High-Voltage Hybrids

High-Voltage Hybrids

Hybrids are here to stay and they’re appearing in increasing numbers in your customers’ service bays. They need the parts, you need the knowledge.

Hybrids are a hot commodity these days, thanks to soaring gasoline prices. And so, they are appearing in your customers’ repair shops in increasing numbers. Though the number of hybrid vehicles currently on the road is still quite small (less than half a million), some industry analysts predict that within five years 20 to 25 percent of all new car and light truck sales will have hybrid powertrains — especially if gasoline prices remain high. So as time goes on, you will probably start to see more and more customers buying parts for hybrid vehicles.

As you may know, hybrids get better fuel economy than “ordinary” vehicles by shutting off the engine when the vehicle stops moving. In “full” hybrids such as the Toyota Prius and Camry, Honda Civic and Accord and Ford Escape, there is also a full-electric mode where the vehicle starts out from a stop on battery power alone. Depending on the rate of acceleration and the load on the electric motor and high-voltage hybrid battery, the vehicle may reach 12 to 25 miles per hour before the gasoline engine starts and takes over.

By reducing the “on” time of the engine and using battery power as much as possible for low-speed stop-and-go city driving, hybrid vehicles can achieve impressive fuel economy numbers. The 2007 Toyota Prius has EPA fuel economy ratings of 60 mpg city and 51 mpg highway. By comparison, the next best-rated cars are the pint-sized Toyota Yaris at 34 mpg city and 40 mpg highway and the Honda Fit at 33 mpg city and 38 mpg highway (both of which have conventional gasoline engines but get good fuel economy because of their extremely small size).

A hybrid vehicle is essentially the same as any other vehicle except for the extra high-voltage hybrid hardware. On a full hybrid such as a Toyota Prius, this includes a unique continuously variable transmission, two electric motors, an integrated starter/alternator in the flywheel, various electronic control modules and a high-voltage battery pack in the rear of the car. On “partial” hybrids such as the Saturn Aura and Vue Greenline that do not have a full-electric mode, the only significant difference is the belt-driven starter/alternator that is used for start-stop driving and to recharge the hybrid battery in the back.

The main difference between all hybrids and other vehicles is the high-voltage hybrid battery, which is usually mounted in the rear of the vehicle. The voltage output of a hybrid battery depends on the vehicle. On a Honda Insight, the hybrid battery is 144 volts. On a first generation 2001-2003 Toyota Prius, the hybrid battery is rated at 276 volts and 201 volts on a second generation Prius (2004 and up). On a Ford Escape, the hybrid battery is 300 volts.

Warning: This kind of voltage can be deadly and must be treated with respect. If you think a shock from a spark plug wire is bad, a shock from one of these batteries will kill in a split-second!
The hybrid batteries that are used in current generation vehicles are nickel metal hydride (NiMH) and consist of many individual cells wired together in series. To protect the vehicle’s occupants and service technicians from the high-voltage hazard, the hybrid power circuit is heavily insulated and is usually color-coded orange. So, if you see a heavy orange cable snaking under a vehicle or in the engine compartment, it is carrying the hybrid’s high-voltage current. The circuit may or may not be hot even when the engine is off, so treat all orange cabling with caution.

Hybrids still have an ordinary 12-volt battery for powering the ignition system, fuel pump, lights and other electrical accessories on the vehicle. In the case of the Toyota Prius, the 12-volt battery uses an oddball post configuration that is smaller than standard posts.

No special precautions are required when replacing most maintenance or repair parts on the non-hybrid components in the vehicle. But if any repair work involves hybrid electrical or powertrain components, the hybrid battery must be disconnected prior to touching anything that might carry high-voltage.

The procedure for isolating the hybrid battery varies depending on the vehicle, but typically involves flipping a switch on the hybrid battery pack or disconnecting a battery cable or fuse. On a first-generation Toyota Prius, the hybrid battery is disconnected by opening the trunk, removing the liner from the left front corner and pulling straight back on a small orange handle to remove the battery connection plug.

Always refer to the vehicle manufacturer’s recommended disconnect procedure. Wearing protective rubber gloves that are rated to withstand up to 1,000 volts is also recommended for added protection. Also, your customers shouldn’t touch any high-voltage components for at least 10 minutes after disconnecting the battery. This gives the high-voltage capacitors in the hybrid control system time to discharge.

Actually, hybrid vehicles are not as dangerous to work on as they might seem. If the key is off and the key is out of the vehicle, the hybrid system is powered down. The battery can’t shock anyone unless someone goes poking around the high-voltage battery connections with bare hands or uninsulated tools. Even so, there are some hidden dangers with these vehicles.

When the key is in the ignition (or the keyless entry fob is inside the car) and the “power” button is pushed on a Toyota Prius, a “ready” light on the dash comes on. This means the hybrid powertrain is active and is ready to go — even though the engine is not running and the car isn’t making any noise that would indicate it is on. So when the ready light is on, the engine may suddenly start itself without warning if the hybrid battery is low and needs to be recharged. This presents no danger to the driver because the car won’t go anywhere unless it’s in drive or reverse, but it could be a hazard to someone if they are working under the hood and don’t realize the ready light is on. So warn your DIY customers to always make sure the ready light is out before doing any routine maintenance like changing oil or filters or other parts.

