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"Variable Voltage Battery charger"

Electric-T

Jun 4, 2017
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Ok ive drawn up this this schematic to the best of my knowledge. Its taken a couple days of research and im ready for you guys to completely tear it apart haha. Listen im not an expert. But i want to learn so i hope to only(mostly) get educational criticism. Im not starting the build until im sure but according to what knowledge i do have i shouldnt be that far off. Heres the schematic. I also need help with my values (caps,resistors,leds,diodes). But i have a rough idea what they should be. Formulas would be greatly appreciated.
 

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Audioguru

Sep 24, 2016
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Your circuit has no voltage regulation and has no current regulation. It has nothing to detect that a battery is fully charged and has nothing to shut off the charging when the battery is fully charged so that it does not become over-charged and boil away its fluids, catch on fire or explode.

A potentiometer that is rated at 150W is not available. They are usually 0.5W and a few are 2W. Potentiometers feed low currents to electronic circuits that do all the power handling work.

You need to learn about the different types of rechargeable batteries and the different charging circuits required for them. Here is a site that will tell you all about how to charge lead-acid, Ni-MH and Lithium:
http://batteryuniversity.com/
 

Electric-T

Jun 4, 2017
212
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Jun 4, 2017
Messages
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Your circuit has no voltage regulation and has no current regulation. It has nothing to detect that a battery is fully charged and has nothing to shut off the charging when the battery is fully charged so that it does not become over-charged and boil away its fluids, catch on fire or explode.

A potentiometer that is rated at 150W is not available. They are usually 0.5W and a few are 2W. Potentiometers feed low currents to electronic circuits that do all the power handling work.

You need to learn about the different types of rechargeable batteries and the different charging circuits required for them. Here is a site that will tell you all about how to charge lead-acid, Ni-MH and Lithium:
http://batteryuniversity.com/
Hmm. What if i find a rheostat rated for the power im using? I had thought about the overcharging issue. I am thinking of a way to fix that. Any suggestions?
As far as battery chemistry i know very little. I will study up on that. Thanks
 

BobK

Jan 5, 2010
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Hmm. What if i find a rheostat rated for the power im using? I had thought about the overcharging issue. I am thinking of a way to fix that. Any suggestions?
As far as battery chemistry i know very little. I will study up on that. Thanks
You are scaring me. You don't have near enough knowledge nor experience to do thus project. You don't start with high power applications that are notoriously dangerous as a first project.

Bob
 

Electric-T

Jun 4, 2017
212
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Jun 4, 2017
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You are scaring me. You don't have near enough knowledge nor experience to do thus project. You don't start with high power applications that are notoriously dangerous as a first project.

Bob
And what would you suggest? I dont believe a battery charger is that far over my level of knowledge. What am i wrong about?
 

kellys_eye

Jun 25, 2010
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A rheostat will only vary the voltage according to the load. Vary the load and the voltage will vary too (for a given setting of the rheostat).

Do you want constant voltage, constant current, 'controlled voltage', controlled current, staged charging, managed charging, trickle charging etc etc?

Clearly you don't understand the basic principles of 'charging' which would be necessary before you can even begin to consider WHAT you want to charge as well as HOW you charge it.

I listed three or four areas of understanding in your other thread on this subject - have you looked into any of them?

You're trying to run before you can walk.
 

Electric-T

Jun 4, 2017
212
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Jun 4, 2017
Messages
212
A rheostat will only vary the voltage according to the load. Vary the load and the voltage will vary too (for a given setting of the rheostat).

Do you want constant voltage, constant current, 'controlled voltage', controlled current, staged charging, managed charging, trickle charging etc etc?

Clearly you don't understand the basic principles of 'charging' which would be necessary before you can even begin to consider WHAT you want to charge as well as HOW you charge it.

I listed three or four areas of understanding in your other thread on this subject - have you looked into any of them?

You're trying to run before you can walk.
Controlled voltage is my goal. Id like to keep amperage constant. However you and others bring up good points. I think i need to do more studying. Im not ready to abandon this project but doing some simpler projects and getting more experience is never a bad idea. Do you have some good projects/videos/reading i could look at?
 

kellys_eye

Jun 25, 2010
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It's the type of battery you intend to charge that decides whether constant current or constant voltage (or a mix of the two) is required.

Research battery chemistry basics to see how each type delivers power and the way in whch they are required to be recharged.
 
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