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Electronics and Circuits

Power supply with LM317T to charge batteries

osvaser
osvaser
16
hace 6 años
hace 6 años
Good morning, I have a regulated power supply with CI LM317T and I want to use it to charge aaa rechargeable batteries of 1.2 Volt 700miliamper / hour. Question: I can use it directly and connect it to 3 batteries in series by regulating the milliamper that will circulate to charge them For example; I regulate the source at 5 Volt and measure the current that circulates ?? .. And how do I know when they are charged? .. How can I place the source, an LED that indicates that the batteries are already charged so I do not harm them "overloading them? ??Thank you!
JOSE MIGUEL SIRGO PASCUAL
hace 6 años

You can't charge the batteries that way. you have to build a constant current regulator using another LM317.
Ideally, you will mount an adjustable regulator with its milliammeter and adjust it to a tenth of the nominal current of the battery, allowing it to charge for 10 or 12 hours.
If you want I can give you the scheme.

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osvaser
osvaser
16
hace 6 años

But if for example, I turn the potentiometer and leave it regulated to 4.5 VDC or 5 VDC (measuring with the tester voltmeter of course), and connect to three rechargeable batteries of 1.2 Volt -700 m in series .. .load them? .. If I would appreciate a scheme

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osvaser
osvaser
16
hace 6 años

The source is adjustable between 1.5 VC C. and 15 Volt or so

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JOSE MIGUEL SIRGO PASCUAL
hace 6 años

I will tell you for the second time, you cannot charge a voltage battery unless it is an acid lead.

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osvaser
osvaser
16
hace 6 años

Do you have a circuit to use the LM317 and the traffic?

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JOSE MIGUEL SIRGO PASCUAL
hace 6 años

You can use the same power supply that you already had to regulate voltage, you would only have to connect another independent output than the lamellae of the output of the bridge of diodes.

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osvaser
osvaser
16
hace 6 años

Good, but unfiltered, without electrolytic capacitor ...

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JOSE MIGUEL SIRGO PASCUAL
hace 6 años

It is assumed that if you have an adjustable source you already have an electrolytic capacitor at the exit of the bridge

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osvaser
osvaser
16
hace 6 años

Ah yes of course!

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JOSE MIGUEL SIRGO PASCUAL
hace 6 años

I look for the scheme and upload it.

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osvaser
osvaser
16
hace 6 años

Well, I still have a source of a screwdriver that I think can help ...

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JOSE MIGUEL SIRGO PASCUAL
hace 6 años
hace 6 años
On the left the voltage regulator based on the LM317. The point + b is where we connect the constant current regulator and the battery is connected between the AYB points that are the positive output of the current regulator and the mass of the voltage regulator. Another option is to arm it independently of the voltage regulator that you already have for which you will have to use a transformer, a bridge of didos and a capacitor. The input voltage of the current regulator has to be higher than the batteries you want to charge. To have a good current regulation range you would have to use a 24 volt transformer but you can use a lower voltage one even though that way the maximum current you can have will be lower. I remind you that the charge of a nickel cadmium or lithium ion battery has to be slow by putting a tenth of its nominal current for 14 hours if it is fully discharged.
osvaser
osvaser
16
hace 6 años

Perfect Jose, thank you so much !!

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