I would like to present a new "Direct Drive" type of desulfator circuit that I have designed and built. Please read the following description of the design for the particulars. If you want to build one I'll post the schematic and PCB pattern and give assistance.
First an introduction
Hi, my name is Mark and I am a retired electrical engineer. I have a large background in high energy pulsed applications so when I started reading about desulfators I was immediately interested. Through the years I have personally acquired a verity of test equipment and a small wealth of electronic parts. It is no surprise that designing and building gadgets is an enjoyable hobby of mine.
Design Overview - My toys are powered from small motorcycle batteries to big 6 volt deep discharge golf cart batteries. I also found that there is a lot of mysteries/unknowns about desulfators. I wanted to build a desulfator that I could use to discern fact from myth and to "do good science" as far as understanding what the possibilities are in extending lead acid battery life.
Evaluation of current designs
- Inductor kick back design - This beautifully elegant design is very close to perfect for its intended purpose, which is a low to medium power desulfator with fixed parameters.
- High Power design - Far less forgiving design than the inductive kick back circuit. Adjustability of parameters is limited. The transformer-less design makes this circuit a VERY VERY dangerous shock hazard. (This circuit is a "Widow Maker".)
Goals for New design
- Peak current adjustable from a few amps to hundreds of amps.
- Pulse width adjustable over a wide range.
- Repetition rate adjustable over a wide range.
- Fast rise and fall time.
- No custom inductors or transformers required
- Line isolated/low shock hazard.
- Parts selection not critical
- KISS (Keep It Simple Stupid)
Description of "Direct Drive High Power Desulfator" design
- 120-volt A.C. line current is converted to approximately 40 volts D.C. using a traditional transformer and bridge rectifier.
- The 40volts DC from above is feed to a capacitor bank through a group of selectable resistors. Selecting different resistors sets the current output of the pulser.
- A MOSFET device acts as a switch to apply energy from the capacitor bank directly to the battery being desulfated.
- The MOSFET switch is controlled by a 555 timer chip where the pulse width and PRI is adjustable.
Below is a block diagram
I have prototyped the above design can switch from tens of amps to as high as 200 amps (so far)with changing one jumper wire. I'll add more data in other posts.