I have 2 18650 batteries in serial that I'm powering a Stepdown USB 3A module for emergency charging. I want o add a ESP32-cam to the mix and power via the batteries.
Do I need a step down module to take the charge directly from the batteries, or can I piggy-back on the USB jack?
Thinking that I might want to charge a device that will draw 2A+ via the USB, if it's connected to the ESP32 board at the same time, will it send high amperage and fry my ESP32? or the ESP32 will only take the amperage it needs?
The ESP32 can draw from 20ma (deep sleep) up to 790mA when WiFi and BlueTooth are running. The cam typically might draw around 180mA without flash and 310mA with the flash at max but that will depend on the model of the cam being used. The total current draw could be 1.1A when running full whack in addition to the 2A+ of the device under charge. Since the ESP and cam run at 3V3, then drawing 1.1A at 3.3V requires 3.63W of power. This would draw around 726mA at 5V, plus conversion inefficiencies.
It will depends on how much allowance is being made for the + on the 2A+ figure, how much current the ESP draws in practice when running and the level of current drawn by the model of cam being used. You might get away with it but IMHO it looks a bit borderline.