Airlines don’t insist that nickel-metal hydride (NiMH) batteries travel as cabin luggage, although a few carriers prefer this. We delve into the reasons why some airlines mistrust NiMH batteries this way. We reach the conclusion that airlines don’t dislike nickel-metal hydride batteries because they are dangerous. It’s more a matter of making it easier to apply the rules.
Why Don’t Airlines Trust NiMH Batteries?
Hydrogen is a flammable, explosive gas, that we can neither see nor smell. If we overcharge or crush a nickel-metal hydride battery, or short-circuit its terminals, then it can vent flammable hydrogen gas.
However, each NiMH battery only contains a very small quantity of this gas. We would therefore need a large number of them to leak hydrogen at the same time, to cause a significant explosion. But airlines write their safety rules around worst-case scenarios, and there are other reasons too …
Concerns Over Bulk NiMH Short-Circuits
Airlines know that NiMH batteries can short-circuit, if both their terminals touch a conductor like metal at the same time. And that, as we now know, can cause them to overheat and release flammable gas.
This problem could conceivably arise in a bulk shipment of nickel-metal hydride batteries with faulty packaging. The heat could rapidly spread from one battery to another. This raises the question: when is a shipment a bulk one. Perhaps it is easier to say no NiMH batteries allowed in checked baggage?
Give a Dog a Bad Name and Let It Sleep
Earlier nickel-based batteries, especially nickel-cadmium (NiCd / NiCad) ones, originally had a bad reputation for overheating due to poor charging systems. Modern NiMH batteries are safer. Perhaps the airlines that mistrust these batteries should think again?
We have great respect for airlines and for their safety records. We also understand their need not to over-complicate the system. NiMH and lithium-ion cylindrical batteries look similar. Perhaps it is better (and safer) to let sleeping dogs lie.
More Information
First Nickel-Metal Hydride Batteries Arrive
