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raul-v avatar image
raul-v asked

100/20 direct conection of 12 V fridge

I have checked all the manuals and documents in pdf but cant find accurate assuring answers.

I had bud experience in the past with an isolated system with an inverter that spoiled bateries in less than a year due to internal self consuption too high.

So ,y obsesion is to use as few cycles of the batteries as possible and to work as efficent as possible.

My question is:

20 A is the maximun amperage that I can connect to the dc power out of the charger avoiding usuing that energy from the battery when direct sunlight?

My idea is to connect the 4 A 10 V dc fridge direct to the load out and im not sure if that will work. deccision of buying a danfoss compresor fridge has to be taken upon it may work in that way.

I also have a phoenix 500 va inverter and wonder if in the same sense i could conect it to the dc load output avoiding again wearing the battery during daytime, and conmuting to battery when dark.

Does it make sense or maybe im way exaggerated in my idea.

Tnx a lot for your feedback and expertise.

charger
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Michelle Konzack avatar image Michelle Konzack commented ·
A Fridge using a Danfoss BD35F Compressor works with 12/24V and the power consumption is much lower then with a 120V/230V version.


I run a Fridge 110l Fridge with a BD35F, a Luxor Freezer 70l with a BD35F, a Freezer Box 320l with a BD50F (was from my second Luxor) and the power consumation is amazing low.


If you have the money or it is important for you to save energy, go with a Danfoss BD Compressor.


Oh, currently I am building a Earth-to-Water Heatpump using a Danfoos BD360GH (Twin) compressor with 24V (suck maximal 660W or 27A). The Compressor alone cost only 480€ plus the two Heat Exchanger for which I have no offer yet.


DC is the way to go if it comes to efficiency.

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k-k avatar image k-k Michelle Konzack commented ·
@Michelle Konzack

i know the bd50 and esp. Bd35f or k from 20years ago, but its hard to find some buying place for a bd35f -- bd50 or bd360gh seem to be no more existent in germany (as production type) so please can you give a hint where to buy or where to fetch technical data? This could help me to solve my inrush-problems. Tia

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Michelle Konzack avatar image Michelle Konzack k-k commented ·
I buy them directly from my distributor in Estonia. This is a enterprise for clima system installations.


In which country are you?

I can ask my distributor for a contact in your country if in Europe.


All three Compressors (BD35F, BD50F and BD350GH/Twin, also the BD80F) are still in active production.

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2 Answers
Justin Cook avatar image
Justin Cook answered ·

Connection of inverters or other high-inrush current devices (such as a refrigerator) directly to the load output port of the solar charge controller is expressly forbidden in the user manual; additionally, the load output port of the solar charge controller is powered from the battery in any case, so you would not be accomplishing anything by doing that.

So long as your solar controller is charging the battery appropriately during the day, and your inverter and your fridge are connected appropriately to the battery as well, you'll already be doing exactly what you're trying to do!

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kevgermany avatar image kevgermany ♦♦ commented ·
@Raul V

I'm running a 12V compressor fridge directly from battery. No issues, consumption is low, but in winter when solar isn't enough I monitor batteries and charge from grid as needed.

If you're concerned about battery exhaustion damage, consider adding a battery protect.

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raul-v avatar image
raul-v answered ·

Thank you very much to both of you.

@Justin Cook, perfect answer. I had no clue that load output was getting energy from the battery itself even if ive read manual several times.

So, what is the purpose of the load output implementation into chargers.

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klim8skeptic avatar image klim8skeptic ♦ commented ·
@Raul V I use my load output for security lighting.

Dont 12v fridges have a (selectable?) low volt cut out?

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Michelle Konzack avatar image Michelle Konzack klim8skeptic ♦ commented ·
The Danfoss BD Compressor are fully configurable in Speed and Low-Voltage Cut-Out and can not only run from 12/24V but also from Solarpanels, if the Voc does not exceed 40V. (see Datasheet)
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kevgermany avatar image kevgermany ♦♦ commented ·
Load output monitors battery voltage and disconnects load when voltage drops to the preset limit.
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