 HEVs are nothing more than a traditional automobile with advanced technologies that deliver the same end result as a traditional automobile, but with unique service hazards  Safety is of utmost importance when approaching a HEV  Isolation of HV systems for routine system service may be a necessity  ALWAYS refer to the manufacturer’s recommended isolation techniques when servicing an HEV

 When approaching an HEV, it is important to recognize the potentially high voltage you may be working around  Manufacturers have developed a way of identifying high voltage systems with brightly colored markings 2009 Prius A/C compressor with ORANGE sheathing surrounding HV supply to compressor

 Sheathing has been categorized into colors that indicate voltage levels present  Black – 12-42V  Yellow or Blue – ~42V  Orange – V Information courtesy of Jim Halderman

Information/images courtesy of Jim Halderman

 While hybrids may look and feel similar to traditional vehicles, the introduction of HV to the vehicle creates unique work risks  For example, the THS-II system on the Toyota Prius can exhibit 500V under operation  Identifying the location of HV components on any HEV is key to working safely

 Gloves  Must be routinely inspected (as in EACH use!)  Must have a Class 0 rating (safe up to 1000V)  Should have protective capabilities beyond insulation, i.e., puncture resistance  This is why traditional HEV service gloves have a leather our glove and an insulating Class 0 rated primary glove  DISCARD if damaged!  Recommended replacement every 6 months  Do NOT gamble when dealing with high voltage!

 Testing gloves  Blow air into glove and roll it to inspect for fractures that may allow HV to penetrate  MUST be free from water, sweat, oil and other potentially conductive and combustible/flammable chemicals  Glove Dust may be used to reduce sweating in gloves

 Tools  Insulated tools, which commonly have been tested at 10kV, are recommended  Typically have a safe working voltage of 1000V  Are relatively inexpensive ($500-$1000 per set)  Should be routinely inspected  Should be used as recommended by the manufacturer

 Clothing  Sleeved shirts  Short sleeve vs. long sleeve  Jewelry should be removed as it is conductive  Should be free from water, sweat, oil and other potentially conductive and combustible/flammable chemicals

 Digital Multimeters  CAT III rating recommended  According to D. Marinucci (MOTOR, 2008), automotive manufacturers have not endorsed a particular rating  CAT III-CAT IV recommended by leading industry experts with extensive HEV service research experience  Rating will be indicated on the face of the meter  Gloves MUST be worn when testing HV circuitry

 Multimeters  A meter with insulation testing capabilities is also recommend to test HV insulation properties  Do NOT insulation test yourself as the meter supplies HIGH VOLTAGE and low current to check conductivity (Fluke 1587 outputs 1.60mA)  Leads must also be CAT rated appropriately for the systems you are evaluating  Test Voltage should be selectable  Fluke 1587 ranges are: 50V, 100V, 250V, 500V, 1000V

Measured Resistance DMM Voltage Output HV Output Warning In Progress

 On HEVs, it is important to note that some may start with the key in the proximity of the vehicle  Toyotas use a READY light to indicate the engine may start  MEA Article by Dave Scaler MEA Article by Dave Scaler

 In the event the auxiliary battery dies, you can remove the lock cylinder key to enter the vehicle Chrome Toyota symbol identifies this key as a Smart Key

 Brake pedal must be depressed to start Prius  Note READY light on dash

 Known good (tested and inspected gloves) must be used to isolate HV circuit  Refer to manufacturer’s information to locate the HV disconnect plug

 Even though the plug may be removed mechanically, HV is still available at the battery terminals  NEVER service the HV system without first verifying HV is no longer present (with a properly rated DMM)

HV Disconnect

1. Pull Up 2. Rotate

Wait 10 minutes, test for HV and proceed if no HV is present before servicing vehicle 3. Remove

 It is possible to charge a HV battery, but not very common  Typically, the 12V (auxiliary battery) will fail and cause a no start condition  Jump starting the 12V battery varies from mfr. to mfr.