TIME’S UP

With hybrids moving to out-of-warranty service, the moment is right for independents to gain some market share.

Most of you haven’t worked on a hybrid yet, but more than 150,000 have been sold worldwide. Many thousands more are in the pipeline for next year: Automakers Ford and Nissan have even made arrangements with Toyota to use the Prius’ design next year. 

You will need to get ready for the inevitable service these half-electric/half-gasoline autos will require. Maybe you have taken a hybrid class, maybe not. But one thing is for sure: Hybrids are here to stay. These weird-operating gas/electric cars are advancing automotive technology, but which design will win the hybrid war? Will it be Honda’s Integrated Motor Assist (IMA) or the Toyota Hybrid System (THS)? The battle is already waging. Remember VHS vs. BETA? The battle for home-entertainment supremacy was a shoot-out back then, and people were betting on both sides. This contest looks as if it’s even closer. Let’s see how it is going in “Hybrid Land.” 

A quick history
The Honda Insight arrived in December 1999, which makes this car almost four-years-old and already out of warranty. Some people really do drive 60,000 miles per year, so high-mileage Insights are common. 

The Prius was the world’s first mass-produced hybrid, sold in Japan in 1997. Here in the United States, the Prius was sold in small numbers during 2000 as a 2001 model car, but now dealers sell all they can get. In 2002, Honda introduced their Civic version of the hybrid, but it hurt the Insight sales. As production capabilities are increased, both Toyota and Honda will be ready for hundreds of thousands of worldwide sales by the end of 2004, if the demand is there. Currently, these hybrids sell for around $21,000 and average 50 mpg (with the Insight much higher), but they are still largely unknown to many consumers and techs. As long as gasoline is relatively cheap, hybrids may stay anonymous, but we all know too well that gas prices skyrocketed this past summer and can go up again at anytime. 

Much has been written about gas/electric hybrid cars, but there’s not been much information that will help you with the practical side of real problems in real bays. Here is your first installment. Let’s take a close look at the Prius. Will this be the hybrid technology of the future? Is THS synonymous with VHS? It’s a good possibility.

In this corner …
Introducing the Toyota Prius: Weighing in at 2,765 pounds and using a conventional steel body, this smallish sedan has room for four adults (Toyota says five) and their stuff. Behind the wheel, you’ll find the Prius’ power is good. It handles fine, has a nice ride and gets great gas mileage. It is the size of a Corolla, has the feel of a Camry and has plenty of creature comforts and your typical Toyota construction. 

Plugging along: With a potentially lethal 274 volts in its battery pack (above), you must first drain down the capacitors before attempting any service. Raise and remove the battery pack’s service plug (below) and wait at least five minutes before checking voltage.  (Photos: C. Van Batenburg; Toyota)

Your average customer might buy one, as these cars perform like normal internal combustion (IC) engine cars. If you are afraid to service these new hybrids, don’t be. It is only the high voltage that you need to have a lot of respect for. Anyone who has worked on 110-volt (V) or 220V systems knows to be careful and to de-power the system before you take any wires off. 

The Prius has 274 volts, which is a lethal amount; but we’ll address how to stay out of trouble later in this article. This Toyota comes with a 100,000-mile/eight-year hybrid component warranty and three-year/36,000-mile warranty for the rest of the car. Toyota also offers a complimentary first five scheduled maintenances up to 37,500 miles of ownership, and many of these vehicles are just at that point. So, don’t be surprised if a hybrid finds its way to your shop this year. 

So what do you need to know about servicing the Toyota Prius? First you need to know that orange cables mean high voltage (HV), and you need to know how to de-power the HV system. If you are not near the orange cables, then you are fine, unless of course the car has been in an accident. Fluke makes a HV tester, knows as a meg-ohm meter, P/N1520. A HV test tool is required to make sure an accident job is repaired properly and none of the insulating properties of the HV cables have deteriorated. 

