I am not there so I cannot speak of "your noise" in decibels or the straining but yes at different times in all of my TT's I have heard this at one time or another versus "most of the time."
Of course the more electric appliances you are running the more it is working. We forget all of the "phantom loads" we place upon our electric demands in our home and then we transfer those habits to the RV.
Look around and see what all you have plugged in that doesn't really need to be. A lot of our electric products even in the OFF position still draw electricity. The worse culprits are those convertor devices like the ones used to charge cell phones; THESE ARE THE WORST OFFENDERS!
Of course the more electric appliances you are running the more it is working. We forget all of the "phantom loads" we place upon our electric demands in our home and then we transfer those habits to the RV.
Look around and see what all you have plugged in that doesn't really need to be. A lot of our electric products even in the OFF position still draw electricity. The worse culprits are those convertor devices like the ones used to charge cell phones; THESE ARE THE WORST OFFENDERS!
In my case the TT is parked in my driveway on 30A service without any appliance on and nothing plugged into any outlet. When I turn on one of the mentioned lights the converter makes an unusual staining noise. If I turn on more load the noise from the converter becomes uniform. Kind of difficult to explain.
wdk450
Well-known member
Convertor Noise
Rsturge:
Rockerga seemed to be talking about 110 Volt AC "phantom loads" while the lighting in the trailers is 12 volt DC. The 110 volt AC comes directly from the shore power cord (if you are plugged in) while the 12 Volts DC is derived from the 110 Volts AC by the convertor and stored up in the 12 volt batteries.
I have never heard the convertor in my BH 3670 making ANY noise under the quietest conditions or the heaviest 12 volt DC loads.
I would call Heartland for advice, and at least get the batteries and battery associated wiring checked.
The batteries are like storage reseviours behind big water dams. They hold a large ready supply of DC current. The convertors act like water wells, pumping 12 volt DC current into the 12 volt circuitry up to the well's flow capacity (30 amps?), and (well) excess not being used by the load can go to replenish the battery current reseviour. But if a current demand in excess of what the convertor (well) can supply (30 Amps?) is needed, the battery reseviour can supply very large amounts of current. Think of a water dam collapsing. Starting a car with a battery can draw 200 to 500 amps.
Your convertor probably uses a circuit known as a switch mode power supply. This circuit first changes the incoming AC into DC (about 150 volts DC). This 150 volts DC is passed through a large switching transistor controlled by logic circuitry and a step down voltage transformer primary coil. This 150 volt current is switched on and off VERY rapidly, and the resultant vibrations of the transformer metal parts is the "singing" you hear. The secondary coil of this transformer gives current at a voltage that when rectified back into DC and filtered, gives the desired voltage around 12.6 volts.
Why go through all of these conversions to get 12 volts DC? The old analog voltage regulators wasted the excess current as heat, and the high frequency AC pulses enable a much physically smaller transformer to be used for the same power wattage saving weight and metals expenses.
Rsturge:
Rockerga seemed to be talking about 110 Volt AC "phantom loads" while the lighting in the trailers is 12 volt DC. The 110 volt AC comes directly from the shore power cord (if you are plugged in) while the 12 Volts DC is derived from the 110 Volts AC by the convertor and stored up in the 12 volt batteries.
I have never heard the convertor in my BH 3670 making ANY noise under the quietest conditions or the heaviest 12 volt DC loads.
I would call Heartland for advice, and at least get the batteries and battery associated wiring checked.
The batteries are like storage reseviours behind big water dams. They hold a large ready supply of DC current. The convertors act like water wells, pumping 12 volt DC current into the 12 volt circuitry up to the well's flow capacity (30 amps?), and (well) excess not being used by the load can go to replenish the battery current reseviour. But if a current demand in excess of what the convertor (well) can supply (30 Amps?) is needed, the battery reseviour can supply very large amounts of current. Think of a water dam collapsing. Starting a car with a battery can draw 200 to 500 amps.
Your convertor probably uses a circuit known as a switch mode power supply. This circuit first changes the incoming AC into DC (about 150 volts DC). This 150 volts DC is passed through a large switching transistor controlled by logic circuitry and a step down voltage transformer primary coil. This 150 volt current is switched on and off VERY rapidly, and the resultant vibrations of the transformer metal parts is the "singing" you hear. The secondary coil of this transformer gives current at a voltage that when rectified back into DC and filtered, gives the desired voltage around 12.6 volts.
Why go through all of these conversions to get 12 volts DC? The old analog voltage regulators wasted the excess current as heat, and the high frequency AC pulses enable a much physically smaller transformer to be used for the same power wattage saving weight and metals expenses.
I have not noticed what you describe on our North Trail 21FBS (but we've only had it a week), but I do know exactly what you are saying as it was prevalent in our Eco TT. It happened usually when the bathroom light was on - but sometime it was another light - and often this was the only electrical item on when I would hear the "strain". I don't have a clue why it happened, but it did happen.
