The OP was questioning the seperate charger that was already installed and was looking at a low budget solution.
The intent is to not just buy stuff, rather to investigate your options and select what is best for your situation.
Secondary is to consider some folks may need to get creative with limited budgets or availability of parts.
Some may not need to quickly recharge their batteries and then can get great results with a slower charger with less cost and risk to their battery where others who need a faster recharge will need to unsure they use the correct equipment.
The OP also asked about equalization, this needed to be explained as it no longer is a common task and it could cause more harm than good if attempted by someone trying something suggested by someone who does not know much about it.
Many folks have no real understanding of design, care and feeding of DC plants so I added additional information to assist in understanding how the different types of batteries act.
I tossed in a process to roughly estimate charge times to assist one in guessing the outcome of their choices without doing much investigation or figuring.
The guessing part helps the owner make better choices as to which road to take, then they do the heavy math to determine exactly how the design will work.
Referencing the manufacturer data sheets is the final part, they are the final say regarding rate of charge and capacity, not meeting the needs of the battery or expecting more capacity will guarantee an installation that does not meet the expectations of the owner.