Adding a new DC Fridge during a LA Heatwave

[themexicandoctor]

The original thread was BATTERIES GONE ... which you can find here;
https://www.classbforum.com/forums/f...e-10996-6.html
But the Batteries weren't gone, I simply replaced my Dometic RM2354 3 Way* Fridge with a Novakool R3800, a 3.5 cubic feet DC Compressor Fridge.

And while I instantly noticed "the tax" on my electrical system via demands on my Solar System it wasn't until a day or before this ridiculous Heatwave did I have to pay attention ie; one 12 hour, 7.30pm-7.30am nighttime period of a 52 amp hours draw, 12 of which I will say was a Fantastic Fan & then a Carado Yacht Fan combined draw.

[themexicandoctor]

The Lifeline Batteries Group 27 AGM 100AH units are 2 years old & performed perfectly on the capacity testing.

Bulletproof!

But in going backwards & forwards with Novakool, absorbing your input & talking with my installer today & the advice of Rod Lambda (AC & Refrigeration Guru), it appears that on today's initial inspection;

1. The existing gauge wire the installer plugged into was in fact, 10 gauge. All Crimping, etc looks fine.

2. The unit is running almost constantly at 2.1amps according to the Clampmeter.

The Fan most certainly hasn't stopped since install.

3. Next week when they install my new under bed battery system, they will do a deeper inspection.

4. The fan, is only there to keep the module cool & the installer said the unit has plenty of ventilation with the existing Roadtrek upper & lower grills.

The Compressor has always been warm to touch but not impossibly hot, as it is, he said it doesn't need a fan on the compressor.

5. It appears the issue is the HEATWAVE we are experiencing, today was hazy in Burbank with 99 degrees.

Here are four temperature snapshots of my rig at 2.30pm today with an outside temperature of 99 degrees.

116.0°F Drivers Seat Area

97.4°F Under the Rear Bed - the inverter was OFF

103.4°F In the Rear Lounge Sleeping Area - with the Fantastic Fan in the center of the rig @#2 speed of 3 & a Carado Fan at high in the rear

38.8°F in the Novakool Fridge - sensor attached to the rear wall

[themexicandoctor]

My goal is in lowering my amp hour draw, if at all possible, in the future, post heatwave, by 15-30%.

There is another unit called the Novakool R4500 which .7 cubic feet bigger internally & fits into the same dimensions as this unit but for the fact it is 3" deeper but its a 4.4amp hour unit* & it appears thst is how Novakool measure amo hour draw even though in normal weather, the unit should run on average q2 hours per 24 hour period. That unit uses a BD50 versus the BD35 I have. The Engineer was very clear, for my needs, the R3800 is perfect.

I don't know if it has any bearing, but I live in Southern California & Novakool is in Canada.

I do have a suspicion once this Heatwave passes, the lower demands, some driving & my solar will be sufficient.

Not interested in keeping IceCream* hard.**

But always keeping the fridge below 39.0°.

Would supplying one of the interior fridge trays with a series of cold ice blocks (created by the Freezer), give me that advantage?

I know a couple of you mentioned "variable speed/more thermistors/etc", again this is a little beyond my understanding, certainly I would be adrift explaining these concepts to the Head Engineer.

The unit is only set to 4.25, its not digital, that is my interpretation of the manual setting between the lowest @1 & the highest @7.

Having said that & knowing that fan never stops during the day, would putting the unit to say a setting of 4.5 or 5.0, have a positive effect since the unit is already running (the fan that is)?

After all the Engineer did say that 2.2amp hours is the unit running nonstop. And the Guru said it cannot be affected by start up spikes because of its design.

Any suggestions, and, if they are technical, could you please supply with terminology only an Engineer would understand.

*Novakool are very clear & on their website is a pdf file on the composition of Ice Cream * how their unit will NOT keep it hard.

**I chose Novakool for many reasons, I am sure there are many purists that say "if you cannot keep ice-cream hard, your system is a failure ..." But I am not qualified to answer that.

