So, I Designed a Simple Lead Acid Battery Charger for a Friend Of mine, I went to Google and Find either over Simplified or extra complicated one, so I designed this on my own (The moderate One ), I used an Adjustable Zener 431 as a Reference that somehow created a Stable 2.5 v which I fed this to inverting input of the Comparator, The Non Inverting one is fed through a Resistor voltage Divider of which one is a trim pot to set the threshold. So by comparing the two voltages and setting the threshold trips the base which then forces the Relay to "N.O" position and the Charging stops (theoretically).
The Circuit Works as expected but the time it Fully reaches 14.4v (The threshold voltage) it Behaves like crazy and Switches Relay Back and forth at high speed and it no longer becomes a Battery charger, instead, like a PWM generator. I thought the OP-AMP is doing its business very Aggressively, So I Threw a Big Capacitor C1 to hold the base For a while. It seems that it worked but the Relay still Doing "Tik" and "Tok" (At slow speed). So my question is This an Inherit Problem of such chargers or I went too far or there any Improvement you want to suggest 🧐