Travel tips: How to keep the kids from overusing data in Hawaii?

OUR FAMILY, TWO ADULTS AND THREE TEENAGERS, IS TRAVELLING TO HAWAII. EACH HAS AN IPHONE AND WE'LL TAKE A LAPTOP AND A HAIR STRAIGHTENER. HOW CAN WE RECHARGE ALL, AND HOW DO WE KEEP THE KIDS FROM OVERUSING DATA AND COMING BACK TO EXCESSIVE BILLS? ARE OUR 240V DEVICES SAFE TO USE IN US POWER POINTS? R. DAVID, WOLLONGONG NSW

I use an Allocacoc PowerCube which has four standard electrical outlets plus two USB ports. Team it with an adaptor plug suitable for US sockets and you should have no arguments. Costs about $25, works like a charm. A hair straightener might work, check the voltage on the label. Get the kids to turn off data roaming on their phones and keep it off. They can use free Wi-Fi when it's available, for example in hotels.

If they're likely to turn on global roaming – and even if they do so for a couple of minutes it's probably going to cost a couple of hundred bucks – you could sign up with your telco for a data package for just your phone when you're overseas, which usually costs about $10 per day, then create a hot spot using your phone and allow them to tether off that. You will still need to keep your eye on the data limit – it's not huge, so maybe turn it on only for a couple of hours per day. You can also use the same trick in hotel rooms if they charge for Wi-Fi access, just sign up with one device and tether the others.