Residential Fridge - Long Drives

[saddlesore]

Originally Posted by AirBossdavid

Engine running your alternator well exceeds the 80 amp draw so you can actually charge your batteries WHILE the fridge is running and have lots of capacity left over.

Based on what you have said about your travel habits I would say you can forget about it EXCEPT make sure your batteries are maintained.

I Concur..Put that hoss in the wind,apply the spurs and get back to turning dead dinosaurs into smoke and noise!.........

[DandyDon]

Someone can correct me if I'm wrong, which I often am, but when you are running a regular Electric/LP gas fridge on LP you're still using a little electricity just to keep it operating, probably not as much as running a residential, but some?? I'm probably wrong, so someone please correct me.

[imnprsd]

OP asked: Is the alternator charging the house batteries at all?

Answer, you need to check.

1) Run your inverter to power the frig for over ~6 hours... or until you see 12V-12.3V on your power panel. (You want your house batteries to be ~50-70% State of Charge.)

2) Now start your engine and measure the voltage to the to house batteries with a volt meter. If you have 13.6-14.5V then you know your engine alternator is charging your engine battery and your house batteries.

If you don't own a $20 voltmeter, pick one of these up with a DC-Probe-Light for another $10.

3) If you coach is not charging your house batteries with the engine running, then you can buy a $90 Voltage Sensitive Relay (VSR) that will connect the + side of your engine battery to the + side of your house battery; and like magic your house batteries will not charge when ever your engine is running.

https://www.amazon.com/Dual-Battery-...41&sr=8-2&th=1

Note: Your 160+ Amp alternators will do a good job charging both your engine and house batteries; so you can run your inverter on the road to power your residential refrigerator the whole time; and when you arrive at your destination (6+ hours later) you can always count on having a full charge on your house batteries. Also, your power panel will show automatic switching between shore power, generator power, and inverter power. So you don't need to switch anything off. There is a transfer switch that will do all that for you automatically. What you need to do is get familiar with reading your power panel.

Note: Your residential refrigerator will only run for 12-15 hours with four GC2-6V house batteries.
...And 100W of solar is woefully insufficient to power anything! ...You can upgrade your solar controller and add more panels, but this will only buy you another 2-3 hours/day of power; so it's hardly worth the effort and added costs IMO. I have 400W of solar, and I get some benefit, but there is no ROI until you get past 5 years of use!

Summary:

As long as you are driving down the road, you will have all the AC power you need to run your residential refrigerator... plus another 12-15 hours of battery reserve into the next day (with TV and/or computer running at times). Try not to open your refrigerator when you are trying to conserve power. However, you will find on day 2 and 3 and so on, that your battery reserves will drop to 8-12 hours of use... depending on your power consumption. This is normal since your batteries will be working hard and then harder and you can never get back to a full 100% State Of Charge (SOC) even though your battery meters will suggest you reached a full charge. There are reasons for this I will not go into here, but trust me, boondocking takes discipline or you just need to run your generator at a rate of 1 gal/hr. So don't think it's cheap when you run your generator 3+ hours/day at the cost of $3/gallon for fuel.

On the other hand, when you need air conditioning you will not care how much it costs, but 8+ hrs of running a generator will use fuel and cost $20+/day.

You can plan on running your generator when boondocking 3-5 hrs/day with a residential refrigerator; and 8+ hours/day when you need air conditioning.

So traveling from Point "A" to Point "B" is no problem. And when you get to an RV stall with AC-shore power... no problem.

People like to talk about "going green", but solar is not really that great for an RV application.

Note: You may not know that your house batteries will not last very long (1-2 years) if you run them down below 11.9V all the time. However, some people do not care and prefer to run their batteries below 40% vs. running their generator. Currently, you can buy 4-GC2-6V batteries for ~$500. So this is just the price you will pay every 1-2 years if you don't treat your batteries nice. ...As opposed to paying $100/yr in fuel and trying to extend your battery live to 2-5 years.

[twinboat]

Originally Posted by AirBossdavid

Your fridge likely draws around 6 amps @ 120 volts (probably a bit of a surge at start up but not for long) when it is running. It is impossible to guess its cycle time because it depends on ambient temp, how often you open it, and how much stuff you just put in the fridge that it is trying to cool, but worst case assume a 20% duty cycle.

You inverter will draw around 80 amps (I'm guessing) at 12 volts to create the 6 amps at 120 volts. I am guessing at your battery capacity as well but 4 golf cart batteries is likely 400 ish Amp hours. Assuming they are lead acid that is usable 200-250 amp hours of battery capacity (if they are Lithium double this number). If we assume all those are true, and you are not running anything else;
On batteries you should be able to go - 80 amps/20% duty cycle = 16 amps average. 200 Amp hours / 16 amps is 12.5 hrs of battery capacity while parked. Other draws (lights, TV's coffee maker, microwave, heater etc etc will reduce this time. Your solar panels will add to this time.

