Need Advice - Refrigerator on separate Inverter

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Hi All! I have an older Class A Motorhome (1986 Champion Titan Signature). The previous owner had installed a residential refrigerator that runs on AC/DC only. So No Propane. Its never been a huge issue as we have mostly went to campgrounds where I could plug in. The setup itself is there's a toggle switch from AC to DC for the fridge, so it has it's own inverter and battery. That battery I believe is tied to my larger battery bank that is located up front of the RV. This year we have boondocked a good amount. After this last trip I decided something needs to change as the battery drains very fast. I have to run my generator ALOT/bring a spare battery, etc just to keep the fridge from faulting out. All the things you would imagine needed to keep enough power to run the fridge.

Anyway, I had resound to just buying a new fridge and getting one equipped for Propane. After looking into that, there seems to be a good amount of options out there to stick with the residential fridge setup and just go with Lithium batteries or other upgrades. I am not interested in going solar. I do have an 120W portable solar kit that I hardwired to my battery bank to help maintain things. I am leaning toward just putting a Lithium battery for the dedicated Fridge battery as it's got long life and would charge fast. It's just a large cost initially I want to be sure its a good option.

Does anyone have any advice/input on this? Much appreciated!

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I think I figured out my question on how that Fridge Battery is connected to the front two coach batteries. Where the + wire going from the Fridge Battery to the Generator connects to the Gen, is also the + large gauge wire that comes back to the Gen from one of the Solenoids up front. So I believe that explains how they are all tied together. Below is a pic where both come together at the Gen.

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MrWizard wrote:
I would want the inverter wire run directly to the batteries, with the biggest wire possible, I recommend using welding cable very flexible, makers it easier to route and connect
Using the generator path will make for a long run and voltage drop problems

The shure power isolator, let's the alternator charge house and engine batteries while keeping them separate, Lithium batteries can be safely discharged to a lower level than lead acid and recharged faster at more amps, so yes if you ran them down they could accept more charge than your alternator will produce, but you should only need to remove one wire to take the isolator out of the circuit to protect alternator

The relays aka solenoids provide battery combining for the EMG start button (jump start the engine from the house batteries) and battery disconnect function for RV storage,

Battle Born drop in replacement Batteries are supposedly compatible with existing RV electrical
But you do not float charge them, aka leave them on charge full time while plugged in to shore power,

Thanks for all the help here. Battle born is supposed to call today. Seems that it should be pretty doable to do the swap being that I am not great with electrical I am a little hesitant to do it myself. We will see what BB tells me today after they answer my questions.

The main thing I am not sure of at this point is what to do with that hot wire that currently runs from the generator to the Fridge Battery. If I route that battery up front to a new location, I will then need to run that same wire all the way up front, but to do that i'll need to increase the wire size, yes? Would I keep the fridge inverter at its same location at the fridge and just run that Weld cable you mention from the inverter to the battery up front?

You previously asked where the Power Converter was. Its in the kitchen area which is middle of the RV. I am pretty sure it's connected to the Generator and thats how that third battery at the fridge gets tied to the other two batteries up front.

If all else fails, I could just keep everything as is and just get myself a 3 way fridge and hookup to my Propane or look at a DC compressor fridge and see if those would draw a small enough amount of power to work for our needs. I just really like the idea of going Lithium.

[MrWizard]

I would want the inverter wire run directly to the batteries, with the biggest wire possible, I recommend using welding cable very flexible, makers it easier to route and connect
Using the generator path will make for a long run and voltage drop problems

The shure power isolator, let's the alternator charge house and engine batteries while keeping them separate, Lithium batteries can be safely discharged to a lower level than lead acid and recharged faster at more amps, so yes if you ran them down they could accept more charge than your alternator will produce, but you should only need to remove one wire to take the isolator out of the circuit to protect alternator

The relays aka solenoids provide battery combining for the EMG start button (jump start the engine from the house batteries) and battery disconnect function for RV storage,

Battle Born drop in replacement Batteries are supposedly compatible with existing RV electrical
But you do not float charge them, aka leave them on charge full time while plugged in to shore power,

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MrWizard wrote:
Moving the 3rd battery will keep all house batteries at the same voltage,
But unless you replace the wire going to the inverter larger gauge wire going directly to the batteries, the inverter will still see voltage drop on fridge compressor start up

The battle born tech is referring to charging voltage at the battery

Yes if I relocated the fridge battery to be up front I figured I would have to change out that wire going back to the inverter. That seems pretty straight forward but the hot wire at the Fridge battery now goes back to the Gen so not sure what to do with that existing wire? Maybe just run it all the way up front to the same battery at its new location? So its essentially hooked up the same as now, just up front. Or could I connect that hot wire from Gen thats at the fridge now to the + side of the Inverter?

