Refrigerator draw on LP mode

[Whangler]

I'm evaluating my total amp draw in order to properly size a new solar system with lifepo4 batteries and all that entails.

My Fridge is a Norcold N821 2-way. The decal inside says it draws .8 amps dc. Over a 24 hour period, that calculates to 19.2 amp hours. I thought the draw was minimal on LP mode. Can 19.2 ah per day be right? Or... does it only consume 8ah when the igniter is running? If so how do I figure amp draw over a 24 hour period?
Thanks!

[Whangler]

I just got off the phone with Norcold. He couldn't give me an average amp draw during LP mode but he did give me this:
Igniter: 5a
Divider Heater: .25a
Inside lamp: .46a
Gas Valve: .146a It draws no current when open.
That's all he had for the model N821 2 way 8 cubic foot unit.

[BurbMan]

Gdetrailer wrote:
You forgot about the gas valve..

I did. The hotter the ambient temp is, the more the burner runs, I know mine was almost continuous during the day in August. OP is probably best off planning for max draw at 0.8 amp in his calculations then he won't be caught short on capacity.

[Lwiddis]

After buying four Li batteries, I'd plaster the RV's roof with solar panels. Panels are inexpensive.

[wopachop]

Fun stuff. I can check mine. I think I have a good amp or two worth of fans in there.

[Gdetrailer]

BurbMan wrote:
Maybe that includes the light inside too? The only thing that runs constantly is the circuit board, I can't believe that alone takes almost an amp.

You forgot about the gas valve..

According to THIS blog, someone measured the draw of .6A with gas valve on and .2A with gas valve off.

The gas valve on would mean the burner is running and off means burner is off and .2A is what the circuit board draws 24/7 during idle time.

Gas valve in this case is drawing .4A.. So yes a RV fridge CAN consume 1A at 12V easily..

[Gdetrailer]

Whangler wrote:
I'm evaluating my total amp draw in order to properly size a new solar system with lifepo4 batteries and all that entails.

My Fridge is a Norcold N821 2-way. The decal inside says it draws .8 amps dc. Over a 24 hour period, that calculates to 19.2 amp hours. I thought the draw was minimal on LP mode. Can 19.2 ah per day be right? Or... does it only consume 8ah when the igniter is running? If so how do I figure amp draw over a 24 hour period?
Thanks!

You actually will have two different current draws.. One with gas burner off and one with gas burner on.

Gas burner off should be minimal and gas burner on will be near the max rating.

12V is not only used to operate the control board but it also is used to open the gas valve, hence the two different readings.

Generally the gas burner does not run 24/7, it should cycle on/off through out the day.. May be as much as 50% on/off or as little as 30% on to 70% off depending on outdoor temps..

You can use 50% or even 100% duty cycle to be on the safe side if you are auditing your electrical use or perhaps monitor the burner for a while to get an idea of how long it runs and how often for a more precise number.

[ndrorder]

The circuit board will have one rate which is super low. The .8 amp draw is more likely the current necessary to hold the gas valve open while running and not a continuous load.

[CA_Traveler]

That spec is likely the maximum and not the aveage. You could use a ammeter to measure amps at different times like ignition, cooling, etc.

The easiest and most accurate way to do an energy audit is to use a battery monitor and even $30 ones will provide accumulated power usage for a hour, day, etc. I use one for another application that gives me Wh and I divide by 12.4 to get Ah.

However my first step was a $160 battery monitor and I made a list of amp usage for everything in the rig, turn it on and note the amp change and voltage (charger off). It has many parameters like SOC, usage per day, etc.

Recommend a good battery monitor.

[wopachop]

Clamp meter and walking back and forth works. I was checking the draw with certain things plugged in. I didn't check fridge only.

[BurbMan]

Maybe that includes the light inside too? The only thing that runs constantly is the circuit board, I can't believe that alone takes almost an amp.