Apartment fridge install

[Sabatical]

For this project i am replacing 2 way rv fridge with a 110v fridge. It is a 4.3cf Insignia brand from Best Buy.

The rv fridge worked fine but i wanted to see if it was possible to run a solar powered apartment fridge in our camper. Also it has a freezer that is twice the size of the rv fridges. My wife really wanted more freezer space.

We had a well used dorm fridge in the basement with similar power demands. I ran the used one for several days to test things out before making the purchase.

The pics below show the space that the rv fridge occupied and the new one sitting in it's place. After all the electrical is sorted out, the finish work will be done on the install.

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[SternWake]

 I ran the used one for several days to test things out before making the purchase.

What kind of test, Like did it turn on and get cold, or something more useful like using a Kill a watt and seeing how much electricity it actually used for the time it was on?
The Dorm/ residential fridges generally are not very efficient.  Also feel the sides of the new fridge when it is running. Some of them put the condenser( the part which vents heat remved from insulated box to atmosphere) in the sides of the fridge, and if one installs them in a cabinet with no air circulation, well this is like covering both sides of ones vehicle radiator with carbboard and wondering why the engine overheats.
REemember that these dorm/residential fridges are built around the minimum possible price/ max profit mindset, and the easiest way to save money/ reduce price, is by using the sides of the fridge as the condenser instead of a separate finned condenser on the backside with dedicated airflow to and around it.
Thjat little energy saver yellow sticker is along the lines of useless marketing and bereaurocratic ******** with 17 cent a KWH electricity from the grid powering it.

 

[Sabatical]

Today i finished the inverter install. I had purchased the Morningstar 300w pure sine to be dedicated to the fridge. I picked this inverter because it could handle the higher absorb voltages that sometimes occur in colder weather. It also would self reset if it shut off do to overvoltage.

After grounding everything i reattached to the battery bank and plugged in the fridge. It ran momentarily then popped the 3amp fuse on the ac out side. Well crap!

I ran a lead cord from the house and plugged the fridge in to make sure it was good. It was. It took a bit to figure out but apparently this model has a momentary surge to 5.6amps. Wow that's way more than expected. The rated watts for this fridge are 150.

Apparently this inverter will not work.

Pics are morningstar installed with 2 ga on the dc side and the romex is from the fridge receptacle. The power center mess is me connecting to the ground bus bar (chassis ground).

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[Sabatical]

What kind of test, Like did it turn on and get cold, or something more useful like using a Kill a watt and seeing how much electricity it actually used for the time it was on?
The Dorm/ residential fridges generally are not very efficient.  Also feel the sides of the new fridge when it is running. Some of them put the condenser( the part which vents heat remved from insulated box to atmosphere) in the sides of the fridge, and if one installs them in a cabinet with no air circulation, well this is like covering both sides of ones vehicle radiator with carbboard and wondering why the engine overheats.
REemember that these dorm/residential fridges are built around the minimum possible price/ max profit mindset, and the easiest way to save money/ reduce price, is by using the sides of the fridge as the condenser instead of a separate finned condenser on the backside with dedicated airflow to and around it.
Thjat little energy saver yellow sticker is along the lines of useless marketing and bereaurocratic ******** with 17 cent a KWH electricity from the grid powering it.

I don't have a kill-a-watt so the test was whether the batteries could keep up with it's demand for a few days. The test fridge was 110 watts.

I checked on it frequently and the test period happened to be a cloudy week here. We maintained soc well above 50%. In fact the whiz bang jr. on my midmite kid cc claimed more ah after the first full day. I attribute this to a rise in ambient temp and a full day of charging.

As you can probably tell, i am not an engineer. I do take calculated risks and am willing to work extra hours while i still have a job in order to test this stuff out. I like trying things to see if they work and i share here so that maybe others will benefit or say nope not for me.

I figured the new fridge would draw 90ah +/- on a warm day with a claimed 35% duty cycle. (20% @ 70 deg f. 35% @ 90 deg f.)

As far as cooling goes, the fridges sides are cool to touch. There will be circulation provided. The space has vents top and bottom for comvection cooling. The rear of the fridge will have approx 4" of open space. The sides will have a gap of approx 1.5" although that gap will be sealed on the front side so we don't have free airflow into the cabin.
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[Sabatical]

Currently the fridge is running quite happily plugged into our Bestek 1000w modified sine wave inverter. I'm pretty sure this will be upgraded at some point sooner rather than later. Maybe something better quality and big enough to run a drip coffee pot also.
At startup the voltage drops to 12.5 from 12.7 and bounces back up when it shuts off. The solar is currently in the resting stage. We'll see how it does overnite and i will report amp hour usage (from the charge controller readout) tomorrow.

