Solar - batteries - refrigerator issue

[imolared]

Howdy
Once again I look to you all for answers

New 3120 with factory solar and 4 6-volt deep cycle batteries
Batteries read 12.6 volts
Clear skies 5pm
Solar panel reads 180 watts
Inverted switched on
Switch refrigerator to electric
After 25 minutes voltage reads 11.8 volts


Doesn’t seam right

[DQDick]

We had seven large panels and six golf cart batteries in our old unit and still had to run the frig on propane. All frigs will pull a lot of juice particularly residential.

[PNW Fireguy]

I am using the mobile browser and it does not show signatures so if I get this wrong on what you are using for a fridge I apologize. Our RV is very inefficient and uses quite a bit of power. Based solely on my results 180 watt panel is woefully insufficient to run the load. Also with lead acid batteries or AGM for that matter when a larger load is applied to them the voltage will drop. Once the lid is removed, like the fridge cycling, the voltage will bounce and recover a bit. Residential fridges are generally more efficient but still require more energy to replenish the batteries beyond a single 180 watt. Simple solution may be to add additional panels assuming you have space, budget and the factory wiring and controller can handle.

[jeffba]

Well you did not tell us what capacity your batteries are.

Assuming he refrigerator is running at the full 3 amps that whole time.
That is 360 Watts.
less 180 for solar means you are drawing 180 Watts or 15 amps DC-- I jumped a head
Your batteries may not have been at full capacity

Okay you are using an RV refer so I am off. I do not know what an RV refer pulls on electric.

Why would you want to do that vs propane?

[PNW Fireguy]

We do that because we have the capacity to do so and want to use the paid for PV vs the commoditized gas.

[AZ Traveler]

Imolared,

Since your fridge is an RV unit vice residential recommend you run the fridge on propane unless you are on shore power or a decent sized genny. An RV fridge is a hog on electricity compared to a residential unit.

[imolared]

Thanks for the replies
My internet access is limited so I cannot reply quickly
The 6 volt batteries are 232 amp hours rated at 20 hours
The refrigerator is RV

The rate the batteries drop then recover does not seam right

[PNW Fireguy]

Originally Posted by imolared

Thanks for the replies
My internet access is limited so I cannot reply quickly
The 6 volt batteries are 232 amp hours rated at 20 hours
The refrigerator is RV

The rate the batteries drop then recover does not seam right

As stated previously the RV fridge on electric is an energy hog. It will drain your battery capacity pretty quickly. The 180 watt replenishment is simply not putting back as much as the fridge is pulling out.

[WaltBennett]

I've 4 T-105 12v with 400 watts solar and a 3kw inverter, BUT will still run the AC/propane refer on propane when not shore power. Think about it. To cool the inside of an ammonia based ref., heat must be generated. Electricity of either kind isn't the most efficient way to generate heat - propane does it very nicely!

[Nat_Park_Travelers]

Not sure if this reply posted or not so here it is again

We have a 2019 3700LK with RV fridge. I have 400AH lithium batteries with a 3000w pure sine inverter, and will be putting 1200W of solar on the roof in a couple weeks. Just as a test I ran the fridge on the batteries for a few minutes to see the draw, and the BMV-712 meter showed it pulling 54 amps dc. There was also some minor electric items running but the only major thing was the fridge ... hope this helps a bit...