Re: powering Sony a7s with external 12V battery
 

I was linking to the P-tap cable, they've added those battery solutions to the page since. I myself use Anton Bauer Dionics which are priced similarly, I suppose "outrageous" is all relative.

Re: powering Sony a7s with external 12V battery
 

Woodencamera.com also makes various accessories and battery adapters for A7s.
And they won't be cheap ;-) They are well made from what I saw at NAB.

Re: powering Sony a7s with external 12V battery
 

I got this for a little over $20
Amazon.com : BestDealUSA AC Power Supply Adapter For Sony AC-PW20 7.6V 2A : Camera & Photo

The Small Rig Sony NP970 battery plate plugs right into the dummy battery cable and will give me more than 3 hours.

The A7s will only record 29 minutes internally and no 4k. So I got an Odyssey 7Q+.
So far I have not needed much more than 3 hours continuous recording,
but The 7Q+ is also a battery hog and that same NP970 battery will not last 3 hours,
so I got a dummy battery for the 7Q+ and plugged it into a 32,000 mAh Poweradd.

With power to spare, I am sure it will last for days hooked only to the A7s doing a sequence of stills.
I ordered a 2.1mm DC cable splitter to see if it will run the Camera and Recorder at the same time.

Re: powering Sony a7s with external 12V battery
 

My plan is to power the A7S with the video devices pix-e recorder which can hold two two of these.
S-8972 DV Battery for Sony NP-F970/770
They have an extra 7.2 V DC out to be connected to a second device which will be the A7s via a battery dummy. And the pix-e will switch from one to the other battery when needed. Will that work? If yes, it may be as good as the atomos powerstation.

Re: powering Sony a7s with external 12V battery
 

I'm interested in this guy's solution - he uses an xtpower battery but this outputs 9v - will the a7s run off a dummy battery supplied with 9v? even though the actual batteries are 7.2v?

Re: powering Sony a7s with external 12V battery
 

I am not sure what the upper limit is that the A7s can handle.
It certainly handles 8.4 volts well.
This is typically what my Sony NP batteries show at full charge.

I just started using the new (BestBatt.com) NP-F990 with great results.
The 7.2 volt battery is taller and weighs close to one pound but actually delivers way over the 3 hours of recording I need. It is (I think correctly) rated at 10400mAh and 74.9Wh.

Re: powering Sony a7s with external 12V battery
 

The A7s takes 9v with no problem. I bought one of the dummy batteries and power it from an Anker Astro Pro Powerbank.

I have the newer version with doesn't have the 19v option but the old model does, 5v on USB, 9v/12v or 19v on a dc jack.

I just made a cable with the correct connector and running the A7s for 90min uses about 15% of the battery according to the display on the anker.

I must admit having all those voltages from a 20000mAh battery for less than $80/ £50 is incredibly useful. I can use it for ipads or anything that needs usb or power my smallhd monitors etc.

Anker 2nd Gen Astro Pro2 20000mAh Multi-Voltage 4-Port: Amazon.co.uk: Electronics

Re: powering Sony a7s with external 12V battery
 

If you are worried about using a 12 volt battery on your A series camera, you can get a regulated dummy battery and connect that to an external power source.