The Sony one is a bit pricey - anyone using other makes such as the one below?

Meike MK-AR7 Built-in 2.4g Wireless Control Battery: Amazon.co.uk: Camera & Photo (http://www.amazon.co.uk/MK-AR7-Wireless-Control-Battery-VG-C1EM/dp/B00OZUJ5W0/ref=sr_1_fkmr1_3?ie=UTF8&qid=1434359584&sr=8-3-fkmr1&keywords=VG-C1EM+Vertical+A7-Series+Camera+Grip)

Pete

I have the Neewer version and it works flawlessly.
However, double nothing is still nothing.
And, I've tried a half dozen aftermarket batteries
all with less or only slightly longer life regardless of mAh rating.

The solution I found for unattended Video of over 3 hours
was a Neewer dummy battery with Small Rig Sony 970 battery plate
and an Odyssey 7Q+ with Indigo dummy battery plugged into a Poweradd power bank.

Well I ended up buying it and it seems ok - nice to go twice as long without changing battery :)