Btw i should give system specifics.
Currently 260 watts of solar charging 225 amp hours of battery bank (2 trojan t105's). I will be reinstalling a second panel that we previously didn't need. The total watts will be 520.

If i find that 225ah isn't going to be enough, we'll consider doing something different for batteries. Ultimately i'd like to be using solar for everything except space heating. I have been considering a future change to 12v agm batteries in the 350-400 ah range. After reading Sternwakes experience with 12v agms, i think they would suit our needs well.

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[jonsun]

Someone linked an older thread the other day where a guy killowatted his over many days and it came out around 30A a day. Im skeptical but he did a pretty thorough job testing it. I think it was about half the size of yours.

 

[Sabatical]

Someone linked an older thread the other day where a guy killowatted his over many days and it came out around 30A a day. Im skeptical but he did a pretty thorough job testing it. I think it was about half the size of yours.

I noticed the other day that harbor freight has kill-a-watt meters in stock. Next coupon i get will go towards one of them. For now i have the midnite whiz bang jr amp hour reading but it will be nice to confirm it's accuracy. Either way, i will post here.

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[Sabatical]

Current readout as of 7:30pm.

I was mistaken about system status. It went to rebulk during the fridges initial startup cooling. It's now in bulk but no sun on panels so 0.0 amps and 0 watts coming in.

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[SternWake]

There is a similar device to the Kill a watt that measures start up surges. BradKW got one and had a thread on it. it was the same price as the KAW IIRC. Can't remember details as to how well it worked.

Also keep in mind my positive experience with my Northstar AGM is because i can meet its peculiar recharging demands. This means high amp recharging it when most depleted and holding absorption voltagr until amps taper to a specific level at which point it can be considered fully charged. It would not perform well on a solar only low and slow recharge diet. All AGMS like to be charged at upto 30 amps per 100Ah capacity when dischrged to the 50% range, and a solar only low and slow diet will not allow them to get close to their 'lab' rated cycle life.

The trojans t-105s would be way more resilient on a low and slow solar only recharge diet. AGMs are petulant princesses in comparison.

 

[Sabatical]

There is a similar device to the Kill a watt that measures start up surges. BradKW got one and had a thread on it. it was the same price as the KAW IIRC. Can't remember details as to how well it worked.

Also keep in mind my positive experience with my Northstar AGM is because i can meet its peculiar recharging demands. This means high amp recharging it when most depleted and holding absorption voltagr until amps taper to a specific level at which point it can be considered fully charged. It would not perform well on a solar only low and slow recharge diet. All AGMS like to be charged at upto 30 amps per 100Ah capacity when dischrged to the 50% range, and a solar only low and slow diet will not allow them to get close to their 'lab' rated cycle life.

The trojans t-105s would be way more resilient on a low and slow solar only recharge diet. AGMs are petulant princesses in comparison.

I was considering Lifeline batteries. About 300ah worth. I can provide approx 16 amps of solar charging and can set end amps for switching out of absorb. No room on the roof for anymore watts.

I was figuring that 300ah would give enough capacity that most days would start in the 80% soc range. Only nightime draw will be fridge.

I am going to install a 20 amp power supply next. I'll tie it into the cc to take advantage of it's charge algorhythm. It will be poweref by a small generator when needed. I'd like to go with a bigger power supply but the Kid will only take 30amps.

Given all that, do you feel fla is still the best choice?

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[SternWake]

Lifeline states a minimum 20% charge rate when cycled to 50% State of charge, 20 amps per 100Ah of capacity.

They also state there is really not recharging current too highas long a 14.4v@77f is not exceeded.

i would not recommend any plug in charging source which cannot meet this 20 amps per 100Ah of capacity.

Also regarding power supplies, these should have constant current on overload. There are many power supplies which have rollback current limiting or Hiccup limiting. Rollback will cut back amperage to some percentage of its capability, Hiccup will stop charging then try and restart then stop again, over and over as long as the battery bank can accept more than the power supply can output.

Safe to say that 300AH of lifeline could exceed 20 amps up until about 93% charged, perhaps higher.

While the higher amp recharging becomes more important the lower the AGM batteries are drawn, saying that most of the time they will not fall below 80%, is kind of a pipe dream as the times where it does go lower, well those higher amp recharges will be missed. Once can hold absorption voltage a bit longer or bump it up a bit more to try and offset some of that sulfation, but really when taken to 50%, blast low $$ AGMS with 30 amps per 100AH capacity and high$$ AGMS as much as can possibly be mustered.

How many less cycles will ultimately be achieved with less than ideal recharging is depepndent on many factors. Lifelines are Expensive. Their owners manual PDF has a lot of good information. I'd not disregard it unless accepting less of a cycle life is also acceptable. There are many reports of lifelines not living up to expectations and the root cause always comes out to being deeply discharged to 50% regularly, and never being high amp recharged. the owners usually say but but but I charged them to full each time. Does not matter if they do not ever get the high amp blast. Lifelines can also be 'reconditioned' which is very similar to a flooded battery equlaization charge, which can greatly extend the cycle life of flooded batteries when performed when needed.

