Tuesday, November 18, 2008

Must RV's electrical converter be on at all times?

Dear Mark,
I live year round in a large 5th wheel trailer and I am plugged in at all times. I hear the battery charger kicking in from time to time and the humming of the converter. Do I need to have the converter on at all times? Is it on only to charge the batteries? The manuals are the pits and I am really trying to know all about converters. The more questions I ask from different sources the more answers I get.

Mark:
The converter in your RV basically does two jobs.
1) When you are plugged into electricity it converts a portion of the 120 volts coming into the RV down to 12 volts so all of the 12 volt devices like overhead lights and fan motors will operate without draining the RV battery.
2) It has a battery charger built in the converter to keep the RV battery charged (topped off).

The noise you are hearing is most likely the fan on the converter. The converter gets warm when it is on so the manufacturer adds a fan to help keep it cool. Some are very noisy. You DO NEED the converter on when you are plugged in. If the converter wasn't on, or wasn't operating properly you would run the RV battery down because you are using the 12-volt appliances and devices.

Some older RV converters charge the batteries at a constant rate and will continue to charge the batteries when they are fully charged. This can result in the battery or batteries losing water, so battery maintenance and inspections are important when you have the RV plugged in for long periods of time. Newer converters have three stage chargers that know when the battery is fully charged and at that point only provide a float charge (less charge) to prevent overcharging conditions.

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Posted by Staff Report at 11:32 AM

3 comments:

  1. After three years we found out we had a converter in our Horizon Diesel Pusher. In talking with the manufacturer I was told to turn off the switch outside by the power system and leave it off all the time. Our system has a three stage charging system for the house batteries. When plugged into shore power it always charges the batteries. The inside switch should only be turned on when you wish to run something on 120. If it is left on all of the time anything drawing 120 volts will run down the batteries. So we leave all switches off except when I want to make a cup of coffee early or we want to watch TV late in a National Park and do not or should not run our generator. We get several hours of TV without a gen by doing this
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  2. In other countries the converter has a primordial function: convert the input voltage (110/220V) to 12/110 or 12/220V. In Brazil there are areas where the input voltage is 110 and other areas is 220V. Also there are factories that produce RVs with internal voltage 110 and others with 220V regards
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  3. If you have a more modern converter/charger, the occasional humming being heard may be the charger going in to desulfation mode. This is a mode designed to desulfate your RV's batteries and prevent material build on the battery plates. This mode will typically last for an hour or so and then return to the normal float voltage.

    You can read more about smart chargers here: http://www.modmyrv.com/2008/06/08/rv-battery-charger/
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