A spare battery or 2 is always a good idea.It shouldn't take more than 2 hours to charge a stock battery pack-you need to use a voltmeter to see if the battery you have is taking a good charge.If the battery got hot,you could have a bad cell that will keep it from charging properly.The batteries that come with the less expensive helis are not the best quality to begin with so they won't take much abuse before they go bad.