Waeco fridge maintains different temps at 120 AC and 12 volt

Handymans342

You did say that the compressor was running when it got 54 inside right????

redlightning

what about the type of battery.  i have similar issues and i was considering replacing my house batteries with these expensive virgin lead odyssey batteries.  I bought one after installing my new stereo.  if the voltage gradually drops it could be an issue.  I do believe the recovery is super bad.  i have gotten in the habit of keeping my generator on and the cabin cool with 120v to the refrigerators when out.  My cockpit frige will not stay cool if its hot outside regardless.

YYZRC

The coil is across the top of the fridge. 

Spyderweb

Handymans342 said:

You did say that the compressor was running when it got 54 inside right????

Yes, I’m hearing a definite hum and assuming that’s the compressor.

Spyderweb

redlightning said:

what about the type of battery.  i have similar issues and i was considering replacing my house batteries with these expensive virgin lead odyssey batteries.  I bought one after installing my new stereo.  if the voltage gradually drops it could be an issue.  I do believe the recovery is super bad.  i have gotten in the habit of keeping my generator on and the cabin cool with 120v to the refrigerators when out.  My cockpit frige will not stay cool if its hot outside regardless.

My house batteries are 2 Interstate lead acid deep cycle group 27’s.  I never let them get below 12.2 volts as measured at the panel.  And if I measure directly on the batteries, I get a reading of 12.4.  And this is with compressor running.  

I notice you don’t even have a dark hull.  But I suspect you get a lot hotter air temps where you are.  And as @Handymans342 says, we may all be suffering some from older compressors that lose some effectiveness with age.

Spyderweb

YYZRC said:

The coil is across the top of the fridge. 

Ok.  I guess forget what I said.

I might drop one of the fridge temp sensors under the trash can to get a reading on what kind of temps are produced in there.  And then put one in my daughter’s white Bayliner and see what the difference is.  

Handymans342

Spyderweb said:

Handymans342 said:

You did say that the compressor was running when it got 54 inside right????

Yes, I’m hearing a definite hum and assuming that’s the compressor.

Assume??? You know what that means. That may be the fan your hearing

YYZRC

The fan only runs when the compressor is running - unless of course the compressor is dead but that should mean no cooling at all. 

Spyderweb

More info.  Left dock yesterday at noon.  Fridge was 37 after shorepower all night.  By 5PM out on anchor, fridge was 51, running on house batteries all day.  I had placed a temp sensor in hull to get idea of heat behind fridge with black hull.  Temp in hull and cabin was only 74, not bad.  By 7:30, fridge was 54, hull 74, cabin 76.  Fridge was only opened maybe 4 or 5 times all day.  (Was drinking ice water from ice maker a lot).  Volts on panel read no lower than 12.3, so direct on batteries would have been 12.5.

Back at dock at 7:30, by 8:30 on shorepower, fridge dropped to 47.  By midnight it was 39.

I did notice that at the dock, when I turned on fridge breaker, the hum coming from behind fridge stopped for a couple of seconds, then a sound like the compressor kicking in.  Shortly later, I turned off breaker, fridge went silent for a couple of seconds, then kicked on again.  And then same thing, when I turned breaker on.  I suspect that is just normal when switching back and forth between AC and DC.  

Is is possible that a compressor just won’t run as efficient on DC as on AC?

I know my gaskets aren’t air tight, but because temps recover so good at dock, there’s more going on than gaskets.

raybo3

I think you're getting a little confused with the voltages the compressor is 1 voltage. When you switch from 120v AC to 12 volts DC an inverted takes over to supply the correct voltage to the compressor. What I would do is get a voltmeter and check the voltage at the compressor on Shore power then on battery power the voltage basically should be the same. At least that's how mine works

Spyderweb

@raybo3So I should expect to read 110-120 volts at compressor no matter on AC or DC?

Handymans342

12 volts

raybo3

@Spyderweb I don't remember what mine was but I think @Handymans342 is correct. 

davidbrooks

I talked to the manufacturer and they said the primary reason was that you kept opening the door to check the temperature.  Recomended buying a yeti. 

Handymans342

Actually you may see a higher DC voltage with the AC on

raybo3

Not more than 10%

YYZRC

I think I finally solved this one. 

The Waeco control unit won’t kick the compressor on if DC voltage drops below a certain threshold. One of my fridges (both 330 and 350) would not work below about 12.4 volts - it gives the dreaded two blinking red lights on the thermostat. 

I bought an adjustable voltage step-up unit on Amazon and set it at 14.5 volts. Problem seems to be solved! Hope this helps someone. 

Spyderweb

@YYZRC, I’m still having same problem.  Only difference is I never get the flashing red lights.  After some research I’m leaning towards replacing the inverter/controller.  Apparently it’s a common problem with these fridges.  Where does your step up unit go?  Is there a downside to them?

YYZRC

I just disconnected the female spade connectors from the control unit and wired this module in-line. It takes the 12v power in and ups it to whatever you want. I zip-tied it to the coil next to the fan so that it gets some cooling. 

Downside is that it is inefficient I’m sure as it has heat sinks on it. But a lot cheaper than a new fridge! 

Spyderweb

And cheaper than a $220 inverter/controller.  

By inefficient, meaning uses more battery?  So perhaps the fridge would draw 5 amps instead of 4 (or something)?

LaRea

I think the efficiency is usually around 80% to 90%.  So if it draws 5 amps now, it will draw maybe 6 amps with the step-up converter.  

Liberty44140

I do find that on my Rinker and cruisers the interior refrigerator light is brighter on ac than dc. Not sure what that means though….

Spyderweb

@YYZRC, so is that wired in-line to the red positive wire going into the controller?

Also, have you got the Amazon link for the step up unit you got?   I can’t seem to find it.

YYZRC

I bought it on Amazon.ca so I’m not much help but the brand and description is in the pic above. 

I disconnected the circled wires and wired the step-up in line. Sorry I didn’t take pics of the step-up as honestly I didn’t think it would work!!

Spyderweb

@YYZRC can’t find the exact item but is this it?

https://www.amazon.com/Converter-Module-12-32V-Adjustable-Voltage/dp/B07R9WHHPD/ref=asc_df_B07R9WHHPD/?tag=hyprod-20&linkCode=df0&hvadid=532825377821&hvpos=&hvnetw=g&hvrand=14279166318713807091&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9005311&hvtargid=pla-968050870070&psc=1

Am I correct that I would solder a piece of wire onto the “in” and “out” tabs on the unit, then crimp them inline with the red wire (circled) on the inverter?

YYZRC

Looks the same to me. No soldering needed. There are screw terminals for the in’s and outs. 

Spyderweb

Oh I think I see that now on the bottom picture from Amazon.  Looks like 2 inlet ports and 2 outlet.

YYZRC

Exactly!

Spyderweb

Tested input dc voltage at dock yesterday.  With fridge off, 13.5 (charger was on), turned fridge on and it dropped to 11.5.  Compressor started but in a short time shut off.  Is this a sign of a bad connection (fuse box, ground buss, ?), or is that a normal drop?

If bad connection, and I add a voltage booster, is that apt to cause more heat at bad connection?

YYZRC

That’s what mine did. Compressor would cycle on and off constantly when on DC power. Worked fine on AC.