A video of a fire last year in Fort Collins, Colorado, that was started by 9-volt batteries recently made the rounds again on Facebook. Months after the video first went viral, consumers are still fascinated with the idea that small batteries can start fires. But indeed they can.

The culprits in the Colorado fire were 9-volt batteries — these are the ones that have the positive and negative terminals next to each other on the top. They are typically used in smoke detectors and some remote controls. The owner of the Colorado home had taken the batteries out of his smoke detectors (in order to replace them) and put them in a paper bag for later disposal.

The problem: When metal touches the two terminals at once (or "shorts" them) it can create a spark. The same thing can happen if multiple batteries contact each other. In the Colorado fire, the batteries apparently sparked and ignited due to a short.

What that incident demonstrated is what fire officials have long warned – that even batteries that have lost much of their charge can still have enough energy to produce a spark and start a fire.

Virtually any object containing metal — paper clips, keys, coins, pens, steel wool, aluminum foil, metallic shavings, other batteries — can create the spark. That’s why batteries shouldn't be stored loose in a junk drawer that contains any of these items according to the National Fire Protection Association (NFPA).

So how should you store them? Follow these rules from the NFPA:

  • Leave them in their original packaging until you’re ready to use them.
  • If you don’t have the packaging, put a piece of electrical tape, masking tape or duct tape over the terminals of loose batteries.
  • Stand the batteries up instead of laying them on their side when you store them.
  • Do not leave them loose in a drawer (unless you’ve put tape over the terminals) and do not store them with other batteries.

What about throwing them out? The NFPA advises consumers to dispose of them as hazardous waste, not in the regular trash.

The best bet is to ask your local public works department or whomever is in charge of trash collection in your community about where to dispose of the batteries. Some communities have special waste collection days, and others have drop-off sites for such waste. Before throwing them out, cover the terminals with electrical tape, masking tape or duct tape. This is a good habit to practice for any kind of battery you're getting rid of.

Other regular, single-use alkaline batteries such as those AAs you have lying around can be thrown out in the household trash, but Duracell advises against putting a lot of them in the same trash bag. You may also be able to recycle these batteries. Where? That’s another good question for your public works department.

Rechargeable nickel cadmium (Ni-Cad), nickel metal hydride (Ni-MH) and lithium batteries (Li+, Li-Ion, LiCoO, LiFePO4 and others) should be recycled through a program (offered through retailers such as Home Depot and Staples) that accepts recyclable batteries. A nonprofit organization called Call2Recycle offers a locator tool that lets you find a battery recycling location near you.

Mitch Lipka is a consumer columnist and product safety expert. He was the 2011 recipient of the "Kids Best Friend Award" from Kids In Danger for his commitment to reporting on children’s product safety.