Reconditionings will offset the low and slow solar only recharging, to some unknown and undefinable degree.

A well wired alternator and a morning highway drive for an hour might accomplish the high amp quenching when the batteries are well depleted, but then one is at the mercy of the vehicles voltage regulator. it will not hold 14.4v for very long and much less amps flow at 13.7 as do at 14.4v.

I recommend those with AGMS be able to quench them with high amps when they are depketed to the 50%range. I will intentionally deplete mine to 50% or lower, if it has been many cycles of low and slow solar aonly recharging, if I can provide my 90AH AGM with at least 40 amps charge current until the Solar can take over and hold it until amps taper to 0.45 or less.

I doubt I would be closing in on 600 deep cycles, several dozen well below 50% soc, without being able to do this. I don't see Lifelines shallowly cycled as handling a solar only diet very well either.

So unless one is capable of delivering at least 20 amps per 100AH of capacity, or can at least bump up absorption voltage hold it longer and occassionally to the 15.5v for 8 hour reconditioning as well.....well It is easier to be able to drain to 50% and blast them with high amps.

Bypass the Kid if you have to. Battery monitors need to be rezeroed anyway. Best to do so after a high amp recharge to a true full 100% state of charge. At least have the ability to do the high amp thing with AGMs.

I view the high amp recharge as the 'capacity reset' Does it reset it to like new capacity, of course not but it seems to restore it back to its full remaining potential capacity. When I notice voltage sagging lower than expected for the AH removed, ansd I know I can plug in or drive for an hour on the highway, then i will drain 65 or more Ah from the 90Ah total capacity, so that the battery can accept high amps for a lomng time before reaching absorption voltage.

i am overdue for this procedure, but have been house sitting and using less juice overnight, cycling just 18 to 30Ah per night instead of the usual 30 to 55Ah, and pretty much just allowing 200 watts of solar do its thing. I can tell voltage wise, at 18Ah from full inder x amput of load that it needs the high amp thing. It is just a matter of drining to 50% or less than plugging in or driving for at least 25 minutes on the highway, as i can set my vehicles voltage and hold it as long as I have 850+ engine rpms.

Flooded batteries also want a 10 to 13% charge rate, their ability to be equalized is really a sulfation beater, when performed regularly when needed. AGMS need the high amp thing when sulfation/ loss of voltage retainment ability under load for x amount of AH removed, becomes obvious.

But head in the sand/ignorance is bliss cannot be discounted either. Everything is just fine, until that day when it is not and replacement is required. Hopefully an acceptable amount of cycles have been obtained before that day

 

[Optimistic Paranoid]

My main concern with these dorm fridges is not whether you can get enough batteries and solar panels to make them work electrically.  I'm sure you can. It's whether they are mechanically rugged enough to take being bounced around in a moving vehicle. 

As Stern said, these things are built as cheaply as possible to sell as cheaply as possible while making as much money as possible.  That doesn't sound like a formula for "built tough to take it" to me.

My personal suspicion is that you're not going to get much longevity from a fridge like that under these circumstances. 

But that's just my suspicions.  Come back after a year on the road and let us all know how it's holding up.

 

[Sabatical]

I ordered a Meanwell sp-240-15 power supply. It does have constant current limiting.

As for the agm charge requirements... i don't forsee being able to provide the amount of amps you are suggesting with my current level of knowledge. That might be a blessing in that i will stop spending on upgrading and get back to applying extra toward the mortgage. We'll be just fine with our flooded lead acids for a good while if we continue cooking with gas and making coffee with the pour over cone rather than a drip pot.

Whether or not this Bestek inverter is up to the task will remain to be seen.

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[Sabatical]

My main concern with these dorm fridges is not whether you can get enough batteries and solar panels to make them work electrically.  I'm sure you can. It's whether they are mechanically rugged enough to take being bounced around in a moving vehicle. 

As Stern said, these things are built as cheaply as possible to sell as cheaply as possible while making as much money as possible.  That doesn't sound like a formula for "built tough to take it" to me.

My personal suspicion is that you're not going to get much longevity from a fridge like that under these circumstances. 

But that's just my suspicions.  Come back after a year on the road and let us all know how it's holding up.

I'll keep you posted.

I was thinking about the life it would live when making the purchase and added the 5yr extended warranty. Even if i had to buy a new one every five yrs at $180, i'd be ok with the $36 per yr that works out to.

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[tx2sturgis]

I like this.

I did almost the same thing in my old RV...I used a smaller, inexpensive 'dorm' fridge and ran it from shore power mainly, but also from an inverter when driving. I did not use solar on that rig for fridge power though...

