Mods: None
This is not about charging Li-ion batteries (directly). Rather, I wanted to check the change in the current draw of a mobile phone when supplying less than 5 V. Supplying power via USB is getting a bit complex. There are different protocols like Quick Charge and USB-PD to negotiate the current and voltage. However, there are billions of stupid chargers that just deliver 5 V, and phones have to deal with the case when the chargers can’t quite keep up.
The hope is that it’s possible to vary the power usage by reducing the voltage. I’d like to make a solar to USB charger, and stay on the Maximum Power Point of the solar panel. So it needs to be able to step back and not pull as much current as it can from the solar panel.