Engel old style

Submitted: Saturday, Dec 06, 2014 at 19:14
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Does anyone know if it is possible to install a cooling fan (computer type) in the old style 29 litre fridge/freezer please?
Thanks
Ian
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Reply By: Ken - Saturday, Dec 06, 2014 at 19:47

Saturday, Dec 06, 2014 at 19:47
Yes it is Ian but be aware the voltage supplied to the Engel motor is about 21 volts. This is derived from the 12volts from the vehicle. I had an old 29 ltr Engel with a computer fan in it and at the time was fortunate to know a bloke who made a little printed circuit board which took the motor voltage and dropped it to 12 volts. Lost contact with him now so can't put you in touch.
It really made a difference to the run time [and therefore total amphours used ] and is well worth doing if you can: a) get a suitable voltage fan ; or b) get some electronic guru to make a suitable 21 volt to 12 volt supply.

The circuit board had several components on it, not just a voltage dropping resistor but possibly if you knew the current drawn by the fan and measured the exact voltage into the motor, you MAY be able to use a simple resistor to drop the voltage.
Good luck.
Ken
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Follow Up By: Member - Ian F (WA) - Saturday, Dec 06, 2014 at 20:15

Saturday, Dec 06, 2014 at 20:15
Thanks for the info Ken.
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Follow Up By: TomH - Saturday, Dec 06, 2014 at 20:17

Saturday, Dec 06, 2014 at 20:17
You can buy a kit from Jaycar to do what you want. A bit of soldering required but have used them before

Part number is KC5463 can output up to 15v at up to 4 amps
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Follow Up By: Member - Ian F (WA) - Saturday, Dec 06, 2014 at 21:18

Saturday, Dec 06, 2014 at 21:18
Thanks Tom $17 from Jaycar
Ian
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Follow Up By: Member - Phil G (SA) - Saturday, Dec 06, 2014 at 22:51

Saturday, Dec 06, 2014 at 22:51
Ian, I doubt that kit will work.
Need a Rectifier because the Engel compressor is 21V AC not DC.
See my post below for the kit we used years ago.
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Follow Up By: The Bantam - Sunday, Dec 07, 2014 at 11:53

Sunday, Dec 07, 2014 at 11:53
Any simple 3 terminal regulator kit will do the job....adding a rectifier is a non issue.

Ive been running fans off similar regulator kits for ages...there are some more suited kits that have the option of rectifiers on board..and you only need a 1 amp regulator.

for that matter..there are a number of other ways of doing this.

1. fit a 24 Volt fan with a series diode or a full rectifier.
2. bring 12 volt supply from the inlet socket direct to the fan

here are some options to think about.
even if running direct off the 12 volt input......run a 24 volt fan.....it will happily run at half speed and be a hell of a lot quieter.

regardless of the source of supply, run a variable voltage regulator to vary the speed and noise from the fan.
most dc fans in good comndition will run at well below 1/2 their plated voltage quite happily with a matching reduction in noise.
I've been doing this for years when noise is an issue for clients.



Whatever you decide.....look for a magnetic levitation fan......these suspend the ermiture and the fan on a magnetic field...they are much quieter than a ball bearing fan and run much longer than bothe ball bearing and bushed fans.

It is reasonable also to run some sort of temperature switch ( simple or complicated) to automatically switch the fan on and off or run it as a two speed fan.

OH...don't think there is a problem with series resistors either......in this situation it is a perfectly reliable and safe method of speed/ voltage controll for computer fans...as long as the resistor is properly selected and mounted.

cheers
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Reply By: pop2jocem - Saturday, Dec 06, 2014 at 20:54

Saturday, Dec 06, 2014 at 20:54
I have installed a computer fan in my 18 year old 39l Engel.

I simply ran a seperate 12v supply line to the fan which gets switched on when the 12v supply to the fridge is powered up. Saves having to have a voltage regulated setup.

Cheers
Pop
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Follow Up By: Member - Ian F (WA) - Saturday, Dec 06, 2014 at 21:16

Saturday, Dec 06, 2014 at 21:16
Thanks Pop, I assume it is via a relay.
Ian
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Follow Up By: pop2jocem - Sunday, Dec 07, 2014 at 11:25

Sunday, Dec 07, 2014 at 11:25
Ian,

You certainly could use a relay. I just used a suitably rated on off switch to power up the fridge and fan. The fan runs continuously while the fridge supply current is on. Been like that for many moons. Those little computer fans draw bugger all current and seem to outlast most computers.
The fridge will freeze anywhere in the "Top End" no worries.