[GallenH]

Originally Posted by themexicandoctor

one 12 hour, 7.30pm-7.30am nighttime period of a 52 amp hours draw, 12 of which I will say was a Fantastic Fan & then a Carado Yacht Fan combined draw.

Wish I could figure out how to quote from 2 different posts. But.........

What I don't get is that if I follow what you've said, 52AH draw with 12 AH owed to the fans = 40AH to the fridge. Ok: some is also going to the LP and CO detectors. But still that's over 3AH draw from the fridge if it was running continuously. Yet in your 2nd post you state the documented draw on the fridge is only 2.1AH. Do you know why there is this discrepancy?

And did you say that your original LL batteries test ok; and you're still replacing them?

Not arguing with you.........just trying to figure out what's going on.

[avanti]

Originally Posted by GallenH

Wish I could figure out how to quote from 2 different posts.

1) Click on "MULTI-QUOTE" at the bottom of each of the messages.
2) Click "POST REPLY" (at the bottom left).

[themexicandoctor]

Here are some readings from my Sensorpush Bluetooth that I attached to the rear wall.

In the first you see the present temperature at 39.8 with an average of 31 to 41 degrees however this am I saw it as low as 21.1 degrees.

Then over the the Hourly average you see it falling from 40.3 - 39.8.

Then a daily low of 21.1° all the way up to 42.9*.

*this may have happened because we had the fridge turned off while inspecting it.

Then a weekly average of 33.6 - again that ridiculous #of 46.2 was when I had the unit off & the door open trying to find some answers.

[themexicandoctor]

Originally Posted by GallenH

Wish I could figure out how to quote from 2 different posts. But.........

What I don't get is that if I follow what you've said, 52AH draw with 12 AH owed to the fans = 40AH to the fridge. Ok: some is also going to the LP and CO detectors. But still that's over 3AH draw from the fridge if it was running continuously. Yet in your 2nd post you state the documented draw on the fridge is only 2.1AH. Do you know why there is this discrepancy?

And did you say that your original LL batteries test ok; and you're still replacing them?

Not arguing with you.........just trying to figure out what's going on.

I appreciate the detail Mate!

Spoke about that 12 hour period of 52 amps at length with tje Head Engineer (I did not account for the LPG, CO2, etc) & he felt at the time that there was another draw not being accounted for ie; 12 x 2.2amps = 26.2ah.

Plus 12ah from the Fans approximately.

Then I remembered an extra source, I have a computer fan installed under the bed to exhaust hot air produced by the inverter (it blows it into the space where the legs go when sitting at the dinette), if I turn the inverter on.

AND I forgot to turn it off.

Testing it now it runs approximately .35ah x 12 hours is another 4.2ah.

26.2ah
+ 12ah
+ 4.2ah
= 42.4ah

And I may have had some lights on & even the water pump may have been on but not running (however it does run intermittently every now & again if it is not turned off at the wall).

This was 4 nights ago, I was on Shore Power the last 2 nights.

I have yet to figure out how much those safety sensors draw.

[themexicandoctor]

So it appears, worst case scenario - think a continuous Heatwave until the end of Eternity, my rig is destined to consume a minimum 26.2ah every 12 hour period or 52.4ah just to run the new DC Fridge.


Plus whatever other usage in terms of Lighting, Water Pump, occasional use of Inverter, an average of an additional 30-48ahs per day, without running the motor or starting the generator.

For a daily total of 82-100ahs.

Which is an average of 984 -1200 watts per day if I am using Solar alone.

[themexicandoctor]

I made an error of attributing the extra 13amps to the fridge, my mistake which I will clear up with Novakool by email tonight.

I most certainly did not realize until later Monday that the inverter fan had been on, all that time.

There is talk of building a chimney versus the space I have behind the fridge, its 20.5 inches wide, over 35 inches high & its about 6 inches deep.

The way the lower vents works, there seems to be adequate airflow.

And the upper grill extends at least 7 inches above the top of the fridge.

There is a small area of which I could affix a piece of Reflectix to.

Knowing that the fridge compressor doesn't need the fan, its there only to keep the electrical block cool, I wonder if adding an extractor fan is worthwhile?

