This is a continuation of the story where I complained that "smart battery chargers" were not working well for my batteries. Mine are about 160 AH deep cycle batteries.
The charger that I bought on eBay, that turned out to be a Walmart charger in fact, also did not work. It would "hang" showing partial charge 88%, only to overcharge the battery. It was a piece of garbage with poorly written software.
I gave the suggestion to use a big ol' power supply a second look and decided to do just that.I decided to use a PP-1104B/G power supply that is almost exactly the same as PP-1104C/G. It has two ranges: 13.5-19 volts, up to 100A, and 26-39 volts, up to 50 amps.
I tried using one to charge my deep cycle batteries. I noticed right away that it has a very annoying quirk. When powered off, if connected to a battery, it exhibited "reverse current", with the battery quickly drained through the power supply. I think that it is due to the supply having a big capacitor bank and a beefy discharge resistor -- so that the battery would discharge itself through that resistor.
That problem was solved by adding a diode to the output so that DC current can only flow one way. Problem was solved. (see pictures)
I also added clamps, and casters to this power supply so that it can be easily moved. Having casters moe or less addresed the weight issue.
I will also buy and install a Intermatic timer to it so that I can limit the amount of time that the charger runs before shutoff. I will buy one that has a hold capability in addition to timer capability.
Future plans also include making a linear regulator to further limit voltage and current to make into a CC/CV power supply. I have two Darlington transistors and people over at sci.electronics.design said I could use them.
The handles that I added on top come from Logistech dehumidifiers.i