I need to charge my car battery (12V)

[ranatungawk]

I need to charge my car battery (12V) from my home when it’s very low. I found this circuit from the internet. Please tell me..

1. is this a good circuit for my requirement ?
2. 1N4007 (1A) diodes are used for rectifying. But I think it need to use 5A rectifiers instead of 1As. If so tell me a what is good for this ?
3. can I use this to charge my car battery when it is in the car, ( with out disconnecting battery wires which are connected with the battery)


about the circuit




This very simple circuit uses a transformer ,two diodes , a capacitor 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.

 

[MikeMl]

The 1N400X diodes will act as fuses

Use ones like these:

You will likely overheat the transformer if you connect this to a mostly discharged battery. What I suggest is to put a small lamp in series with the transformer PRIMARY to act as a current-limiting ballast resistor, relying on the non-linear resistance of the lamp. If your mains voltage is 120V (US), then try a 12V 10W automotive lamp. For 240V, try two such lamps, likely lower wattage, but you may have to experiment.

In this circuit with the 12-0-12V transformer secondary voltage, you are relying on the peak voltage out of the rectifier being close to that of a fully charged battery, ~14.5 to 14.7V. This will produce the tapering charging current, but I sure as hell would not leave this charger connected long-term, unattended. After a battery is fully charged, the long term float voltage should drop to ~<13.2V (corrected for ambient temperature).

The capacitor does nothing and can be left out.

 

[ranatungawk]

thanks for the clear reply!!!

 

[MikeMl]

Go to PowerStream.com
Click on "Technical Resources"
Click on "How to Charge Sealed Lead Acid Batteries"

This applies to flooded cell batteries, too.