[themexicandoctor]

I make $0.14 Canadian if you buy a Novakool Gallen.

[themexicandoctor]

Today was a normal day & I earned a 900 watt yield from Solar alone with about 20 minutes of driving not included in the graph.

The last 2 hours there may have been some tree shadows.

Ignore the graph from the previous 3 days, 2 days I was on shoreppwer & the solar was unaware to my rig being worked on.

[themexicandoctor]

Ignore the graph columns from the previous 3 days, 2 days I was on shoreppwer & the solar was unaware to my rig being worked on.

Here you see 7 hours & 26 minutes in Bulk.

1* minute only in Absorption

5 hours & 40 minutes in Float.

*I need to address the Absorption, I just moved it from 6 hours to 4 hours only. I think y hours of Absorption using Solar is okay because it does switch to Float automatically**.

**I presume it does anyway

[GeorgeRa]

You could consider Isotherm Smart Energy controller. It operates the unit at a variable speed / higher efficiency and it lowers set temperature in the fridge if charging voltage is available. It was originally developed for marine folks. You have AC/DC Danfoss controller so it is no plug and play application, some wiring is necessary. The unit was designed for Danfoss DC for simple plug and play installation. I posted earlier installation diagram. We like it, it is flawless for the last few years.

https://www.youtube.com/watch?v=F2hAWqFVkUI

https://www.youtube.com/watch?v=MeP7X1K3v5c

[themexicandoctor]

Originally Posted by GallenH

Wish I could figure out how to quote from 2 different posts. But.........

What I don't get is that if I follow what you've said, 52AH draw with 12 AH owed to the fans = 40AH to the fridge. Ok: some is also going to the LP and CO detectors. But still that's over 3AH draw from the fridge if it was running continuously. Yet in your 2nd post you state the documented draw on the fridge is only 2.1AH. Do you know why there is this discrepancy?

And did you say that your original LL batteries test ok; and you're still replacing them?

Not arguing with you.........just trying to figure out what's going on.

I have had, for the past 5 years, 2 x Lifeline Group 27 Batteries 100ah, mounted in the Roadtek 190 configuration;

1 behind* the rear wheel & then another one in the optional space in front of the rear wheel attached with 6 feet of cabling. This difference in length cumulatively causes an imbalance of which I hadn't accounted for.

*yesterday driving I saw the reer battery which has a Vivtron sensor reach a record 46° & then climb to 52° or 125° F.** This is because of the Heatwave & very importantly, the Battery sits behind & on top of the Chevrolet exhaust!

**while at Lifeline, Andrew explained to me how the US Military tested Lifeline AGM Batteries in a controlled laboratory environment with the heat at a constant 125F - the batteripergormed flawlessly after 365 days! I worked many times in the Middle East for 32 years & 120° is not unusual for months.

In August 2018 I replaced the near new Lifelines.

Not because they were faulty but until that day, I was only charging via anytime I ran the Inverter (rarely), or when I ran the motor & I know that because I lacked today's knowledge of sulfation, etc I was probably abusing the batteries.

added the Victron BMV712 Smart Meter & a Victron MTTP 75/15 Controller along with a Go Power 170 watt kit, gave the PWM Controller to the Installer because of adding the Victron MTTP.

A few weeks later, I added another 80 watt panel. This meant the little MTTP Controller was always working too hard. Three months ago I upgraded to a Victron MTTP 30/100 & instantly, the big heat sink ran cooler & i got better yields.

Fast forward to today; I want the best system I can build & while at Lifeline I got 2 new Lifeline Group GPL 4CT 225ah 6 Volt batteries & they fit, under my bed.

Next week I am going to place them up against the old electrical box which used to house the TrippLite 612RV unit Roadtreks came standard with in 2005.

This way, after gathering all the info published before me, the batteries will have the shortest possible run to where the Solar comes down off the roof & runs to that box & the Shunt.

The almost 2 year Group 31s passed the capacity testing with flying colours.

But they won't fit under the bed close up against that box & being a Perfectionist, I wantbto start with a new slate.