You will need proper training to safely handle the 274 volts that a Prius stores in its battery pack. To keep from getting a potentially lethal shock, you first need to open the trunk and remove the liner at the left front corner and find the service plug. It is a small handle that you raise and remove. Toyota says to use a rubber glove when removing the plug. The Toyota manual also tells you to keep the plug with you; I imagine they know about the pranks that some techs will play on one another. This high voltage is no kid’s stuff, so pay attention and be extremely careful. Any voltage over 60 volts can be lethal.

After you have removed this plug, wait five minutes and test for low voltage – close to zero – at the orange cables. It is the three large capacitors that can hurt you, and this process drains down the capacitors so they are safe. If they are under 12 volts, all is clear. Don’t forget that the 274-volt battery pack always has the potential for supplying you with a lethal charge, so handle this battery pack with care.

Until you are thoroughly trained to work on these types of vehicles, just be careful and do only work that you are qualified to do. All the body electrics are 12-volt, and Vetronix makes the scan tool software. The Vetronix scan tool is OEM for Toyota and provides a fair amount of information. Most of the service and repairs are the same as any other car. The IC engine is a 1.5L four-cylinder, similar to the Echo, and requires the same preventive maintenance that any normal Toyota does. Brakes are conventional at the wheel end, but power boosters are history. The Prius has a marvel of electronics that takes over all the braking. The brakes are designed to take advantage of the regenerative braking that hybrids use to recharge the main battery pack. It incorporates ABS and traction control, which are tied into the hybrid control system. 

Gearing Up: The Prius CVT’s planetary gear (above) set uses one electric motor connected to the sun gear.  The dash readout display (right) includes driver-friendly information about what’s happening under the hood and in the battery pack. (Graphic source: HowStuffWorks.com; Photo: Toyota)

Understand that regenerative brakes do not mean electric brakes. Decelerating, braking or descending hills supplies alternating current (AC) energy that is converted into direct current (DC) and stored in the nickel metal hydride (NiMH) batteries instead of being wasted heat (friction). When descending a hill in “D,” or low gear “B” if you want more engine braking, the electric motor is computer-controlled to offer resistance, much like a dyno does on the drive wheels. It uses that energy to produce AC energy. A digital processor then converts the AC to DC so it can be saved in the battery pack. The amount of electricity needed, along with the Vehicle Speed Sensor (VSS) and other inputs will determine how fast the car will slow down and how much force will be applied to the drive wheels. 

If the regenerative brakes aren’t slowing the car down fast enough, it is human nature to press down further and harder on the brake pedal. As you do, the on-board computer will apply the conventional brakes that then come in contact with the rotors and drums and the car now has both systems operating. There are times when the regenerative brakes will not turn on, such as instances when you are almost stopped or ABS is being used. The PCM and other computers are very busy keeping an eye on lots of inputs. The system works so well you hardly know it is operating.

The NiMH battery pack, manufactured by Panasonic, consists of 234 batteries arranged in cells. At 1.2 volts per battery, the pack has 274 volts ready for electric-assist and stealth mode. Also onboard is a DC-to-DC converter that is used to supply the 12-volt system with a constant 14-volts. An AC-to-DC and DC-to-AC processor is used to allow an AC motor to work off of the DC system. Seven years ago, this car would not have been possible because computers were too slow. The amount of memory and speed required for a hybrid to work is mind-boggling. 

One interesting note: A lead-acid battery loses it potential as the temperature of the battery drops. NiMH batteries are the opposite: As they get colder, they build in power. If they get too hot, they lose their strength. Air-cooling systems are used to keep the main battery pack from overheating and to ensure long battery life. One study shows the NiMH battery life can be as long as 15 years or 200,000 miles.

The Prius is a series/parallel design. This means that the IC engine can power the car independent of the electric motor and vise-versa. Both power sources also can work together. The trick here is a cleverly designed CVT transmission. 

