silly question or not?

[Robin]

rerefrigerstor freezers on mobos. Do they only run on 220VAC or will they run on 12VDC also without having to engage an inverter or turn on a generator. The motor yacht we lived o in the USA was dual voltage DC and AC even though we had a sizeable generator also Our sailboats have always had 12 volt DC refigerators which meant we had no need to do anything after disconnecting shorepower since the batteries recharged from multiple source when underway or even when at anchor, like from the engine mounted alternator, solar panels or wind generator. Our last several sailboats also had decent sized 12VDC-220VAC inverters, but these were there to run things like microwaves ovens, computers or TVs

MIGht be a daft question but something I saw elsewhere has me uncertain.

 

[[2068]]

Both the refrigerators on our Mobo will work quite happily on 12v, no inverter, generator, or shore power required.
(Waeco models).

 

[penberth3]

Surely this depends on the individual appliance. Check the data plate on the appliance or the instruction manual.

 

[[2068]]

Surely this depends on the individual appliance. Check the data plate on the appliance or the instruction manual.

On most mid-sized Mobos (35-40ft), they will run on 12v.
Most 35ft Mobos (UK Spec) will not have a generator.
Probably different for a Med Spec boat where you need to run the Aircon.

 

[Robin]

On most mid-sized Mobos (35-40ft), they will run on 12v.
Most 35ft Mobos (UK Spec) will not have a generator.
Probably different for a Med Spec boat where you need to run the Aircon.

I'm hoping we will eventually have an installed generator. but not all we have seen specs for do so I always sort of expected that with engines running there would be plenty of battery charging underway to cover any 12 VDC demands from whatever piece of kit is running, from autopilot and instruments on up If that is incorrect then I need to modify my 'must have' lists and put a big notice up saying 'start genset before casting off. :ambivalence:

Remember please that although we spent a year living/cruising on a 47ft trawler yacht, we are 50 year plus rag and stick people and still think in those terms.

 

[Portofino]

Ours are duel , 24 V in our case ---and 220 v .We have two a big one like in a house under counter in the galley and a smaller cockpit one under the helm .seat - both have freezer compartments like a house fridge .
They work like this , when they detect 220 v from shore power or geny they will use that as the default setting -thus easing the strain on the domestic batts .

If the 220 V is off ,they detect 24 V and switch automatically then they run off the domestic 24 v bat bank .

1- under motoring the alternator s are topping up the domestic bank , no issues here as they are sized accordingly .
2- @ anchor ( engine and geny off ) still 24v off the domestic bank ,--- but here's the clever bit. They have a voltage sensor and will cut out / switch off if the V drops below a certain point ,so,s not to flatten the dom bank .
The fridge light does not come on I think --- time for geny on or motor somewhere .
From memory 8 hrs ??

How ever with a bigger freezer in a livabord situation ( not us btw) I can see a potential problem with long periods @ anchor relying on the domestic bank voltage.

Sounds like you are gonna need a geny ( mobo ) and monitor things and factor in some geny time @ long periods on the anchor .

It's been discussed many times on here , -"power management " @ long periods anchoring in a mobo .
There's many variables and many different workable solutions . " Hurricane " has recently fitted solar panels to assist -primarily to prevent a culmulative deep domestic bat depletion.

Depends on the size and health of the domestic bank
The current draw ,@ anchor fridges / freezers being the biggies
Lights - LED ? - toilets , water pump , any nave gear left on ? Shower sumps ,bilge pumps etc .

Then if you are willing to " geny up " -- % bat depletion Vs size of bulk charge - type of charger , type of bats -some accept bulk chg quiker than others .
If you are ok with the geny running ? --- other uses as well as running the main charger ( s ) like cooking -electric hob , water heating , general 220 v sockets are live e.g. Charging device( s) these days .Air con etc

How you use your boat will determine which parts ( not exhaustive ^^ ) of the above menu you pick n choose --- it's different -each to there own ,

I suspect as liveabord then the geny instal - another subject and /or -solar agian another subject need to be investigated .

But essentially your fridges / freezers run on both AC and DC with auto switching and a voltage cut off when on DC -batts .
We are just under 50 ft and do not need to run the geny while underway to power the fridges -- engines alternators seem to cope .

 

[Portofino]

In the Med regarding our power management and actual boat usage -----
Ideally if poss we go in to a visiting berth every 2/3 days when touring .
Basic tourism really and reprovision .
Or turning it around max time @ anchor 3/5 days** ( with negligible motoring )
Regardless of how many days @ anchor we have pretty good battery instrumentation so can see depletion etc .
We are a none gas boat --- geny on in the morning breakfast -charger n kettle and eveningtime for an hour or so .--- charger and hob
I some times turn it on during the day with charger on only if we are messing about in the sea or it's windy .
Surprisingly when it's windy the wind noise is greater ,so you can,t tell it's on so to speak .

We have a dog so if we do a shore trip in the tender I switch it on .

Don,t really have an issue with running the geny + charger , now and again @ anchor just got to think ahead a bit .

Don,t run the geny @ night while sleeping -- Carbon monoxide -- we have detectors in each space , but even so .Theres no need .Others will have a different take on CO hygiene on a boat while folks sleep no doubt.

