New Gear – Tether Tools ONsite Relay For Continuous Power

Sometimes we need to run cameras longer than the stock batteries allow for. Time lapses and shooting video are just some of the activities that can benefit from a continuous power source. Most camera manufacturers have a way to provide external power to the camera, but there are drawbacks to these systems that the Tether Tools ONSite relay (formerly/also called the Case Relay) address.

For most of the systems, there are two parts, a power supply and a battery adapter. The adapter fits into the battery compartment of the camera, and provides the correct interface between the camera and the power supply. Tether Tools provides both parts of the system, although some camera systems require the use of the OEM battery adapter (check for compatibility information.) If you have multiple cameras, check them all to see if any have special requirements. My Nikon D610 is listed as working with the Tether Tools battery adapter, while the D850 needs the official Nikon one.

The main advantage to the ONsite system is in the power supply. Instead of being locked to a specific plug type, it uses a USB connection, so anything that provides a 5 Volt, 2 – 2.4 Amp power, including wall chargers and power banks, will work to power it. Even better, the adapter includes a battery, allowing it to be moved between power sources. For example you can switch to a new power bank without interrupting the camera. This also eliminates the concern over a power interruption, since the battery will keep the camera running for quite a while. The battery is 1200 milliamp hours, making it about two thirds the size of a stock Nikon EN-EL15 (original, a, and b at 1900 milliamp hours, or a little over half an EN-EL15C at 2280 milliamp hours.)

The OEM Nikon battery adapter and Case Relay power supply

What I like:

  • Provides constant power for video or time lapse.
  • Internal battery to to move to a fresh power bank and protects against power fluctuations.
  • USB input for maximum flexibility

What could be improved:

  • To work with Nikon and Canon OEM battery adapters, an additional adapter cable is required. I would prefer the whole camera-side cable could be replaced with a compatible one.
  • The power level of the on-board battery is only visible as a 3-color LED, it would be nice to have something a little more detailed, such as a 5-LED strip.
Adapter for the Nikon OEM Battery adapter.

Other notes:

  • The cables are rather short. This makes sense for using power banks, but you will probably need an extension if you plan to use AC power adapters. You can get a camera-side cable from Tether Tools, any standard male to female USB extension for power side, or an AC extension cord. I prefer the shorter cables, since it makes it easier to keep cables organized.
  • Make sure to check compatibility for your camera. There are some instances where specific cameras need the OEM battery adapter and others can use the Tether Tools version. If you are looking at a new Nikon or Canon camera, you probably want to err on the side of ordering the OEM adapter.

You Might Need One if:

  • You do time lapses that run up against battery limits.
  • You shoot a lot of video.
  • You use a video rig that makes it hard to access the battery.
  • You shoot weddings or other events and frequently have to change batteries.
  • You have a camera set up for YouTube, streaming, or the like that stays in one place.
  • You shoot in the cold. Not only can you use a larger power bank, it could be kept insulated or even warmed to maintain power.

You can buy one at:


Overall, this is a strong product, and the integrated battery is a great idea. If you are looking for a constant power system, I would recommend this over the standard manufacturer adapters.

Do you use constant power? What are your use cases? Let me know in the comments.

Looking for more gear information? Check out my post on whether high-end memory cards are really worth it.

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