converter vs. battery charger

I live in my trailer full time, going on two years. I've already replaced the converter once, it started making noise and then eventually wasn't charging so good. Now I've noticed the new converter seems to be running more than it did when I put it in. I'm also running 12V tank heaters now, so I understand that could be part of the reason.

My question - can I put a battery charger to the batteries to help take some of the work load off the converter?

A battery charger is a lot cheaper than a converter. I would look for something with an auto on / off feature. I have a little one, called a battery tender for my motorcyle that I just leave plugged in during the winter and the battery stays charged, but I think that might be a little lite duty for the trailer.


Senior Member
Re: converter vs. battery charger

Yes you can and a lot of comments I have seen in the past they recommend using a battery charger over the converter to charge the batterys.


Senior Member
Re: converter vs. battery charger

As an electrician, I must strongly disagree with your first response.

A battery charger will work fine to charge your batteries, but not to serve as a constant use converter. Converters are designed for continuous duty but no battery charger is. That is the main reason for the difference in cost. Your converter probably has a rating of at least 40A and it will deal with constant service at about 80% of peak. A battery charger usually has a duty cycle at peak output of 10 to 30 minutes.

Your RV uses 12V power constantly as all of the appliances, even the refrigerator require 12V power to operate the control circuits. Your refrigerator will not work even on 120V power if it don't have 12V power. All of your lights are probably 12V as well as are pretty much everything except the air conditioners and the microwave. I have known several RV owners who have tried what you have in mind and not one has found it to be satisfactory, if they use the RV very much.

Your 12V tank heaters are probably drawing at least 10A each when in operation. Add that to the typical current use of most RVs and you are looking at far too much to work well with most battery chargers. Do this if you want, but this electrical tech says you won't be happy with it.

When you say that it is running more, exactly what do you mean? I suspect that what you are hearing is a cooling fan running which is common in RV converters. Most cycle the fan on when under more load but turn it off when loads are light. You probably never drop much below a current draw from your converter of about 5A. Add to that the 20A or so to your tank heaters and that would probably turn on the fan. But that is no indication that there is some problem developing with it.
Re: converter vs. battery charger

Hi Kirk,
You seem knowledgeable on this whole converter thing, something has been baffling me for 2 years now, the fan on my converter is sometimes very noisy but most of the time it’s not-I would suspect that if it’s going bad, it would make noise all of the time. One thing I’ve noticed is if something is dropped on the floor near the converter (or if one of my kids jumps from the bunk) that is what makes the noise start and It will go away after a while. Any ideas what I should look for?


Senior Member
Re: converter vs. battery charger

Sorry to be so slow in responding!

As to the noise, could it be something hitting the fan blades? That might be something that would move when jarred. It is possible that it could be something inside of the converter also. If fan noise, I would suspect the shaft of having some movement. You might be able to lubricate the bearings to solve that.
Re: converter vs. battery charger

krautdog, it could also be a loose power connection to the fan. I've seen wired connections held in place under a loose screw by the wire bundle tension. A slight jar can make the connection break for a brief moment. Just guessing.

Your description makes it sound like cheap fan bearings going out. You might be able to disassemble the converter fan, but if it's like mine it has a little 'muffin' fan and bearings on that would be inaccessible for all practical purposes. Should be easy and cheap to replace, though.
Re: converter vs. battery charger

Thanks for the info guys! I've packed up the trailer for the winter but come spring, I'll pull off the access cover and see what the fan looks like.