External Battery pack for A7r

Hi all , its there an external battery pack that works with the A7r? , I've recently bought a motorised rail for Timelapse and the a7r batteries are the weak link , I see Sony have a mains powered pack but need a battery powered version , I've also seen some DC couplers but they seem to just mention the A7s not the a7r? Ive also seen a thread where a guy sauys these work with his a7s but not his R

Any ideas? I'm not very electrical so I really need plug and play if possible..

Thanks in advance

Seems I'm the only one who needs external power for my A7r - for anyone interested in the future I managed to find the below - works like a charm


http://www.amazon.co.u​k …oh_aui_detailpa​ge_o02_s00

I actually ignored the compatibility list because it doesn't mention the A7 range and just followed the fact it uses the same battery.. happy days

nice!