I'm sharing a common question about battery shutdown asked this time by a California fire officer after a discussion between his fire house 'experts'.

Question:
There is some debate here at our department regarding this subject and some believe that cutting the battery CAN cause an air bag to discharge. PLEASE HELP! Second question. If we should disconnect the battery, should we pull the negative side first or positive side?

My reply:
My recommendation is to consider total electrical system shutdown as a high priority for effective vehicle crash scene management. This is especially true if you're going to commit tools to the car for some rippin' and tear'in or if there is a lot of interior medical work to be accomplished.

If it's a crash with ambulatory patients upon arrival or possibly just damaged vehicles and no one injured, I still like to see the battery cables disconnected before you turn the vehicle over to the 'happy hookers'.

A late model vehicle will typically drain its' airbag capacitor between 2 to 5 minutes after shutdown. This doesn't mean that an undeployed airbag will never deploy; it just means that you've greatly reduced the possibility of that happening.

From my experiences with this issue, the act of disconnecting a battery will not cause accidental airbag deployment. Within the electrical circuit of the vehicle, a surge in power won't deploy the bag. If that were the case, then every time we jump started a car, the airbags would fire off.

Now, if a static charge or surge of as little as 7 volts DC was injected into the twin wires running directly to the airbag itself, that's another story. While spreading or ramming something, you could easily short out or cut into those airbag power wires if they are still energized and cause something exciting to happen.

Don't let the misconception of accidental airbag deployment deter you from completing total electrical system shutdown. Negative first, then positive and do them both. Either disconnect at the terminals or double-cut the cables.