Adding a new DC Fridge during a LA Heatwave

[themexicandoctor]

Originally Posted by themexicandoctor

Yes that's the one.

I just drive 30 minutes & have beeb parked for 45 minute.

At around 10pm, it sat at 40 degrees & wouldn't go down.

Before I started driving I turn the knob back to #4 & you can see the temp is 28.3°

So its cooling but I drove a distance & its 2.08am.

[themexicandoctor]

Gentlemen & Women,

This is the latest, my truck is in the Sun on the fridge side right now.

I placed one of my Sensorpush Bluetooth units against that very same wall pictured (I will need to add some Reflectix next week).

Also as I mentioned last night, after I experimented with the fan at horizontal, it was a failure - essentially it was simply grabbing air as soon as it came in & then sent it up, it was not bringing cool air around the block.

So I bent the fan down to a 30% fashion, closer to the block itself & it appeared to have an improvement, it would be impossible to move it to less o lf an angle because then it would be merely sucking air in while simultaneously blowing much of the same current back against the vent opening.

My fridge itself, where the Sensor is now velcrodled to the back wall, is reading 28.5°F & this is A FANTASTIC CHANGE considering the sun is on that skin.

Please NOTE; Drivers Seat is actually now a sensor attached to the Roadtrek Wall yhat is not insulated & opposite the back of the fridge.

The Sensor is now reading 103.34°F.

These sensors give me hourly changes, showing it in a graph.

[themexicandoctor]

What I might do is;

1. Place a baffle opposite the fan so that the air is blowing up& hopefully out.


2. Bend the fan to an angle of less than the 30% it is now.

3. The fan is set to 4.25 of 1-7, I just turned it to 4.

Fingers crossed, this was the issue, the fan was too far away from the block it was supposed to cool.

[themexicandoctor]

The Sensor is attached to the midway point of that Chevrolet metal skin, between the two lower & upper cutouts.

I expect the sensor to get really hot.

[avanti]

Originally Posted by themexicandoctor

The Sensor is attached to the midway point of that Chevrolet metal skin, between the two lower & upper cutouts.

I expect the sensor to get really hot.

It is the air temperature you would like to know, not the metal temperature.

[themexicandoctor]

I cannot see anywhere else to attach it except for the back of somewhere high on the fridge.

[themexicandoctor]

Originally Posted by themexicandoctor

I cannot see anywhere else to attach it except for the back of somewhere high on the fridge.

I may attach it to the fascia/baffle at the top of tr fridge, thank you for the idea.

[themexicandoctor]

Have yet to move the Sensor yet but here are the latest figures;

NOTE; the Drivers Seat temp is now the inside wall opposite the fridge.

The Fridge is looking great, hopefully it was simply thr facts;

1. The fan was too far away from the electrical block it brings air over to cool it

2. Together with the fact there is too much volume of air back there.

3. And its 96 degrees outside ambient air temperature.

Not including very little breeze & the rig is sitting on a very hot road.

So when I open that door, see that soft white light & am able to enjoy whatever is safely stored in the fridge, I am in Heaven especially when I know the temperature its being kept at.

Fingers crossed, despite the Heatwave, the teething problems have ended & I love* my Novakool.

*just got to work out how to make it more efficient.

Any more ideas Gentlemen *

[GeorgeRa]

Originally Posted by themexicandoctor

…………………..
1. The fan was too far away from the electrical block it brings air over to cool it
2. Together with the fact there is too much volume of air back there.
……………

What is electric block? Except compressor and condenser nothing should be hot.

I question if the fan is more of a problem than help, if it recirculates hot air it is not cooling. The condenser is high so it should develop reasonably good convection air flow without the fan. I would personally try disconnecting the fan and compare the notes.

See the picture of my fan, it blows air directly at the compressor and across the condenser.

[themexicandoctor]

The block, is the electronic module.

This is what The Guru Rod Lambda explained by text when I sent him the photos;



It Looks like the wiring is large enough
Can't quite see what kind of condenser they're using , tho

Now I see
It's a vertical wire and tube
And It does not need any fan at all.
The fan you see is only to keep air moving over the module.

When the units running, just put a meter on the 12volts at the module .... it should be around11.8 to 12.3 v dc
And yes the module is where all the wires connect to



They tested the unit with a Clampmeter yesterday, was running 2.1amps.

As it is, nothing blows over the rear of the unit at all, it acts more like an extractor fan, bringing outside air in, across the module & them out & hopefully up.

With all your knowledge, do you think this is a good design?

I think the issue is simply the volume of air I have available & the distance from the vent, module & fan.

I did on several occasions over the past couple of weeks & the compressor isn't hot at all, the Installer said sometimes these get so hot as to burn your hands.

[booster]

I think that in all these ventilation systems, the fans should be seen as assisting devices only, with gravity being the main driver and main thing used to determine the style of the baffling and/or fan(s).


Heat rises and small chimneys work better than big ones, so a small crossection chimney right over and along vertically what you want to cool, that has to get it's air from the lower vent and air the comes out of it has to go out the top vent. Heat will make the air flow if done correctly, but if it isn't enough air to keep it cooling well, a fan to assist the airflow without changing any of flow directions would be next to add.

[themexicandoctor]

This is my remaining concerns during hot summer months;

Yesterday I ran the Generator for 3-4 hours. This input isn't shown on the Solar MTTP Meter but at around 12.30am or 15 hours ago I stopped the motor & all charging when the unit was at 100%

[GeorgeRa]

Originally Posted by themexicandoctor

The block, is the electronic module.

This is what The Guru Rod Lambda explained by text when I sent him the photos;



It Looks like the wiring is large enough
Can't quite see what kind of condenser they're using , tho

Now I see
It's a vertical wire and tube
And It does not need any fan at all.
The fan you see is only to keep air moving over the module.

