View Full Version : Residential fridge and inverter.
Getn off
11-04-2018, 05:58 AM
Have a new Sprinter Limited 3551fwmls with a residential fridge that comes with an inverter for it. When camping with electric, I keep the inverter on. I only turn the inverter on while it is not plugged in to electric. Am I doing this right? Question is do I need to leave the inverter on always, even with ac powering?
Next related question: how long will (roughly of course) the batts last while only powering the fridge? I have dual tv batts but nit sure size and dual hd batts with the truck - lets assumed plugged in. This was on my mind since I had to move my rig to the street without plugging in for the night due to demo of a garage on my property.
Thanks!
Troy
Btw, yes I realize that it is just a simple (to some) math question, but not for me!
jsmith948
11-04-2018, 06:24 AM
The TV batteries are not relevant. The inverter for your fridge gets the 12 volts it needs from the trailer battery/batteries. If your TV is running, it will add a small amount of charge from the TV's alternator, but not enough to be of much help. You will have to rely on the number of amp/hrs you have available from the trailer battery bank. Divide the available amp/hr of your battery bank by the amp draw of the inverter while it is powering the fridge to determine how long you can power the fridge.
Added on edit: On Ford trucks, the "hot" wire in the 7 way plug is cold unless the ignition switch is in the "on" or run position.
Getn off
11-04-2018, 06:37 AM
Did not know the truck had to be on for the batts to charge, ty.
So, how long would an ave dual batt setup run an ave residential fridge? I dont have the math info to plug in. 2,4,24 hours?
Troy
jsmith948
11-04-2018, 06:46 AM
Can't even guess without more info. You have to know how many amp/hrs you have available when the battery/batteries are fully charged. Then you have to determine how much power is being drawn by the inverter while it is powering the fridge. Then you have to get an idea of how often the fridge cycles on/off. I would think this is a variable depending on how often the fridge is opened and the ambient temperature. The only other way (and probably the only really accurate way) to determine how long the inverter will power the fridge would be to simply time it.
Does the information supplied with the trailer offer any insight?
Getn off
11-04-2018, 06:54 AM
I know that with the info ur asking for it would give an exact time. I am only asking if, from other peoples past experience with similar setups, my fridge would die before morning when i can move it again.
I do thank you for your help though.
And no, no info came with the rig.
Troy
jsmith948
11-04-2018, 07:02 AM
Adding to my earlier post and to offer an example, our Laredo has a small, 120V fridge in the outside kitchen. I installed a 1000W inverter that is powered by two golf cart batteries rated at 200 amp/hr. I can run that little fridge all day while traveling without issue - even in our 105 degree plus valley. Of course, the batteries are receiving some charge from the TV while in transit. I don't know how much, but, I doubt that it is very much given the size of the wiring in the trailer cord. Also, while the fridge resides in a poorly insulated outside compartment and is subjected to the extreme heat we sometimes experience, the door isn't being opened while we are in transit.
None of this serves to answer your question regarding how long your fridge will run off of the batteries. I only offer the info to give you some idea.:)
JRTJH
11-04-2018, 07:08 AM
To answer that question, someone would have to know the amp-hour rating for your specific battery system, whether there are one or two batteries connected to the inverter (some systems have a single dedicated battery, some systems use the trailer battery. They would also need to know the amp draw for the refrigerator and whether the ice maker is turned off or left on (yes the ice maker is a significant draw on refrigerator electric demand because of the heater element that causes the ice to release from the mold).
As an example, if you have a single GP 24 deep cycle battery, you might have an Amp/Hr rating of 75 and if you have a dual GP27 deep cycle batteries, you might have an Amp/Hr rating of 180, or more than double the capacity to run your refrigerator. If the ice maker is turned off, that may extend the run time possibly by double the hours, but depending on the state of charge of the batteries when you start and what other "hidden draws" are on the system (stereo memory, LPG detector, CO detector, Smoke detector(s), and remote control/electronic management system) which also affect the ability of the battery system to provide power to the refrigerator. Additionally, the ambient temperature around the refrigerator will affect the amount of time the compressor runs (more in hot weather, less in cool weather) as well as how often you open the refrigerator door and how long you leave it open.