The harder question is them referring to having to remove the isolators and BIRD relay. That I am not comfortable doing myself if he means removing all 3 solenoids. The Sure Power isolator (pic above) I have now I thought was doing what he said could happen in terms of overtaxing the Alternator or draining the batteries when not turned on. I thought that isolator was preventing that already. I also have a main shutoff on the left of the battery bank you can see in the pictures on my original post.

[MrWizard]

Moving the 3rd battery will keep all house batteries at the same voltage,
But unless you replace the wire going to the inverter larger gauge wire going directly to the batteries, the inverter will still see voltage drop on fridge compressor start up

The battle born tech is referring to charging voltage at the battery

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MrWizard wrote:
The Fridge battery wire probably goes up front
To a post on one of the solenoids,
It is also possible that it goes directly to the wiring from the converter that leads to the house batteries up front, is your circuit breaker power center in the kitchen area near the fridge, your converter for charging is part of the power center

It is being charged by the converter when the generator is on , or plugged into shore power just like the two house batteries up front,
Most likely the 3rd battery was not installed at the same time as the fridge and inverter, but the voltage drop from the long wiring path (all the way up front) was too much and the inverter would give a low voltage fail when the fridge kicked on, so the third house battery was installed at the fridge to alleviate the problem
All 3 house batteries are parallel, and supply power to fridge and house unless some how disconnected from each other,
The inverter is dedicated to the fridge, but that battery is Not the only one powering the inverter

The blue finned box with battery cables is the diode based battery isolator that charges your batteries from the ALTERNATOR when the engine is running, it keeps the house batteries separated from the chassis/engine battery

Thank you, this helps! Yes from what I recall the previous owner had added the battery at the fridge himself along with the inverter. I never did get the reason, but that makes sense as you describe. The isolator is from Sure Power Industries and below is a pic of the label. Says its meant for 1 Main battery and ! Auxiliary.



I did get a response from Battleborn today I think I need to call them to see if we are all on the same page as I thought I would be okay dropping in the Lithium batteries since I have the isolator in thereI. But I am not a professional. I would love to clean up all the wiring/batteries but there is so much wiring going on besides batteries I don't want to screw things up.

Their response below:

"I had a conversation with my techs here and we went over the system together.

With your current set up, you would need to remove the isolators and BIRD relay from the system to function properly with Battle Born Batteries. After some research on the relay system, it looks like it will always be connected when the batteries are 90% or above, which could lead to issues with overtaxing the alternator, and it staying continually connected even if the engine is turned off.

We also discussed the 3rd battery back in the middle portion of the coach. I think that this battery would need to be moved to the front so that voltage drop can be minimized from the batteries to the inverter.

let me know your thoughts, and we will see what we can do."

[MrWizard]

The Fridge battery wire probably goes up front
To a post on one of the solenoids,
It is also possible that it goes directly to the wiring from the converter that leads to the house batteries up front, is your circuit breaker power center in the kitchen area near the fridge, your converter for charging is part of the power center

It is being charged by the converter when the generator is on , or plugged into shore power just like the two house batteries up front,
Most likely the 3rd battery was not installed at the same time as the fridge and inverter, but the voltage drop from the long wiring path (all the way up front) was too much and the inverter would give a low voltage fail when the fridge kicked on, so the third house battery was installed at the fridge to alleviate the problem
All 3 house batteries are parallel, and supply power to fridge and house unless some how disconnected from each other,
The inverter is dedicated to the fridge, but that battery is Not the only one powering the inverter

The blue finned box with battery cables is the diode based battery isolator that charges your batteries from the ALTERNATOR when the engine is running, it keeps the house batteries separated from the chassis/engine battery

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Update!

