Driving w/ Fridge running

[wecker1]

Ok, so I think I remember someone saying that there’s no such thing as a dumb question on the MOC…well here it goes…

Our main trip each year is from our sticks and brick in GA to the family farm in upstate N.Y., about 14 hours. Because of the remoteness of the farm, we like to stock the fridge/freezer prior to departing. As such, we run the fridge at intervals during travel and especially during the last few hours of travel because we boondock overnight and turn the fridge off/disconnect the batteries.
While driving I run the fridge with both disconnects (battery compartment and convenience center) switches engaged and converter on. Fridge stays cold and no problems in that respect. The problem is that this appears to have a major draw on my batteries. I’m assuming here because my batteries show low voltage upon our overnight stop

Three years ago, I reconfigured the Montana OEM battery install from two 12 volt to two Trojan 6-volt AGM. I’m now replacing one of the batteries as it will take a charge but not hold it.

Question: Is my approach in running the system in this manor while driving flawed or did I just get a bum battery?

Much thanks!

[DutchmenSport]

We have 2 twelve volt batteries and can run our refrigerator when towing all day without depleting the battery, because the truck is sending a trickle charge to the battery. We have overnighted without shore electricity and the refrigerator did fine.

The longest we went with no shore power was 3 full days and night while we had a truck failure, mechanical repair, and it was in the shop and we stayed in a motel (long story). The camper was NOT located located anywhere near an electric hook-up. So I had to nurse the refrigerator for 3 full days to keep things frozen. I ran the inverter (and thus, the refrigerator) about an hour every 6 or 7 hours and we did not open the refrigerator unless it was absolutely necessary. The batteries did fine. When we had to move the camper (when we FINALLY got moved to a campground), there was still enough (umph) in the batteries to move the front landing jacks just fine.

So, if you switched over from 2 golf cart 6 volt batteries and go with 2 twelve both marine batteries, you'd definitely have longevity you didn't have before

[Daryles]

Assuming you have a residential fridge...
Maybe install a DC-DC charger for traveling.
It would provide plenty of power to the batteries and you can leave the inverter running to run the fridge.
When running on batteries, While the INVERTER is ON
I would turn OFF the CONVERTER circuit breaker to prevent a loop that would run down your batteries.
Turn the converter back on when you are back on shore power and turn the inverter off.

https://www.montanaowners.com/forums...hlight=charger

[Pa_5er]

We boondocked last night and ran the fridge on propane. We had a 6-7 hour travel day today and ran the fridge off our 300 ah lithium battery bank and inverter. When we got our full hook up campsite we had ice cold drinks in the fridge. We had 42% charge left on the batteries when we plugged in.

[rohrmann]

Do not just replace one of the batteries, do both matching in age and type, or you risk damaging the new battery.

[Daryles]

IF you have an RV fridge, it is more efficient when boondocking or traveling to run it in Propane mode.
IF running the RV fridge in electric mode through an inverter from the batteries it draws about 40A DC from the batteries.

[wecker1]

Thanks to all for the quick replies.

First to clarify, I intended to say with the inverter rather than converter turned on.

So, the correct system configuration is with both disconnect switches on/open/connected allowing current flow, and the inverter on, correct?

Bob, the good battery is reading 6.34 volts, roughly 83%, do you still recommend replacing?

Thanks again!

[Daryles]

I have never turned off the "BATTERY DISCONNECT" switch.
The labeling is confusing. Ignore the word DISCONNECT. Just read it as "BATTERY ON", " BATTERY OFF".

This is a generic diagram of the inverter powering the fridge and depending on your model rig and size of the inverter you may have other receptacles also on the inverter. These receptacles will be labeled.

Yes,
CONVERTER OFF when boondocking and the the INVERTER ON.

On shore or generator power, CONVERTER ON, INVERTER OFF.

There should be a disconnect switch for the inverter on the wall behind the batteries. I believe the inverter also has a power button AND a GFIC reset button. It would be a good idea to become familiar with these for future troubleshooting.

[wecker1]

Thanks for the info and diagram Daryles. My intent of this posting was to confirm what I thought I knew but again wanted to confirm since the battery died in just under three years. When I switched from the OEM 12V's to the two 6V AGM's I also upgraded the Inverter from the OEM Magnum Dimensions CSW1012 to the CSW2012 as well as increasing cable gauges, etc.

Decided to play it safe and order a second battery as suggested by Bob and confirmed with a second source.

Safe travels to all.