Tony Brooks Posted August 1, 2022 Report Share Posted August 1, 2022 3 minutes ago, Alan de Enfield said: I'm guessing that "his" 2-way is 12vdc & 230vac, rather than Gas and 12vdc, or gas and 230vac. It seems it is the use of gas that is concerning him. Just buy either a 12v OR a 230v fridge and be done with it. If that is what he means I fear he may be going down the Peltier route and if so he will be back to high electricity demand. Especially of the 240V is via a wall wart. As you say, just get a 12V or 240V COMPRESSOR fridge and be done with it. 1 Link to comment Share on other sites More sharing options...
MtB Posted August 1, 2022 Report Share Posted August 1, 2022 31 minutes ago, Tony Brooks said: If that is what he means I fear he may be going down the Peltier route and if so he will be back to high electricity demand. Especially of the 240V is via a wall wart. As you say, just get a 12V or 240V COMPRESSOR fridge and be done with it. I think you're right. I've never seen a 12Vdc/240Vac compressor fridge. They might well exist but if they do, they are rare. I'm also not sure the OP understands the different refrigeration technologies and how much they differ in power consumption. Careering off at a tangent, I'm vaguely surprised there are not 12Vdc fridges on the market from third-party companies who professionally integrate an inverter into the fridge rather than the swapping the compressor to a generic 12Vdc/24Vdc unit. Fitting an inverter must be a cheaper way to create a standalone 12Vdc compressor fridge out of a cheap 240Vac fridge than changing the compressor. Link to comment Share on other sites More sharing options...
Alan de Enfield Posted August 1, 2022 Report Share Posted August 1, 2022 1 hour ago, MtB said: Careering off at a tangent, I'm vaguely surprised there are not 12Vdc fridges on the market from third-party companies who professionally integrate an inverter into the fridge rather than the swapping the compressor to a generic 12Vdc/24Vdc unit. Fitting an inverter must be a cheaper way to create a standalone 12Vdc compressor fridge out of a cheap 240Vac fridge than changing the compressor. That is how 12v Microwaves are (normally) converted. Link to comment Share on other sites More sharing options...
MtB Posted August 1, 2022 Report Share Posted August 1, 2022 16 minutes ago, Alan de Enfield said: That is how 12v Microwaves are (normally) converted. So I wonder why fridges are not done the same way. My guess is finding an inverter to deliver a high enough transient start-up current but cheap enough and reliable enough. 1 Link to comment Share on other sites More sharing options...
BEngo Posted August 1, 2022 Report Share Posted August 1, 2022 11 minutes ago, MtB said: My guess is finding an inverter to deliver a high enough transient start-up current but cheap enough and reliable enough. Probably. If such an inverter existed it would be so handy for DIY installations of 240 V fridges so there would not be much call for a professional integration. Plus finding space, and ventilation for an integral inverter unit. The 'hole behind the veg drawer' is a crap place to put an inverter because it is already pretty full of compressor, which also warms the space up when running and makes the inverter's life harder. A BD35 and purpose designed electronic unit just replaces the similar sized 240v compressor. A bit of pipe work, do up a few nuts, add gas and the jobsaguddun. From a technical point of view, adding an inverter also introduces another point of failure and so reduces overall reliability. N Link to comment Share on other sites More sharing options...
Alan de Enfield Posted August 1, 2022 Report Share Posted August 1, 2022 (edited) 30 minutes ago, BEngo said: Plus finding space, and ventilation for an integral inverter unit. And, running 12v cables from the batteries to the fridge ( 50 foot each way of volt drop ?) capable of carrying the current / volt drop would not be a simple DIY task for many who are just wanting a plug & play device. May as well just use a mains fridge plugged into a mains socket and use the already suitably installed inverter. Are there many boats these days that do not have an inverter ? Edit to add : My Waeco fridge manual suggests that for a 12Vdc fridge at 20 metres from the batteries it would require ~25mm2 cable. Edited August 1, 2022 by Alan de Enfield Link to comment Share on other sites More sharing options...
cuthound Posted August 1, 2022 Report Share Posted August 1, 2022 2 hours ago, MtB said: So I wonder why fridges are not done the same way. My guess is finding an inverter to deliver a high enough transient start-up current but cheap enough and reliable enough. Yes, typical inrush of a compressor is 8 times running current. Good inverters can support a short overload of twice the badge rating, therefore an inverter at least four times the running current would be needed. Probably cheaper just to install a 12 volt compressor. Link to comment Share on other sites More sharing options...