Some customers may wonder how durable hybrid batteries are. On a Toyota Prius, the factory warranty on the hybrid battery and other hybrid powertrain components is eight years or 80,000 miles, or 10 years and 150,000 miles if you live in California. The actual design life of the battery, according to Toyota, is 15 years and more than than 200,000 miles.

So far, hybrid batteries have proven to be extremely reliable and trouble-free — which is a good thing because hybrid batteries are only available from car dealers, and they are very expensive. The current list price of a replacement hybrid battery for a Toyota Prius is $2,985!

Hybrid batteries generate a lot of heat and require extra cooling. Most hybrids have some type of special venting for the battery pack, which may even include a separate cabin air filter (Ford Escape, for example). On the Prius, there is a cooling fan for the battery inside the right rear trim panel and two battery temperature sensors in the hybrid battery compartment.

In theory, a hybrid battery should never run down. The control module should start and run the engine to maintain battery charge any time the battery drops below a certain voltage. But if a vehicle is not driven very often, sits for weeks at a time in a garage or has a problem that drains the battery or prevents the engine from running to recharge the battery, the hybrid battery can go dead. If this happens, a special jump start procedure or charging procedure may be required to get the vehicle moving.

On a Prius, there is a special jumper connection under the power distribution center cover in the engine compartment. A 12-volt battery charger can be used to boost the regular 12-volt battery enough to start the engine (Toyota recommends using their special 12-volt charger instead of a conventional 12-volt battery charger). Once the engine is running, it should be left running for at least 30 minutes to recharge the hybrid battery. No attempt should be made to recharge or jump start the high-voltage hybrid battery directly.

Though hybrids have a high-voltage battery and some other exotic hybrid components, they still have conventional gasoline engines that require scheduled maintenance and will eventually need various repairs and replacement parts. The same is true for the cooling system, brakes, steering, suspension and exhaust system. The parts in these systems will wear out over time the same as in any other vehicle. But there are some differences.

The availability of parts for hybrid vehicles is similar to that for other late-model cars, with some exceptions. The aftermarket has common maintenance and repair parts such as oil filters, air filters, spark plugs, oxygen sensors, ignition coils, water pumps, thermostats, fuel pumps, shocks, struts, wiper blades, belts, hoses, brake pads and rotors for hybrids, but you may have trouble finding some parts.

While researching this article, we called a number of local auto parts stores to see what kind of aftermarket parts are currently available for a 2001-2003 Toyota Prius. Most of the parts stores we called had listings for all of the above, but several had no listings for a replacement fuel pump. Later we found one store that said it could get us a fuel pump for a Prius.

If a customer needs an A/C compressor for a Prius, he had better be sitting down when you tell him how much it costs. The Prius uses a unique electric-driven A/C compressor so the A/C system will keep cooling, whether the engine is running or not. Honda uses a dual-drive compressor that is both belt driven or electric driven when the engine is off. Toyota sells a reman compressor and clutch kit for the Prius ($679), but one price we got for an aftermarket reman A/C compressor was more than $1,000! Yikes!

The cooling systems on some hybrids have some extra parts, such as an auxiliary pump to keep coolant circulating to the heater. The power inverter under the hood may also have its own coolant supply and a 12-volt pump to circulate coolant. Otherwise service and operation of the engine cooling system is the same as any other vehicle.

If a customer says he needs an alternator or a starter for a Toyota Prius, don’t waste your time trying to look up these parts because the Prius doesn’t have a conventional alternator or starter. Instead, it uses a combination alternator/starter in the flywheel that is only available from Toyota.
What about common replacement items like brake pads? Aftermarket pads are available for the Prius, but you probably won’t sell very many of them because regenerative braking helps the front pads last a long, long time on these cars. Some Prius owners say the front brake pads are lasting up to 80,000 miles or more before they’re worn out.

Engine maintenance parts such as oil filters, spark plugs, air filters and even repair parts such as water pumps may last longer on full-hybrids like the Prius because the engine isn’t running when the vehicle is driving under electric power alone. Consequently, the service life of these engine parts should be longer than those on other vehicles.

As for engine oil, most hybrids recommend a low viscosity 5W-20 synthetic oil to maximize fuel economy. On high-mileage hybrid engines, a little heavier 5W-30 or 10W-30 (synthetic or conventional) may provide better oil pressure and high temperature protection.

As for body appearance products such as wax, polish, surface protectants, etc., there are no special requirements for hybrids. Hybrid owners may also need other chemical products such as fuel injection cleaner, cooling system sealer and engine oil treatments.

Shocks, struts and other suspension parts are mostly the same as those on other vehicles, though the Prius does use an electric-assist power steering rack (which are now available in the aftermarket).

As time goes on and hybrid vehicles become more common, even many of the “dealer-only” hybrid components may become available in the aftermarket. Right now, most of these vehicles are still under factory warranty for major repairs. But many of the 2001 and 2002 Toyota Prius and Honda Insight hybrids have enough miles on them to place them out of warranty. Consequently, the aftermarket should see more and more demand for replacement parts from owners of hybrid vehicles that are out of warranty.

We also called several Toyota dealers to inquire about hybrid warranties, parts availability and prices. It seems even the Toyota parts and service people have some learning to do about the hybrid vehicles they sell.

One dealer parts counterman had no idea where the high-voltage hybrid battery was located in a Prius and couldn’t even find a part number or a price for a replacement fuel pump.

Several service people we spoke with had to ask another employee what the warranty coverage was on the hybrid battery and other hybrid components. These are things they should be able to quote right off the top of their heads.

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