Simple Car Battery Charger

Hi there!! i guess this would be my last post perhaps. Have you gone through your car make you sick early in the morning just because you made a big mistake by forgetting to switch off the headlights? Well I've gone through it always. Thus instead of buying new battery, i just made my own simple car battery charger which only use few components. The circuits are shown below.

As simple as it should, it only consist of  two 1N4007 diode, one 2200uF electrolyte capacitor, a transformer and an ammeter.

To charge a battery just connect the + and - terminals of the circuit to the corresponding terminals of the battery.
When the battery is not charged, the ammeter reading shows 1-3 amps.

When the battery is fully charged the ammeter reads Zero  or nearly zero, after which the battery should be removed from the
charger.
The circuit is a full wave rectifier using 2 diodes for rectification. The capacitor is used for smoothing.
I think the circuit works fine without the capacitor since the battery itself acts a BIG capacitor. But when you are using the
circuit to supply 12V (as a battery eliminator) the capacitor needs to be present.
Care should be taken NOT to reverse the + and - terminals while connecting it to the battery.

So if you get it , it is much more cheaper than buying a new battery. That's all from me and singing off.