It's not as simple as: "If you have one battery, it will run the refrigerator for 20 hours".
chuckster57
11-04-2018, 07:09 AM
If I can add, if your parked without being plugged into shore power, any lights, water pump, furnace usage will shorten the number of hours available for the fridge.
Really, there isn’t any accurate way of determining the length of time due to the variables involved. I would venture that a pair of gp27 batteries may make it through the night without the furnace being operated.
notanlines
11-04-2018, 07:12 AM
Troy, I don't have an answer to your entire question,, but I can tell you that our fridge (large, three door residential) will run from 6 PM when we stop until 6 AM when we leave without any problems, including us using our lights. Keep in mind that it is already cold from running during our travelling the day before.
I can't see why Walmart won't install 50 amp service in their parking lot for people like us....:D
Getn off
11-04-2018, 07:19 AM
Thanks guys.
It is not used while parked on the road. Just the fridge. Batts are fully charged. I keep them plugged in while parked next to my garage at all times.
Just got nervous while it was going to be parked without power and didnt want to unpack the fridge.
Troy
Old Mustanger
11-04-2018, 09:30 AM
I don't think anyone addressed the other part of your OP, It is OK to turn the inverter off anytime you have shore power, it is bypassed when you're plugged in anyway. Just don't forget to turn it back on when you hitch up and go. :)
Getn off
11-04-2018, 10:11 AM
Thanks Jerry, that is what I thout but wanted to clerify.
Troy
JRTJH
11-04-2018, 11:59 AM
What Old Mustanger said applies to about 75% of all inverter systems. On some (unsure of the OP's system) the refrigerator inverter/battery are a separate system and not connected to the trailer 12 VDC charger/battery system. In those types of inverter/battery/refrigerator systems, the inverter is the only battery charger for the battery that supplies the power for the refrigerator. So, if you turn that inverter off, you won't recharge the battery and it will be "DOA" when you get ready to tow the next time.
So, check to see if your refrigerator battery is charged by the converter/power center or by the inverter. Depending on what you determine, you may need to leave the inverter turned on, at least until the refrigerator battery is charged.
Getn off
11-04-2018, 01:16 PM
John, as far as I am aware, the fridge just gets juice from the rvs batts when I turn the inverter on. The inverter is a 1000w that is used soley for the fridge. The charging I thought was only when tv hooked up, or with 110v.
Are you suggesting to leave the inverter on at all times? Will that hurt anything either way?
I am sloooowly starting to understand this beast!
Thanks again.
Troy
JRTJH
11-04-2018, 02:17 PM
Some Keystone RV's with domestic (home style) refrigerators have a dedicated battery to operate the inverter. It is separate from the RV battery system and is not attached to the converter or to the power center. On that type system, the only way the refrigerator battery can be charged is with the inverter/charger that is also a part of that system. When plugged into shore power, the inverter functions as a charger for that battery (not for the RV battery/batteries). About 25% of RV's are wired this way.
The rest of the domestic refrigerators have inverters that are connected to the RV 12 volt battery system. Most of them have an inverter (not an inverter/charger) and draw their power from the same battery bank as the lights, water pump, slides and jacks. On that type system, the batteries are charged by the converter in the power center, just like most other RV 12 VDC systems.
On the first type, you need to leave the inverter turned on to charge the "dedicated battery". On the second type, you can turn the inverter off because the batteries draw their charge from the power center for the RV.
I don't know which type you have, so you'll need to determine whether your inverter is wired to a "dedicated battery" or if it is wired to the "RV battery system. Both wiring systems are found in Keystone RV's.
Getn off
11-04-2018, 04:14 PM
Good info. Pretty sure mine only has the rv batts. I will just keep turning the inverter off when plugged into ac then.
Thanks!
Troy
chuckster57
11-04-2018, 04:17 PM
If you can put eyes on the inverter, just give us a make and model # and we can tell you.