Cheers
Pop
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Reply By: Member - Phil G (SA) - Saturday, Dec 06, 2014 at 22:45

Saturday, Dec 06, 2014 at 22:45
I've done it to my 22 year old B-series Engel.
Need to convert the 20V AC going to the compressor to 12V DC to power the fan.

Here is a link with all the details:
http://www.gpsoz.com.au/faninstall.htm
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Reply By: Ross M - Saturday, Dec 06, 2014 at 22:53

Saturday, Dec 06, 2014 at 22:53
Ian F
get two 12vdc computer fans and wire them in series so you end up with one red and one black wire.
Position fans in condensor area where you think it is the best position for both, ie blow in and draw out. This will make it a positive air change and not just wind in the willows.

Source a small rectifier bridge from jaycar 10 mm dis and it has an ac input ie two legs and the other tow legs are +ve and -ve to the fans. Add a small electrolytic capacitor across the +ve / -ve rectifier output and the fans will run a bit faster than if just of the DC created
The input to the rectifier is the taken from the 21vAC of the inverter. Mine is 19 to 20vac.

Because the fans are in series they don't quite get their normal full voltage but it is close.
the fans happily run and make the fridge able to freeze in 30C ambient because the condensor is able to get cooled an it's heat removed quickly.

Doing this saves heaps of battery through less run time.
I did mine before the Engel company started making Turbo models.

If you spray the metal sides with an insulating material ie stops rust through condensation, and also add an insulating bag + plenty of additional thermal insulation ie sleeping bag over the case only, it will even freeze in above 30c temps.

Without the bag and the fans most engels are pretty useless as a freezer. maybe ok as a fridge only.

Ps I put a switch on the, ac to rectifier wire, so it can be switched off in winter or alpine conditions.
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Follow Up By: Member - Phil G (SA) - Saturday, Dec 06, 2014 at 23:10

Saturday, Dec 06, 2014 at 23:10
Hi Ross,
this is the diagram for the common 12V fan conversion. I'd suggest that the extra $2 for a voltage regulator is well spent!


Out of interest, the turbo fans in the E- and F-series only turn on when the compressor is running and the compressor gets hot (because of high ambient temp or heavy use). I've rarely hear a fan on the turbo engel models.
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Follow Up By: Member - Phil G (SA) - Saturday, Dec 06, 2014 at 23:15

Saturday, Dec 06, 2014 at 23:15
Forgot to acknowledge Brian at GPSOZ who has provided that diagram on his website for the past umpteen years.
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Follow Up By: Frank P (NSW) - Saturday, Dec 06, 2014 at 23:17

Saturday, Dec 06, 2014 at 23:17
"make the fridge able to freeze in 30C ambient because the condensor is able to get cooled an it's heat removed quickly. "

This is the guts of the problem - quickly getting rid of the heat from the condenser.

I made a water-cooled condenser for my van fridge - the Danfoss compressor unit is remote from the fridge so access was ok. It has halved power consumption in hot weather by a combination of reduced compressor speed and reduced duty cycle.

Friend of mine did the same for his built-in 3-way fridge with a significant improvement in hot weather.

Cheers

Frank

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Reply By: Allan B (Member, SunCoast) - Saturday, Dec 06, 2014 at 23:52

Saturday, Dec 06, 2014 at 23:52
Excuse my ignorance but doesn't the Engel thermostat switch the 12 volt DC before it goes to the 21v inverter?
If so then it is simply a matter of connecting a 12v fan to that circuit.

Sorry that I do not have an Engel to look at it.
I have a Waeco to which I added a second fan, wired in parallel with the original fan.
It was an improvement in performance.
Cheers
Allan

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Follow Up By: Member - Keith C (NSW) - Sunday, Dec 07, 2014 at 10:23

Sunday, Dec 07, 2014 at 10:23
Allan,That is what I have done with my old engel,I hooked two computer fans straight to the 12v circuit, one at the bottom sucking the cool air in and another at the top on the grille sucking the hot air out. I also have a switch on the grille to turn them off. Jaycar had all the parts Regards Keith
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Follow Up By: Allan B (Member, SunCoast) - Sunday, Dec 07, 2014 at 10:30

Sunday, Dec 07, 2014 at 10:30
Keith, are your fans controlled by the thermostat or do they run all the time that they are switched on?
Cheers
Allan

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Follow Up By: Member - Keith C (NSW) - Sunday, Dec 07, 2014 at 14:42

Sunday, Dec 07, 2014 at 14:42
Yep, run whenever they are switched on. Keith.
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Follow Up By: Member - Keith C (NSW) - Sunday, Dec 07, 2014 at 14:46

Sunday, Dec 07, 2014 at 14:46
Oops, should have said power circuit, not 12v. Keith
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Follow Up By: AlbyNSW - Sunday, Dec 07, 2014 at 16:18

Sunday, Dec 07, 2014 at 16:18
Are you guys putting the fan inside the fridge case or externally on the face of the side grilles?
I normally have my fridge in my canopy but recently did a long trip with fridge on my tray and I was surprised how much better it ran with good airflow around it, had to turn it up as my beers were freezing
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Reply By: Hoyks - Sunday, Dec 07, 2014 at 00:18

Sunday, Dec 07, 2014 at 00:18
Armed with a multimeter and a nice dose of ignorance, I just wired it in where I had 12V power switched by the thermostat.

