Such a thing as a variable voltage/current overcharge protection? Answered
I've had a couple of bad transformers in battery chargers in the last couple of months and I am thinking of building my own variable voltage/current battery charger with an ST Microelectronics L200.
But I would like to have overcharge protection so I don't have to monitor the batteries charging once I set the volts and current for that battery. Something that would just shut off or switch to a trickle charge when the battery reaches the voltages I want or set.
Also, another question - I am intending to use a salvaged transformer from an old chamberlain garage door opener for this project and need to know the best method for lowering the voltage from it to something the L200 can handle. It's a 1:3 and takes my 125v main to roughly 42v and the L200 is rated at a maximum of 40v input. I was figuring on just using a resistor, but I don't know how to calculate what I need since the current and voltage will be changing the load on a per battery basis.
Also I think the transformer might be a little small for this project, it only measures about 2"x2", while most of the chargers transformers were twice the size or more. So I'm wondering if it might not be able to handle the constant power or heat requirements for charging. *Added a pick of the transformer.
And since I've asked this many questions, I might as well add another. I was looking through the "how to get free electronic parts" pages and I didn't see any on solar cells. Does anyone know if any company does samples for cells the way they do for electronic parts?
I am capable of following simple to moderate schematics and can solder well. But when it comes to making new circuits and such, I tend to just hobble together something I've seen or used before that works. When it comes to programming and calculating circuit load and all that I become bogged down pretty fast. If I can see it and experiment with it till I get it right, I am better off and maybe learn something. So the simpler the better.