Automatic 12V Battery Charger
Charger can work with gel, AGM and acid 12 V batteries. Led Indicates when battery is fully charged.
Components
C1 - 220uF 25V Electrolytic Capacitor
D1 - P600 Diode - 50V 5A or greater rectifier diode
D2 - 1N4004 Diode
D3 - 5.6V Zener Diode
D4 - LED
R1,R3 - 330 Ohm 1/4W Resistor
R2 - 100 Ohm 1/4W Pot
R4, R5 -82 Ohm 2W Resistor
R7, R8 -82 Ohm 2W Resistor
R6 - 100 Ohm 1/4W Resistor
R9 - 1K 1/4W Resistor
Q1 - BT136 TRIAC (need heatsink)
Q2 - BRX49 SCR
T1 - 12V, 4A Transformer
F1 - 3A Fuse
S1 - ON-OFF Switch, > 5A at 110 or 220V
Misc- If circuit work on box then a fan is might be necessary.
It's fully automatic and will charge at a rate up to 4 A until battery voltage reaches a preset point at wich it still switch a very low current float charge. If battery voltage drops again, charger willl begin charging until the voltage reaches the cut off point. We can be left connected a battery forever maintain full charge without causing damage.
If circuit is powered off, disconnect battery otherwise battery drain slowly to it.
Adjusts:
R2 adjust proper charge voltage. Flood and Gel batteries charging at 13,8V otherwise AGM or GEL use 14,5 or 14,9. To adjust, turn on charger and a battery, R2 in midway, turn on charger. Monitor charge with a voltmeter until battery reaches proper end voltage then, adjust pot until led grow. Charger has set.