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Post Info TOPIC: HELP PLEASE WITH 12V ISSUE - HOW TO REDUCE CURRENT TO FRIDGE FAN
Baz421


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HELP PLEASE WITH 12V ISSUE - HOW TO REDUCE CURRENT TO FRIDGE FAN
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Hi all..

As per a previous post my Danfoss BDF50 compressor fan packed it in on 43 deg C day.

Have had considerable problems getting replacement that has the required airflow in cfm. MOST fans don't deliver the 80cfm minimum.

Danfoss don't supply fans in Aust now - go buy one. typical.

Found one at about 138cfm. Great news. Fitted and runs great EXCEPT IT RUNS FOR <2 SECONDS AND fan and compressor shut down due overloaded fan 12v circuit.

Fan draws about 833mA and trips the compressor controller as it's rated as 1A start and 500mA running. Hence my problem.

Tried to use a relay but doesn't solve the problem

I need to reduce the amps without reducing voltage to fan circuit.

Can someone work it out please,,,,,, my brain is scrambled.

 



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DeBe


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DANFOSS CONTROLER.1.JPGDANFOSS. 101N0500.3.JPGDepends on which controller. Showing the 2 different controlers using a relay with a diode fited across the relay coil.



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Old Col


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what about a pcb relay like
www.jaycar.com.au/12v-dpdt-special-pc-mount-relay/p/SY4052
draws about 0.04211 amps at 12v


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Baz421


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DeBe

 

101N0220 is the one. What are the values of the relay and diode???

I see what you are doing where do I getthe bits please.

Baz

 



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Baz421


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Old Col wrote:

what about a pcb relay like
www.jaycar.com.au/12v-dpdt-special-pc-mount-relay/p/SY4052
draws about 0.04211 amps at 12v

so the current draw to relay is 42mA is that correct,,, I'm brain dead today

thanks for response Col

 



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iana


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Since your fan is delivering nearly twice the required air flow, have you tried blanking of the face of the fan to reduce its air flow, hence reduce the load.

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Baz421


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iana wrote:

Since your fan is delivering nearly twice the required air flow, have you tried blanking of the face of the fan to reduce its air flow, hence reduce the load.

How will that help the load? Will just starve fan of air will it not,,, may run faster but how will the current be reduced??

 



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iana


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Wrong wording, partially blanking off the inlet of the fan. The load of the fan would be related to the work each blade is doing, so I am saying as an experiment with say some cardboard, cut a hole in the cardboard of a reduced diameter to the fan and with the cardboard partially blanking off the face of the fan, measure and see if the milliamps have dropped. Its just a suggestion.

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Baz421


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iana wrote:

Wrong wording, partially blanking off the inlet of the fan. The load of the fan would be related to the work each blade is doing, so I am saying as an experiment with say some cardboard, cut a hole in the cardboard of a reduced diameter to the fan and with the cardboard partially blanking off the face of the fan, measure and see if the milliamps have dropped. Its just a suggestion.

Thanks  Current draw is almost constant,,, so airflow changes wouldn't have any significant effect IMHO. 



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DeBe


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1N4004 diode available from Jaycar will do the job. The relay suggested by Old Col should be fine.

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Baz421


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DeBe wrote:

1N4004 diode available from Jaycar will do the job. The relay suggested by Old Col should be fine.

Thanks a lot DEBE,,, I went to Jaycar to see if they had a low draw relay for the control circuit,,, no was answer grrrr.

Ill try that relay first as everything else is in place and fan is great,,, keeps compressor cool at last.

 



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Peter_n_Margaret


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Baz421 wrote:
iana wrote:

Since your fan is delivering nearly twice the required air flow, have you tried blanking of the face of the fan to reduce its air flow, hence reduce the load.

How will that help the load? Will just starve fan of air will it not,,, may run faster but how will the current be reduced??

 Iana is correct. That will usually reduce the current draw of an axial fan.

Less work done = less energy required.

Cheers,

Peter



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DeBe


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Not correct with Brushless fans, restrict the air flow the current actualy rises. Totally different to Brush type motors.FAN CURRENT free flow.JPGFAN CURRENT restricted.JPG



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kgarnett


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You could always purchase a genuine replacement fan from CaravansPlus as per the link below.

https://www.caravansplus.com.au/4441200001-fan-bd35-50-cool-unit-p-14018.html

or Jaycar have this one:

https://www.jaycar.com.au/ip55-rated-120mm-12v-dc-ball-bearing-fan/p/YX2522

 

Alternately you could use a series resistor to reduce fan speed and current.

Ken

 

 



-- Edited by kgarnett on Tuesday 12th of March 2019 09:05:51 AM

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Whenarewethere


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I put this 120mm fan in my 28L Weaco fridge to replace the 80mm fan. Been running it long enough now & am very happy will it. Mwave & Techbuy sell them. Good pressure & only draw 0.1amp 121m3/h.

https://noctua.at/en/nf-f12-industrialppc-2000/specification



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T1 Terry


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Buy a solid state relay from Jay Car www.jaycar.com.au/pcb-mount-solid-state-relay-12v/p/SY4093 and wire the switch/control side as marked, + to + and - to - . The load side how ever is different, the + and - relate to the current flow and not to voltage. It you wire the relay in the positive wire, then the positive from the battery/fridge control feed goes on the relay load + terminal and the fan + goes on the relay load - terminal. The fan negative connects direct to the supply negative and not to the relay. Get that part wrong and you will need to buy a new relay, they are not forgiving, death of the relay is instant.

