About securing the 12volt battery. The Hybrid class I took just last week we looked at a 2010 Yukon. When ya pop the hood these little red helmet stickers are stuck under there letting personnel know what to touch and cut. The positive cable on the battery is what they recommend cutting. We've always cut the negative first? But whats up with cutting the positive first. The instructor just told us that is was the manufactures recommendations? Does it really even matter. Just checking to see what others are doing.
take the keys out and 30 feet away from the vehicle. the vehicle can be in the ready mode and not make a sound hit the gas and you are ran over. they are similar to a electric golf cart. watch for the Orange or red cable!!! the vehicle stores a lot of energy.
That was the first question I asked the firefighters after a "show-and-tell" session. Their answer was: We have to make sure not to cut any cables I know that this has already been said been said, I just wanted to share my answer.
The positive cable is the one that carries the electricity away from the battery. Pulling or cutting the positive cable/terminal first limits the number of places that can create a spark to the immediate 12-V battery area while you're working on the negative cable/terminal.
The bigger issue is that if the vehicle is an all-electric or an electric hybrid, NEVER cut the large orange high-voltage cables from the power cell to the electric motor. Avoiding the power cell and the high-voltage cables may restrict your ability to tunnel the rear seat back in some models of electric or hybrid cars, too.
Easiest thing first, turn off the ignition, this will disable the high voltage side, then to be safe disable the 12 volt system NEG first, due to the direction for electricity flow, there will be no arcing, remove all accessory plugs from the dash, cell phone chargers can back feed into the 12v system.
On some even though you disable the power source it still has a charge hold time. Also on some of your new Toyota's the have a solar panel in the roof which is a charging system. In order to shut that down you need to put a tarp over the roof to stop the light from hitting it. The other danger to us fir fighters is in those cars the powers wires run above the head liner and down through the B post. Just to give everyone a heads up. Our Department covers 14 miles of the New York State Thruway. We've seen them out there but haven't had to deal with one yet.
Common sense and good basic training. Your department should have a standard operating guideline/procedure specifically pertaining to handling MVA's. I won't knock anyone, but a few myths need to be debunked.
1. You must disable the high-voltage system.FALSE.
Just like regular cars, the standard control systems operate off the regular 12VDC battery. Disconnecting the 12VDC battery will disable ALL drive systems, including the hybrid electric motor control. When you do so, cut the NEGATIVE first. This prevents arcing between the cable stump or tool and the frame of the car and reduces risk of fire. You MAY disable the hybrid battery by means of a switch, however, many hybrids have breakers, fuses, or service disconnects that require removal. Leave these in place. They may arc during removal causing electrocution (a service technician was killed several years ago removing the service disconnect from a Toyota Prius).
2. You must disconnect all devices with batteries plugged into the vehicle.FALSE.
Although not a bad practice, virtually all new vehicles have isolated the SRS capacitors from the auxiliary power relays, eliminating the risk of back-feeding the system and charging the SRS. Of course, it doesn't hurt...
3. The SRS system runs off the high-voltage battery.FALSE.
The hybrid battery runs the electric motor. Simple as that. The alternator that charges the 12VDC battery, depending on the model, may run only with the gasoline motor, or both electric and gasoline motors. Either way, ALL other systems in the vehicle operate off the 12VDC battery.
That being said - these basic steps will help keep you safe at ANY collision scene, including one involving a hybrid.
-Check for hazards such as leaking fuel and downed wires on approach.
-Place the vehicle in park, set the parking brake, and remove the key from the ignition. If it has a proximity key, make sure ALL keys are removed from the vehicle and taken away (put them in the police car :-P).
-Chock and/or crib the vehicle to prevent movement.
-Disconnect the 12VDC battery. If you cut the cables, take negative first, and remove a 3 inch section of the cable to prevent arcing.
-At a minimum, keep an ABC class extinguisher handy for the duration of the operation.
-Remember that SRS systems have capacitors that allow the system to function for a period of time after the 12VDC battery has been disconnected. The time varies with make and model from 5 seconds to 10 minutes. A little research (or a Holmatro Extrication Guide) will help you determine if the capacitors have discharged.
If extrication is required, take the time to look before you cut and pry. Expose your pillars and rails to check locations of SRS and other safety systems. Avoid high-voltage system components. If you MUST remove a high-voltage component, find the system disconnect or breaker and pull it to isolate power to the battery pack. DO NOT take apart the battery pack itself. They can usually be removed with a few wrenches and ratchets or a sawzall to cut the bolts only.
Be smart, and use your head. It's just a car with some fancy electronics in it. Proper size up and common-sense tactics will keep you safe for the most of it. A little research and a few Hybrid Vehicle ERG's from manufacturers will take you the rest of the way. Best of luck and stay safe out there.
National Alternative Fuels Training Consortium
West Virginia Univ in cooperation with the U.S. Dept of
Transportation/clean cities learning program has a 16 hr class
That is being taught around the country at different colleges.
It is grant funded class.
Look at the app for iPhone called QRG