We have a new to us travel trailer. Right now we have these batteries and plug. I am looking at buying the renogy 100 watts 12 volts monocrystalline solar starter kit with 30a pwm wanderer from amazon for $196.99. I will also update my batteries to deep cell marine 31 or 2 6 volt golf cart batteries depending on size of the space. Is this the correct set up? What am I missing? The past owner said just buy a panal and plug it in. I am learning that it is a bit more than just plug them in. Any advice will be great. I am new to all of this. Thanks.