The transformer works and I have a diode setup that gives me 12 volts dc. I need a controller card that lets me use the transformer to charge batteries. The transformer has 3 taps. I have applied power to the black lead with blue to neutral and I get 12 volts dc after the diodes. I assume this will give me one amperage and brown to neutral will give me another amperage, please correct me if I am wrong. I have not tested this theory yet. Any help is appreciated.

 

By the gauge of those wires you should get way over 1a!
They also appear to be beefy diodes, what are the markings?

 

Welcome to AAC.

You need at least 13.8v to fully charge an SLA.

Be very careful how you connect the primary side of the transformer. Brown (L) and Blue (N) are normally the pair to use, but it does depend on what country you are in, I'm guessing you're in US (120v). Black could be Earth, or it could be the common between two phases. Before you go any further measure the AC voltages from brown and blue to black and between brown and blue.

 

the diodes are both SD75 with a line under it and 2002 below the line. I cannot find any markings on the transformer.

Originally the transformer was outputting 11.8 volts dc after the diodes. Upon retesting the transformer has an internal short. I guess it was dying while I was trying to salvage it. Oh well, it was given to me so easy come easy go!

Thanks MaxHeadRoom and Irving for your responses.

Thread is now dead.

 

Looks like a battery charger from an older unit designed to charge a car battery. It's possible the multi-taps are for selecting between charging a 6V battery and a 12V battery.

12VAC can reach as high as 17VDC when charging a car battery. I've seen MY "Dumb" charger charging a car battery go over 15 volts. At high voltages batteries outgas hydrogen, and can be explosive if a spark occurs within the hydrogen envelope. Always make connections before turning the charger on and always turn the charger off before disconnecting.
I keep my old charger because it has five options by way of selector switch. 6V @ 2A, 6V @ 10A, 12V @ 2A, 12V @ 10A and 12V @ 200A. The last is for aiding in starting a car.

While those old Dumb chargers worked well, there are better chargers on the market. An SLA (Sealed Lead Acid) battery isn't quite the same as an automobile "Wet Cell" battery. SLA's can get hotter than wet cell batteries.

I worked for a short while servicing emergency lighting equipment. A LOT of wall mounted emergency lights that ran on a 12V SLA battery. We had a set voltage of 13.8 volts that would maintain a float voltage on them. Anticipated lifespan was approximately 5 years. The company I worked for sold a lot of SLA's. They also serviced 12V wet cell battery systems. Those also were held at a float charge of 13.8V.

With such a charger when the voltage was low they would charge quickly. But as the voltage rose the current draw would drop until eventually there was a negligible current, and the voltage never went above 13.8V. Depending on how you want to use your charger, whether to charge a car battery or to charge SLA's for power storage - different choices are needed. For long term charge and maintenance you don't want a car battery charger. They WILL over charge your batteries and ruin them. So a little more information on your goal would help us help you in achieving the best results.