On the other hand, you could just use the 120V AC outlet on most power stations. It works like a car battery wall-charger, converting the power station's AC to DC for battery charging.

A good-quality 12-volt charger can easily output 2.4 amps per port at 5 volts, and many newer models support Quick Charge (QC) 3.0 or USB Power Delivery (PD), which boost the voltage up to 9 volts ...

Here is a crude but efficient tricky charger for Lead Acid Battery. It uses a 12 volt car bulb as current regulator and charge status indicator. The brightness of the bulb indicates how much charge is ...