Max Burton fridge/freezer

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jimindenver said:
Thank you for the report.
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I am interested in how the fridge side was doing when it was so hot in the truck.
Anybody know if there is a sticks n bricks location where one could be looked at?
 
I don't know if they have a show room but their headquarters is in Gardnerville NV. I have ordered paint from them before. call them and ask where you can see one. 775-782-0100. highdesertranger
 
highdesertranger said:
I don't know if they have a show room but their headquarters is in Gardnerville NV.  I have ordered paint from them before.  call them and ask where you can see one.  775-782-0100.  highdesertranger

Danke'.
 
I may have discovered a shortcoming with the 37qt MB that I recently purchased.  It might be the same with other brands.  I have no other 12v fridge experience.  

Today, I was playing with the new solar set up in the van.  Ran the fridge as a load onto the batteries for a bit to use the LCD read out on the solar controller to see how it all works.  

All was well and I shut things down.  A bit later in the afternoon I went back out to the van for another round of learning curve and the fridge/freezer would cut off after a minute or so and the red LED indicator would flash slowly.  The guide stated low battery so I fiddled with the three settings.  No luck.  I then hooked the fridge to shore power and it did the same thing so battery power was not the reason.  A VOM reading showed voltage was ok even though they had not rested for an accurate read.

I surmised that perhaps the ambient temp in the closed up van was creating the ailment.  It was 98* today around 4 pm so that means about 298* in the van.  Could it be this simple?  Well i removed the fridge from the van and put it in the garage.  It's been cooling off since then.

The present time is 9:30 pm and 79* outside.  The fridge is plugged into shore power and acting normal.  Just checked.  It dropped from 83* degrees according to the display panel down to 49* in fifteen minutes.  9;45 and it dropped to the set temp of 32* . At least the fridge is not damaged.

This makes me want to MacGyver another fan somehow.  Doesn't have to attached to the unit but I now know that high ambient temps impede performance to a fault.  

Comments and/or solutions welcome
 
Likely an intentional shutdown protecting the power unit and electronics.

Yes in high ambient temps you need active cooling, ideally exhausting out of the living space.

Will buy better electrical efficiency as well.
 
The excessive heat was likely the issue as you surmise.


2 routes, keep the interior of the vehicle cooler, and increase ventilation around the cooling vents on the fridge itself.

A third route is to increase the insulation on the fridge

So fans to hook upto fridge.

The Noctua NF-f12 ( 1500 rpm) movesd ~53 cfm and draws only 0.05 amps.  It attached to the fridge, pushing air into one vent of the fridge, the intake vent, will likelyu more than make up for the 0.05 amp consumption even if it is left running 24/7.  This fan is also very quiet.  The overclocker Computer nerds worship noctua fans in general, but this fan is pretty amazing.

It has 2 industrial versions too, one that spins 2000 rpm, and one that spins 3000 rpm.  This 3000 rpm fan is loud, but consumes only 0.3 amps and moves 110CFM when unrestricted.  But it also performs very well in comparision to other fans when it is restricted with the restriction in front of or behind the fan, preferably in front of.  

As far as more insulation goes, get some foil backed foam board.  Look up Nashua Flexfix tape, Ise some bamboo skewers to hold the 3d shape in place while you tape the seams.  leave plenty of room around the vent or build it to encompass the NF-f12 fan.

It might be possible to tap the 12v feed for whatever fan the Max burton compressor uses.  I know the Danfoss BD35f could power upto 0.5 amps of fans, meaning it could in theory power 10 NF-f12's

I've had a single NF-f12 fan on my Danfoss condenser since 0ctober 2012.  I mounted it to push air instead of the stock fan's orientation to pull air through condenser.  My compressor run times basically dropped about 45 seconds, from 5.5 minutes to under 5 just with this alone.  The NF-f12 also draws 0.07 amps less than the provided fan, and makes much less noise doing so.

It is also possible the power cord itself, and the 12v plugs, in such ridiculous high ambient temperatures, caused an insane amount of voltage drop, which will cause the fridge to stop working.

