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Step down the mains to 15V or 16V AC using a LARGE transformer. Rectify to DC and filter. Use a regulator circuit to regulate to either 13.5V or 14.4V depending on the battery voltage level which is detected by another comparator-based circuit. There is an active switch in the path that is on during charging and turned off when the comparator circuit detects that battery has been fully charged.
This is one method. There are many other methods. Construct one for lower capacity first. Then scale up.
I suspect the L296 circuit performs a taper charge. The idea is to reduce the charge rate as the battery reaches near full. This allows the battery temperature to settle down, while permitting it to absorb maximum charge. It is preferable to making the battery rise to over 15 or 16 V, then shutting off the charge.
To charge my batteries from my solar panels, I constructed a circuit which performs an in-between method. Turn off charge when the battery reaches 14.4V, wait for the battery to settle below 13.4V, then turn on charging again. Cycle indefinitely this way.
Simulation screenshot:
It shows a transistor as the switching device but a mosfet is suitable.
The zener value is 5V but it can be almost anything up to 12 V.
It is a switching topology, using an IC called UC3842.
The switching method looks very sensible. It is likely to be more efficient than the simpler analog method.
The article appears well done. It has sufficient instructions and photographs.
The IC offers a big benefit because it replaces a number of components.
However it is exposed to mains AC, therefore it's a good idea to purchase a few of them, because we all know how easy it is for mistakes to happen!
Notice the warning it gives: "Switching supply is not for beginners".
Suppose it does not work right the first time you apply power. Then it will be difficult to troubleshoot. Many of the components are exposed to high voltage. Between setting your meter to check voltage and then to check current, there is a lot of opportunity to blow up your meter.
If you find the IC-based charger does not work, then be prepared to try another topology made from simpler components.
As you can see there are many battery charging circuits on the internet. And many different charging regimens, etc. It's a lot to take in. Even more difficult to look at a schematic and say whether it has any shortcomings.
You'll want to weigh factors such as expense, complexity, ease of building, ease of troubleshooting.
thanks for the detail response . . above charger can charge max upto 2-3 amp . . i want to charge battery of 200Ah . is there any other way in switching topology to achieve this ??
thanks for the detail response . . above charger can charge max upto 2-3 amp . . i want to charge battery of 200Ah . is there any other way in switching topology to achieve this ??
A safe charge rate is typically C * 1/10 (where C is Amp-hour capacity).
That works out to 10 hours to fully charge the battery.
Therefore with a capacity of 200 AHrs, a suitable charge rate is 20 A. It can be more. It can be less.
It depends on how much charging time you can allow.
Also on how powerful and expensive you wish the transformer to be.
I believe you want a faster charge rate than 2-3 A.
I don't think you should try to scale up the danyk.cz design. Look for a design that has been shown to be successful with a battery of the same size you have.
The datasheet states the OB2354 is designed for sub-20W power range. This sounds too low for your purposes. You need a circuit which draws about 320 W. This amounts to 1.5 A of 220V mains AC.
It gives a list of applications. These are in a lower power range than you need. (Even though the list contains 'battery charger'.) I believe these would draw a fraction of an ampere at 220 VAC.
This IC does not appear powerful enough to charge a 200 AH battery, unless you can find a project which shows you exactly how to do so. It might require the addition of more components, to handle the power.
The charger is based on a 317 adjustable voltage regulator.
It is set to provide 1 A charge rate.
The instructions say to set its volt level at 14.2 V, so that it does not continue to charge a battery above that. This is proper for a 12V battery.
The charger is satisfactory for a battery capacity of about 10 Amp-hours. Common advice says that C/10 is a suitable charge rate. The photograph shows a 7 AH battery which is about right for this charger.
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