Please make sure if travelling through Beijing Airport that you keep your battery pack in your hand luggage so they can inspect it with you present. We did this on our outward journey and got through with only a short questioning time. On our return journey because we had only 1 hour and a bit to change planes we thought we should put the battery pack in our suitcase so as to not get delayed going through. Big mistake!! They held the suitcase back as it showed up on the x rays. The battery pack was removed and the case did not make it in time to get on our plane home. So we spent ages at the carousel looking in vain for our second piece of luggage which had not travelled with us! We returned home minus our case and had to wait for it to be delivered a few days later minus the battery pack. This may well happen at other airports too so be aware!