Compressor fridges should be fed battery voltage with as little voltage drop as possible, and should have the coolest possible air forced through their condensers.  Everything is a compromise, but these are not that difficult to mitigate.

The high speed  Industrial Noctua fans, can be tamed with the Noctua Speed controller recently made available.  

Also get some reflectix, and make some tight fitting window shades to stuff in the windows to keep the vehicle internal temperature down.

you might now have plenty of electricity to have the compressor fridge run continuously, but it will wear out much faster if asked to work that hard often. 

 Remove some stress from it.

I can keep the interior of my white van no hotter than ambient temps, until late afternoon, with ventilation and window shades, and my fridge condenser is fed the coolest possible ambient air, with no chance it is recycled
 
Optimum Ambient Temperature
60oF - 109oF (16oC to 43oC)
If the ambient temperature is above 90oF (32oC) the minimum temperature might not be attained.

Thanks guys.  The above is a copy/paste from the MB manual.
I'll have to rethink and adhere to given ways to help this 'lil bugger out.  

At least now I know some of its limitations .
 
I had a looksie at the business end of the thing.  Lots of screws hold the entire corner piece onto the main body.  

The vents are only on the sides.  The front vents are fake.  The side vents measure 4x4 but prolly only have an effective opening of 3x3, perhaps a bit less.  * edit.  32 - 1" x .25" openings.  That equates to 8 square inches vs 16 sq in of vent grille face.

My first thought was to remove the entire corner piece and perhaps reform it with 1/4" wire mesh or something just to allow as much natural heat dissipation as possible.  

I then took a bundle of sage since it smokes a lot and held it to the intake side.  To my surprise, that little fan creates some nice airflow because I was seeing a nice stream of smoke exiting through the other vent.  This tells me that my first theory is not correct as it seems that the design is for a nice stream of air to cross through from one side to the other, hence the fake front vents.

The coil part of the cooling system could use some attention .  It looks to be an L shape.  The short side of the L is at the vent end and has the fan attached.  The long side of the L is almost as wide as the fridge itself.  Understandable design given the amount of space to work except that the long side of the L is up against the fridge body.  Its not getting hardly any of the cross ventilation.  Moot point perhaps but if it was away from the interior side about a half inch it would get more airflow.  

I have no qualms about this lil fridge/freezer considering the cost.  I now know some performance limits and will work within its parameters.  

Was there a point to all this bandwidth burn up?  Not really.  Just sayin'
 
Hey thanks for the scoop on the design of the L shaped condenser and grille openings.

My danfoss uses a condenser which looks lke a car radiator, and a 120Mm computer fan screws directly to it. My precious Norcold had a larger passive compressor and fans which only came on at 115F or something ridiculous. I pushed cooler air up at the compressor condenser from below with an 80mm fan, to aid heat dispersion.

The Noctua fan I use on my danfoss was designed to push Air through a restriction. They recently came out with a new fan which apparently outperforms the NF-F12 in such an application, and is 10Mm thinner and 3db quieter doing so. it does consume 0.13 amps vs the NF-f12's 0.05, but 15mm wide instead of 25mm wide could allow its use in places where a 25mm fan would not work.

This new Noctua fan:
http://noctua.at/en/nf-a12x15-pwm/specification

could increase the performance over the NF-f12 in my (front loading) fridge cabinet as there will be 10 more MM of space for the fan to pull air through. Way on the other side of my cabinet I have a puller fan exhausting the heat, and would transfer the NF-f12 to here running 24/7. together they are kind of a push pull venmtilation setup and should increase the already impressive cooling performance of my fridge.

As to the Airflow inside younr MB fridge, it kind of sounds like one portion of the L has a lot of fan flow, the other portion receives very little fan flow. How the air actually behaves inside is of course an unknown, but a little steering vane to direct air over the other portion of the L, could improve heat removal, as well as keeping the wall next to it cooler, which would then transfer less heat to the insulated portion inside the box.