This CVT automatic transmission is like no other. It is simple in design, brilliant in use and suited perfect for a hybrid car. The planetary gear set uses one electric motor connected to the sun gear. This motor starts and shuts down the IC engine; it also can generate power to recharge the main batteries. In addition, it has a very important second function: It keeps the IC engine speed low. The sun gear (starter motor/generator) is used to control the speed of the planetary carrier (IC engine) by raising the speed, stopping completely or reversing direction. It is simple but amazing. By using this CVT transmission, the driver has little effect on rpm because he or she can’t shift it. This allows the computer to do what they do better than humans, make decisions quickly to provide power, lower emissions and have the feel of a “normal” car.

The second electric motor is used for power to the wheels and for reverse. It is connected to the ring gear. The IC engine is connected to the planetary carrier, and the IC engine can be off while the car moves forward with the drive motor only. Reverse gear is the main electric motor running backwards; the IC engine does not play into the reverse function.

The transmission of power to the front wheels is what allows a lot of other things to happen. A standard shift is not available, nor would it work. By keeping the engine speed fairly constant, Toyota can control tailpipe emissions. Ignition timing stays within a 5-degree window most of the time.

While watching the dash readout, the driving experience can easily mislead you. See Figure 4. Toyota has put together a customer-friendly information center, with an optional GPS navigation, sound system controls, and a couple of displays that tell the driver what is going on under the hood and the back seat. The “energy monitor” display shows a picture of the engine, NiMH battery, front wheels and the electric drive motor. For your own knowledge, the owner’s manual will help you understand the dash readouts more than the shop manual.

If you follow the arrows and color changes of each component, you are led to believe the engine is off when indeed it is still on. Some magazines have reported that the car uses its electric motor as its main power source and the gas engine is a backup; however, it isn’t so. The design gets you going on electric only, but unless you keep your foot at 25 degrees or less of TPS (my estimate), the gas engine is right there with you. Under normal driving the IC engine starts and runs at about 7 mph. It is possible to keep it in stealth mode (electric only), but you must work at it by creeping along or going downhill. 

There is another myth circulating that you can use an outside source to charge the batteries – not so. There is a normal-sized 12-volt battery in the left corner of the trunk, but it is far from “normal.” Study glass mat batteries before you even try to charge this one up. Toyota is having more than their share of trouble with this 12-volt battery. Watch for TSBs about this in the near future. A pulse charger is used, but my studies show the car itself is the best charger to use. That is true for the main battery pack as well. 

The 2004 Prius was shown at the New York Auto Show last spring, and I was allowed access under the hood and around the car. Stay tuned to Motor Age for an update on what looks like a huge leap forward in hybrid design for the 2004 model. By comparison, the 2001 to 2003 Prius is in some ways old technology. 

And in this corner …
Enter the 2003 Honda Civic Hybrid. The IMA technology is now proven, and the second-generation IMA is more powerful, less complicated, more compact, lighter weight and integrated more compactly into the Civic Hybrid. What is revolutionary about the Civic Hybrid is that the same Civic body you can buy in a gasoline version is used for the hybrid model.

Versatility: Honda’s IMA system (above) required only minor changes to the Civic’s body, and opens up the chance of the automaker offering hybrid versions of all its vehicles. To recharge the batteries faster in stop-and-go traffic, the V-Tec (left) disconnects the two-piece rockers and lets three cylinders freewheel.

Honda is using the same unibody with some small changes up front in motor mount locations. If the IMA system can be used this way in the Civic, then Honda could offer an IMA system with your choice of a CVT, regular automatic transmission or a standard transmission in every car and truck within two years. That is, every car, truck, van, sports car, you name it, in a hybrid version. Officially, Honda says they have no plans to do so, but think about the implications if the Middle East has more problems in the future. Is Honda, once again, ready to lead the pack like they did in 1973 with the Civic 1200 and in 1975 with the CVCC engine? Don’t count them out.