As it is, the same time I added Solar I gave away the TrippLite (piece of junk), & replaced it with a Magnum MMS1012 Pure Sine Wave Inveter.

That inverter is nstalled outside of the box, upside down & attached to the under bed, to the rear of the original electrical box.

At the moment I have a huge subwoofer which I will place somewhere else or put in a smaller unit.

So I will either move the batteies further to the rear where the door is that defeats the purpose of a short cable run, or, have the installer move the Magnum back about 10 inches.

I will enclose photos next.

So Yes, whenever I can, I pay for the best equipment,based on what I have learnt from people like you here & that includes giving up perfectly good Lifeline Batteries with less than 20% of their life, in order to reach Electrical Nirvana.

[themexicandoctor]

Here are some photos of where the new batteries are going to go, there are two photos of "The Box", one showing the old MTTP unit & then the bigger one.

No wonder the Tripplite fail to perform, frequently gettting too hot - there was no air circulation.

Any answers from The Giants amongst us as to whether or not, its better to have the Batteries sitting closest to the shunt, etc or leaving the inverter & installing the batteries at the end of the rear luggage area?

[themexicandoctor]

Originally Posted by GeorgeRa

You could consider Isotherm Smart Energy controller. It operates the unit at a variable speed / higher efficiency and it lowers set temperature in the fridge if charging voltage is available. It was originally developed for marine folks. You have AC/DC Danfoss controller so it is no plug and play application, some wiring is necessary. The unit was designed for Danfoss DC for simple plug and play installation. I posted earlier installation diagram. We like it, it is flawless for the last few years.

George,

Thank you!

You know I looked at the Isotherm ITEC & ISEC Systems as an add on when I was deciding between the Novakool, Vitrifrigo or Isotherm 85 or Isotherm Cruise 100.

I reaeatched everything about them & how people with the ASU's had issues sometimes, etc, especially on boats & in Sportsmobile Vans.

I won't pretend to understand the intricacies of how it works but I do know when more current is available it essentially stores more cold energy into the unit.

But I never thought to see if it would work with the Novakool system?

Will send an email to them tonight.

[themexicandoctor]

But are you using yours in a Novakool unit?

[booster]

I think there is one simple question to ask Novakool about the energy use and the temp swings.


If the unit is "tracking" the outside temperature, eg hotter when it is hotter outside. It has the be running out of cooling capacity.


If the unit is only pulling 2.2 amps running, it is set at the lowest, or very close to lowest, running speed per the charts that have been posted earlier.


The slower the speed of the compressor, the lower the cooling capacity of the unit is per those charts.


Thus, here is the question for Novakool



Why has no one told me to turn up the speed and given instructions how to do it?

This is a separate issue from the power use, sort of, but both can be related to poor ventilation, also.

[avanti]

Originally Posted by themexicandoctor

Knowing that the fridge compressor doesn't need the fan, its there only to keep the electrical block cool, I wonder if adding an extractor fan is worthwhile?

As several folks have advised, the way to answer this question is to measure the temperature in the free air space behind your unit. If it is significantly above ambient after the unit has been running for awhile, then adding a fan will likely help. If not, then convection is doing its job.

[tgregg]

Originally Posted by GeorgeRa

You could consider Isotherm Smart Energy controller. It operates the unit at a variable speed / higher efficiency and it lowers set temperature in the fridge if charging voltage is available. It was originally developed for marine folks. You have AC/DC Danfoss controller so it is no plug and play application, some wiring is necessary. The unit was designed for Danfoss DC for simple plug and play installation. I posted earlier installation diagram. We like it, it is flawless for the last few years.

George / TMD,

Isotherm has a newer unit that works with either a DC only or an AC / DC Danfoss controller called the 'Isotherm Intelligent Temperature Control'.

It adjust compressor speed, provides fast cool and overcool to provide 30 - 50 % energy savings and it's more user friendly than the ISEC unit. It doesn't use dip switches and has an external display for programming, setting the temperature and displaying the refrigerator. temperature.

it works with any refrigerator that uses the Danfoss / SECOP compressor and the appropriate Danfoss controller.