ONsite Relay A Camera Power System

ONsite Relay A lets you power your camera continually with an external battery pack or wall power, providing peace of mind knowing you have an uninterrupted power source for your camera. Requires Relay Camera Coupler (sold separately)

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Uninterruptible Power for Your Camera

Key Features:

  • Perfect for: astrophotography, night photography, timelapses, shooting video, long exposures, travel photography
  • Continually power your camera with USB battery packs
  • Hot swap batteries mid-shooting with no downtime
  • No need to purchase multiple camera batteries
  • Compatible with most Canon, Nikon, Sony, Panasonic, Fujifilm, and Olympus cameras and many Sony NP-F L-Series video monitors and lights
  • Can be adapted for use with D-Tap batteries

With ONsite Relay A, you’ll never run out of power and never need to stress about forgetting your camera batteries. If you’re shooting and get low on battery power, simply swap out external batteries throughout your shoot. ONsite Relay A’s internal UPS battery will keep your camera powered while you exchange external batteries. Utilizing a wall outlet or external batteries, you could in theory shoot forever with consistent power flowing to your camera through ONsite Relay A.

How Does it Work?


Simply insert the Relay Camera Coupler directly into the camera battery port, attach it to the ONsite Relay A CPS and power your camera with the included Rock Solid External Battery Pack or an AC power source using an USB to AC wall adapter or use the ONsite D-Tap Battery with V-Mount. Because ONsite Relay A also has its own secondary internal 1200 mAh battery, if your external battery runs low you can easily hot swap the external battery and not lose power to the camera.

ONsite Relay A is compatible currently with many Canon, Nikon, Sony, Panasonic, Fujifilm, Olympus, and Black Magic cameras and can be powered by any 5V USB power bank any 2.1+A USB Wall Adapter or any D-Tap (V-Mount) battery system. It can also power any monitors and accessories that use the Sony NPFL Series batteries.

FAQ, Instructions and Product Manual

Suggested Uses:

  • ONsite Relay A is ideal for time-lapse photography, astro-photography, or any photography that requires extended shooting time such as nature, fashion, landscape, architecture and more.
  • ONsite Relay A is ideal for video production as you can swap the External Battery Bank, without having to stop shooting to change camera batteries.
  • Use it to power Photobooths to ensure consistent uptime throughout an event.

“I’ve used it to shoot a three months time lapse!!!!!!! It was a place without electric power so it has been super useful!!!!!!!”
– D. Pepe, Tether Tools Customer

Behind the Scenes with Ron Risman: Tether Tools ONsite Relay A Camera Power Sysetm from Ron Risman on Vimeo.

Timelapse by Ron Risman
Timelapse Pro Ron Risman sets up a three access motion control timelapse in Newcastle, New Hampshire. Learn more

“We do Dog Show Event photography. The ONsite Relay A attached to the 10000mh battery powers the D750 that is tethered to our laptop. Before I got it we would go thru about 5 or 6 Nikon batteries in a day long assignment.
– B. Kurtis, Tether Tools Customer

National Parks at Night Timelapse
National Parks at Night Calls ONsite Relay A a “Game-Changer” and “The Best New Piece of Gear for Night Photographers” Read more

“It’s perfect to power my second Sony A7S II camera during weddings. Because I’m not with eyes on the camera most of the time, it allows me to connect any power pack. The most important thing is to allow swapping power banks without loss of power and corrupted files.”
– P. Portela, Tether Tools Customer

Product Specifications:

What is the Proper Way to Connect the ONsite Relay A? Here’s the Recommended Connection Sequence:

  1. Keeping the cables unconnected, insert Relay Camera Coupler into camera, completely close door.
  2. Connect the ONsite Relay A to the power source.
  3. Connect the Relay Camera Coupler to the ONsite Relay A
  4. Turn Camera On

More questions about the ONsite Relay A? Check out our FAQ and instructions page.

Find Your Relay Camera Coupler

Relay Camera Couplers from Tether Tools work in tandem with the ONsite Relay C and ONsite Relay A to keep your camera powered continually with an external USB battery pack, D-Tap battery, or wall power.

Chart of compatible cameras and couplers

What’s Included:

  • One (1) ONsite Relay A
  • One (1) Adapter for Nikon Couplers
  • One (1) Adapter for Canon Couplers
  • One (1) 4.2mm female to 5mm female reducer
  • One (1) 5mm female to 5mm female coupler