Engine running your alternator well exceeds the 80 amp draw so you can actually charge your batteries WHILE the fridge is running and have lots of capacity left over.

Based on what you have said about your travel habits I would say you can forget about it EXCEPT make sure your batteries are maintained.

Lots of off base assumptions.

First, the fridge will draw about 2 to 3 amps running 33% of the time. 20 minutes per hour.

The conversion from 12 to 120, volts thru the inverter, is about 125% X 10 amps.

3 amps × 125% X 10 = 37.5 amps when the fridge us running. That's only if it draws full 3 amps. Nowhere near the 80 amp figure you guessed.

37.5 amps @ 33% run time is 12.5 AH. Run that fridge with no added charging or other draws on the battery for 24 hours and you will use 300 AH. Run a generator for a few hours a day and all will be well.

Drive the MH and use 0 AH, the alternator will cover the load occasional 37 amp load.

[Griswald One]

Originally Posted by Ken Thompson

Unless your government has passed a law or executive order, you aren’t stuck in your house. You can leave in your RV. At that point, you technically staying at home. In Oregon, our governor wants everyone to stay home, even though Oregon has one of the least case counts in the country, but it’s not a law. We still travel in our RV, but take precautions. The government is extending their control further than they have jurisdiction to do, but most don’t question it.

Unfortunately here it pretty much is the law. Campground’s are deemed non-essential and as a result are limited to full timers who have no other home or emergency service personelle who are using their RV to quarantine away from their family. Provincial, parks are closed until May 31st and that date has already been extended twice.

Can/Am border is closed and the Provincial border to Quebec is essentially closed.

Our Health Directors have a scary amount of power. They have even closed cottage country to seasonal residents and they are paying property tax... Gonna be interesting to see when the people are fed up and ready to take power back from the government.

[Walt Graham]

First I would check with the manufacture of the fridge because some of the large residential units include a soft start system that reduces the amperage draw on starting to be the same as when it is running thus taking out the heavy surge. But in saying all of this the actual amperage used by a modern fridge is very low and with a 2000 Watt converter (12 Volt to 120 Volt) a minimum bank of 2 batteries is more than needed and yes the engine alternator normally has enough amperage to keep the house batteries at full charge while traveling. In the old days it wasn't unusual to turn off the fridge to save the 12 Volt batteries and it seemed that the fridge would stay pretty cold for almost 8 hours and at that time we switched over to propane when dry camping because most state and federal campgrounds didn't have power connections or water and the 12 Volt was needed for lights. The only draw back on a residential fridge is that it can't switch over to 12 Volt or propane but to me it's a better unit and will last longer and yes I have a residential unit in my motorhome and it's great for hard ice cream unlike the anmonium units.

[BikesAndGuns]

Originally Posted by Griswald One

As Covid-19 keeps us stuck at home my bride and I are working through learning our new rig inside and out so that we can be ready to travel as soon as the Province says GO!

The residential Fridge is one place that neither of us feels confident. We have always had two way fridges in our other units and were comfortable with their operation. The residential fridge is big and daunting and both of us are concerned about power supply.

We are in a 2020 Fleetwood Bounder with a Samsung fridge and a 2000w inverter, 4 6v batteries and 100w of solar.

I understand that when under shore power or running the generator we will have sufficient power to operate the fridge. My concerns are when travelling, particularly long distances. We are not boondockers so I have no concerns about being parked.

I am assuming that in order to power the fridge via the inverter I will have to initiate the switch that is located over my entry door to turn the inverter on and supply power to the fridge. I also assume that the 2000w inverter is plenty powerful for running the fridge and any other minor draws we might have. My real question comes on the days with long drives, we often travel 10 hour days when working our way South. Do I need to be concerned about my battery bank and the draw the fridge is placing upon it? Is the alternator providing sufficient power to the house batteries to offset any draw from the fridge? Is the alternator charging the house batteries at all? Should I consider setting up the Generator Auto Start to cover any draw down during those long drives?

We have a 2018 Heartland Cyclone 4200 Fifth Wheel Toy Hauler with two batteries and an inverter for the residential refrigerator. While traveling, the truck keeps the batteries charged and powers the refrigerator through the inverter. We've been traveling for almost 3 years now and have never had a problem.

[BobRay]

Just to add a little more information -- I have remote temperature sensors in the fridge and freezer. In about an hour of driving at 70 degrees ambient, the fridge hits 46 degrees. I run the generator for 5 to ten minutes and it's back down to 38. The freezer will almost never get above 10 degrees.

My fridge is a GE that doesn't get very cold when the fridge is running (seldom goes below 38 on the top shelf at its coldest setting). Otoh, I put some extra insulation in the cabinet. YMMV.

Since most authorities say that the fridge should be kept below 40 degrees, I'm skeptical about people's claims that they can go 8 or 10 hours with no power to the fridge and not risk anything spoiling.