T1 Terry

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Baz421


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Whenarewethere wrote:

I put this 120mm fan in my 28L Weaco fridge to replace the 80mm fan. Been running it long enough now & am very happy will it. Mwave & Techbuy sell them. Good pressure & only draw 0.1amp 121m3/h.

https://noctua.at/en/nf-f12-industrialppc-2000/specification

Thanks,, looked at these when you posted before,, not quite min airflow I think,  but close 



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Baz421


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kgarnett wrote:

You could always purchase a genuine replacement fan from CaravansPlus as per the link below.

https://www.caravansplus.com.au/4441200001-fan-bd35-50-cool-unit-p-14018.html

Thanks   . I asked local van supplier to source a genuine one - they found a sleeve type (read bush) $75. Can get em in Adelaide for <$10,, sent it back.

Danfoss told me genuine not available in Oz,, get one after market,, Danfoss agents appear to only be interested in 240v stuff

or Jaycar have this one:

https://www.jaycar.com.au/ip55-rated-120mm-12v-dc-ball-bearing-fan/p/YX2522

Interesting,, have 2 of these at top of fridge vent ie the top vent to exhaust for use on very hot days (we had 43C when fan failed and 47C next day),, but at 88cfm I'm told they just do the job,,, as a compressor fan.

Thanks again for info.

 

 

Alternately you could use a series resistor to reduce fan speed and current.

Ken

 

 



-- Edited by kgarnett on Tuesday 12th of March 2019 09:05:51 AM

 



-- Edited by Baz421 on Tuesday 12th of March 2019 09:57:09 PM

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Baz421


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T1 Terry wrote:

Buy a solid state relay from Jay Car www.jaycar.com.au/pcb-mount-solid-state-relay-12v/p/SY4093 and wire the switch/control side as marked, + to + and - to - . The load side how ever is different, the + and - relate to the current flow and not to voltage. It you wire the relay in the positive wire, then the positive from the battery/fridge control feed goes on the relay load + terminal and the fan + goes on the relay load - terminal. The fan negative connects direct to the supply negative and not to the relay. Get that part wrong and you will need to buy a new relay, they are not forgiving, death of the relay is instant.

T1 Terry

Thanks Terry   I bought the relay recommended in prev post,, I can get relay to click in but no output.  I can get my wiring to work with low wattage light globe so I know wiring is good just need relay - off to jaycar again



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Whenarewethere


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Have you looked as RS-online they should have something.

https://au.rs-online.com/mobile/c/hvac-fans-thermal-management/fans/axial-fans/?applied-dimensions=4294440647,4294531136,4294644631



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Baz421


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Whenarewethere wrote:

Have you looked as RS-online they should have something.

https://au.rs-online.com/mobile/c/hvac-fans-thermal-management/fans/axial-fans/?applied-dimensions=4294440647,4294531136,4294644631

This the one I bought,,

https://www.altronics.com.au/p/f1165-sunon-120mm-12vdc-maglev-bearing-fan/

can't see it in rs pages.  Thanks for link 



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oldtrack123


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The simplest & cheapest way is a relay connected as per JB's post.

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Baz421


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oldtrack123 wrote:


The simplest & cheapest way is a relay connected as per JB's post.

yeh I'm trying to source one with low enough (<500mA) control circuit,,, think I've found one.



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Tech48


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Hi Baz

I use this fan with my BD50 based frig, as a direct replacement.

Jaycar YX-2584, 120mm, 12V, 0.22A, (220mA) 64 CFM.

Works well and is very quiet.
Have used this type of fan for ten years in my frig, one replaced by another of the same type after 5 yrs.
I don't fret that the CFM is very slightly lower.

You have to cut off the plastic connector on the new fan, trim back and insulate the unused yellow (tacho) wire, then crimp two female spade connectors to the new fan red and black wires, and then it just plugs directly in.

No need for any additional relay.

Fan airflow direction is outwards, ie away from the compressor.


For reference, the original fan with my BD50 was a Yate Loon type GP D12BM-12.
Its spec is 72 CFM.

Good luck



-- Edited by Tech48 on Friday 15th of March 2019 02:33:15 PM



-- Edited by Tech48 on Saturday 16th of March 2019 09:48:29 AM

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Baz421


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Thanks all for your replies much appreciated.

Fitted a relay from Altronics works well.

Fan is rated at 48dB but I'm not sure. See how we go  sleeping.

 



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Whenarewethere


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If the fan is mounted on acoustic isolation blocks it will help. Also some butyl acoustic material on the flat surrounding surfaces, & some acoustic foam on top & also on the remaining surfaces. If



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