I have a 15Volt 20 A Charger i want to get 13.8Volt from it .
How can i do that with components handel the 20A

 

A linear voltage regulator is probably not the best option because of the high current requirement (of course that current depends on the device). If you are going to be drawing <1 amp, a linear regulator might be an option.

If you are drawing 20 amps, you will need something like a switching power supply, but be aware that these introduce a lot of noise into your system and aren't appropriate for every application.

If you want an easy solution, put two large diodes(that will handle the current you need) in series in your circuit. 0.7 volt drop on each one = 1.4 volts, and there you have it, 13.6 volts.

 

the idea of the diode is good

you can also try to connect series variable resistance

and put it on max then try to reduce until you get the voltage you want

good luck

 

15 volt charger? are you sure of the battery voltage or is that an open circuit voltage you measured. I don't remember ever seeing a 15 volt battery..
But then again,there's a lot I don't remember, just ask my wife.....

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gerty

 

Gerty appears correct. if you load it by say 0.5 amp, it will come down to 13.8V

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Regards,
Sarma.

 

Thanks alot
Hi gerty if you want to fast charge a 12V lead acid battery the charge voltage ~ 15 Volt and float volt ~ 13.8

 

I disagree, a linear regulator is an excellant choice here because the voltage drop is very low which will give 92% efficiency - much better than some switching regulators!

The only problem is finding a linear regulator with a low enough dropout voltage than can handle the current.

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