Tracy D'arth Posted August 1, 2022 Report Share Posted August 1, 2022 18 minutes ago, cuthound said: Yes, typical inrush of a compressor is 8 times running current. Good inverters can support a short overload of twice the badge rating, therefore an inverter at least four times the running current would be needed. Probably cheaper just to install a 12 volt compressor. They are not simply 12v DC compressors but have windings sequentially powered by the electronic module that does the clever switching. At least that is how the popular Danfoss ones work. Explains the cost to some extent. 1 Link to comment Share on other sites More sharing options...
Tony Brooks Posted August 1, 2022 Report Share Posted August 1, 2022 Just now, Tracy D'arth said: They are not simply 12v DC compressors but have windings sequentially powered by the electronic module that does the clever switching. At least that is how the popular Danfoss ones work. Explains the cost to some extent. And as far as I can tell expensive powerful permanent magnet rotors that allow them to get the same power from less electricity. Link to comment Share on other sites More sharing options...
OldGoat Posted August 1, 2022 Report Share Posted August 1, 2022 I borrowed a lower cost 1200W inverter from Bimble a couple of years ago and it ran not only a very efficient 3/4 height FF but (separately) an ancient full sized FF with two compressors without any trouble. However it would not start either when on the reduced standby setting. IMO the 'challenge' with running 240v compressor fridges is the standby power requirement of the inverter. It's less of a problem IF folks had a more than basic battery capacity - which looking at threads on this forum is as reare as hens' teeth..... Link to comment Share on other sites More sharing options...
Tracy D'arth Posted August 1, 2022 Report Share Posted August 1, 2022 22 minutes ago, OldGoat said: I borrowed a lower cost 1200W inverter from Bimble a couple of years ago and it ran not only a very efficient 3/4 height FF but (separately) an ancient full sized FF with two compressors without any trouble. However it would not start either when on the reduced standby setting. IMO the 'challenge' with running 240v compressor fridges is the standby power requirement of the inverter. It's less of a problem IF folks had a more than basic battery capacity - which looking at threads on this forum is as reare as hens' teeth..... I have been arguing this problem for years. To avoid the standing power, quiescent, the inverter could be switched on by the fridge stat so that it is only on when required. Link to comment Share on other sites More sharing options...
David Mack Posted August 1, 2022 Report Share Posted August 1, 2022 2 hours ago, Alan de Enfield said: My Waeco fridge manual suggests that for a 12Vdc fridge at 20 metres from the batteries it would require ~25mm2 cable. But there can't be many narrowboats where the fridge and batteries are 20 metres apart! 1 Link to comment Share on other sites More sharing options...
Alan de Enfield Posted August 1, 2022 Report Share Posted August 1, 2022 8 minutes ago, David Mack said: But there can't be many narrowboats where the fridge and batteries are 20 metres apart! Batteries in the stern, kitchen in the centre 33 foot apart 60+ feet boat (20 metre return trip for the electical fairies) Link to comment Share on other sites More sharing options...
Tony Brooks Posted August 1, 2022 Report Share Posted August 1, 2022 1 minute ago, Alan de Enfield said: Batteries in the stern, kitchen in the centre 33 foot apart 60+ feet boat (20 metre return trip for the electical fairies) But the Danfoss & Shoreline instructions are written in a way that only requires one leg of the supply to be measured. In other words they specify a cable of twice the size but for effectively half the total run length, so it works out correctly. Link to comment Share on other sites More sharing options...
Tracy D'arth Posted August 1, 2022 Report Share Posted August 1, 2022 2 minutes ago, Alan de Enfield said: Batteries in the stern, kitchen in the centre 33 foot apart 60+ feet boat (20 metre return trip for the electical fairies) Factor of 2 error. Normally I allow 1sq M for every metre distance between battery and fridge not cable run length. Link to comment Share on other sites More sharing options...
Alan de Enfield Posted August 1, 2022 Report Share Posted August 1, 2022 Just now, Tracy D'arth said: Factor of 2 error. Normally I allow 1sq M for every metre distance between battery and fridge not cable run length. I know that is the oft quoted figure but my waeco fridge manual is a bit more conservative. Link to comment Share on other sites More sharing options...
