How long will the batteries last?

[Chalkie]

That is the question that I am having trouble deciding. When we took delivery of our 3791RD we were told that the inverter powered the refer, the theater seating and the TV. That seemed odd but then made some sense. Being able to close the seats if you needed to close up, same for the TV, or if it was weather related or something being able to get the news.

Of course, going down the road you would have the input of the truck to help the batteries, and the seats and TV would not be in use.

Now to the crux of it. Our unit came with the option of two small refers in the basement that are not on the invertor but I would like to wire them to the invertor so they too would stay cold while going down the road.

Would I be overloading the batteries if we were stationary and needed to run off the invertor with the added load? Would I be better off having a switch over to leave them on shore power until traveling? Or should I leave well enough alone and just hope they stayed cold while we travel?

All comments/advice welcome.

[rames14]

I am sure you were looking for a simple answer, but it isn’t that simple. I did not know they added the TV and theatre seating to the circuit but it’s easy enough to tell, just unplug shore power. I believe you have a 2000 watt inverter. You should have no problem from the inverter, your batteries will be the limiting factor. Remember, 10 amps per hour on 120v is 100 amps/hour (volts x amps =watts) on the 12v side. Also, AGM or lead acid deep cycle batteries shouldn’t be discharged below 50% of their rated AH capacity. Best way is to find the hourly wattage of your devices x # hours used prior to recharging. That will allow you to know where you stand with both the inverter and batteries.

[RMcNeal]

I have a 2019 3791RD. The only thing on the inverter in mine is the residential fridge. There is a plug directly into the outlet on the inverter that goes to the auto transfer switch which switches to shore power when available. I would think you could run a cord to the other outlet on the inverter and plug in the 2 mini fridges when travelling, but it will reduce the run time you have on battery. I'm guessing the 2 mini fridges are for the outdoor kitchen slide out option in the basement?

[RickyRobert]

Given the description of your rig, did the option(s) not include a solar charge system? If not, given your desired use, I would strongly suggest that you add one. As for choosing the battery (batteries, please) to install, the amount of money that you are willing to invest will be the determining factor. Many threads regarding the options can be found on the forum. Another thing to consider is the length of drive time you'll be doing each day - four hours on inverter is one thing, eight hours is something else (especially as the batteries start to degrade over time). And, as a p.s., you may find that you have a kitchen receptacle and a bedroom receptacle wired in to the inverter. If you do, be careful on amount of use - an electric coffee maker or a bedroom fan draws a lot of amps.

[irvgates]

IF you can, I would recommend you switch to two 6 volt batteries for your solar system and coach operations . Putting the batteries in a Series hookup will work extremely well for solar ops and long term power uses. The batteries will charge more equality and have a longer life. I have been using 6 volt batteries for Thirty years in my 5th wheels and I wouldnt change back to the one 12v or two 12v batteries for service . Irv Gates
Communications Tech. F350 ford diesel, 2014 Montana HI Country -HM343RL-14

[firestation12]

Originally Posted by irvgates

IF you can, I would recommend you switch to two 6 volt batteries for your solar system and coach operations . Putting the batteries in a Series hookup will work extremely well for solar ops and long term power uses. The batteries will charge more equality and have a longer life. I have been using 6 volt batteries for Thirty years in my 5th wheels and I wouldnt change back to the one 12v or two 12v batteries for service . Irv Gates
Communications Tech. F350 ford diesel, 2014 Montana HI Country -HM343RL-14

Check this YouTube video about batteries. This video is a must see for anyone looking at what battery is best for your RV. The author is a full timer who often boondocks. As others have explained, lead acid and AGM batteries only yield 50% of their amp hour rating. This video makes the case that switching to lithium is a better choice. Combine lithium batteries with a couple of 300+ watt solar panels, and you will have a reliable source to run the fridge inverter and tv when not connected to shore power. I've installed 2 280 amp hour lithium batteries and 640 watts of solar panels with a Victron shunt (records all the parameters of voltage and amps going in and out of the batteries). Unless I need a/c, I have no use for a generator.

