Don't put any spare batteries in your luggage. I had my dewalt 18v drill kit in a suitcase. Drill + 2 batteries + charger.
Air NZ flight from Wellington to Auckland... a flight I've taken more times than I've had hot dinners... pick up bag in AKL and see the security label on the handle. Open up kit, and they removed the spare battery, but left the one connected to the drill. And then a nice little note saying the battery had been disposed. I was filthy.
Although, never read in to what the actual rules were, but their (Av-Sec) actions spoke fairly loudly.
Even though they say they have disposed of them, if its Wellington airport then Jetstar has a cupboard of seized goods such as this. I mistakenly left a new power bank in the hold but was able to retrieve it when I came back to Wellington a few days later. Just ask nicely at the counter (don't know if Air NZ do this as well?).