110v AC to 12v DC Power Converter WWW.RAPIDRELAYS.COM

I am looking for something to power the 12volt pump and lights in my outdoor camper which my wife and I will be living in for an extended period of time, but I don't want to burn out the battery. Will this do the trick so we can constantly have power going to these lights which will balance the charging? Or will this relay kick on the moment the battery needs to charge?

How expensive is this?

Is this a converter or transformer? I believe you need a transformer to step down from 110 no?

Will this power a 50 inch light bar?

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