JMAC

https://www.youtube.com/watch?v=iy3hga_P5YY

[81SHOVELHEAD]

Our 2021 295RL came with 2 batteries with a 2000 watt converter with only the residential fridge plugged in . During a severe lighting storm i unplugged from 15 amp shore power. Voltage was reading 13.4 on converter. 14 hrs later i hear a beeping from storage area & seen i only had 11.2 volts . Plugged back in & all is well
So looks like 14 hrs on 2 fully charged batteries with only Residential fridge plugged in to converter.

[Gracie346]

I have, 2 6 volt batteries from Batteries Plus. 2021 3231ck, 800 watts of solar. Unit sits all night at home with fridge running. Batteries at 75% in the morning, back up to 100% by noon, at the latest. Still not sure how long the batteries will last until 50% charge.

[steiny93]

Originally Posted by Chalkie

Would I be overloading the batteries if we were stationary and needed to run off the invertor with the added load?

Your question has a few parts to it

1) will the inverter handle the added load (2 extra refers)
2) how long will the existing batteries last with the extra load
3) how to handle power distribution (switch, existing, ???)


Here is how to figure it out.
1) Find the size of your inverter in watts
2) Figure out your desired new load in watts; if load is less then inverter size then that part is good

Or, just plug em in and see if they trip the inverter.

A full 2000 watts at 110volt is going to be about 200amp/hrs on the 12 volt side.

[bcrvman]

Originally Posted by Chalkie

That is the question that I am having trouble deciding. When we took delivery of our 3791RD we were told that the inverter powered the refer, the theater seating and the TV. That seemed odd but then made some sense. Being able to close the seats if you needed to close up, same for the TV, or if it was weather related or something being able to get the news.

Of course, going down the road you would have the input of the truck to help the batteries, and the seats and TV would not be in use.

Now to the crux of it. Our unit came with the option of two small refers in the basement that are not on the invertor but I would like to wire them to the invertor so they too would stay cold while going down the road.

Would I be overloading the batteries if we were stationary and needed to run off the invertor with the added load? Would I be better off having a switch over to leave them on shore power until traveling? Or should I leave well enough alone and just hope they stayed cold while we travel?

All comments/advice welcome.

The stock PI 1,000W inverter is only for the fridge. My unit came with a pair of 75AH 12V lead acid hybrid batteries (not even deep cycle). They would power JUST the fridge for 14.4 hours. That is why I switched to Lithium. Never heard of extra refrigerators. Remember compressor devices are the worst for battery life. The residential fridge you have is super efficient, IIRC only 3 to 4 amps max instead of 12 or 13 but they run at variable speed in theory all the time. My Samsung uses 1,500WH per day as measured by a Kill-A-Watt meter over many weeks.

[Chalkie]

Originally Posted by bcrvman

The stock PI 1,000W inverter is only for the fridge. My unit came with a pair of 75AH 12V lead acid hybrid batteries (not even deep cycle). They would power JUST the fridge for 14.4 hours. That is why I switched to Lithium. Never heard of extra refrigerators. Remember compressor devices are the worst for battery life. The residential fridge you have is super efficient, IIRC only 3 to 4 amps max instead of 12 or 13 but they run at variable speed in theory all the time. My Samsung uses 1,500WH per day as measured by a Kill-A-Watt meter over many weeks.

The invertor we have is a 2000W. There are invertor connected plugs at the refer, theater seating and the TV/TV lift. I think I need a one of those Kill-A-Watt meters to nail down some hard numbers. Amazon, here I come!

[bcrvman]

Originally Posted by Chalkie

The invertor we have is a 2000W. There are invertor connected plugs at the refer, theater seating and the TV/TV lift. I think I need a one of those Kill-A-Watt meters to nail down some hard numbers. Amazon, here I come!

