Hey guys, interesting topic, I also have the external power questions for my SX530HS and M10. Having enough Amps is key, as many people have said.
Some sources for various Vregs below. Hopefully the info is useful to your experiments.
For my ixus160 rig, I use this buck V reg:
https://www.dpcav.com/xcart/Adjustable-Voltage-Regulator-1-35V-SEPIC-Type.htmlIt is 3 - 35V input, adjustable output, 2A continuous
I give it input of 19V, and step down to 4.1V at fake battery. Best camera results and reliability.
This buck Vreg seems to fit your requirements of 7.4V @ 4A as long as your battery pack is enough volts more than 7.4
https://www.pololu.com/product/2883It is ?(9) ~ 40V input, 7.5V output, 15A
I have not used this one yet, but might be promising for M10.
If high amps AND different input/output voltages are required, as if many cams sharing a common power supply, you may be interested in this buck boost Vreg.
http://www.mini-box.com/DCDC-USB-200It is 6-34V input, 5-24V output, 15A continuous
In my rig, I give it input from 12V batteries and make 19V output.
And this device is not a Vreg, but is useful in external battery configurations. It switches between the highest of 2 input voltage sources to a common output.
http://www.mini-box.com/Y-PWR-Hot-Swap-Load-Sharing-ControllerWith this, I can disconnect half of my batteries and rig continues to run. The Intel NUC at receiving end does not notice the switch..
Anyway, hope the info is useful. Looking forward to hearing more about your experiments!
