Loud Ticking from Power Converter

[Kevin A]

We have a 1986 UHaul VT that has suddenly developed a loud, rapid ticking sound from the power converter box when it is unplugged from other power. We have a roof solar panel (original) but it is not hooked into anything since we don't have an on-board battery. We only plug in to shore power (110 v.) for camping stays. When we packed up camp yesterday, turned everything off, and disconnected the 30 amp cord from the site power pole, a loud ticking started under the sink. I pulled a drawer and felt the converter box to find it was vibrating slightly while ticking. While driving home, we stopped several times over 4 hours and it was ticking sometimes and sometimes not. The sound is loud enough to be heard clearly all the way around the outside of the VT. Just now, 28 hours after unplugging the trailer from power, the ticking is going again. Could there be some sort of capacitor that is slowly draining, causing the ticking? Is it dangerous as a fire hazard? Any suggestions will be considered!

[mmeyer]

Kevin attached is the converter cut sheet as good as I have it. we have the RAC series in the VT and likely it is in CTs also as it the only one that charges the battery. There are no capacitors shown that I can see only diodes and fuses. The UHaul solar charger had a relay that will kick out on a selected voltage which can make an audible click. If no battery it may be hunting for something to charge to and finding nothing kicks out, then looks again to kick on

[Kevin A]

Is that relay internal to the converter? If so, can I just disconnect the line to it? Also, since the solar is not hooked to a battery, is there something I should do, like tape the ends of the wires from it?

[mmeyer]

Mine was on the battery box, it is about 4"x3"X1" but mine has different things than yours. It is likely hooked to the battery wires that are hooked to the charger wires from the converter. Mine were hooked together by wing nuts on the battery box. Try shutting off the 12v master switch. The 12v wireing and that switch is wierd. If that doesn't help disconnect the solar and tape the ends.


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[steve dunham]

If you are disconnected from shore power (120VAC) and have no battery to supply 12 VDC and no capacitors in the converter to discharge what would be the source of power for the coil in a relay ? The only source of DC /power would be from your TV when towing. Low voltage to a relay can cause on off cycling
When the relay is off and the relay contacts feeding a load are open ,the supply voltage will be at its high point .When the relay pulls in and the contacts close ,supplying voltage to the load the voltage will drop and then will be too low to hold the relay coil in .IE; The contacts open ,the voltage rises , the coil pulls in ,the load is energized, the voltage drops ,the coil drop out, the voltage rises ,the relay coil pulls in , the load is energized ,the voltage drops etc etc etc

*Relays have a pull in voltage and a hold voltage*

[Pam Garlow]

My husband opened it up, tighted things down, and cleaned between two metal thingies with emery paper.. they were chattering together.. I'll have to ask him what he did. It totally stopped the issue.

[Bob Miller]

Sound to me, even though you don't have a battery in place, that the solar panel is sending some voltage to that relay. Relays just don't click or chatter without some voltage and any capacitors in there would have bled down quickly. If there is no battery, be sure that the solar panel is physically disconnected.

[Kevin A]

Thanks, everyone. When I get the chance, I'll get into the guts of the trailer and take a look at what's been mentioned so far. Since the clicking is happening while the trailer is unhooked, I think it has to be connected to the solar panel power. Funny it hasn't done this before now!

[Kevin A]

When I got home for lunch today, the sun was shining brightly and the ticking noise was clearly evident. I took out a tarp and through it over the solar panel and the noise stopped immediately. I guess my solar panel has suddenly starting generating power or the relay has awakened, causing the ticking sound. At least I know what to disconnect!

[CindyL]

Sounds like a bomb too. The neighbors are going to be concerned if we don't get this fixed soon. Temporarily, Kevin covered up the solar panel.

CindyL