Richard10002 Posted August 1, 2022 Report Share Posted August 1, 2022 6 minutes ago, Alan de Enfield said: Batteries in the stern, kitchen in the centre 33 foot apart 60+ feet boat (20 metre return trip for the electical fairies) That's not quite what you said, is it!? "20 metres apart", is somewhat different from "20 metre return trip". 1 Link to comment Share on other sites More sharing options...
David Mack Posted August 1, 2022 Report Share Posted August 1, 2022 1 hour ago, Richard10002 said: That's not quite what you said, is it!? "20 metres apart", is somewhat different from "20 metre return trip". Exactly my point. For my 71ft 6in ex working boat I would have to have the batteries under the counter and the fridge in the bow locker to get them 20 metres apart! Link to comment Share on other sites More sharing options...
PaulJ Posted August 1, 2022 Report Share Posted August 1, 2022 6 hours ago, MtB said: I think you're right. I've never seen a 12Vdc/240Vac compressor fridge. They might well exist but if they do, they are rare. I'm also not sure the OP understands the different refrigeration technologies and how much they differ in power consumption. Careering off at a tangent, I'm vaguely surprised there are not 12Vdc fridges on the market from third-party companies who professionally integrate an inverter into the fridge rather than the swapping the compressor to a generic 12Vdc/24Vdc unit. Fitting an inverter must be a cheaper way to create a standalone 12Vdc compressor fridge out of a cheap 240Vac fridge than changing the compressor. Waeco would also supply a mains /12 or 24v unit that ran the fridge off the mains when present and would automatically switch to 12v when disconnected from shore power. They may not do them anymore ,dont know as I havent needed to look recently but I always thought it a good idea as did the folk I fitted them for. Link to comment Share on other sites More sharing options...
MtB Posted August 1, 2022 Report Share Posted August 1, 2022 5 minutes ago, PaulJ said: Waeco would also supply a mains /12 or 24v unit that ran the fridge off the mains when present and would automatically switch to 12v when disconnected from shore power. They may not do them anymore ,dont know as I havent needed to look recently but I always thought it a good idea as did the folk I fitted them for. Interesting, thanks. But was it a compressor fridge?! Link to comment Share on other sites More sharing options...
Alan de Enfield Posted August 1, 2022 Report Share Posted August 1, 2022 There are 12/24v Dc and 230v Ac fridges but they are not what I would call a convetional fridge - they are more of a cool-box design that can either freeze, or refrigerate. They are compressor 'fridges' and are available up to 60 litre Dellonda 36L Portable Car Fridge/Freezer, 12/24/230V Dual Zone Compressor - DL13 : Amazon.co.uk: Automotive 60L Portable Car Fridge, Freezer, 12/24/230V Dual Zone Compressor - DL - Dellonda Link to comment Share on other sites More sharing options...
ditchcrawler Posted August 1, 2022 Report Share Posted August 1, 2022 4 hours ago, Alan de Enfield said: Edit to add : My Waeco fridge manual suggests that for a 12Vdc fridge at 20 metres from the batteries it would require ~25mm2 cable. Most do , 1mm2 per meter run Link to comment Share on other sites More sharing options...
PaulJ Posted August 1, 2022 Report Share Posted August 1, 2022 27 minutes ago, MtB said: Interesting, thanks. But was it a compressor fridge?! Yep.Still do them though output is limited to 4A @24V https://www.piratescave.co.uk/waeco-coolpower-eps100-mains-adaptor-230v-12-24v.html?id=153580265&gclid=Cj0KCQjw852XBhC6ARIsAJsFPN3KTuZb6hCOyaqw6figwNNmuLEmcPeqEiLTcxnyxIDAVI4t3D7fbOsaAktgEALw_wcB Link to comment Share on other sites More sharing options...
Tony Brooks Posted August 1, 2022 Report Share Posted August 1, 2022 (edited) 1 hour ago, ditchcrawler said: Most do , 1mm2 per meter run But only on one leg, not both. In reality 0.5 sq mm per meter of total wiring run length. Edited August 1, 2022 by Tony Brooks Link to comment Share on other sites More sharing options...
David Mack Posted August 1, 2022 Report Share Posted August 1, 2022 50 minutes ago, Tony Brooks said: But only on one leg, not both. In reality 0.5 sq mm per meter of total wiring run length.10 minutes with the specialist and a quick second visit and a condition she had suffered with for many years was considerably improved. Your wife has wiring to her legs? And that improved her condition? 😁 1 Link to comment Share on other sites More sharing options...
Featured Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now