Let’s take a close look at the Civic and Honda’s IMA approach to hybrids. Automotive engineers know that if you want good fuel economy and low emissions, there are only a few places to look for a solution. Start with the combustion chamber. Isn’t that where most of the emission problems come from? If we can combine all the hydrocarbons and oxygen and leave the nitrogen alone, we are left with carbon dioxide (CO₂) and water. Water is good for the environment, but CO₂ is not. If you burn less fuel, you have less CO₂. Did you know that a good working catalytic converter adds about 1 percent more CO₂ to the exhaust stream than what the engine produces? Honda has spent a lot of time and money inside a four-stroke engine, and its hybrid system was no exception. Much like the Insight, the Civic hybrid uses a 144-volt battery pack, which is half the size of the Prius’s counterpart. The Civic also incorporates many computers and sensors and a flywheel-mounted electric motor to keep it all going.

What size IC engine should go into a Civic hybrid? Answer: The most fuel-efficient one you can that will still give enough power to be attractive to the average consumer. The size of the IC engine then is determined by the size of the electric motor, battery pack, weight of the car, aerodynamics, rolling resistance, internal friction of driveline components and performance desired. Both hybrid Hondas have their own hybrid-specific engine. The Civic uses a specially built 1.3L, four-cylinder with a chain-driven cam, V-Tec and OBD II. 

What is unique is that the V-Tec valvetrain technology – which Honda has been using for well over 10 years on their fleet – has a new twist: Instead of going with a different cam profile, they went for no cam profile at all. This means that the hybrid IC engine makes things harder for electric regenerative braking because of compression braking. 

The Toyota has no engine braking to speak of based on their CVT design, but the IMA system does. On Honda’s design, the electric motor (EM) is in-line with the crankshaft, so slowing down under compression limits the amount of regenerative braking that you can capture. Honda solved that problem by deactivating three-cylinders, and in this case, it works. When the Civic starts to slow down, three of the four cylinders have a 
V-Tec-type system that disconnects the two-piece rockers and lets three cylinders free-wheel – no air in, no compression. This recharges the batteries faster in stop-and-go traffic. 

The IC engine also runs very clean and has a horsepower and torque curve that complements the updated EM. The IC engine is at it’s worse down low, and that is where an EM will shine. This is a great time for a powerful EM to take some work away from the IC engine. The electric motor is thin, mounts up easily and leaves plenty of room for your typical transmission. As all hybrids do, the ICE shuts off at idle and automatically starts again when you are ready to move. The Civic hybrid is available in a five-speed or CVT version. 

The Civic Hybrid is about the same size as a Toyota Prius. It sells for about the same money, gets approximately the same mileage and has a good reputation. No tricks are needed to make this Civic a hybrid other than electric power steering, which is now standard on the non-hybrid Civic hatchback; a sensor that detects low vacuum in the brake booster; and the usual IMA controls. The body is steel and the suspension is the same. It’s a bit more aerodynamic, but not much different than the gas-powered Civic. One side note: we’ve heard that the Insight will not continue in production after next year.

Are you ready?
Don’t think that hybrid service is ‘just too weird’ to really be a part of your career choice. I hate to be the one to tell you, but this stuff isn’t going away. 

More than 60 percent of our gasoline is imported. Even if we started drilling today on our own land, it still takes 10 years from when the drill bit hits the ground to the time gasoline is in our tanks. If CO2 emissions are regulated, there are only three ways to reduce them: Use less fuel, drive fewer miles or burn something other than a carbon-based fuel. Add in predictions that the world’s oil supply is dwindling, and we could have a hybrid war going on – possibly in 2005 or sooner. 

What about fuel cells as an answer? Most automakers say “not in the near future.” We will wait and see. One thing is for sure: Honda and Toyota are ready today if gas prices shoot up, if fuel supplies become limited, or both. 

Hybrid service will be a part of your future. As soon as it is economically feasible for consumers, more of these new fangled half-and-half vehicles will be driving to your shop. You might as well jump on-board: Both Ford and GM will be launching hybrid vehicles within the next 12 months. More are sure to follow. 

So what should you do as a tech to prepare? Learn more about brushless DC and AC motors, make sure Ohm’s law and you are friends. Keep using those lab scopes and current probes, and be up to speed on the current 12-volt cars so the bridge between what is coming and what you know is as short as possible.