I tried both cables just to make sure it was not them. I fully charged the pack 3 times. I never got more than 3.5 hours of recording with my gopro hero 4 set on 1080 x 30fps. The cable is also a terrible idea with this product. It's the obvious week spot. I went with digipowers re-fuel 12 hour pack that plugs right into the gopros rear accessory port "where the gopro battery pack and lcd screen plug in". I tested continuously with different settings and decided on using 1080x30fps and got just over 7 hours 3 times in a row.
On a side note I just wanted to say I purchased this to use while on my paddle board. We go to some cool places and just wanted to put a 128 gb card in and record all day then edit what I wanted to use. The Brunton battery pack looks well made and I had high hopes for it. Keep in mind there's a definite possibility this was a defective unit. I am returning it for a refund for 2 reasons, 1st we'll it didn't do what it said and 2nd the cable is a terrible design and I saw a future of broken cables.