Fwiw, I did some measuring on my IP2M-841B-V3 cams and I want to share the results with you.
First I checked the power supply (rated 5V/2A) that came with the cam and measured voltage while changing the load (or current):
4,8 V at 1,0 A
4,6 V at 1,5 A
4,0 V at 1,8 A
For comparison, I also...