simple 12 volt lead-acid battery charger

Here is a very basic 12 volt battery charger to charge any lead-acid battery small or big.I used what I had to build this except for the transformer . The enclosure is from a broken Pc subwoofer.

When the 12volt battery is fully charged the ammeter should drop significantly which indicates that at this point the battery is nearly full.The battery should measure 13.8 volts at full charge.

This charger produces pulsed DC.

The circuit schematic.

Original schematic found here.

Check the battery specs before connnecting.
You should check the battery specs before connecting it to the charger.There is a chance that the battery will draw too much initial current.In this case you need a current limiter.A simple and very cheap way is to connect a 12volt 10watt car lamp in series with the positive terminal.Like this.