Hybrid compressor 4 way fridge.

[Richard n Ann]

Our van has got a standard 3 way under counter fridge in it and we power it with LPG mostly because electric is metered and expensive where we go in Spain.

So I've been thinking of adding a compressor system on and off for a while. Today I had a measure up to see what evaporator would fit inside and it turns out the husky counter top fridge evap is a millimetre perfect fit it would have to be horizontal in the ceiling of the fridge but sloped down at the back so the condensate drips off the back into the existing tray. It's just a matter of degassing the doner fridge cutting or unbrazing the pipes and feeding them through a 20mm hole in the back of the fridge and reconnecting with the compressor /condenser at the back.

The excess solar just isn't used during the day so it could run during the day and back to gas at night or maybe it would be ok 24hr in the Spanish sunshine. Got a 1000w PSW inverter for Ann's tongues so that's ready to go

These husky fridges can be got for £30 second hand or about £120 new. Just an idea anyway, don't think Ann will let me do it but it's a hell of a lot cheaper than buying a new compressor fridge and you've still got the 3 way gas option.

One disadvantage, you'd lose the freezer while on compressor.

 

[Steve and Denise]

Sounds like a great project

 

[Bolti]

Why don't you change your solar controller to one the feeds excess solar to the fridge?
The voltronic one does.

 

[Richard n Ann]

Why don't you change your solar controller to one the feeds excess solar to the fridge?
The voltronic one does.

They work by using the 12v element and it takes about 10 amps. Our solar is only 150w and maxes out about 9.2 amps.

The compressor runs at about 3 or 4 amps.

 

[Lenny HB]

Why don't you change your solar controller to one the feeds excess solar to the fridge?
The voltronic one does.

That's what I do but the fridge does take 15 amps, it does 2-3 ours on 12v on a good day as the Votronic switches over at half hour intervals so you don't flatten your batteries. Also I had to fit a relay inline with the signal or the dumb fridge selects 12v when on EHU.

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[68c]

I have wondered if a lower wattage 12v heating coil could be wrapped alongside the standard one and be powered by solar. This lower wattage coil, perhaps 25W, would surely produce some cooling during the day. OK not as good as the standard 12v setup but enough provided the door is not opened too often, I am thinking of those times you go out for the day, a sunny day may be enough to maintain an already cold fridge.

 

[Lenny HB]

25watt would do naff, all my 12watt element is 190 Watts.

 

[gus-lopez]

ot a 1000w PSW inverter for Ann's tongues so that's ready to go

If you run the compressor off the solar what is Anne going to charge her Tongue with?

 

[Richard n Ann]

If you run the compressor off the solar what is Anne going to charge her Tongue with?

Lol never realised it was a different spelling, not something I've ever used

 

[Richard n Ann]

Well I think I can forget running it off an inverter. Just tried a table top compressor fridge so only a 2cc compressor, and it runs at 7 amps off the inverter dropping to about 6.4 after 10 minutes our 12v compressor coolbox runs at 3 amps.

Looks like inverters aren't very good with inductive loads then. Runs the mains TV very efficiently but it's a fail today.

The 12v 2cc Danfoss compressor BD35F is £220

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[Raul]

They work by using the 12v element and it takes about 10 amps. Our solar is only 150w and maxes out about 9.2 amps.

The compressor runs at about 3 or 4 amps.

I like your attitude of being inventive. Maybe a small AC incorporating a fridge compressor? Would that work?,

on the above, the compressor draws 3-4a when running, but, it has a surge on start up. Our CRX 50 compressor is fed by 6mm wire and I had to switch to 7,5a fuse, as it was blowing the 5a. So don’t use solar controller load side for compressor. It’s meant for a relay or low loads, like lighting.

 

[Richard n Ann]

Maybe a small AC incorporating a fridge compressor? Would that work?,

Wouldn't do much cooling with a small fridge compressor. Wouldn't last long either. The forced warm air over the evaporator on an AC, even a small one would overload the compressor, the back pressure would be high because the small compressor wouldn't be able to suck in all the large amount of vapour overwhelming it. It would run hot and last about 2 weeks.

Even leaving the fridge door open stops the evaporator frosting, they are very small capacity compressors.

 

[Richard n Ann]

don’t use solar controller load side for compressor.

No, I haven't even got a load side. It's the Votronic duo 250

 

[EuroTrotters]

Well I think I can forget running it off an inverter. Just tried a table top compressor fridge so only a 2cc compressor, and it runs at 7 amps off the inverter dropping to about 6.4 after 10 minutes our 12v compressor coolbox runs at 3 amps.

Looks like inverters aren't very good with inductive loads then. Runs the mains TV very efficiently but it's a fail today.

The 12v 2cc Danfoss compressor BD35F is £220

You can buy cheaper 12v compressors.

what about a small inverter compressor?. That is, 240v feed. But it will run at variable speeds and save energy . You can use an R600a one

 

[Richard n Ann]

You can buy cheaper 12v compressors.

what about a small inverter compressor?. That is, 240v feed. But it will run at variable speeds and save energy . You can use an R600a one

There is a cheaper one on ebay by a German seller. No info or dimensions on it though and it's still £170.

Yes I'm open to any inverter driven system, they are super on AC
I looked at 134a compressors because I've got a couple of kg of that. Never used the 600a stuff, years ago a girl down the pub wanted me to look at her chest freezer, there was no gas in it and it was on R600a... So I put 134a in it! worked spot on.

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[Richard n Ann]

But it will run at variable speeds and save energy

Actually it's a brushless 3 phase dc motor so is variable speed anyway. If you just fit a thermostat it runs at it's lowest speed of 2000rpm but you can get an additional controller that will crank it up to 3500rpm (as long as the condenser is big enough) probably won't need that on a little fridge though. I bet it soft starts too
I'm saving up

 

[Lenny HB]

3 phase dc motor

???

 

[EuroTrotters]

There is a cheaper one on ebay by a German seller. No info or dimensions on it though and it's still £170.

Yes I'm open to any inverter driven system, they are super on AC
I looked at 134a compressors because I've got a couple of kg of that. Never used the 600a stuff, years ago a girl down the pub wanted me to look at her chest freezer, there was no gas in it and it was on R600a... So I put 134a in it! worked spot on.

Usually the R600a is not compatible with R134a oil. Though it’s okay the other way around

 

[Richard n Ann]

???

Yes I know it sounds wrong. After all, we are so used to our 3 phase ac system and 3 phase ac motors, but microprocessors can pulse brushless DC motors that have 3 windings and make them turn .
This is how inverter air con compressors are speed controlled too

 

[Lenny HB]

Yes I know it sounds wrong. After all, we are so used to our 3 phase ac system and 3 phase ac motors, but microprocessors can pulse brushless DC motors that have 3 windings and make them turn .
This is how inverter air con compressors are speed controlled too

A stepping motor then.

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[Richard n Ann]

A stepping motor then.

Yes a fast stepper motor

 

[EuroTrotters]

Did you see my post here.

I halved the power consumption by changing to a more efficient compressor

 

[EuroTrotters]

Did you see my post here.

I halved the power consumption by changing to a more efficient compressor

 

[Richard n Ann]

No didn't see it

 

[Richard n Ann]

Found it

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[Richard n Ann]

If I was to go to the lengths of changing the compressor I'd fit the danfoss 12v one.. Think that's about 40w