My hands seem to be painful today so I am going to plead for help here.
Start off with a MEGAWATT 36-amp power supply. Then a four hour wind-up spring timer INTERMATIC, housed in a PLASTIC duplex box for safety. A 6' 16/3 power cord. A pair of el cheapo 10 gauge jumper cables with one end clamps chopped off.
The parts are on Google and Amazon. Order the parts and I can guarantee forum members will guide you step by step, and this is an EASY project. VELCRO the Intermatic timer to the top of the Megawatt. This thing will actually work and keep working to recharge batteries correctly. All you have to do is trial and error figure out how much time to put on the timer. When you pop the cell covers to charge the battery, look at the liquid inside, when the liquid is bubbling the battery is charged. Just remember roughly how much time it took the time before to charge the battery. The GREAT advantage to this setup is it is lightweight, rugged, and will actually charge a battery to 100% full.
Other Mega and Meanwell owners please chime in!