Lightweight batteries in toy helicopters can pose burn hazards

The popularity of remote-controlled helicopters has skyrocketed in recent years as new technologies have driven down prices and simplified their operation, transforming what was once a product only for serious hobbyists into a favorite for kids.

But even as more and more adults and kids are buying and playing with remote-controlled helicopters, there are serious and growing concerns about the safety of the battery technology used in millions of the pint-sized choppers.

At issue are rechargeable lithium ion and lithium polymer batteries that are increasingly being used in remote-controlled toys. They are significantly lighter than older-style batteries and can be manufactured in virtually any size or shape, making them perfect for the diminutive whirlybirds.

But because they pack so much energy into such a small package, lithium ion and lithium polymer batteries can burst into flames or even explode if they are not handled correctly or charged with precision.

The Consumer Product Safety Commission says it has received dozens of reports of remote-controlled helicopters igniting while being charged or even while in flight. The CPSC has received related reports of both minor burns and property damage.

Those reports have led to the recall of more than a million remote-controlled helicopters so far this year, according to the CPSC. The largest of those recalls involved more than 685,000 "Sky Scrambler" and "The Sharper Image" wireless indoor helicopters in July.

All of the helicopters recalled this year were manufactured in either mainland China or Hong Kong.

One tip sheet we found from an online retailer for handling and charging lithium polymer batteries was, well, somewhat shocking, considering it was talking about an item used to power millions of toy helicopters for kids.

For example, it advises lithium polymer batteries "must be CHARGED and STORED in a fire-safe container" and to "KEEP BATTERIES AWAY from children and pets at ALL times." (Emphasis added by the online retailer, Maxamps, not us.)

There are several videos on YouTube, including this one, that vividly show what can happen when a lithium polymer battery is not charged properly.

At this point, the Institute of Electrical and Electronics Engineers has not yet established any general standards for lithium ion or lithium polymer batteries, although the group recently asked its members for help in the characterization of lithium battery technologies in terms of performance, service life and safety attributes.

The CPSC offers these safety tips when charging or using lithium ion or lithium polymer batteries:

• Do not leave the toy unattended while charging it.
• Battery charging should be done by adults.
• Charge the toy on a non-flammable surface and keep it away from flammable items.
• Turn the charger off when the toy's battery is charged, and always unplug it from the toy.
• Disconnect AC wall chargers from outlets while not in use.
• If the toy has been damaged, immediately stop using it, unplug it, and safely move the toy away from flammable materials.
• Follow the manufacturer's instructions for charging the toy. And do not charge longer than recommended.