I would like to know that you use it as a battery because it looks totally improbable to me unless you use batteries of poor quality.
For my part, 3 batteries lasts more than 6 hours of shooting and I do more than 1200 photos and usually I have almost 1 battery available.
I use Patona brand batteries and Baxxtar pro.
I had been using ChiliPower batteries for a while, which could not keep the charge for a long time.