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Forum Index : Electronics : 240v Freezer through Inverter Experiment
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Jaffasoft Senior Member  Joined: 03/11/2010 Location: AustraliaPosts: 102 |
LoL. Funny you should mention that I just received a very insightful array of answers to my questions direct from a very helpful fellow at the manufacturing plant explaining a Wancool compressor is used in all of the above five similar products and that they produce them all. This is most probably the reason the seller backed off and would not answer questions about if it was a BD35F Compressor. He also said that on request could manufacture fridges customised to your needs and instal BD35F Danfoss Compressors. Anyone wanna but 100 fridges and put your name on them ). |
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| Warpspeed Guru  Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Perhaps Danfoss can tell you who are buying their BD35F compressors and what actual models they are fitted to? Cheers, Tony. |
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| Jaffasoft Senior Member Joined: 03/11/2010 Location: AustraliaPosts: 102 |
I didn't get to Danfoss directly to ask any questions or now called Secop ("yes, I know why on earth would you change a really good name from years of reliable service), it has some good data PDF downloads to read of comparisons of different BD series motors and control units to use particularly designed for offgrid solar applications. For even designing your own fridge/freezers if you're so inclined. The BD35K Compressor with a 101N0400 comes out on top using the a600 refrigerant but not by a great margin and can run direct from a solar panel direct off a recommended 120watt panel. So doing away with the need for a battery at alltogether. I learned much! Using an ice battery instead (just freezing water) in the fridge. Effectively just the same as switching a freezer on running it for hours straight until ice it made and switching it off for three to five days or until you get another good day of Sun. 100mm or more even 150mm of insulation would be better. So how many fridges or freezers do you find on the market that do that, well next to bugger all. The closest I found to getting this all right was NASA The Sundanzer and the price was surprisingly good too but they didn't answer my email so I went off trying to get on in Australia. All this theory sounds good but ive got to come back down to earth. On being set on the size of 80ltrs and a combined fridge with a little freezer space I found something else that is not one of the brands that I mentioned above. I put the money in the bank and will start a new dedicated thread about it when it arrives collecting usage and performance data over a year solid living out of it in a Van in Australia! I will give it a decent workout and test this thing out see if its anygood. It has not got the above specs but this mere mortal on my budget had to settle for something. It has the BD35F Compressor and that gets great reviews all the way back to the old Boaties relied on them at sea to keep there livelyhood icy in customised fridges. The inverter FETs arrived and I got one in and changed a resistor, switched it on and got a red error light but no more smoke. I noticed from image memory after that that i didn't replace the faulty resistor, pretty sure. Since I was walking around I came across an electric fence and tested it to see what the meter read out of curiosity [BANG] the meter blow up in my hand. I cant test the resistor. Still ll pull it out tom or something and test it again. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
That is pure genius ! I looked up some figures: Latent heat of melting ice 334 Kj/Kg Energy density of lead acid battery 170 Kj/Kg So ice is twice as efficient at storing cold as charging up a battery, even before you start thinking about the efficiency of an inverter or the compressor. Reliable too... Cheers, Tony. |
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norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Latent heat of water at boiling even better, thus the efficiency of steam turbines, engines etc. But the reverse is true unfortunately ie latent heat of freezing. The amount of heat required to be removed from water to make ice using a small 12v compressor(50watt or so), wrecks the hope of being able to make a usable amount of ice whilst the sun shines. Check out the spec. sheets of the Danfoss, in particular the correlation between heat removal at different temperatures. Then multiply the Kj/hr`s by the usable sun hours per day divide by 334 and that will give you the kg`s of ice at 0degC you`ll make.(taking the temp of the water was 0deg C before you started)This is without taking into account heat load from ambient temp.ie insulation inefficiency. You would need a much bigger compressor or enjoy a hot beer  . There has been for many years eutectic systems employing the 12v Danfoss, they worked very well if you run at home(on 240) a few days before you went camping. Unfortunately refrigeration whilst being capable of removing more energy then you put in (due to the energy taken ambiently(latent heat of condensation) by the condenser) and the Danfoss DC`s being extremely efficient, I am afraid they will not meet your expectations. We come from the land downunder. Vic |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yes that is all pretty clear. If you have (say) four hours of good sunlight, and you want to keep your beer cold twenty four hours, then it comes down to two choices. 1/ Fit a really big storage battery and an inverter to drive a wimpy little compressor that chugs away intermittently for twenty four hours. 2/ Install a bucket of water in the oversized freezer and fit six times the refrigeration capacity. Something that has some real balls when the sun shines. It's a cost/benefit problem. Different solutions suit different folks. But it's an option well worth some serious consideration in a very hot sunny situation. Cheers, Tony. |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I still have not bought that Haier freezer I was intending to in Run a standard freezer off-grid? BUT the older freezer that I tested and was horrified at the Amps that it pulled on startup, died shortly after on mains power. So it was probably on the way out and would have fried an inverter if used off-grid. I think the Haier 148 and 208 are the pick of the bunch for low startup amps on paper but I would still like to hang my clamp meter on the inverters battery lead and run a few cycles before I give it the thumbs up. I'm confused, no wait... maybe I'm not... |