Old Mustanger
11-04-2018, 08:42 PM
Always learning!:hide: If the inverter has a "BYPASSED" light that comes on when plugged into shore power is it safe to assume that it is not charging the batteries? (Yes I know what assume can mean but I couldn't think of another word to use) The service advisor had told me it was OK to turn the inverter off but now y'all have me doubting. :confused:
Getn off
11-05-2018, 01:18 PM
Here are the inverter pics...
Troy
JRTJH
11-05-2018, 04:29 PM
I edited your posts to combine all the photos into one post. The top photo shows the name of your inverter, the second (black schematic) shows the connections/relay for the power transfer switch and the bottom shows the output plugs and power switch for the inverter.
The way your system is set up does not include a "dedicated battery for the refrigerator. The main 12 VDC battery system powers all of your requirements. There is no "refrigerator inverter/charger"... So, the way your system works is this:
The trailer battery charges from either the tow vehicle (when it's running) or from the trailer converter/charger when you're plugged into shore power. The refrigerator has a inverter that provides 120VAC when the trailer is unplugged which is powered by the trailer battery system.
When you unplug the shore power, the transfer switch automatically switches the power from the shore power side to the inverter side. This assures "seamless" power for the refrigerator. When you stop and plug in the shore power cord, the transfer switch automatically switches from the inverter to shore power, again assuring "seamless" power to the refrigerator.
In order to turn off the refrigerator, you can either turn off the inverter at the inverter power switch or turn off the refrigerator at the refrigerator control.
As long as you have batteries connected to your RV, you will have power to the inverter (unless there is a switch in the power cable from the battery to the inverter).
You can disable the inverter (and possibly prolong its life) by turning it off when you are on shore power. That is not "mandatory" but rather a personal preference.
Your inverter/transfer switch does not have any battery charging capability, so you must rely on the "WFCO converter/charger" in the power center to keep your trailer battery bank charged.
I hope this doesn't confuse you more than helps you understand your system.
Getn off
11-05-2018, 07:45 PM
Perfect John, thank you.
No idea how to upload mult pics. When I put all 3 in the upload area and clicked upload, only 1 stayed. I am just happy they arent sideways any longer!
Appreciate the explaination of the inverter system. It makes sense.
Troy
Irv gates
11-11-2018, 08:35 AM
I talked to a dealer last year about the use of the Inverter full time and his infro gave me the idea that the system was not engineered to work full time on the inverter. He was telling me that the frig couldnt get down to the cold temps that were needed when it was on the inverter. The Manuf recommended that you use the inverter system only when going down the road and limiting the travel time to 8 hours to maintain the frig at its best cooling level.
I can see where its possible for the inverter to maintain only a small amount of the energy neeeded if its limitations are such to only keep the frig in a limited cooling state. The specs on the inverter would indicate to me the capacity of the inverter for running full time on it. I dont believe your batteries would handle a very long time period on the inverter unless you have shore power to charge them or solar panels.
chuckster57
11-11-2018, 09:53 AM
I talked to a dealer last year about the use of the Inverter full time and his infro gave me the idea that the system was not engineered to work full time on the inverter. He was telling me that the frig couldnt get down to the cold temps that were needed when it was on the inverter. The Manuf recommended that you use the inverter system only when going down the road and limiting the travel time to 8 hours to maintain the frig at its best cooling level.
I can see where its possible for the inverter to maintain only a small amount of the energy neeeded if its limitations are such to only keep the frig in a limited cooling state. The specs on the inverter would indicate to me the capacity of the inverter for running full time on it. I dont believe your batteries would handle a very long time period on the inverter unless you have shore power to charge them or solar panels.
Sorry but that makes no sense. Think about it, the inverter provides AC Voltage and a number of watts (amps) to operate the refer. the refer doesnt care where the power comes from, just that it gets a minumion amount and the inverter surely is rated for that. Maybe the ice maker will overload the sytem but I'm skepical of that too.
Local150
11-11-2018, 10:59 AM
Thanks guys.
It is not used while parked on the road. Just the fridge. Batts are fully charged. I keep them plugged in while parked next to my garage at all times.
Just got nervous while it was going to be parked without power and didnt want to unpack the fridge.
