This is a simple circuit that will indicate a low voltage on a 12V lead acid battery. Many that have golf carts, small EV’s, RV’s, or solar power banks for homes have a number of 12V lead acid ...

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 ...