Straighten me out on filtering

[travlinjayco]

Converters are new to me. I understand converters take 120 and put out DC, but where is the filtered side of the converter, this I do not understand. I know some things, (from reading) need to be on filtered side. I am re wiring an Iota, does it or any converter for that fact have to be hooked to a battery to operate. I realize the input of 120 creates the 12v dc, just seems I hear some say a battery must be involved. Just start at square one with me, tell it all. Oh, off my converter comes a red wire, capped off nothing attached about a foot long, why ? Can't wait for all your input. Thanks

[Harry B]

The battery acts as(is) a giant capacitor which filters the converted DC voltage. If you don't have a battery attached there will be a significant AC ripple present. On audio equipment running off of DC you will hear a 60~ hum that is usually not controllable by a volume control.

["007"]

Here is a good place to start and reference back to.
You will electrical tutorials also.
Once you have this in your head you will be answering the questions not me.

[travlinjayco]

Thanks for the input, really helpful. Now since I have read a little, are there many who opt to go with the inverter/charger route rather than a converter. I have a travel, the inverter/charger seems interesting. Share your thoughts.