That does sound different. Keep in mind, the inverter is ONLY used if you are NOT plugged into shore power. If you haven't upgraded to 4 to 6 LiFePO4 batteries plus >1,000W of solar then using the stock batteries will not last long. If you do not have a battery monitor from Victron or Bogart and you plan on being off grid get one. I bought mine before I bought the RV, it's that important. With lead acid only use 50% of the battery. In order to get 24 hours of battery for just the fridge plus some misc (NO furnace) you need 4 golf cart batteries at 67 lbs each. Use HUGE wires from batteries to inverter (I use 4/0 as short as possible and a 16 ton hydraulic crimper to put the marine grade (tinned) lugs on the end then protect with the double wall heat shrink).
If you do NOT plan on boondocking then stick with what you have, otherwise prepare to spend some $'s to properly modify your rig for off grid living.

[bcrvman]

Originally Posted by 81SHOVELHEAD

Our 2021 295RL came with 2 batteries with a 2000 watt converter with only the residential fridge plugged in . During a severe lighting storm i unplugged from 15 amp shore power. Voltage was reading 13.4 on converter. 14 hrs later i hear a beeping from storage area & seen i only had 11.2 volts . Plugged back in & all is well
So looks like 14 hrs on 2 fully charged batteries with only Residential fridge plugged in to converter.

Keep a close eye on those batteries, taking them below 12V means they will not last long. Get a battery monitor from Victron or Bogart.

[laverdur]

The life of a battery is based on several factors. Batteries only have so many charge/discharge cycles before they fail. Never letting a battery fully discharge and keeping the electrolyte level above the plates will go a long way to extending the life of a battery. My Monty is connected to shore power unless I'm towing so the batteries stay fully charged and conditioned thanks to the nice converter that Keystone provides. My original Centennial batteries lasted from September 2011 to July 2017. I was pleased with that life span.

[Gracie346]

Sitting at home, with just fridge running, batteries show between 60 and 75% of capacity, over night. Charge back to 100% by noon at latest. First time on the road using system. Batteries at 100%, after a days traveling. I feel I will need to upgrade from the 2, 6 volts to 4, or lithium. Expect to run these batteries down when using them in evenings, while dry camping. On the road for 6 days, system working fine for us.

[kowbra]

No one has commented on the power draw of those mini fridges. I would recommend to the OP to check that.

Mini fridges are typically not very efficient, and can easily burn 50% or more of the power of a full size. IOW, to power those 2 mini fridges will likely take as much power as the single large one does now.

So, really simple math, you will probably need to double the size of the existing inverter and batteries.


Brad

[RipNC]

Most of the coooer style fridge/freezers run on 12v or 120v. There is loss inverting 12v to 120v to power a device that is using a 12v compressor anyway. New model Victron inverters are 94% efficient compared to the "old" models at 93%. If possible, power them off the 12v system. Also most have a configurable low voltage cutout that you may want to set higher than your inverter so they cutout before the residential fridge does.

[kowbra]

Originally Posted by RipNC

Most of the coooer style fridge/freezers run on 12v or 120v. There is loss inverting 12v to 120v to power a device that is using a 12v compressor anyway. New model Victron inverters are 94% efficient compared to the "old" models at 93%. If possible, power them off the 12v system. Also most have a configurable low voltage cutout that you may want to set higher than your inverter so they cutout before the residential fridge does.

I think the OP has the "outdoor kitchen" option from Montana. They use a pair of "bar fridges". If I'm correct on that, then they are 120v and very inefficient.

To me, finding out what those fridges draw is a key part of the conversation and the OP should really check that out.


Brad

[RipNC]

Brad,

Got it, I was thinking those pull out basement drawer setups with the Dometic type cooler.

[Gracie346]

My inverter had a second ac outlet on it. I assume you could plug small fridge into it. The question would be can your batteries handle it during a daily trip. I would just try it.