I need to charge 12V car battery (from main battery), but I have to limit current, because power cables are quite thin and I don't want to draw too much power from main system (in case battery is empty). What would be simplest solution (without ineffective linear regulators)? I though about PWM controlled LC circuit, but maybe there are controllers (ICs) made for that? I would like to charge the battery at no more than 3A.
Those cheap chinese converters have current limiting option through potentiometer, but I want something less delicate.