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| Jaffasoft Senior Member Joined: 03/11/2010 Location: AustraliaPosts: 102 |
I looked at these and thought they were impressive too. Not sure if star ratings mean anything but in a line up of chest freezers at our local Harvey Norman the 148Ltr was think it said 220kwh year. It was the lowest of them all. Lowest price to $339. I wandered how they could do it. Then got on my hands and knees to look at the compressor and schemtic around the back and stuff and there is a run capacitor installed. Can see the big capacitor clearly. Be interesting if it had a start capacitor, probably hasn't though. I will have a read of your thread! |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
westinghouse and kelvinator (same brand) list their units at 6 amps starting load (average)then say "not to be used on offgrid power systems" in the manual. My old westinghouse freezer is a lot higher than that, probably 15 to 20 amps, it dims the lights in the house as it starts. I have seen an upright haier starting and running happily on a 600watt inverter, till the batteries started to fail through neglect then the whole lot did a Fukushima. I'm confused, no wait... maybe I'm not... |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Are there any sealed unit compressor units out there fitted with low voltage dc motors ? Cheers, Tony. |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
My Bushman camper fridge/freezer runs only on 12VDC and is a compressor type. Very happy with it (so far). David M. |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Other then the Danfoss DC compressors there is a fair few DC compressor brands available, Made in Italy, Brazil, China etc. From experience today`s off-grid household is served better by inverter driven 240v standard refrigeration. They have evolved, having better insulation(not thicker), more efficient compressors-refrigerant combinations plus the inverter has evolved. Personally I go for the West, Kelvi`s not because they are more efficient but their parts are available as are they. They are mainstream and chasing the all efficient refrigeration system is a little like seeking the Holy Grail. Having manufactured DC compressor driven refrigeration for solar households through the 80`s & 90`s, I now believe we are better served by today`s 240v systems, DC`s refrigeration serves portable applications nicely. Interesting that they(West,Kelvi) do not recommend using in off-grid applications. Perhaps that is an old policy that they should review and hopefully they will as more households go off-grid. Go for around 1000 Ah/hr battery banks firstly, the battery is the heart of the off-grid systems. I am afraid if you cannot afford to do that a total off-grid standard household is not yet for you. Of course this will change once we have batteries(mainstream) that can be drained to 10% rather then 70% of capacity and still give a long life. Although grid power is becoming dearer it is still a cheaper option then off-grid. I am totally off-grid and very happy with my system I know when the batteries are due for replacement in 5 or so years, the replacement cost of them alone costs near as much as the power bills I saved over their 10 year life. If I get more then 10 years then the formula changes. Time will tell and battery technology will change my current formula. We come from the land downunder. Vic |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Actually I am on grid, but a full third of my power consumption is the damned refrigerator, and another third is a very small constant load from things that draw constant low level current all the time, even when switched off. It does not take much, a small transformer inside an appliance that has the main on/off switch connected on the low voltage side can can draw 60mA when turned off. For 24 hours a day that works out to (.06 x 240 x 24hrs) 346 watt hours per day, and there are several things that have that very annoying characteristic. With everything turned off my daily power consumption is still around 1.5kWh. I was hoping to run the refrigerator (1.2kWh/day) from solar, but that appears not to be a cost effective solution, no matter how I go about it. Beginning to think running a fridge from natural gas, with propane back up may be my best option. It's a bit of an odd thing to do, but quite possible and should be more cost effective than going solar. Cheers, Tony. |
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| Jaffasoft Senior Member Joined: 03/11/2010 Location: AustraliaPosts: 102 |
I noticed that an old retired refrigeration serviceman has a Fridge-mate Compressor on ebay. Ebay Link!. I don't know anything about these compressors. |
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| Jaffasoft Senior Member Joined: 03/11/2010 Location: AustraliaPosts: 102 |
Just put a replacement resistor in! On powering up the inverter same FET popped, EXPLODED. It's all a bit beyond me, will leave that as a failed idea in my situation. Others will get different results. We've learnt here that a poor battery bank will end this idea in tears! It cost money for these luxuries.. I just had to folk out to have them. |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Fridge Mate (my take on this) was a OZ Co in Qld, they built an innovative fridge/freezer around the mid 90`a (from memory). The idea seemed a brilliant one it had the complete compressor, condenser and evaporator built into the removable lid. It failed (again my take) because the compressor had no life. The idea had a lot of merit. The unit wasn`t available for long because of the compressors shortcomings. Have one a customer had asked me to repair, I advised against repairing (costs) and the customer left it with me. He took his lose and didn`t chase good money after bad results. 