Hey guys so I did a little digging on the electrical setup on my RV. And I am confused. As a reminder this is how I bought the RV back in 2016 in terms of the battery setup. There is 1 chassis battery up front for cranking, 2 more batteries up front for Coach and a Battery at the Fridge that is (I believe) also connected to the other 2 coach batteries up front. The first photo below shows the battery at the Fridge. I thought the cable I am holding went up to the other 2 batteries since it carries a load, but after tracing, it goes back to the onboard generator. So that explains how it charged when I am running the generator. When I unhook that same cable from that Fridge battery, it still has power though and the generator is NOT running. I never traced it until today as I just assumed it went up front to the other batteries since it was carrying a load while not plugged in and not running the Gen. The fact that the cable has a load without hooked to the battery and without Generator on its got to be getting power somewhere?? The Voltage on the battery noticeably increases when I plug into shore power, so to me that battery is getting power somewhere when plugged in??




The other pics shows the battery bank up front. All three battery grounds go to the main shutoff you can see on the very left. I see a total of 3 solenoids. I tried to get a pic of all three together so you all can see where cables/wires run but it was tough to get it all - Its a bit of a mess 🙂 I haven't touched any of that stuff as I am afraid to mess something up. There is so much electrical going on it's a bit intimidating. I am not sure with this setup if these batteries are considered in Parallel? Which gets me back to my original questions on going with the Lithium battery setup. I have been in contact with Battleborn and their customer service has been top notch so far. I sent them a few pics and am waiting on their recommendations. If I cannot just drop in the batteries I will likely just stay with how I have it set, but from what I have explained to them on the setup, they seem sure that just dropping the Lithium batteries in will be just fine. Anyone have any input on all these solenoids? From what I could tell 1 solenoid is standard and goes to the starter. Another goes back to the Generator and I will have to check on the other. But they all seem to be connected to each other which explains why I also charge while driving down the road. Anyway, a lot to unpack here but appreciated any and all help!







Threw is a side view for the heck of it 🙂 May post a few inside as well as thats been updated quite a lot. Thanks all for any input you can provide! Oh the joys of an older motorhome. I must say I do love it though.

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theoldwizard1 wrote:

rcksblr wrote:
I already have the Fridge. Previous owner put in a Danby 7 Cubic Ft. It's wired to a switch for AC/DC. I also have an 1000W inverter dedicated to the fridge for that setup.

Okay, I am official CONFUSED !

I am guessing you don't have accurate wiring diagram so I am going to make an ASSUMPTION ! I do not believe that Danby makes a DC compressor refrigerator. It is an AC powered refrigerator with a dedicated inverter. The switch either connects the refrigerator to shore power (AC) or to the inverter and battery (DC). Not sure how that battery gets charged.

How long you want to boondock, WITHOUT running the generator is the key point. The simplest solution is to just replace the current battery with a lithium battery. The size depends on how long you want to run the inverter and refrigerator before firing up the generator.

If you do this, you need to find out how that battery is charged and replace that charging source with a lithium battery charger.

Last and probably MOST IMPORTANT is install a good battery monitor on that lithium battery, like a Victron Energy Battery Monitor. Now you can tell from a quick glance how much longer you have before your battery will no longer run the inverter (i.e. you need to charge the battery)

You are correct, sir! It's AC Fridge w/dedicated inverter. There is no wiring diagram and to be honest being an older motorhome the wiring is quite a mess as its been changed/modified by previous owners through the years. Plus I am no expert, just an average guy when it comes to electrical.

The current battery setup is there is a chassis battery (for cranking) and three coach batteries. 2 of the 3 coach Batt are up front next to the Chassis battery and the other coach battery is located at the fridge, but it's wired to the other 2 coach batteries up front. So, all 3 batteries are charged by converter charger when plugged into shore/generator running. This is at least how I have traced it out.

I called Battleborn and after speaking with them, based on my current setup they recommended me changing all three coach batteries to Lithium, installing a battery monitoring system and using a Lithium battery charger to charge up the batteries when running my generator/plugged in.

[theoldwizard1]

rcksblr wrote:
I already have the Fridge. Previous owner put in a Danby 7 Cubic Ft. It's wired to a switch for AC/DC. I also have an 1000W inverter dedicated to the fridge for that setup.

Okay, I am official CONFUSED !

I am guessing you don't have accurate wiring diagram so I am going to make an ASSUMPTION ! I do not believe that Danby makes a DC compressor refrigerator. It is an AC powered refrigerator with a dedicated inverter. The switch either connects the refrigerator to shore power (AC) or to the inverter and battery (DC). Not sure how that battery gets charged.

