To get more out of your GoPro battery you can use a power bank. A power bank is typically used to charge your cell phone in a mobile setting, without the need to find an outlet. A power bank can be used to charge your GoPro camera as a stand alone charger. The power bank can also be used to power the GoPro unit and extend the single use life of the battery by 4 or more times.
Using the skeleton housing, you can use a myriad of the GoPro accessories available. The skeleton housing allows the charging cable to be plugged in to the side and still be in a housing. The skeleton housing is not waterproof. It is the one downside. It sure beats drilling a hole in the standard housing.
The Power Bank that I am using is the Targus 5500 mah. This unit will charge the GoPro battery in 1 1/2 hours versus 2 hours for the PC. A normal battery will last around 2 hours and 20 minutes shooting a 30 second interval time lapse. Using a fully charged GoPro battery and plugging in the power bank the same time lapse will go for just under 12 hours. This is great, because time lapse projects usually take more than 2 hours. This means that I can set up a time lapse project and not have to rely on 110v power. There may even be bigger power banks out there.
This link is to a list of the best selling power banks on Amazon.com. Make sure and look at the mAh value as the higher the mAh the longer it will last.
You can use the 30PIN POWER CABLE WITH WATERPROOF BACK DOOR HOUSING FOR GOPRO HERO3+&HERO4 in conjunction with a power bank. Using a power bank will drastically increase the situations that you can extend your battery time. Getting the GoPro 30 pin connector with waterproof back door will extend your ability to leave the gopro oustide or even submerge the gopro under water.