One thing to keep in mind is ventilation of the sides, that is where the heat is dissipated when the compressor is running, so you need either good natural ventilation or a small fan to move air.

I sealed off the outside vent with foam board insulation, since that was not needed, and used a small vent fan that exhausted thru the roof RV vent.

I used a ratchet cargo strap looped over the top to hold it to the subframe I built for it, and the strap hooks attached to a couple of eye-bolts screwed to the floor of the compartment.  It never moved.

I then added trim with ventilation holes, plus an AC powered thermostatically operated duct-booster fan to gently move air when it got above about 80 degrees in the compartment.

Another concern expressed here is ruggedness, or lack of it.

Take my word for it, the shipping from overseas, truck freight in the USA, and handling by dock workers and store workers is a LOT rougher than the fairly smooth ride in a normal RV. The guts are designed to tolerate some vibrating around.

If this was going in an over-lander 4x4 rig, then yeah, I'd be worried.

You will need to use some type of stay to keep the doors closed during travel, (I used velcro) and you might have issues with the interior shelves bouncing around, I just used foam padding in the slots.

The last advantage is the cost of replacement. Very reasonable compared to a standard 2-way or 3-way fridge.

You can wear one out every 5 years and you still come out ahead after 20 years.

Good plan sir!

Keep posting updates please.

 

[Sabatical]

tx2sturgis
Thanks for the kind words and advice. All input is appreciated.

I hadn't thought about closing the outside vent and using a fan to exhaust warm air. That is worth considering. I had figured convection current would take care of it if vents were left as is, but air gap on sides of fridge would be dead space. That might work against me.

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[SternWake]

I'd think there is a difference when the fridge is being shipped and abused, versus actually having the compressor  running and being bounced around.  They might be susceptible to being run a few degrees off level as well.


BUt we do not really have enoiugh data to say whether the residential fridges do or do not handle the bouncing around in actual use.

I feel these residential fridges were not really made with efficiency in mind, and when run on an inverter seem to typically double the electrical consumption of the much more expensive 12vDC compressor fridges.

Much of this would depend on inverter efficiency and standby current.

My 800 watt MSW inverter draws 0.68 amps turned on powering nothing.  My 1.8 cubic foot danfoss averaged 0.62 AH per hour over 3 days in ~70F average ambient temps the last time I stuck my wattmeter on it.

So my MSW inverter turned on powering nothing, nothing even plugged into it,  uses more battery than does my 12v fridge, most of the time.

I view the inverter as Evil, a necessary one, that I rarely employ unless there is no other option.

 

[tx2sturgis]

Man, I agree with you Stern, as to efficiency, but here we have a man that is gonna let us know how well it all works...

I had good luck with mine, but it was a much smaller dorm fridge with a single door.

So it was much less weight, especially when full.

But I say go for it!

In his post he does say he wants to experiment with it...I'm all for it...

Sab, mine had free air flow from the bottom, from within the cooled airspace of the interior. About 3 inches of space on the sides, maybe 8-10 inches behind it, and about a foot above it, with the small duct-booster fan over that, blowing towards the fridge roof vent thru a curved P-Trap shaped 4" flex duct.

The booster fan was controlled with a cheap attic fan thermostat, set for about 80 degrees. It rarely cycled. Mainly on hot days or when the AC was off while I was away. On cool days it never came on.

The outside vent, I covered with foam board on the inside and used screws and spray foam to seal it all up. It looked the same from outside, and inside, no-one could see it except if the fridge was removed. This kept cooled or heated air inside the RV, and noise and bugs out.

I installed the inverter, upside down (inverted, see what I did there?) under the fridge subfloor, and then built a nice trimmed out storage cubby under that.

Dang, I wish now I had taken pictures....this was 10 years ago...I never even HEARD of cheap RV living back then....I was just doing it.

Anyway, I can tell you I had good luck with mine, for about 5 years or so. I still have the fridge, it still works, but the RV is LONG GONE!

Dangit...

 

[Sabatical]

I feel the same way about imverters as you do SW. That said, i choose inverter use over propane assuming i have enough battery capacity to make the deal work.
This fridge is the only inverter powered thing besides an infrequently used food chopper.
If my choice was propane or $1800 danfoss compressored 12v fridge freezer combo, i'd choose gas. We don't have the space, with our current layout and head count for a chest fridge and a chest freezer. I know we could do 12v for less than $1800 but fresh food is an essential part or our life and one area not to be skimped on. We could have two Whynter units but still be in the $1000 range.
Many ways to skin a cat. We'll see how this one works. If not, we're out $180.

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[Sabatical]

This Bestek inverter is right around .8 amps when on and powering nothing.
The Morningstar i wanted to use would idle down to .4 amps.


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