Lessons learned while moving from a 3 Way to a DC Fridge ...

[themexicandoctor]

The original thread; https://www.classbforum.com/forums/f...ave-11025.html

1. Make sure that not only do you have the Solar & Battery Capacity to accommodate the increased amp hour draw but that your System is in perfect condition.

I attributed my "teething problems" to the Novakool R3800 I installed when in fact it had NOTHING to do with the new fridge but EVERYTHING to do with a loose ground/negative connection near the shunt (?), on my DC Charging system.

Yours truly was the problem, NOT Novakool & because I had very little demand before adding the Fridge I was blissfully unaware of the issue until closer examination by a RV Professional.

The issues of continual cycling, high amp hour draw were all symptoms of this poor connection that was suggested as a possibility from the beginning by the Head Engineer of Novakool.

Novakool Suport was phenomenal, I was put in touch with their Head Engineer as mentioned, in fact he would call me each morning to follow up & make sure I was happy.

2. My suggestion, unless you are technically gifted, have your Solar & Battery System set up by a Professional & if like me, my system was 18 months old, have it checked as per #1 prior to installing the fridge.

My system may have been running at a loss for 12 months or more, having worked its way loose under the bowels of my Chevy.

3. Ensure that you have a reliable way of reading your usage, I have a Victron BMV712 that for a while I was doubting but now that MY Connection issue has been resolved, the unit is Golden.

I also have a Victron MTTP 30/100 Charge Controller, ditching the 15/75 unit as 250 watts was pushing it to its limits (it would have been fi e because I started with a 170 watt Go Power system but gave the PWM Controller it came with to my installer & instead, added the Victron but a month after, I added a second 80 watt panel & this was pushing the 15amp Controller to its capacity).

Make sure you have good batteries*. I only buy Lifeline AGM's & presently have 2 x Group 27 100ah 12 volt units that I thought could also have been the problem despite never, ever having an issue with Lifeline.

2 weeks ago we gave them a Capacity Test & even though my rig system was faulty, after 2 years they passed with flying colors.

*despite being configured in the Mickey Mouse Roadtrek Versatile configuration, one unit behind the rear passenger side, on top of the exhaust (last week I recorded a record high of 52 Celsius traveling on the freeway), and the other 3 feet away (6 feet of cabling), in front of the rear tire & then a long run to the shunt on the drivers side of the vehicle. There is a work around that Booster detailed before in order to correct what is an imbalance if charging because if this distance bit by the time I had done that it would have been 50% as expensive of the reconfiguration below which is far superior.

*in a week or so the rig will be reconfigured with the batteries being moved up under the bed behind the drivers side rear door. I had already purchased 2 x Group L4CT 225ah 6 Volt Batteries because I was going to have them placed next to the battery box & the 6 volts fot better than the 12 volts in the space between the rear tire well & that box but I might just keep the 12 volts, they are good for 7 years plus.

4. Make sure you have enough ventilation behind the fridge, above & below but then again, if you are upgitting a Roadtrek like I did, it comes with more than enough existing venting cut out for the old 3 Way. As one Marine Refrigeration Guru told me, the heat produced by a DC unit is infinitesimal compated to a 3 Way.

5. Expect a Novakool to run, in a hot climate, 50% of the time, at the stated amp hour draw. Up to the R3800, the draw is listed as 2.2amps or 26.4 amp hours.

The larger units, R4500 have a 4.4 amp hour draw or 52.8 amp hours over a 24 hour period.

I will include a chart of the stated amp dtaw & you can also download it from Novakool's website.

6. The only other DC Compressor Fridge manufacturers I would recommend are Isotherm, Vitrifrigo & Truck Fridge *.

Isotherm make the smaller, low level units that are marketed under the TruckFridge label here in the USA.

Both Isotherm & Vitrifrigo, are the same company also. And both of them share their average 24 Hour Amp Hour Draw alongside each of their models, not TruckFridge.

At the same time, you can purchase additional technology known as the ITEC & ISEC, that acts to drop that stated draw by 30% or more.