Troy
If not opened it should easily last all night. Jmo
I read this thread with great interest as I have a unit with the Residetial fridge. Mine came with 1 series 27 house battery and after complaining to the dealer was given another. From the separate house battery compartment there are + and - connections to the front belly to connect to the the inverter and fridge battery. Therefore, in my setup it will draw from both batteries if not connected to shore power. Both John and Chuckster57 were bang on with there responses. I replaced my belly battery with 4 deep cell Golf Cart Batteries. Also installed a Blue Sea shut off switch so I can power the fridge separate from the house battery. I turn on the fridge inverter only when traveling and I make sure that the ice maker is turned off. This makes a huge difference in battery usage. Also recommend that while hooked up set freezer on a higher temperature (-18C) before you leave on your trip and turn it up when you start trip. This way your fridge will not have to work as hard to maintain temperature on the road. The key with these fridges and lead acid batteries is to make sure you do not drain them below 50 % of their capacity which will shorten their useful life. As an aside, I carry a Honda generator and have a separate Progressive Industries converter to charge my batteries. Next step will likely be solar as they are the best option for charging and maintaining batteries at their peak and extend their life. We love our residential fridge.
notanlines
11-11-2018, 01:18 PM
Regarding the inverter and the residential fridge: Irv, "the system was not engineered to work full time on the inverter. He was telling me that the frig couldn't get down to the cold temps that were needed when it was on the inverter"
That statement is simply false. Your dealer has gotten some bum info or he/she was trying to BS someone to get out of fixing the problem.
Turn off the ice maker and head down the road....
On edit: I see Chuckster already covered this.
George1
11-11-2018, 08:01 PM
I'm glad you posted this because I was actually thinking about getting a residential fridge in my next 5th wheel upgrade. But I'm beginning to think that is a big pain in the butt as the inverter battery thing would not make it very much fun to do much boondocking. And in my world that's the whole point of having a camper not to be plugged into a Campground all the time. So thank you, in a roundabout way you just made up my mind for me that I will just stick with your generic old Dometic propane slash 50 amp plug in RV fridge
JRTJH
11-11-2018, 08:41 PM
George1,
Take a look at the owner's manual for Keystone RV's, 2019 edition, page 44:
"Refrigerator-Residential Style
By design, these refrigerators will not operate properly when indoor air temperatures exceed approximately 110 degrees Fahrenheit. In addition, operating the refrigerator in these conditions could cause compressor failure which may not be considered warrantable. Leave the air conditioner set at a temperature below this if the refrigerator is left running in a vehicle that is not being used or shut it off."
Living around south Texas will put a significant limitation on towing with the refrigerator operating (interior RV temp will be well above 110F on a hot, sunny day and trying to boondock, not only will the battery limit your ability to operate the refrigerator, but even if you have a generator to provide power, unless your generator is big enough to also air condition the coach, you risk damaging your refrigerator cooling system if you're boondocking in "summer temps"....
That statement has been in the owner's manual for the past 5 or 6 years, so it's not new, just something many people either ignore or haven't seen. Towing a "residential refrigerator" through the desert in July, even with 4 batteries and all the extra power the tow vehicle can provide, unless you're also running the air conditioner, you risk damage to your refrigerator.....
There are some significant limitations to residential stuff in a travel trailer.
lindy46
11-13-2018, 09:19 AM
I don't think anyone addressed the other part of your OP, It is OK to turn the inverter off anytime you have shore power, it is bypassed when you're plugged in anyway. Just don't forget to turn it back on when you hitch up and go. :)
We keep our RV on a permanent lot and it is always plugged in. I do leave the inverter on just in case there is a power failure at the campground. The batteries will keep the fridge running for 8-10 hours and we've never had a power outage that long.
Local150
11-13-2018, 03:04 PM
I don't think anyone addressed the other part of your OP, It is OK to turn the inverter off anytime you have shore power, it is bypassed when you're plugged in anyway. Just don't forget to turn it back on when you hitch up and go. :)
Good information,, thanks
Vernon G
11-17-2018, 05:36 PM
We have a 2019 Montana high country 5er with a Samsung residential fridge. We like to leave the door open to vent the fridge when in storage however, the internal lights stay on when the doors are open. Does anyone know how to deactivate the light while power is off and the doors are open?
