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Voltage to bathroom fan
1997 Midbath

I decided to replace the bathroom fan with a Maxxfan 4000K fan as the old fan had broken fan blades. It was working ok with no electrical issues. When I connected power it beeped once and the fan started immediately. When I turned it off with the on/off button it stops. When I pushed the on/off button once more it would not start until I disconnected and reconnected power.

I connected it to an external 12vdc power supply and it works as it should. I checked the voltage from the RV wiring and it measured 12.7vdc with no load. However when I connect the fan the voltage went up to 17vdc then dropped to 12vdc when the fan started. When I turned the fan off it would not start until I disconnected and reconnected the power to the fan.

I am not sure how to fix this issue at this point. Maxxfan sent me a new control board under warranty but I have the same issue with the new board. and When I use an external power supply the voltage stays at 12vdc when I hook up the fan.

Anybody else had a similar issue?
1997 MB
Re: Voltage to bathroom fan
Reply #1 –
Hi Dave. You probably have a high 'ripple' component on your converter output.  Try operating the fan on just your rig's batteries. Unplug from shore power.  If the fan works, and you have your original 1997  parallax converter, up grading the converter would be a good step.  The converter is a linear power supply. Transformer and diodes, an electrolytic capacitor that has decreased capacity with age, resulting in bad filtering of the 12v dc output.      RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Voltage to bathroom fan
Reply #2 –
Hi Ron,
Many thanks for the suggestion. Sounds like that is the answer. I'll check it out.
1997 MB
Re: Voltage to bathroom fan
Reply #3 –
I upgraded my inverter so my Weboost and some LED lights would work better.  All fuses are now filtered with the new inverters.
Upgrade Kits for Magnetek/Parallax
Steve and Jill, Steve posting
1999 26.5 Mid-Bath
Re: Voltage to bathroom fan
Reply #4 –
You're referring to your converter upgrade, yes?
2003 TK has a new home
Re: Voltage to bathroom fan
Reply #5 –
Quote from: Davehca  - 
1997 Midbath
I connected it to an external 12vdc power supply and it works as it should. I checked the voltage from the RV wiring and it measured 12.7vdc with no load. However when I connect the fan the voltage went up to 17vdc then dropped to 12vdc when the fan started. When I turned the fan off it would not start until I disconnected and reconnected the power to the fan.
The issue may well be as Ron described - but the reading with your meter is still odd. If the problem is excess ripple, then after measuring the 17 Vdc, switch the meter to the AC ranges, and see what you get. Also, in our '83, which came with a bath fan similar to your original, the wires to the fan were much too small a gauge for the higher current draw of the new fan. When I installed a FF in that rig, I ran new wires over from an adjacent ceiling light fixture.

Steve
2004 FL
2013 Honda Fit
Re: Voltage to bathroom fan
Reply #6 –
I checked the voltages this morning (no fan attached). Wire gauge in coach appears to be 14ga. It's a larger gauge the the fan wires for sure.

Shore power:
VDC = 12.7
VAC = 7.0

No shore power:
VDC = 13.6
VAC = 0.0

So my plan is to replace the converter with the PD 4655VL 55 Amp Converter Upgrade, Optional Remote Pendant.

Many thanks for the replies. It's great to have a resource like this forum.  :)
1997 MB
 
Re: Voltage to bathroom fan
Reply #7 –
Hi Dave, Thanks Steve, I was going to mention that part about measuring the AC component of the dc supply. If a diode of the bridge rectifier was bad the voltage would have dropped with a load. The same with  a bad wiring connection, or insufficient wire gauge.  Most electronics meant for an RV would be able to withstand even that much 'ripple' without locking up like that. Usually the batteries are a load, and provide for a lot of filtering by absorbing the peaks, but they may have been fully charged.
      So the new converter should fix that problem, and have better voltage control. A better battery charging system, so called four stage.  You'll get a new fuse board also. More branch fuses, reverse protection. I got the VL jumper also, just in case i take the leap to LiFePO4 batteries.  I didn't get the remote pendant. That just allows you to control which mode the charger section is in, and that can be done at the panel, if I ever wanted to do that.    RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Voltage to bathroom fan
Reply #9 –
Quote from: RonB  - 
Most electronics meant for an RV would be able to withstand even that much 'ripple' without locking up like that. Usually the batteries are a load, and provide for a lot of filtering by absorbing the peaks, but they may have been fully charged.
If I recall correctly the oem converter in our '83, when connected to shorepower, a relay disconnected the batteries and connected them to a rudimentary charge from the converter via a resistor. If this is the case here, it would be why excess AC ripple from the converter would not be filtered out by the batteries. The basic converter was designed simply to run the 12V systems in the rig, and battery charging was an afterthought. The newer multistage converters are designed from the ground up to be efficient battery charging systems.

Steve
2004 FL
2013 Honda Fit