These units are not optimized for airflow, and certainly not at a budget price. My Vitrifrigo fridge came with a 120mm sleeve bearing fan. It was mounted to pull air through the condenser. My relocation of the Noctua NF-f12 fan to other side of condenser to push air, was a significant increase in performance, and the NF-f12 fan is actaully rated at 20CFM less air movement, in unrestricted space, but it is restricted, and the Noctua fan reduced the compressor run times by about 45 seconds, and drew less amperage doing so.

My vitrifrigo sleeve bearing fan was moved to my intake vent shroud, and now requires that I manually spinthe blades after turning it on. it is failing, likely not worth the effort of relubing the hub as I want a better fan in its place.

My point it, is that the fan that max burton used was likely the cheapest one they could buy in bulk, and computer fans have ridiculous amounts of engineering going into them. Sleeve bearing fans wear out quickly. a $1.30 fan might cause the downfall of your fridge, or perhaps cause it to consume 20% more electricity and perhaps shut itself off spoiling your food, compared to a better fan installed in its place.

If you want to open up the cooling unit's panels, and see how hard it is to get at that fan, I bet we can find a far superior replacement which will likely be quieter, move more air, consume less amperage, and last 3 times longer. Pics would be great, but even the part numbers off of the fan can give an idea of the airflow of the existing fan.

Noctua's new 120mm x 15mm thick fan is about 20$ on Newegg, and i got a hankering to own one, being a confessed muffin fan maniac.
 
Its in my nature to explore all things mechanical.  I will be digging a bit deeper and will take pics.  It'll be a coupla days.
I'm under the influence of a tasty adult beverage diet at the moment, so not today.

I wish I knew proper terminology but the , Cooling, condensing, fan cooled coil thingy, that has the fan attached, is not the radiator type.  It is a tube that's twisted all around in the letter L and has other solid pieces soldered to it.  Like a mesh.

Plus, mind you, I'm peeking thru tiny slots in the side vents.  I could be view askew.  But nonetheless.
 
Couldn't let it rest.  Heres some pics.  Kudos to them for having the compressor snubbers a bit loose otherwise it might be a bit louder.  The short side of the L doubles back on itself then heads down the side.  I stand corrected about the front vents.  They are slotted but at an upward angle.  I did not notice until it was tipped up onto the end.  All in all not a bad design, I guess.  Cant really see much room for improvement other than trying to keep 'er cool during the hot days. Add a second fan perhaps.

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Fan is 3 1/4 diameter seven blade
 

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I applaud your inquisitivness.

The fan is an 80mm fan, the open end shown is the suction side. Can you see where this fan's wires run? Can you access them, or follow them to where they enter the compressor controller? It looks like there is a pretty good gap inbetween condenser and the casing/cover? More than 25mm/ one inch?

The compressor is a cute little thing. It does look like the air circulation over it is limited by the wiring bundle. The fan will be pushing some preheated air from condenser at it. the compressor generates heat too so it is better that the fan blows

That condenser is not really all that efficient, with not much surface area, and part of it well away from the fan's flow, but these fans tend to have 4 hotspots which exit fan at wider angles when unrestricted. not sure in that configuration.

what are the dimensions on the venting grates. Could a 120MM( 4.75" fan be attached to the inside of them? how about a 92mm(~4 inches)?


I think I would either try adding a fan to blow cool air directly into the existing fan, or if easier, locate it to exhaust on the other side of the compartement. Fans tend to do better with restrictions in front of rather than behind the blades.

It appears as if that existing 80mm fan would be very hard to remove and replace, so i would Aim to supplement the airflow either by forcing more air into the condenser, or haviing an Exhaust fan sucking the heat out and forcing it out the regular exit.

The Noctua NF-f12 at only 0.05 amps is likely a lesser amperage draw than the 80mm fan they used and will likely not overload the circuit intended to power the fan, if added to it.

If I owned that fridge, i would likely attach the NF-f12 to the casing interior , oriented to blow into the existing fan, and likely open up some of the grating. I am usually not worried about warranty voiding though. Once I establish it works properly I will modify.

