Anybody know what 'spillable batteries' are?

[MrsBigD]

Trying to work out what we can take in our hand luggage to keep kids entertained on long-haul flight.

Airline website quotes: Devices with spillable batteries are restricted (i.e. only in checked-in luggage)

Hubbie insists taking the leappads might be issue because of the batteries.. anybody know whether AA batteries are 'spillable'?

TIA

I think they mean things like car batteries, which contain liquid. The AA batteries are "dry cell" batteries, so there's nothing to spill.

thank you