[timjet]

Originally Posted by BobRay

Snip
I'm skeptical about people's claims that they can go 8 or 10 hours with no power to the fridge and not risk anything spoiling.

Depends on the outside air temp. With night time temps in the 60's and using the reverse cycle of our air conditioner for heat in the aft unit, we typically see a 2-5 deg rise in refrig temp after 6 hrs with the refrig off.

I replaced our absorption refrig with a residential and the access panel on the outside wall still has the vents needed by the absorption unit. Those vents allow outside air into and around the refrig, so outside temps make a difference in it's ability to hold cool air over the 6-8 hrs.
When night time temps rise to the middle or upper 70's typical in FL in the summer, then you better have CG power or run the generator for more than just the refrig.

[Paul R. Haller]

I pull a large 38 quad slide 5er with a diesel truck. I installed a Samsung RF 18 in the rig 3 years ago. I have 4 6 golf cart batteries. After pulling my rig for 8 hours when I would pull into a campground i would see my 110shore power amp right about 6 amps with everything off except the Converter charging my batteries. In the morning my amps were back down to under 1 amp. So, my batteries were not anywhere near full charged Even after the truck was running over 8 hours. I looked everything over and after thinking about it i went out and measured voltage at the truck battery post with the truck running at 13.6 volts. Then i hooked up the trailer to the drop cord and measured the battery voltage at the 5er disconnected from shore power12.6 volts. I had a volt drop between the truck and trailer.i went and bought 50 feet of #6 welding wire and added a relay with a winch connector and installed it in the Positive side of the battery back to the winch connector and back to the trailer batteries. I did the same for negative but not through the relay. I added 1 100 amp fuse in The truck lead before the relay and another 100 amp fuse in the trailer just before the battery. I tied everything up to the frame, crimped the heavy duty copper lugs on, and wrapped everything with split loom. The winch connector was attached by the 7 way plug.

The next trip with an 8 hour drive I got a very different outcome. My batteries now showed 1 amp draw from the converter indicating a full Trailer battery charge. On my rig at least, that 12 gauge charging wire going to the trailer batteries isn't up to the task of charging those batteries so far from the alternator. I know your rig is a motor home but it might be worth checking. Paul R. Haller

[theoldwizard]

Originally Posted by imnprsd

3) If you coach is not charging your house batteries with the engine running, then you can buy a $90 Voltage Sensitive Relay (VSR) that will connect the + side of your engine battery to the + side of your house battery; and like magic your house batteries will not charge when ever your engine is running.
https://www.amazon.com/Dual-Battery-...41&sr=8-2&th=1

If you are going to spend $90, spend a few more $$ and get a DC-DC battery charger like the Renogy DC to DC Battery Charger with Multi-stage Charging. That is the 20A model but they make ones go up to 60A. These do a MUCH BETTER JOB of recharging a house battery bank. Watch this video.
Renogy DC-DC Battery Charger Review (similar products are available from other manufacturers).

Originally Posted by imnprsd

... you can never get back to a full 100% State Of Charge (SOC) even though your battery meters will suggest you reached a full charge.

I disagree ! With a good, properly sized, DC-DC battery charger and a reasonable amount of driving time you can get back to 100% SOC (unless of course your inverter is continuously running a heavy load)

[bird6465]

We have a 2015 Bounder with the same set up and you have nothing to worry about. Ours can sit 24 hours with no hook ups at all and the fridge doesn't drain the batteries. Plus, driving keeps everything charged up just fine.

[theoldwizard]

Originally Posted by Paul R. Haller

After pulling my rig for 8 hours when I would pull into a campground i would see my 110shore power amp right about 6 amps with everything off except the Converter charging my batteries. In the morning my amps were back down to under 1 amp. So, my batteries were not anywhere near full charged even after the truck was running over 8 hours. I looked everything over and after thinking about it i went out and measured voltage at the truck battery post with the truck running at 13.6 volts.

Start your truck, let is idle for about 10 minutes. Check the voltage at the vehicle battery at a fast idle. I will bet it is closer to 13.2V which is not adequate to recharge a house battery bank.

Originally Posted by imnprsd

i went and bought 50 feet of #6 welding wire and added a relay with a winch connector and installed it in the Positive side of the battery back to the winch connector and back to the trailer batteries.

Yes, the smaller gauge wire is causing a voltage drop, but installing a DC-DC battery charger in you 5er would do a better job, be easier to install, and probably cost less !

[timjet]

Originally Posted by timjet

Depends on the outside air temp. With night time temps in the 60's and using the reverse cycle of our air conditioner for heat in the aft unit, we typically see a 2-5 deg rise in refrig temp after 6 hrs with the refrig off.
Snip
.

OOPS, meant to say aft furnace. With OAT's in the 60's we typically turn the inverter off and coach holds enough heat to stay comfortable.