Isotherm & Vitrifrigo have more advanced cooling technology than Novakool but they all ise the same proven Danfoss compressors, plus I believe that the finish on the Isotherm & Vitrifrigo, are better, inside & out.

Versus Novakool whom are based in Canada, has a greater network of service providers & focus on keeping it simple.

The other deciding factors for me as Roadtrek 190 owner is that I could slide in either the R3800 or the R4500 with addring just 3/4 inch plywood platform base with no cabinetry rebuild - fits perfectly.

And the fact that the R3800 & R4500 have the motor/,heat producing components down below where I already have existing Roadtrek cutouts & above, the same upper cutouts that provide the necessary Chimney Effect without any duct or cabinetry modifications.

7. Buy yourself some www.sensorpush.com Bluetooth Temperature & Humidity Sensors that you can affix inside your Freezer, Fridge or anywhere you wish to monitor such metrics.

Not only do they give you accurate readings from 100 feet away in real time they also give you averages in numerical & graph form by the Minute, Hour, Day, Week, Month, Year in an easy to see, easy to read & understand format.

No need to get on your knees & squint at a gauge or open the door of your fridge & defeat the purpose. They are pricey at $40 but to me, worth every penny.

I have one in the Front Cab (now doing duty in the Freezer temporarily), one attached to the back wall of the Fridge, one attached to the upper cabinet of my Rear Lounge/Sleeping Area & one underneath the bed, next to my Inverter, soon to be a Battery Compartment.

8. Overall, I am ecstatic about the performance of the Novakool & there is still some fine tuning to take place.

My Electrical system needed repair but for a while I was pointing fingers at Novakool who graciously walked me through the entire process.

Now my system is resolved, my entire Electrical system is performing to its capacity & it hardly notices that the DC Fridge is there.

Moreover, the Novakool is perfect for my needs ...

[themexicandoctor]

Here is a graph showing stated amp hour draw on Novakool units.

Isotherm & Vitrifrigo publish their avg. 24 hour figures next to each model.

Note; even then, there are can be aberrations due to poor venting.

Everyone one else is, well everyone else. I do NOT trust their figures.

If I was to build a Class B unit or bigger from scratch, if Electrical Demand needed to be as low as possible, I would custom build cabinetry around a Chest Unit, specifically a Engel MT 45 Fridge Freezer Combination unit or if I needed more capacity, a National Luna Combination unit.

These two companies far exceed the demands of traveller's in the hottet parts of the planet, with low amp draw & consistent temperature.

The issue with retrofitting a Class B with such a Chest Unit is that they do NOT fit into your existing fridge cabinetry even though theyare shorter & more shallow because they are too wide & they need space to open yhe fridge top & access the contents. You can configure a slide out in the Roadtrek Popular or Versatile but then it encroached 7.5 inches of your Aisle space. The other option, remove a seat which i could not do as I already have existing Cabinetry there.

Check out Msnomer's build for how she incorporated thefridge into her kitchen.

[GallenH]

Good write-up. Thanks

[themexicandoctor]

Thank you Glenn.

Sorry about the typos on the first post, it wouldn't allow me to edit it a second time.

[themexicandoctor]

Its probably not important to anyone but me however since I solved MY electrical issue, a bad ground connection,* my NOVAKOOL R3800 has been performing flawlessly.

It now cycles on & off as it should.

*the Novakool Head Engineer did say that I might want to check the negstive side of my charging system once we established that I was getting 2.1amps at the Fridge using a Clampmeter.

Its been using no more than 20-26 amp hours per 24 hour period & this is in Los Angeles.

As you can see the Freezer is averaging 16° F / - 8.889 C

And the Fridge is averaging 27° F / - 2.778 C

Yes I could adjust but I am taking it slowly, its presently at position 3.75 on a Dial that ranges from 1-7.

I would highly recommend Novakool to anyone not just for the quality of their product but their amazing customer service - the Head Engineer would call me each morning to see my progress each day.

