Charge Controller

sorry, its not AC to DC supply, i wanna know how to convert from AC supply to got the DC to charge the battery, & how to connect it

Mr Guest,

You are not clear! You already have a circuit that is converting the 220V AC to 14VDC (or thereabout), using a transformer and 2 diodes with central taping.

This circuit can charge the 12V battery you mentioned. All you need is to set it properly to stop charging when the battery is full (in your case when the voltage at the battery start to rise above 13.5V). And as mentioned by the site, the SCR1s should be sized to take the required current depending on the battery size etc.(maximum current drawn when battery is empty or discharged at maximum permitted ~10.5V?).

The transformer output will be about 5Amp max.

The negative line to the battery is obliterated by advertising.

One problem with this circuit is there is a bleed across the sensing voltage divider chain so when charging ceases it will discharge the battery, so it should always be switched on if it remains connected to the battery.

The type of battery voltage that can be charged is dependent on the transformer output volts and ZD1 and divider chain resistance.

The charging current should not be set to zero or cutoff to stop charging the battery. Instead it should adjusted and set to deliver a small amount of current for trickle charging the battery. Which is needed to overcome battery's built-in internal resistance, as well as to offset any bleed current from the voltage sensing circuit as mentioned by Mr. Garth.

The circuit provided is a fairly simple charger designed for lead-acid batteries (like car batteries with standard liquid electrolyte). If properly constructed and adjusted, it should work fine for that type of battery. Circuit is basically complete as pictured. You don't need AC-DC conversion because the circuit already does that.

12V, 7A-Hr sounds like a gel-cell battery or SLA = Sealed Lead Acid. This is lead-acid, but the electrolyte is in gel-form to minimized leaks. Gel-cells do not normally like the high charging rates this circuit could provide. I would suggest NOT using this circuit for a gel-cell rated 12V, 7 A-Hr. Look for another circuit which has the capability of:


1) measuring battery(or ambient) temperature for proper temperature compensation
2) adjusting/limiting peak charge current
3) providing a low pre-charge conditioning current for deeply discharged cells
4) sensing peak voltage for determining end of charge
5) providing a "smart" maintenance charge mode

There are many IC's which handle all these functions and a charger can be built around them with minimal extra parts.

No offense intended... if none of this makes any sense then please consider purchasing a ready-made charger specifically designed for your battery type. Your battery will thank you. Good luck!

thanks 4 all advise, but im not sure which circuit is the best for my battery ( 12 V & 7 Ah ) and what ur suggestion of the circuit to my battery....tq