LM317 CC/CV 12V Lead-Acid Battery Charger With Automatic Trickle Charge 2017-06-18

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For proper charging of a lead-acid battery you should start with a constant-current until it reaches full charge ant then revert to a constant-voltage trickle charge mode to avoid over-charge and maintain the the battery.
Below is a variation on the familiar LM317 charger circuit to do that.
The LM317 initially operates in a constant-current mode, until the maximum charge voltage, as determined by the U2 pot setting is reached.
A TL431 precision reference is...

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