They are simple, rugged & if you have a Roadtrek, the existing venting is more than ample & perfectly designed to achieve the desired chimney effect.

Plus on the 2005 Versatile 190, either the R3800 (3.5 cubic feet), or the R4500 (4.5 cubic feet), all you need is a 3/4 ply platform underneath & they no cabinetry work - push them in, attach the 4 frame screws in, wire it up & it works perfectly.

But if you like Hard Icecream, I recommend Isotherm or Vitrifrigo but with the Roadtrek

[themexicandoctor]

This was a great learning experience which also caused me to reconfigure my Battrery placement, taking them off the outside of the rig & inside the truck, under the bed.

No more long runs.

No more outside elements affecting the wiring.

Everything is where I can see it.

Worth the investment already in Peace of Mind & Efficiency.

If like GallenH& a couple of others were thinking about adding a DC Compressor Fridge, the charging & draw profiles have changed so positively that if you stick with a R3800 or something smaller, a single 170 watt panel may be all you need to keep up with the Fridge & other Electrical demands if you are not a heavy user.

And of course, a Lifeline 12 volt or two Lifeline 6 volt batteries - any Lifeline Battery Bank that gives you a 100ah capacity.

And boondock in the summer of shade isn't your favourite choice.

If you drive an hour or so everyday & catch the right amount of sun, even better.

If you hook up every night, of course.you will be fine.

I like the Solar as its Free Energy (after the initial investment), that keeps the Batteries charged & is a slower, but gentler charging source.

[avanti]

TMD:
Not sure if you have reported this already, but what kind of duty cycle are you seeing from your fridge during very hot weather? I.e., how long does it run, and what is the ratio of ON to OFF time?
Thanks.

[themexicandoctor]

Coming from your Avanti I know you will need a technical data answer of which I am not able to give without some further direction.

I am on vacation & dont wish to visit my RV Guy as he already cut me in front of others three times to add the fridge, affect the repair & then reconfigure the battery set up.

But if there is a way, I can try.

I can only attest to the numbers the Victron gives me & the fact that before the repair, the fridge ran non-stop.

Now I hear it when it does click on (love that imperceptible sound), and I can see the numbers on the Victron go up or down depending on its cycle & its approximately 2.2amps.

And to the fact the Engineer says those #'s are consistent with the unit I have - he said they make them simple so if someone is out in the middle if the ocean, repair is simple.

In the middle of writing this, I just got another call from the Head Engineer checking in with me - their service, even though it was my issue, right from the start has been exemplary.

Its bloody hot here, the interior of the rig is never below 90 during the dsy & as high as 122 last week in the front cab, even with the Fantastic Van on - pleae note that any air the fridge gets is from.outside the rig.

[avanti]

Originally Posted by themexicandoctor

Coming from your Avanti I know you will need a technical data answer of which I am not able to give without some further direction.

I am basically just hoping for your best estimate of how many hours a day your compressor is running, and how often it turns on and off. I assumed that this could be read (or inferred) from your Victron display (which looks very nice).

These numbers would tell us about how may Ah you are consuming under your current extreme conditions, which should pretty much be a worst case.

[themexicandoctor]

There is a way - compiling my #'s from when Solat clocks off when I am parked overnight until sunrise.

Driving now, details soon.

[themexicandoctor]

Since my unit has been reconfigured & I am on vacation, my Rig is 100% by 10am when I get up.

Will report some figures over the next few days.

[rowiebowie]

Originally Posted by themexicandoctor

Since my unit has been reconfigured & I am on vacation, my Rig is 100% by 10am when I get up.

Will report some figures over the next few days.

Sounds like you got a lot of improvement and rid of a lot of problems. Win-win!

When I brought my batteries inside, I repurposed the old outside storage are for leveling blocks and a small plastic tote that houses booster cables.

[rowiebowie]

Originally Posted by avanti

TMD:
Not sure if you have reported this already, but what kind of duty cycle are you seeing from your fridge during very hot weather? I.e., how long does it run, and what is the ratio of ON to OFF time?
Thanks.