Thanks for any feedback,
Vernon G
Getn off
11-17-2018, 06:11 PM
I am guessing u may still have the inverter on if the light is on...meaning u still have power to the fridge.
Troy
Vernon G
11-17-2018, 06:35 PM
Thanks for the reply!
elcaminonut69
12-02-2018, 06:44 PM
I have a Sprinter TT with the Samsung Fridge. I installed 2 Group 29 batteries and I don't have any problems with 24hrs. I haven't tested it past that so I don't know. A lot depends on the temp in the camper. To turn the unit off you have to throw the breaker and turn the inverter off or it will still run.
Getn off
12-03-2018, 02:17 PM
Thanks for the feedback. But I think you may have an isue with how your inverter is wired. You should just push the red button and it will turn off the ac power to the fridge. You do have to hold it a sec or two. If the lights go out, you shouldnt have to trip any breakers. Unless mine is wired wrong!
Troy
JRTJH
12-03-2018, 04:36 PM
I have a Sprinter TT with the Samsung Fridge. I installed 2 Group 29 batteries and I don't have any problems with 24hrs. ....
When you ran your refrigerator on the two GP 29 batteries, what was the battery charge level/end voltage after the 24 hours? I ask because if your batteries are typical "marine deep cycle batteries", most manufacturers recommend not discharging beyond 70% to prolong life. That equates to a battery voltage of around 12.3 volts. Many inverters will operate down to about 11.5 volts before they shut down from low input voltage. 11.8 VDC equates to a battery charge level of around 30%. Discharging "marine deep cycle batteries" to that low level repeatedly will shorten their usable life significantly.
elcaminonut69
12-03-2018, 06:38 PM
Thanks for the feedback. But I think you may have an isue with how your inverter is wired. You should just push the red button and it will turn off the ac power to the fridge. You do have to hold it a sec or two. If the lights go out, you shouldnt have to trip any breakers. Unless mine is wired wrong!
Troy
My TT has a automatic parallel switch that lets the 110 from shore power thru on priority. When the shore power goes out it switches to the inverter. So the only way to shut the fridge down completely is kill the 110 and the inverter.
elcaminonut69
12-03-2018, 06:53 PM
When you ran your refrigerator on the two GP 29 batteries, what was the battery charge level/end voltage after the 24 hours? I ask because if your batteries are typical "marine deep cycle batteries", most manufacturers recommend not discharging beyond 70% to prolong life. That equates to a battery voltage of around 12.3 volts. Many inverters will operate down to about 11.5 volts before they shut down from low input voltage. 11.8 VDC equates to a battery charge level of around 30%. Discharging "marine deep cycle batteries" to that low level repeatedly will shorten their usable life significantly.
I didn't check the batteries after but I will make it a point to next time I travel with it. I bought the Duracell Gel cell batteries from Sams Club to replace the original group 24 batteries. I normally only use the inverter while traveling and stay in a campground every night that I can. Work is taking me to Savannah right after the new year but it is only about 5 hours. I will get a battery reading when I get there and post it but with the cool weather I don't think it will use much. Hot weather seems to use the most battery which is understandable.
JRTJH
12-03-2018, 06:59 PM
I didn't check the batteries after but I will make it a point to next time I travel with it. I bought the Duracell Gel cell batteries from Sams Club to replace the original group 24 batteries. I normally only use the inverter while traveling and stay in a campground every night that I can. Work is taking me to Savannah right after the new year but it is only about 5 hours. I will get a battery reading when I get there and post it but with the cool weather I don't think it will use much. Hot weather seems to use the most battery which is understandable.
I'd be very interested in how much drain you have on your batteries and how low they go. If you can run 24 hours and keep them above 70% then you'll probably be "golden"... That said, if you're discharging them to less than 50% every time you tow, they probably won't last much past the warranty period. Something to consider, for sure.....