You could also perhaps add some refelctix in between cooling unit and the fridge box itself to reflect the heat generated there from entering the cold portion of the box.

The coler you can keep that cooling unit interior, the longer the compressor and compressor controller will last. The earlier danfoss bd35f' s failures were from teh compressor controllers overheating when there was a huge heat load placed in the fridge in hot ambient temps. They soon added a finned heatsink on the back of the compressor controller.

Splicing the wiring that leads to the existing fan is pretty simple. The controller should easily handle the 0.05 amps extra of the NF-f12 fan, and this fan should be able to pump ~53 cubic feet od air per minute through the cooling unit. the existing fan likely recirculates 50% or more of the air it moves, whereas a fan on the casing should exchange nearly all the air it moves, which will lead to improved cooling nad extended cooling unit lifespan, and allow for shorter compressor run times, reducing overall battery consumption and allowing it to run for longer in hot ambient temps.

Thanks for the effort of the providing the pics. You have done everybody who reads this thread well to have done so.

The fan wires are usually red and black and about 22 gauge. One of them is likely sharing the ground with the main ground from the input plug, the other wire might have a dedicated output just for it.

Not sure of the sizes but some piggyback connectors can make attachng an additional fan easy without any wire splicing.

https://www.amazon.com/0-250-Female...63&keywords=crimp+connectors+quick+disconnect

if worried about warranty one can make it appear as if no modificatons were ever added. I'd use amazing goop to glue a NF-f12 fan to the side opposite the existing fan and use the piggy back connectors.

Since you have it open, and perhaps do not require the 'portable' moniker anymore, consider bypassing the powercord connector and running 10 gauge wire right to compressor controller. The move voltage one can deliver to the compressor controller, the better it will run and be slightly more efficient too.
 
SW wrote, *If I owned that fridge, i would likely attach ( another fan ) to the casing interior , oriented to blow into the existing fan, and likely open up some of the grating. I am usually not worried about warranty voiding though. Once I establish it works properly I will modify.*

I concur.

The temp inside the closed up van is 121* at ~6 PM.  Poor little thing never had a chance.

This is where it lives.  Two inches of space between it and the seat pedestal so the air flow exit vent has room.  All is well there.  The 4 x 4 grating facing the cabin area is the intake side.  

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I uses 10AWG marine wire throughout. I really like that wire. The factory plug/12v male plug is fairly robust, imo. Always room for improvement though. It draws ~< 4 amps. Battery source is nine foot of wiring away. AND I'm keeping the Aux system separate by using ground wires back to the batteries vs using the body. Just my hang up.
 

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I'm following with interest, as I have the larger version of this unit but it's currently in use in my house, not yet in the van.

I wanted to share this trick: to make a degree sign, as in 121°, hold "alt" and type 176.  
It's one of the few keyboard shortcuts I remember.  The bosses type their own letters these days.
 
Thanks for the tip.
I'm not trying to create a fuss. I still think this is a great device for the money.
 
regis101 said:
Thanks for the tip.
I'm not trying to create a fuss. I still think this is a great device for the money.

Wish I had jumped on this sooner. This $300 item is now going for almost $900 now. Amazon has been out of stock for a couple of weeks now. Not sure if this item is ever coming back. I noticed that because of the events on the 21st that camping items are out of stock or going up 200% in price. Kind of a bad time to buy. Guessing things will be better after the eclipse.
 
There is an up/down flow to pricing on Amazon.
When I found them they were already up to $400 and then quickly went out of stock.
At the same time I saw the Dometics had a price bump as well.
 
I see that Truckfridge has some smaller compressor fridge offerings in the sub 300$ range

http://www.truckfridge.com/store/page9.html

This guy will likely match/beat their price on their product and offer free shipping. Ask him about the models he does not list in the drop down.

http://www.westyventures.com/parts.html#cart_restore

I know the larger models use a danfoss/secop bd35f compressor, not sure about the tiny models, but doubt it.

I bought my Vitrifrigoc51is from him in October 2012
 

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