.

Part of the Puzzle

Of course, while automakers are looking at the most cost-effective ways to meet regulations, and offering affordable cars people will buy in quantity, all the other technologies are still being experimented with, and marketed as well.

The Germans have famously resisted more aggressive moves toward hybridization. In part, it’s because they’ve invested heavily in clean diesel which they’ve “nearly perfected” says Wright. They have thus worked the production costs out and can produce diesels that offer excellent power characteristics, mpg on par with hybrids, and in Europe they sell well.

In contrast, the U.S. can almost appear “allergic” to diesels, and here people are more enamored with electrification of one sort or another.

The U.S. hybrid market yet remains under 4 percent of total sales, but projections are to see hybrid sales – counting all varieties – crest toward 1 million annually, perhaps as soon as 2015. In calendar year 2012, a total of 434,498 hybrids of all varieties were reported sold out of 14,439,684 total U.S. passenger vehicles. That represented a “take rate” of just 3.01 percent.

So far, Toyota is the 800-pound gorilla in the hybrid space. It has paid dues with its full hybrids, having launched the Prius in the U.S. in 2000.

Some advocates wishing to see electrification take off sooner, and in greater earnest, may say other automakers planning micro hybrids are only doing the bare minimum in light of looming regulations.


Wright conceded some may take this view, but from an automaker perspective, the need to meet mandates as cost effectively as possible makes the micro hybrid enormously appealing nonetheless.

Meanwhile, everything else is being tried by various automakers right on up to Tesla Motors founded on the premise that there is no more need for the internal combustion engine, and it aims to prove it.

The corporate will to do something so bold takes a maverick like Elon Musk, or a charismatic leader like Nissan’s Carlos Ghosn to push fanciful ideas into production reality.

Not all makers are so inclined, and while they are all reportedly working on electrified vehicles intended to jump into the full hybrid or all-electric game beyond the few compliance cars we now see, Johnson Controls says look for micro hybrids to fill a gap as myriad variables besides play out on the global scale.