Getn off
12-03-2018, 08:09 PM
My TT has a automatic parallel switch that lets the 110 from shore power thru on priority. When the shore power goes out it switches to the inverter. So the only way to shut the fridge down completely is kill the 110 and the inverter.
Yes, that is what I meant. The fridge will run off the inverter when on and no other power supplying. If shore power, it will use that and bypass the inverter. If you pull shore power and have the inverter switched off, it will not supply power to the fridge.
Troy
elcaminonut69
01-01-2019, 04:39 PM
I'd be very interested in how much drain you have on your batteries and how low they go. If you can run 24 hours and keep them above 70% then you'll probably be "golden"... That said, if you're discharging them to less than 50% every time you tow, they probably won't last much past the warranty period. Something to consider, for sure.....
Ok I got to Savannah yesterday and checked the battery voltage which was 12.4 volts. The trip down was around 70 degrees average and took about 8 and a half hours total. With the cooler temps I don't think the fridge had to work as hard as a normal summer day. I suspect that the hotter the temp the more battery usage.
JRTJH
01-01-2019, 07:20 PM
12.4 VDC is about 70-75% charged, so if you started with a full charge, then 8.5 hours in moderately cool temperatures discharged the batteries to near the recommended limit. A longer trip or probably warmer weather would discharge them further as the refrigerator runs longer. It sounds "do-able" in the current situation and maybe OK for a bit longer trips, even in warmer weather. I wouldn't think it would be OK for a 90+F day with a planned stop over at a WalMart parking lot.
A second thought, do you have the trailer batteries connected to the 7 pin "charge line"? If so, then you're really using 4 or 5 amps from the tow truck (not much more amperage can flow through that little wire) as well as the 25% from the battery bank, so the actual battery drain was a bit more than the 25%...
Anyway, at least it works for this kind of travel. Enjoy your trip.
mlarryeliz
01-30-2019, 08:21 AM
Troy, good question; I have a similar set-up and a similar question. The dealer told me that one battery would "likely" power the battery "around" 12 hrs. We all know that its performance is dependent on many variables. Our unit has two batteries but I do not expect to get double the useage of one battery and there are many current draws on our 12v electrical system. For now we work hard to get to shore power as quickly as possible.
Enjoy!
Local150
01-30-2019, 09:18 AM
Troy, good question; I have a similar set-up and a similar question. The dealer told me that one battery would "likely" power the battery "around" 12 hrs. We all know that its performance is dependent on many variables. Our unit has two batteries but I do not expect to get double the useage of one battery and there are many current draws on our 12v electrical system. For now we work hard to get to shore power as quickly as possible.
Enjoy!
Not sure how much it helps,but while on the road I run the drug in gas, but also put a bag of ice in the freezer
Randallf
06-27-2020, 05:34 PM
Here are the inverter pics...
Troy
I have the same inverter however when I unplug from shore power my inverter does not automatically come on I have to reach underneath and push the button to turn it on. Am I doing something wrong? The other day I was traveling to the campsite and I pulled over at a rest area When I stopped I heard a beeping sound I open the side door and found out that the inverter was at 10.2 V my fridge when I got to the campground was at 50°. It took 2 1/2 days for the For the fridge to cool down to 38°. When I got home from the tripI took the batteries in to the RV shop and they were tested and found out one of them was bad. I did purchase a new battery and I got home charged it up and refrigerator took 2 days to get to 38 .The third day I checked the refrigerator and it was at 40°. Now I’m not sure if I need to leave the inverter on or turn it off please advise thank you. Randallf. 2017 Sprinter
Getn off
06-27-2020, 07:03 PM
If u have the same inverter as I do, make sure it is on when on batts only. When u hook up shore power it automatically uses shore. Once shore power removed, it will automatically switch back to inverter. I dont have to press the inverter on again.
I just make sure it is on without shore power, then it is pretty much set and forget at that point.
Troy
tech740
06-27-2020, 08:36 PM
They call that pass through. Nice thing is if you loose power at the campground it will run off battery also. You don't come back to a warm fridge unless it was long enough that the batteries are dead also.
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