Parasitic battery drain.

[Karl]

Having recently installed a small (600W) pure sine wave inverter to supplement the 2kW modified sine wave inverter, I was anxious to see just how much idle current it drew and what it drew under the load of my electric mattress pad. Arrived at the Quartzsite RV Forum area, shut down, leveled, hooked up water, electric and sewer (yeah, right ;D). With both inverters on but no loads except some LED's, smoke and CO detector, I expected to see about 1A draw. Imagine my surprise when the panel read 15 amps! I ran around shutting off all power strips for the computer and audio stuff, and checked for any lights being on. Nothing; still 15A draw. Then I heard it - the ice maker had just made it through a full cycle and was filing the cube tray again. The 15 amps (actually 14) was the 120VAC heater that partially melts the cubes so they can be ejected into the ice cube bin. The heater is on for about 4-5 minutes; enough time to totally freak me out!

So learn from my oversight. Switch your fridge to gas before checking idle current draw. That way the ice maker heater won't come on. DUH!

 

[Just Lou]

Good advice Karl,

BTW - what was the ultimate current draw when you got things sorted out?

What was attributable to the 600w and/or the 2000w?

thanks again, lou

 

[Karl]

Lou,

Idle current draw was about 1.2 amp., and that included the always-on CO detector and fridge eyebrow. Both inverters on, but no load. I have blue LED's in all overhead light fixtures so they're easy to find in the dark that are on always, but that only amounts to about 120mA.

 

[King]

Rather surprising...  My 600W mod sine wave draws about 1 amp no load.  adding 10A for each 1 Amp load is right on.  (the inverter fan is always on)
Art

 

[Karl]

Art,
My fans only come on when needed - both inverters. With the weather as cool as it is now in Quartzsite, I don't expect that to happen any time soon. :'(

 

[Gary RV_Wizard]

Switch your fridge to gas before checking idle current draw. That way the ice maker heater won't come on. DUH!

I don't think that will have any effect, Karl. At least, it doesn't on the previous Dometic fridges we have owned (have a Norcold now).  Our icemakers have always continued to operate in LPG mode - they require only 120VAC to operate and don't care what makes the fridge cold.  It's that way on purpose - otherwise how would you get ice for your cocktail when boondocking? 

The ice maker is usually plugged in to a separate 120 VAC outlet from the main fridge power and that powers the clock motor for the cycle timer and the little defroster/heater for the tray. That outlet may or may not be on an inverter circuit, depending on which one is selected. To stop the ice maker current draw, turn off the ice maker by raising the bail for the ice tray.

 

[Karl]

Gary,

My point was that while boondocking, the icemaker motor won't turn without the inverter on and won't get to the point where the heater turns on. No inverter power - no ice. There may be cubes in the tray but they'll stay there until 120VAC is available. 

 

[Will]

What is a fridge eyebrow?  My fridge has no icemaker, but I'm trying to track down a power drain.

 

[Karl]

Will,
The eyebrow is the control panel at the top of the fridge with the on/off, AES/Auto/Gas switch, temperature setting switch and various indicator lights - usually about 6" long and a little over 1" tall.
How much amperage are you drawing with everything shut off?

 

[Gary RV_Wizard]

What is a fridge eyebrow?

"Eyebrow" is a cute term that refers to the control panel that runs in a strip across the front, just above the door, in most all fridge models for the last several years. It's like an "eyebrow" over the door.

Your fridge draws a small amount of 12VDC to power its circuit board,  even in LPG mode, and is a contributor to phantom battery drain. And sometimes the door light switch doesn't go out when the door closes, contributing further.  Some models also have an anti-condensation heater around the door, which can use a fair amount of power if switched on. The switch has various names in different models and makes.

When running in 120VAC mode, the circuit board still uses 12VDC but the heat source for the gas absorption cycle is  an electric heating element rather than an LPG burner. That's an outright consumer of electric power (typically 600-800 watts) and not a "phantom" load. We call them a phantom load when it is a load that is still present even when the appliance appears to be off or in a stand-by state.

 

[Karl]

We call them a phantom load

Well, some of you call it "phantom"; others (like me) incorrectly called it "parasitic". Thanks for the correction Gary. Hopefully people knew what I meant, not what I said