** we can cover 100 miles in less than 3 hrs .
Longest stint none stop so far with extra long range tank topped up 300 miles .
It's poss for what ever reason to " bug out " and return to home port in a day should we wish

 

[Hurricane]

AFAIK motorboats are no different to sailboats in this respect.
Usually dual supply fridges - DC and AC.
In our case the DC is 24v but smaller motorboats generally run their DC systems at 12v

A point that I would like to make though, that applies to both sailboats and motorboats, is when leaving the boat in a marina whilst you are at home.
It is often useful to have fridges left working whilst away - keeping food fresh and the beer cool after a long drive down to the boat.
It is then important to leave shore the supply (240v) feeding the fridges rather than a DC supply through a battery charger.
If the fridges were on DC and the shore supply were to fail, the fridges would drain the batteries - you would then need new batteries as well as replacing the contents of the fridges.
I always switch off all my DC systems before leaving the boat - any fridges left running then run on shore supply (240v) only.
Just a point.

 

[Bouba]

Best fridge I ever had was in my motor home, it ran on 220v when plugged in, 12v when driving and gas when engine stopped, all seamless and instant. Why can't we have them on boats?

 

[Portofino]

Best fridge I ever had was in my motor home, it ran on 220v when plugged in, 12v when driving and gas when engine stopped, all seamless and instant. Why can't we have them on boats?

We have ( 24 v ) all seemless " automatically " see my post ^^^

@ Hurricane - when we leave we turn them off .
I fact the only things on are the chargers - assume on float / trickle and the bilge pumps -4

 

[Montemar]

A point that I would like to make though, that applies to both sailboats and motorboats, is when leaving the boat in a marina whilst you are at home.
It is often useful to have fridges left working whilst away - keeping food fresh and the beer cool after a long drive down to the boat.
It is then important to leave shore the supply (240v) feeding the fridges rather than a DC supply through a battery charger.
If the fridges were on DC and the shore supply were to fail, the fridges would drain the batteries - you would then need new batteries as well as replacing the contents of the fridges.
I always switch off all my DC systems before leaving the boat - any fridges left running then run on shore supply (240v) only.
Just a point.

Same here.

 

[CLB]

Best fridge I ever had was in my motor home, it ran on 220v when plugged in, 12v when driving and gas when engine stopped, all seamless and instant. Why can't we have them on boats?

We can, or at least we could. Gas/DC/AC powered fridges in boats were once common, but are now considered a least safe option. A number of fires/explosions were attributed to gas fridges, usually due to poor refuelling practice.

 

[Robin]

It seems my question was not so silly. I will need to check and enquire very carefully it seems or could risk either dead batteries or spoiled food. One to be high on a survey list of questions for sure. Another reason to make an installed generator a priority on the wish list too.

 

[petem]

I don't think you've said what sort and length of boat you're looking at but if you need to retrofit a generator to a boat that doesn't currently have one you're probably looking at the thick end of £10k. And if it's a particularly small boat like mine (34ft) then it's barely feasible to fit one at all (factory boats spec'd with a gennie had the fuel tank split into two so that one could be accommodated). Of course retrofitting one does mean you've got a brand new unit.

 

[Robin]

I don't think you've said what sort and length of boat you're looking at but if you need to retrofit a generator to a boat that doesn't currently have one you're probably looking at the thick end of £10k. And if it's a particularly small boat like mine (34ft) then it's barely feasible to fit one at all (factory boats spec'd with a gennie had the fuel tank split into two so that one could be accommodated). Of course retrofitting one does mean you've got a brand new unit.

I'm looking at potential live aboards between 35 and 45ft and likely contenders include Princess 435s, Fairline Turbo 36/38s Broom 42s Aquastar 38s, all mostly pre 2000 I would guess I did price a new generator for a turbo 36 that had one that was dead and it was IRO £7,000 installed, but of course the plumbing bits etc were already in place and it was from the same maker.

But also as I said sailboat fridges will run off batteries and rarely if ever switch between 220VAC and 12VDC automatically when disconnecting/connecting shorepower. Our last sailboat, here in the USA did have a huge inverter (3Kw) and big batteries but even then the fridge/freezer was wired to run off DC volts alone, the inverter, installed by the previous owner, was reserved for the TVs microwave and limited air conditioning ( one of two, not both together)

 

[JumbleDuck]

Best fridge I ever had was in my motor home, it ran on 220v when plugged in, 12v when driving and gas when engine stopped, all seamless and instant. Why can't we have them on boats?

Gas fridges run on the absorption cycle, with ammonia as the working fluid. It's marked less efficient than the standard reverse Rankine cycle of a compressor fridge, so while being able to run on gas, paraffin or whatever can be an advantage, they waste a lot of power when running on electricity. I used to have an Electrolux absorption fridge at home, which was nice because it's almost completely silent, and using a bit of extra mains doesn't matter as much as using extra 12/24V.

 

[superheat6k]

The issue with abbo fridges is the gas safety issue - caravans don't have bilges, however no reason not to run an abbo without a gas supply, but the cooling effect on 12v is holding only and won't provide much in the way of 'getting the fridge cold' capability. The heating circuit absorption effect is less efficient than a vapour compression system.

The Waeco with the Matsushita Swing compressor is a superb option for 12v, and most fridges include a 240v convertor that will automatically switch to 240v as soon as it is plugged in. The Matsushita is basically a glorified solenoid - just a piston in a cylinder with some valves in - so minimal moving parts and they run forever.

My own Waeco is 12v only and tends to run quite a long time, suggesting it is tired and possibly a bit light on gas, but it keeps the beer cold and will even keep ice creams frozen in the ice box for a day or so.