Like TMD, I don't have specifics to offer just anecdotal observations. But my factory installed Novacool 3.1cf runs a lot. I can hear it running at night when it's quiet. Even in cool temperatures, my perception is that it runs far more than when it is off. It sits right next to the bathroom and in my several trips at night I hear it running through the wall. It surprises me when I hear it cut off since that occurrence is rare.

Next time I prepare for trip and turn the fridge on the day before, I will try and remember to watch my battery monitor for a 24 period with the fridge being the only thing running. When the compressor is running, my eight year old Novacool draws 3.154 amps (41 watts).

[avanti]

Originally Posted by rowiebowie

Like TMD, I don't have specifics to offer just anecdotal observations. But my factory installed Novacool 3.1cf runs a lot. I can hear it running at night when it's quiet. Even in cool temperatures, my perception is that it runs far more than when it is off. It sits right next to the bathroom and in my several trips at night I hear it running through the wall. It surprises me when I hear it cut off since that occurrence is rare.

Next time I prepare for trip and turn the fridge on the day before, I will try and remember to watch my battery monitor for a 24 period with the fridge being the only thing running. When the compressor is running, my eight year old Novacool draws 3.154 amps (41 watts).

Mine seems to run a lot, too. This isn't really a bad thing in itself. A fridge's peak efficiency point is the one at which it just barely runs all the time. This means that the sizing of the compressor is exactly in balance with the needed capacity.

I asked because TMD seems to have excellent instrumentation, and knowing the real duty cycle would permit us to make a better estimate of the total energy consumption.

[themexicandoctor]

This is what happened last night but the figures may be skewed as in the evening I put a lot of room temperature & cold products into my fridge.

I ran a Carado Fan.

And the Fantastic Van.

But not all night.

You will enjoy these data points.

More figures tomorrow.

Please bear with me as I do this all from my phone & I frequently, after chicken pecking out these characters one at a time, have to log in again & through a magical series of eight clicks arrive back at my written word which I previously copied, then paste it and press send.

Notwithstanding saving photos in a reduced format, sending them in small packets to my email, logging in again, managing the attachments, saving them, logging in again, then the 8 mote clicks.

[themexicandoctor]

At 3.37am I woke up.*

SMART METER

As you can see my meter is reading 95%.

Or 12.79 SOC.

That the current draw was 3.18Ah.

Ostensibly the Fridge, Fans, Light, Detectors, etc

I have used 13.6Ah of energy overall since the Rig was turned off & there was no alternator or solar power.


SMART METER HISTORY

Says there has been a 14ah draw since all charging systems were off, its a rounding up of the 13.6Ah above

Specifically it says those 14Ah were used in the last 7 hours & 15 minutes since last Full Charge or a little under 2Ah.

NOTE; I put a lot of stuff, room temperature & cold into the Fridge 8 hours earlier

*because of numerous head injuries & the type of work I did overseas for 32 years, I wake up every 90 minutes/at the end of each REM Cycle. I wake up ravenous hungry & thirsty due to severe Parasomnias, Sleep Walking,Talking & General Agitation until the 3rd or 4th REM Cycle

[themexicandoctor]

I know this a Scientific Study but I was overwhelmed* by the phenomena I encountered on film for all to see at 3.49am & 3.50am; my fridge cycling off.

*Humour goes a long way today

[avanti]

Can the Victron plot amps on a time graph?

[themexicandoctor]

At 7.30am

SMART METER
You will see my bank is at 12.84

That my SOC is 93%

And that my Fridge at least has cycled off

SMART METER HISTORY

That there has been a 20Ah draw

And the last Full Charge was 11 hours & 9 minutes previously

[themexicandoctor]

At 8.14am

SMART METER
My Battery Bank is at 12.93v

My SOC is 93%

My Fridge at least is not Cyclying on

SMART METER HISTORY

There maybe some Solar being generated, will get to thst in the next post

But as you can see my rounded draw is 20Ah

It has been 11 hours & 52 minutes since my last Full Charge