DC DC step down converter for smart battery charger

Hi all!

I come up to the idea to use transformer from my old PC power supply to build the smart battery charger.

This is how I'm planing to realize it:
It's going to have have potentiometer for setting the current!
I found lot's of schematics on internet with using some linear regulators but, but on ebay you can buy something like this very cheap:
http://www.ebay.com/itm/DC-Step-Down-Power-Supply-Buck-Converter-Charger-Constant-Current-LED-Driver-/350751846916?pt=LH_DefaultDomain_0&hash=item51aa707204
But I'm planing to do whole board on my own so is there any schematics which uses this switching regulators with current regulation? I think that 5A max. current would be enough!

Also this charger will have desulfation option, but I already found schematic for that and also it will have LCD screen on which there will be showed how much is the current, also voltage of the battery and current state of charging.

Thanks!

Josip

Ambitious project. You will have to come up with a independent current measurement and output voltage measurement to feedback to your 'smart controller'.

Also you said 5 amps should be enough? The specs on that regulator is 3 amps max and then only if you add heatsinking and keep the voltage/current product (actual wattage delivered to the charging load) at less then 15 watts.

Study and understand the limiting factors in the following specifications they give you:

Output Current: Max 3A ( If more than 15W, please install the heat sink, this item do not include heat sink)
Constant current range :0-3A (adjustable)
Minimum voltage pressure: 2V
Output power: natural cooling 15W

Lefty

retrolefty:
Ambitious project. You will have to come up with a independent current measurement and output voltage measurement to feedback to your 'smart controller'.

Also you said 5 amps should be enough? The specs on that regulator is 3 amps max and then only if you add heatsinking and keep the voltage/current product (actual wattage delivered to the charging load) at less then 15 watts.

Study and understand the limiting factors in the following specifications they give you:

Output Current: Max 3A ( If more than 15W, please install the heat sink, this item do not include heat sink)

Constant current range :0-3A (adjustable)
Minimum voltage pressure: 2V
Output power: natural cooling 15W





Lefty

Hi!

I just put this one as an example, I know how to measure current and voltage only thing what I need is schematics of some step down dc dc converter which can regulate current!

Does anyone knows? :~

I just got one of them myself (except, there's 3 pot's on my version) ...

The annoying part is, the switching regulator, all the components EXCEPT for the little SM IC which controls the current, i'd like to know what component that is! as mine is scratched off, or filed off... I have no idea what kind of regulator it is! - if and when you get on, could you reply here :slight_smile: - cheers...

http://www.ebay.com.au/itm/171003176697?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

here's the one that I have... (probably ideal for your project as it does pretty much what you're asking with the 3rd potentiometer)

Anyone have any idea?

whatisit.jpg

I'd be backing that it's an op amp used to give feedback on the current limiting aspect of the board, not a regulator. Something like an LM358 perhaps, though the lower end of the voltage is below that part's minimum operating voltage.

Geoff

Seems like I've found a schematic of the CV/CC version?


Attached is a conceptual (untested) schematic