The first problem is that you didn’t charge them. Don’t take three lights on the head unit as proof it’s fully charged. Plug the charger in, attach the battery and see if the LED on the charger goes red. As you ran them straight out of the box without checking the charge this way, there’s no way of telling (without using a meter) whether the battery is any good or not. Try charging the pack again, and then do a test discharge – run it at full chat and see how long it lasts. Preferably do this outside so the temp doesn’t go nuts, and preferably check how hot the head unit is every five minutes or so.
As said above, the batteries that come with these lights tend to be cheap and ‘orrible – the money is spent on the lights themselves, not the chargers or packs. Do yourself a favour and buy a new pack with decent cells sooner rather than later. Smudge is excellent.
Hope that helps.