|Battery Safety :|
Batteries are widely used in a variety of devices and because they are so common, people may not be aware of some dangers they may be exposed to when handling certain types of batteries. Two immediate dangers are:
Other dangers include the release of toxic materials into the environment if not disposed of properly.
Kinds of Batteries:
|Primary: Non-rechargeable, discard when exhausted. All primary batteries are dry cells.|
zinc - flashlights|
alkaline - flashlights, toys, clocks
lithium (primary) - cameras and watches
zinc oxide, silver oxide and mercuric oxide - packaged as button cells, used in calculators, watches, hearing aids; often contain some mercury
|Secondary: rechargeable cells|
cadmium (NiCad) - power tools, emergency lighting |
nickel metal hydride (NiMH)-digital cameras, appliances, radios, hybrid vehicles
lithium ion - laptop computers, cell phones, video cameras
small sealed lead acid (SSLA) - electric wheelchairs, electric bikes, power supplies
lead acid - automotive and other vehicles, deep charge
Fire and explosion:
A 9-volt alkaline battery can generate about 9 Amps of current if the terminals are connected together and the battery temperature can rise 60 to 94C within about 7 minutes [NASA Public Lessons Learned series]. A lithium ion battery that shorts out may reach 120C (Safety first -- Why all lithium batteries are not the same).
Car batteries are designed to deliver a lot of current (hundreds of amps) quickly for starting the motor. A note in Popular Mechanics magazine in March 2007 [Car Battery Do's a Don'ts] describes how a person working on a car battery touched the positive terminal with a wrench he was holding. The short circuit welded a ring on his finger to the battery hold down clamp and to the wrench. If you are removing a car battery, always remove the negative terminal first before touching the clamp on the positive terminal. This is because the negative terminal on most North American vehicles is connected to the engine and frame so touching the positive terminal to any metal on the car will allow current to flow. If you remove the connection between the negative terminal and the car metal, you have eliminated a huge area where a short circuit can occur. When installing a battery, connect the positive terminal first, and the negative terminal last.
have been numerous instances of lithium ion batteries overheating and exploding
causing fires. Lithium ion batteries are designed to store large amounts
of energy per unit weight and are preferred for things like laptop computers
and cell phones. In 2006, Dell computer recalled 4.1 million notebook Li-ion
batteries and other manufacturers had recalls too. |
As of January 2008, the US Department of Transportation is limiting the number of lithium batteries carried on aircraft by passengers. Basically you can have a battery installed in a device (carry on or checked luggage) and you can have a spare in carry-on luggage if the terminals are covered. You cannot have loose lithium batteries in checked luggage. There are also size restrictions so that you cannot carry lithium batteries with a capacity over 300 watt-hours. See the FAQ page and chart from the FAA (pdf file) and the SafeTravel web pages.
|The reason for these restrictions is due to the many battery incidents that have occurred such as:|
Check out some photos and video clips of events at airports Battery Fires in Air Transportation (PDF)
Closer to home, in
October 2007, a fire occurred in the back of a University truck returning
from a field site. The fire appeared to have started in a bag/box of various
batteries and was likely caused by a 9-volt alkaline battery shorting
out on some piece of metal or another battery. The fire burned up research
notes, personal clothing, equipment and might have been much worse if
the propane tanks (one full, three empty) had become involved.
Battery terminals should be taped and cells immobilized by strapping together as in image 6.
for Battery Storage and Transport:|
In order to avoid potential fires from battery terminals shorting out, batteries should be packed so that terminals cannot be connected. Leave in the original packaging or for all batteries over 2 volts, cover the terminals with an insulator (electrical tape across both terminals). Do not simply throw loose batteries into a bin or plastic bag with terminals exposed. Even with the terminals taped, it is better to immobilize the cells by packing in a box so the batteries cannot move around.
This applies to all batteries, new and used, unless you have measured the terminal voltage and shown it to be zero. The only batteries that might be bagged without taping the terminals are the 1.5 volt cylindrical batteries (AAA, AA, C and D cells) which by virtue of their terminal orientation are unlikely to short out against each other, however, don't toss a metal chain or bare wire into the bag as these cells can produce currents of 10 Amps and overheat if shorted out [NASA Public Lessons Learned series].
If a battery has a protective cap, leave it in place until the battery is installed in a device.
Do's and Don'ts:
a vehicle battery:
Hydrogen gas is evolved during the charging process and any spark could easily ignite it causing the battery to explode and release the sulfuric acid inside. Follow the manufacturer's instructions for connecting the charger, charging and disconnecting the charger and do it in a ventilated space with no flames or sparking equipment (e.g. electric motors) in the area. The color-coded wires are clamped to the battery first and then the power is connected to the charger. When finished, this power is disconnected before either of the clamps on the battery terminal are removed. Again, the procedure attempts to avoid sparks near the battery terminals where hydrogen gas may occur. If the charger is plugged in to a 120 volt supply and the clips are then connected to the battery terminals, there will be sparking. Whenever possible, run the "trickle charge" mode on a battery charger - takes longer but generates less heat and H2 gas.Detailed instructions are here.
Battery Disposal and Recycling:
There are some very
toxic/corrosive materials in some batteries that should be prevented from
being released into a landfill or water system. Large amounts of lead
and sulfuric acid occur in automotive batteries and toxic elements like
cadmium and mercury occur in NiCd and some button style batteries. Although
there are not any very toxic substances in alkaline, lithium or carbon-Zinc
batteries, it would seem prudent to avoid disposing of these into regular
garbage. Environment Canada has some information about
batteries and recycling. The University of Alberta collects batteries
for disposal through its waste chemical disposal system (Chematix) and the City of
Edmonton accepts batteries from households at its Eco-Station waste recycling
|orig: June 27, 2008|