How long you want to boondock, WITHOUT running the generator is the key point. The simplest solution is to just replace the current battery with a lithium battery. The size depends on how long you want to run the inverter and refrigerator before firing up the generator.

If you do this, you need to find out how that battery is charged and replace that charging source with a lithium battery charger.

Last and probably MOST IMPORTANT is install a good battery monitor on that lithium battery, like a Victron Energy Battery Monitor. Now you can tell from a quick glance how much longer you have before your battery will no longer run the inverter (i.e. you need to charge the battery)

[wa8yxm]

2oldman wrote:
I don't understand your reference to AC/Dc for fridge. A lithium battery is not going to solve your problems, it's still just a 100ah battery from which you can draw a bit more power than an acid.

There are 3 or 4 types of AC/DC fridges
ONE: Original type: Absorption cooling unit
This is the "Standard" propane is an option RV Fridge without the propane options. Nothing fancy sucks over 300 watts when cooling takes a LOT of 12 volt power

Residential fridge with Inverter Sucks 100-200 watts running

High effiency what I call "Danfoss" class (Danfoss is ONE of the companies that makes the compressor. not sure the real class name) Draw about 30-45 watts running door closed (Opening door adds 20 watts for the light)

Both Norcold and Dometic made "RV SIZE" fridges of this type. IF uou do not want to go Propane. that's what I suggest doing. IF you are good with propane.. So am I.

[2oldman]

rcksblr wrote:
One of the main selling points (Li) for me was the longevity of the battery itself along with being able to charge up quickly when running the generator.

I'm a lithium man myself, and yes they charge crazy fast and don't care what state of charge you leave them in. My Li pack will probably outlive me.

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time2roll wrote:
I would not mix the lithium with the other batteries. I would replace ALL the house batteries with lithium. Otherwise you will be managing two different banks with different charging etc. Verify the charging system specs match the lithium battery before you purchase. Even with the increased usable capacity you may still need to increase capacity until you are comfortable withe the power duration. I would want capability of 48 to 72 hours minimum between charging even if you charge daily. This capability for if something goes wrong. You will know more what you need after a few nights off-grid.

This is something I was going to ask separately. Kudos to you! I'm not expert on this subject so it crossed my mind to change them all for the very reasons you mention. I like the idea and piece of mind knowing we can go some time with just batteries. Just this last trip I had to pull the carb off my Onon generator because it stopped running. Choke was sticking. But boy to replace all the batteries to Lithium that a pretty penny when the batteries cost $900 bucks! Thanks for the input here.

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theoldwizard1 wrote:

rcksblr wrote:

Anyway, I had resound to just buying a new fridge and getting one equipped for Propane. After looking into that, there seems to be a good amount of options out there to stick with the residential fridge setup and just go with Lithium batteries or other upgrades. I am not interested in going solar. I do have an 120W portable solar kit that I hardwired to my battery bank to help maintain things. I am leaning toward just putting a Lithium battery for the dedicated Fridge battery as it's got long life and would charge fast. It's just a large cost initially I want to be sure its a good option.

Does anyone have any advice/input on this? Much appreciated!

Do you boon dock much ? If so for how long ?

You still have to decide if you want a DC only refrigerator or do you want a residential unit and then an inverter. The residential refrigerator will cost less, but then you have to adding in the cost of the inverter. Most DC only refrigerators have an optional AC power supply that you can use when on shore power, but that is not adequate for recharging a dedicated battery.

If you have no interest in an inverter for the rest of your coach, perhaps a separate battery just for a refrigerator but it might be a good option ! If you only boondock for a couple of nights, I think a 30Ah-50Ah refrigerator dedicated lithium battery would be adequate. Buy a dedicated lithium battery charger and wire it, the battery and the refrigerator positive leads together. Same for all of the negative leads together.

I already have the Fridge. Previous owner put in a Danby 7 Cubic Ft. It's wired to a switch for AC/DC. I also have an 1000W inverter dedicated to the fridge for that setup.

We don't get out a ton the last couple years as we are a young family. Have newborn and toddler. When we do go, about 50% of the time we boon dock. We just got back from a boon dock trip where we camped 5 days. The Fridge lasted the whole time, but I had to run the generator in the morning and then again in the evening; plus after 3 days I swapped the Fridge battery with an extra fully charged battery I new I would likely need. I can get creative and make it work, but moving forward wanted to get setup so it's a non issue.