Bests & Worsts Reviews from Amazon

The attached image shows measured IV curves for this power supply compared to a 2.0A power supply (Kootek). I generated these with a RPi-based IV curve tracer that I built for solar panels (search for "IV Swinger" on YouTube and/or GitHub if you're interested in knowing more about it). It's not intended for such small voltages, but it worked pretty well. The IV curves show the current (I) and voltage (V) for different resistances (R). This tells the story about how the supply delivers power for different loads (power = I * V). You can see that both supplies have an open-circuit voltage of 5.3V. That is the lower rightmost point. R = ∞Ω, I = 0A, P = 0W. The upper left points of each curve are the closest to R = 0 (short circuit) that we can measure (R = 0.94Ω due to wiring resistance). You can see that the Kootek delivers just about 3A of current and the Canakit delivers about 3.8A. But at this point both are way below 5V (below 3V, in fact.). An interesting point is where the curves cross their rated current values. The Kootek 2.0A supply crosses 2.0A at about 4.6V (2.0*4.6 = 9.2W). The Canakit 2.5A supply crosses 2.5A at about 4.5V (2.5*4.5 = 11.25W). Both of these are well below 5V. Probably high enough that the RPi won't crash, but cutting it close. Another interesting point is where the curves cross 5.0V. The Kootek 2.0A supply crosses 5.0V at about 0.8A (0.8*5.0 = 4.0W). The Canakit 2.5A supply crosses 5.0V at about 1.0A (1.0*5.0 = 5.0W). People who are claiming that this supply doesn't deliver 2.5A are correct - if they are expecting it to deliver 2.5A at 5.0V. But what is important is whether the supply is sufficient for the RPi 3. All I can say for sure is that it does deliver proportionally more power than a 2.0A-rated power supply that has worked fine for me with the Gen 1 RPi B+. For that reason, I'm giving it four stars. For anyone with specific voltage requirements at the rated (or other) current, you can read the values off the IV curve in my attachment.