Have a feeling that a manufacturer will take up on this idea. We come from the land downunder. Vic |
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| Jaffasoft Senior Member Joined: 03/11/2010 Location: AustraliaPosts: 102 |
Yahoo, this is the stuff you need to get your head around if fiddling with Start Capacitors. Math and lots of it! Can't import the Supco 3 en 1 Start Cap Kit you refered to which would have been interesting to try. Couldn't find anything similar in Australia. Maybe there is a reason doing this is not common? |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Personally I don't think it is worth it. As far as I can see a very modern 240 volt freezer and the danfoss 10-30 volt are about line ball on energy consumption. My standard advice after a lot of heavy duty thinkin  is to spend the money on panels, batteries and a quality inverter and use off the shelf whitegoods. There are lowish startup power and low energy options for no extra dollars for most things in 240 volt (water pumps excluded).
the haier freezer is a good example, 600 to 900 watts a day with about half of that coming from battery storage (night) including inverter losses for a $350 unit is pretty good. I accept I could not chuck a pig or quarter of a cow in and expect it to freeze in a hurry but it is not designed for that. my stab in the dark is that the start up would be between 400 to 700 watts and it would run in the 65 to 90 watt range for about 30% of the day. The same thing in DC is $1700+ and $400 freight plus DC wiring and expensive to fix if it breaks down and if you are in the country you are without a fridge or freezer while it is repaired. I will actually be looking to increase my power usage over the next few years and convert part of my system to 3 phase to run my welders, lathes a mill and hopefully a decent cold room. Oh, and perhaps a charger for a hybrid electric shootin wagon so I can sneak up on the feral cats that make my life a misery. I'm confused, no wait... maybe I'm not... |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Yes we can fart around with efficient lights, and other small consumption items to cut our energy consumption but the biggest hurdle is refrigeration. It comes down to if you wish to have the benefit of a fridge and a freezer, look at just what you want there first and size your battery, panels and inverter from there, of course allowing for those other smaller consumption appliances. Appliances like microwaves, turbocookers , welders etc can be used whilst you have the sun but refrigeration is 365/24/7. I believe battery first( in money outlay), you can add extra panels, you can add a second inverter but it is not wise to add to a battery bank. Mixing new batteries whether in parallel or in series with older batteries, can be an expensive mistake. Perhaps the better work around would be if you cannot afford the large battery bank initially then add a separate complete system isolated from each other as you can afford. With the flood of cheap inverters and cheap solar regulators, how many of them are destroying batteries. Better to look at the systems that are and have been operating for many years. I suggest they have the name brand inverters and regulators. Plasmatronics, Outback, Lantrez, Selectronics etc are the brands you`ll find. Yahoo2 keep us posted on your proposed 3phase upgrade. That should bring some better efficiencies into the evolving formula. We come from the land downunder. Vic |
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| Jaffasoft Senior Member Joined: 03/11/2010 Location: AustraliaPosts: 102 |
This is where i am at.. I put 2 x 200watt 12v panels on the roof, then a two meter wire run of 4AWG down to a Tristar Morningstar 45Amp PWM Charge Control a foot away from $2 Ex Telstra 6v Telstra Batteries from the tip until the inverter blew. Since... as stated above I installed 2 Trogan Batteries total 225 Amp Hrs at 12v. Plan is to keep things very simple in this RV all I really been using was charging a tablet on an $24 350watt China Imported Inverter every day the last year. I'm not real big on TV these days but I bought a 13inch the back plug takes 12v so I got a separate plug to run it instead of 240v through the inverter because the inverter gets noisy in the living area of a RV. It's around half the watts used on 12volts. So surprised how low it reads I'm not sure if the Trimetric Meter is wrong. Just thought I might add a fridge next since I could then camp out bush a few weeks at a time. As it is, driving into town each night buying from out of supermarkets fridge/freezers cost more in fuel as well as sick of doing it. The jury is still out on weather the system installed will hold up 24/7/365 days of the year running a fridge then it has compartment that can switch to freeze so thats still to be tested. 80Ltr at $870 delivered. |
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