When the units running, just put a meter on the 12volts at the module .... it should be around11.8 to 12.3 v dc
And yes the module is where all the wires connect to



They tested the unit with a Clampmeter yesterday, was running 2.1amps.

As it is, nothing blows over the rear of the unit at all, it acts more like an extractor fan, bringing outside air in, across the module & them out & hopefully up.

With all your knowledge, do you think this is a good design?

I think the issue is simply the volume of air I have available & the distance from the vent, module & fan.

I did on several occasions over the past couple of weeks & the compressor isn't hot at all, the Installer said sometimes these get so hot as to burn your hands.

The module, whatever it is should be cold, if it needs to be cooled by a fan there something wrong with the module or design.

Your fan is not forcing air flow across the condenser so perhaps it is helping moving air from the bottom through the top opening or not. I would try disconnecting the fan or add appropriate fan(s) and build good ducting to force the air on the condenser.

[themexicandoctor]

It's 3.30pm & it will be 4-4.30pm if I do not start the motor to get me to 100%.

Again no motor or generator supplied charging for 15 plus hours, only solar.

So you can see how much the batteries are being taxed even though its a bright sunny day with no shadows.

This thr next concern.

However at 31-34 degrees I could possibly back off on the knob.

Any suggestions?

[themexicandoctor]

Thank you Gentlemen,

I am going to bounce these ideas off of Novakool.

It just goes to show one needs enough solar to power these rigs.

This am at 9.45 it said my unit was down to 91%, I think that I now have a handle on the soc.

Of course the continued draw of the fridge and al the extrs fans I have back here add to the slower rebuilding to 100% soc.

[themexicandoctor]

Would this crude design of a baffle be similar to what is needed at the bottom?

The upper chicken pecked sketch is what is there now.

In the lower picture I could put a covering over 3/5ths of the condenser & thr module with an opening directly at the rear of the module & with the fan bent even lower to say 25% of an angle, it would bring air from outside in through that small opening, over the module& exhaust it back out?

The black lines would be the outline of a cowl that fits between the outside vent and the opening of the rear base of fridge.

It would dissect the rear of the fridge, channeling air onto the module to be exhausted out via the fan.

[themexicandoctor]

Here it is

[GallenH]

OK. I have to say that this discussion is almost discouraging. I remember rowiebowie's problems and the major contributors to this forum walking him through the issues and solving them. But there seem to be prolonged issues with TMD's installation that make me very wary of going from an absorption to a compressor fridge.

Right now I'm seeing the need for me to go from 100AH to at least 200AH; maybe even 300AH.

At that point my 136A alternator is probably not going to cut it, requiring an upgrade of both the alternator, probably the isolator, and most likely the wiring gauge.

Then probably 200W rooftop solar and a good solar controller to manage that.

Probably an upgrade of my Progressive Dynamics 36W controller/charger to something larger.

And if my battery increase is in the form of lithium, at least a B2B from the alternator.

And then.......after all of that.......I "might" be able to support a compressor fridge?

I know that many of you have done conversions. What am I missing here? Is what I've listed above a good approximation of what has to be done?

cheers.glenn

[themexicandoctor]

Originally Posted by GallenH

OK. I have to say that this discussion is almost discouraging. I remember rowiebowie's problems and the major contributors to this forum walking him through the issues and solving them. But there seem to be prolonged issues with TMD's installation that make me very wary of going from an absorption to a compressor fridge.

Right now I'm seeing the need for me to go from 100AH to at least 200AH; maybe even 300AH.

At that point my 136A alternator is probably not going to cut it, requiring an upgrade of both the alternator, probably the isolator, and most likely the wiring gauge.

Then probably 200W rooftop solar and a good solar controller to manage that.

Probably an upgrade of my Progressive Dynamics 36W controller/charger to something larger.

And if my battery increase is in the form of lithium, at least a B2B from the alternator.

And then.......after all of that.......I "might" be able to support a compressor fridge?

I know that many of you have done conversions. What am I missing here? Is what I've listed above a good approximation of what has to be done?

cheers.glenn

Glenn,

TODAY I am all Smiles.

With the fantastic fan on #2 of 3, my Fridge on #4 of 7 & one small Carado fan on High, everything is good.

Its 7.48pm & my fridge is at 31.0°F & falling.

And the high today was 40°F at midnight before I left the valley.

The fridge is working superbly.

Its still in the high 90's out there.

Just in the lounge part of the rig itself with those fans & humidity, its 91°F.

I have a suspicion that once the regular temps fall below 90 I will be able to put the fridge knob to the middle or 3.5.

4 months a year it will run sun 33°F at 3.5 or less.

And I HAVE YET TO BUILT A BETTER BAFFLE.

And to experiment with an extra fan or other tips.

This was a worst case scenario.

As it was, I have too much venting, in a a heatwave.

The secondary issue is charging. If you are driving anywhere for two hours per day with 200-300 watts of solar, you will be fine.

And if you hook up to shore power, you will be awash with juice.

I love my Novakool, I believe if its on 24 hours, then it is using 52.8amps a day or 633watts.

Changing iut the alternator probably has to happen, its certainly reassuring when you are driving that with the bigger alternator all that juice is going to the battery banks.

[themexicandoctor]

Installers are used to putting these rigs in boats & rvs with very little venting. We are awash with venting.

I know the cooling technology of the Isotherm/Vitrifrigo are better but I didn't want to do any cabinetry build out - it has just a small 3/4 piece of ply underneath.

I will find a way to bring the amp hours down.

But I am also excited about reasonable weather.