/diy/ - Do It Yourself

>>1747529
>Doesn't a buck converter reduces your voltage? I mean, yeah surely if you reduce the voltage the current goes down too, but at the end of the charging cycle the current goes down automatically and then you have to have the full 14.4V at the output

depends on the buck converter. You want a buck converter that will limit current and voltage.
I used this one for my charger I built.

go to ebay and search for
DC-DC Converter 10/12/15/20A 150/250/300/400/1200W Step up Step down Buck Boost
you want the 12amp step down converter like in the picture 4chan would not let me post the link.

You want your battery charger to have a set voltage and maximum amperage. In my case I chose 14.4 vdc and 8 amps.

my transformer put out 17 vdc and 10 amps
I set the buck converter 14.4 vdc and 8 amps.
If the battery draws more current than 8 the buck converter will drop the voltage until the amperage is 8. This is a constant current charge and what you want for Lead acid batteries. Then when the current draw drops to 8 or lower the voltage will go back to 14.4 v and constant voltage charging which at this stage is what is supposed to happen. If you plan on discharging your batteries down to 11v or lower (not a good idea for a car battery) you will want your output voltage to be 15 volts for what is called the maintenance charge this stage is what converts some of the lead sulfate on the plates back to sulfuric acid. But if you ever plan on charging sealed lead acid batteries you should never exceed 14.4 volts dc.