The fan was free as it came out of an old computer. I got 12 years out of it before it died from getting full of sand.
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Follow Up By: Allan B (Member, SunCoast) - Sunday, Dec 07, 2014 at 10:26

Sunday, Dec 07, 2014 at 10:26
Exactly Hoyks. It is amazing what can be achieved with ignorance.
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Allan

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Follow Up By: Member - Phil G (SA) - Sunday, Dec 07, 2014 at 21:44

Sunday, Dec 07, 2014 at 21:44
Hoyks, can you remember where you wired in to the post-thermostat 12V? Was it up near the dial, or down near the input?
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Follow Up By: Hoyks - Monday, Dec 08, 2014 at 19:20

Monday, Dec 08, 2014 at 19:20
It was around 20 years ago now, my memory isn't that good. I can go and pull it apart and have a look.
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Follow Up By: Member - Phil G (SA) - Monday, Dec 08, 2014 at 20:47

Monday, Dec 08, 2014 at 20:47
Hi Hoyks, no need to do that, its just my curiosity - I went through the same thing years ago, but couldn't find a source of 12V DC that came on with the thermostat which is why I did made up the kit that hooks into the 20VAC compressor wires.
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Follow Up By: Hoyks - Tuesday, Dec 09, 2014 at 18:34

Tuesday, Dec 09, 2014 at 18:34
Another option I was thinking of doing for my newer fridge is to get a 12v digital temperature controller (around $13 on eBay) and using that to actuate a relay that will supply power to the fridge.


The temp controller has a thermocouple that will fit into the fridge. When the temp gets above the set point the relay will actuate and supply power to the fridge. the dial temp controller on the fridge just gets set to Freeze and left there. Yes, it is made in china and all, but with the right plugs if the thing craps out, you can just bypass it.

With that you could wire it so that when the fridge is powered up so is the fan.
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Follow Up By: Allan B (Member, SunCoast) - Tuesday, Dec 09, 2014 at 18:46

Tuesday, Dec 09, 2014 at 18:46
That looks pretty good Hoyks.
At $13 all up you could hardly go wrong.
It has 10Amp current capacity so you wouldn't even need a relay.
Cheers
Allan

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Follow Up By: Member - Phil G (SA) - Tuesday, Dec 09, 2014 at 19:37

Tuesday, Dec 09, 2014 at 19:37
Hoyks, Allan,
Are we unnecessarily complicating things? The fridge has a thermostat that does the same job.
If the only purpose of this is to add a thermostatically controlled fan, then why not mount the sensor next to the compressor and use the circuit to switch just the fan?
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Follow Up By: Hoyks - Tuesday, Dec 09, 2014 at 20:44

Tuesday, Dec 09, 2014 at 20:44
Well, you could do it the easy way... but where is the fun in that? ;-)

This way though it involves no modification to the actual fridge.

I just bit the bullet and parted with the princely sum of $12.82. I'll let you know how it goes in the new year.
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Follow Up By: Allan B (Member, SunCoast) - Tuesday, Dec 09, 2014 at 21:17

Tuesday, Dec 09, 2014 at 21:17
Yes Phil, it is probably not the way I would do it but for $13 it will give Hoyks a digital thermometer and a sense of achievement to boot.

Cheers
Allan

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Reply By: Malcolm 02 - Monday, Dec 08, 2014 at 08:18

Monday, Dec 08, 2014 at 08:18
I had an old 17L Engel which I used to run as a freezer. About 1993 I decided to improve the efficiency of the unit by adding a computer fan. I connected this to the 12v input via a switch. The fan was mounted to the top of the cooling area and I used some sheet aluminium to cover the rest of the top to avoid the air recirculating around the fan and to encourage the air to be drawn through the condenser.
Although I didn't do any comprehensive tests, I felt the battery I was drawing from lasted a lot longer. I used it for quite a few more years on Groote Eylandt before replacing it with a larger Evacool.
Also remember being a very popular guy one warm Easter camp when I supplied a Magnum ice cream for everyone for desert on the first night.

Mal
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