Hybrid Safety: Important Tips That Could Save Your Life

By Craig Van Batenburg, AAM Some of you have taken my gas and electric vehicles (hybrids) class, but most haven’t. Safety is a big part of the course.  The Toyota Prius and Honda Insight and Civic gas hybrids are out there. They will have accidents and you will be asked to fix them. Collision shops are usually the first to experience the difference.

So far we have not lost a technician to any electric-only vehicle (EV) repairs, but these techs are typically trained for one week on high-voltage systems. I sure hope the average tech prepares very well before he or she starts to work on a hybrid car. A large spark that would sometimes make a tech jump and a co-worker laugh may not seem so funny if the technician is hurt or, worse yet, dead. The safety issues are real. Read this carefully and pass it on to each associate in your shop.

The threshold for voltage that can be fatal, as in dead, is about 60 volts. For some people, it’s as little as 50 volts. Hybrids use a dual voltage system: 12 volts for most of the car and high voltage (HV) for the drive motor(s) and related systems. The HV is what you need to respect. Electricians who have worked on 110v or 220v know to be careful and de-power the wires before working on the system. Well-trained electricians wear safety gloves, work in teams and know how to read a meter. The Toyota Prius is 276 volts, a lethal amount; and both Honda hybrids come equipped with 144 volts as standard equipment. Always wear safety gloves during the process of de-powering and powering the system back up again.

Most digital volt/ohm meters will read up to 600 volts. Just make sure you are using probes that have safety finger positioners and are rated for high voltage (Figure 1).

For the safety of passengers and emergency medical technicians, once an airbag is deployed the HV system is shut down. These cars have a lot of safety built into them. The Civic hybrid is rated with five stars on crash tests. Until you are trained to work on hybrids, just be careful and do the work that you can. Keep reading so you know how to stay out of trouble.

As in any new technology, play it safe! Read the warning labels (I know we are not prone to do that), get the proper equipment and wear those safety gloves. One note on safety gloves; before you use them, each and every time, inflate them and make sure they do not have even a pinhole.

So what do you need to know about these cars? First, you need to know that orange cables mean high voltage, and you need to know how to de-power the HV system. If you are not near the orange cables (Figure 2), then you are fine, unless of course the car has been in an accident.

Fluke makes a HV ohm tester (part No. 1520) for about $700. That megohm meter (Figure 3) is required to ensure that the insulating properties of the orange cables are still intact after an accident. You don’t want to be the tech starting up a hybrid after a major collision and find out that the HV cables are shorted to ground.

Proper training will get you started in the safe handling of the HV systems. Once you have determined that you will be near an orange cable or junction, you will need to de-power the capacitors and disconnect the HV battery back.

Prius Safety

On the Prius, to keep from getting a potentially lethal shock you first need to open the trunk and remove the liner of the left front corner and find the service plug (Figure 4). It is a small orange handle that you raise and remove by pulling straight back. The Toyota manual tells you to keep the plug with you (I imagine they know about the pranks that some techs will play on another). This high voltage is no kid’s stuff, so pay attention and don’t make mistakes.

After you have removed this plug, wait 5 minutes and test for low volts (close to zero) at the orange cables you are close to. If they are under 12 volts, all is clear. Tape up any cable ends and bare metal. Don’t forget that the 276-volt battery pack always has the potential for supplying you with a lethal charge, so handle this battery pack with care. Also, keep in mind that Mitchell and ALLDATA have good information on this car.

Insight Safety

On the Insight, open the hatch and remove the carpeting with storage box cover, as it is one piece. You will see a small aluminum cover (Figure 5). Remove the two bolts and the cover, and a switch (much like a wall switch) will be looking at you. Remove a red plastic safety lock and turn the switch to off. Place the safety lock back on the switch in the other direction to hold the switch in the off position.

After you have switched it to off, wait 5 minutes and test for low volts (close to zero) at the orange cables or connectors. If they are under 12 volts, all is clear. Don’t forget that the 144-volt battery pack is always hot. Once a cable has been disconnected, tape it up for safety reasons. Once again, Mitchell and ALLDATA can help you.

Civic Hybrid Safety

The Honda Civic hybrid is the new kid on the block, so Mitchell and ALLDATA will not help you. To de-power this hybrid, remove the rear seat upright cushion. You will see a small cover with two screws, an arrow pointing up and the word “up” on the cover. You guessed it! Remove the two screws and the cover, and turn the switch off. Place the safety lock back on in the other direction to hold the switch in the off position. After you have switched it off, wait 5 minutes and test for low volts (close to zero) at the orange cables or connectors. If they are under 12 volts, all is clear. Don’t forget, the 144-volt battery pack is hot. Once a cable has been disconnected, remember to tape it up.

After your work is done on the hybrid car, tighten the connections very well. A loose HV connection is trouble. Turn the switches on or plug in the plug, wait for the capacitors to recharge and off we go.

I want to see you in class some day, so don’t be foolish. If you have any doubts about your ability to perform these safety steps, then leave this for someone else.

Safety in the Oven

For collision shops, don’t bake these hybrids at temperatures over 150 degrees F. Those nickel-metal hydride (Ni-MH) batteries really don’t like extreme heat. Cook a battery pack in a Prius and you are out almost $5,000 and that is only for parts.