I have a project that requires me to make a portable power pack that can be charged up and then power different devices. The product needs to have two USB charging ports and hold around 7Ah.
The problem I have is that the devices it will charge vary in minimum/max current and voltage and I would like to not damage the devices it is charging. What is the best way to do this as the only way I would know is to state the rails, yet I cant list all the devices it could charge so should I go for a general voltage and current.
Also what are some of the important circuits I should be looking to make sure the device has to make it more safe. Any answers are appreciated