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Topic: Humming sound while running on battery power (Read 743 times) previous topic - next topic

Humming sound while running on battery power

Was running on battery power and charging batteries at night during the aloted times.In the bedroom near the breaker area
you could hear a humming sound,crawled under the coach but could not pinpoint the source.Coach runs and everything works
fine,any ideas what the sound could be?Is only on battery power,when we are plugged in the sounds gone.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Humming sound while running on battery power

Reply #1 –
John,

That should be your ATS (automatic transfer switch) for under the foot of the bed. Bet you'll hear it even louder if you lift the bed up. At least the is what used to hum or my coach before I traded out my AC powered ATS for a DC powered ATS.
Jim

2002 U320
Jim Frerichs
2002 U320 42'

Re: Humming sound while running on battery power

Reply #2 –
You are not the first to "notice" this IRRITATING noise (nor will you be the last).  :help:

30 amp transfer switch HUMMING!
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Humming sound while running on battery power

Reply #3 –
The AC relays in the ATS have tht wonderful 60 cycle hum.
Jim
Jim Frerichs
2002 U320 42'

Re: Humming sound while running on battery power

Reply #4 –
Jim,
I would be interested in hearing more about your DC powered ATS... Links, experiences, all would be welcome. How much DC current required? Source from the house bank?
Don
Quote from: Jim Frerichs –
John,

That should be your ATS (automatic transfer switch) for under the foot of the bed. Bet you'll hear it even louder if you lift the bed up. At least the is what used to hum or my coach before I traded out my AC powered ATS for a DC powered ATS.
Jim

2002 U320
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Humming sound while running on battery power

Reply #5 –
Why would it hum on battery power? Does the inverter power the transfer switch? Seems like the ATS should default on battery and power when plugged in.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Humming sound while running on battery power

Reply #6 –
X2 Don
Larry
1996 U295 36'
Build # 4805
Actually we sold it but just like to lurk

Re: Humming sound while running on battery power

Reply #7 –
Hi Don and John,

DC transfer switches are readily available, you just have to search online and read the specs. In a store you might be able to find the schematic diagram in the package. Or just Google the product.
I think they may have the same relay coils but the AC signal to activate them is converted to DC by a full wave diode bridge (and maybe a capacitor to smooth out the ripples). No AC ripple in thre relay, no aggrivating hum at night. Extra current is not needed for these far more quiet transfer switches. I would hope most newer ATS boxes have this benefit. Maybe others will chime in to be more specific.
Jim

2020 U320
Jim Frerichs
2002 U320 42'

Re: Humming sound while running on battery power

Reply #8 –
Quote from: craneman –
Why would it hum on battery power? Does the inverter power the transfer switch? Seems like the ATS should default on battery and power when plugged in.
There are two transfer switches (ATS) in most coaches - the 50 amp unit switches between shore AC and generator AC power, and the 30 amp unit switches the inverter powered circuits between shore/gen AC power and inverter AC power.  So, when running on batteries (inverter), the 50 amp unit is "idle" while the 30 amp unit is energized and (in some cases) humming a tune.

I solved the problem by eliminating both of them.  NO MORE HUM!  ^.^d
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"
 

Re: Humming sound while running on battery power

Reply #9 –
Thanks for that explanation. One more parasitic drain I wasn't aware of.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean