DC-coupler; Can you spot what is wrong here?

Arnstein Bjone wrote:

DC-coupler; Can you spot what is wrong here?

Well, most battery-replacement power supplies require rather specific voltages that are usually around 7.2V, so 5V USB power would need to go through a DC-to-DC converter (which is built-into some devices, but you'd need even more amps supplied at 5V).

The camera doesn't react at all.

Undervoltage by more than about 0.5V usually gets no response. Worst case, it could fry things by drawing more current....  A little higher voltage is usually ok, because in most cameras it gets regulated down.

All info om image, but here are in text too:

- The AC adapter (from my "adapterstock") has the correct numbers (5.0 v DC out, max 3.8 A) Ideally it should have been 4 A...

Most cameras don't need 4A, it's usually less than 2A, but it depends on the model and what the camera is doing. Not good to be underpowered -- it can mess-up things like writes to flash memory, including the camera built-in flash memory.

- I measure output to 5.25 v unlaoded. I assume it will drop to ca 5.0 v when loaded with up to 3.8 A)

- Polarity correct

Well, that's it... All according to demands...but no reaction from camera (Canon EOS 5Ds R)

Not surprising. I see 3rd-party units listing DC8V @ 3A for the 5DS R.

You also should be aware that some cameras have smart power supplies that can report ID strings, battery temp, etc. to the camera. For example, many early Sony NP-FW50 clones didn't work after camera firmware updates because Sony started having the cameras check battery ID strings. Most 3rd-party batteries and AC adapters are now good at pretending to be the real thing, but it's very easy for a camera firmware update to make the camera detect a "fake" supply and deliberately shut down. On Sonys, it typically gives an "invalid battery" display... which is cute, because the battery was obviously valid enough to power the processor and light the display.

I don't think Canon does anything fancy in their batteries. At least some do have a third lead that is an analog battery sensor output on their batteries -- which is a neat feature in that under CHDK in PowerShots you can actually program the camera to use that line as an analog input for whatever purpose you want. Anyway, I don't know how smart Canon's higher-end batteries are now, and I'm sure they'll be getting smarter....