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Need boat battery charger schematic

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Jul 23, 2002
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12v charger schematic

Like said in the subject, I would be very thankfull to anyone who could give me or point me to a schematic for a charger for 12V 35 Ah boat battery. The source is the 10hp outboard engine that gives ~9-~17 V AC current, varying on the power applied.

Thanks very much!

simple 12v flyback sepic acid battery charger

hi,what you must do is:
1:first of all,change the ac to dc,you can use a full bridge reguulator,get a 11v-22v around DC voltage;
2:if you want to charge the bat in 11v,you must change it to a 13.5v voltage(i think mostly your bat is lead-acid one).you can get the voltage by:a sepic converter,ot a flyback or a forward converter.maybe the current is a little big,so a forward converter is a good choice;
3:you can build a current limit forward converter with a output of 13.5-13.8v to charge you bat;
4:if this is a little diffcult for you,you can use a stepdown converter to get a 13.5v charger,but only can use above about 14-15v;if so ,you can visit
for some info
the most simple way is just a LM317 with a current limit of about 1.5a,but it is bad efficiency.
hope this can help you.

lm317t charger schematic

Shanren, thank you very much for you reply. But I'm not "at home" with electronics so I believe making my own schematics is out of the question. I know how to put together an existent circuit, but making my own would be too much for me (like I said, I don't know much about electronics).
So, I would very much appreciate schematics.

batt chrger with ptc as curent limiter

Find something usefull:
This high-performance charger quickly charges lead-acid batteries, and turns off at full charge. At first, the charge current is held at 2 A, but as battery voltage rises, current decreases. When current falls to 150 mA, the charger automatically switches to a lower float voltage to keep from overcharging. When you hit full charge, transistor Ql lights the LED to indicate that status.

Adjust by setting the 500 ohm resistor while attached to a fully charged battery.

An LM317HV regulator is used as a current-limited charger. If current through R4 exceeds 0.6, Ql is biased on, which pulls the ADJ terminal of the LM317 HV to ground and reduces the battery- charging current. This one is for 6V, but you can adjust resistors for 12V.

i need a circuir diagram 12v 35ah battery chargr



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