Jump to content

12V or 240V fridge?


Featured Posts

Our new 57'nb will be powered by a 42hp engine with twin alternators & 240V is courtesy of a 3KW inverter/charger.

The 4 x 140A Vetus AGM batteries are supported by 2 x 250W flexi-solar panels.

My question is simply this: do we have enough firepower for a standard 240V fridge or is 12V still a much better option?

Again, substantive reasons for either helps us and keeps the nb fraternity bubbling!

Jim

Link to post
Share on other sites
1 minute ago, Leggers do it lying down said:

No!...Go 12v.Your inverter will kill the batteries running a 240v fridge 24/7.

Depends on the inverter and its' quiescent current. Anything less than an Amp, and it shouldnt cause too much issue, (Less than 24 Ah a day).

 

I've just paid £500 for a small 12V fridge - no space for anything bigger, so 240V was not an option.

 

If I had the space, and therefore the choice, I would have bought a 240V fridge and a Victron inverter, (0.8A quiescent current).

  • Greenie 1
Link to post
Share on other sites
12 minutes ago, Leggers do it lying down said:

No!...Go 12v.Your inverter will kill the batteries running a 240v fridge 24/7.

Depends on the inverter no-load power and the fridge power. Its easier (and cheaper) to get A+++ rated 240V fridges than 12V ones, the fridge power saving could easily be bigger than the inverter power consumption. Or not...

 

[what Richard wrote while I was posting]

 

Even more true when the inverter is on for other reasons (running other 240V stuff).

 

Lowest consumption 240V fridges average 11W (say 1A).

Edited by IanD
Link to post
Share on other sites
24 minutes ago, James Dunleavy said:

Our new 57'nb will be powered by a 42hp engine with twin alternators & 240V is courtesy of a 3KW inverter/charger.

The 4 x 140A Vetus AGM batteries are supported by 2 x 250W flexi-solar panels.

My question is simply this: do we have enough firepower for a standard 240V fridge or is 12V still a much better option?

Again, substantive reasons for either helps us and keeps the nb fraternity bubbling!

Jim

For the next few months its probably safest to consider the solar input as zero, although you will get some so you will need to rely upon alternator charging unless you have a shoreline in use. I don't see that anyone can answer your question because the problem is usually not getting enough electricity out of the batteries but how you are going to get it back in. So what is your charging regime? What battery monitoring do you use? Anything on a solar controller is very likely to be fiction. What did your power audit (you did do one I assume) show for your other consumption? If you are using filament bulbs for lighting, running a mains TV 12 hours a day, microwave, coffee maker and computers its perfectly possible that the true answer may be no fridge at all until the sun comes out again but we can't know without all the facts. What I do know is that if you are charging a couple of ours a day you may be looking at new batteries long before you expect to.

 

I doubt there will be a significant difference between 12V and mains A++ and QUALITY inverter but its the other electrical loads and your charging procedures that are very important for long battery life.

  • Greenie 1
Link to post
Share on other sites
1 hour ago, Tony Brooks said:

For the next few months its probably safest to consider the solar input as zero, although you will get some so you will need to rely upon alternator charging unless you have a shoreline in use. I don't see that anyone can answer your question because the problem is usually not getting enough electricity out of the batteries but how you are going to get it back in. So what is your charging regime? What battery monitoring do you use? Anything on a solar controller is very likely to be fiction. What did your power audit (you did do one I assume) show for your other consumption? If you are using filament bulbs for lighting, running a mains TV 12 hours a day, microwave, coffee maker and computers its perfectly possible that the true answer may be no fridge at all until the sun comes out again but we can't know without all the facts. What I do know is that if you are charging a couple of ours a day you may be looking at new batteries long before you expect to.

 

I doubt there will be a significant difference between 12V and mains A++ and QUALITY inverter but its the other electrical loads and your charging procedures that are very important for long battery life.

Thanks Tony,

Ours is a new build, currently at sailaway stage about to be fitted out. Should we have, or do we need a power audit? We plan to live aboard for at least a year from mid-Jan and cruise straight away, weather permitting. When moored, or stationary due to weather I assume that's when recharging batteries is key so are 4 x 140A Vetus AGM domestic batteries large enough to provide a robust 12V system, and easily rechargeable?

Other than the fridge, we'll have an under dinette 12V freezer and I believe the LED lights are 240V, which along with any other 240V appliances(toaster, tv, microwave, phone/laptop chargers) will be supplied by a Mastervolt Ultra 3000W inverter/charger; do you have a view on any of this spec in achieving an effective charging procedure?

Link to post
Share on other sites
40 minutes ago, James Dunleavy said:

Thanks Tony,

Ours is a new build, currently at sailaway stage about to be fitted out. Should we have, or do we need a power audit? We plan to live aboard for at least a year from mid-Jan and cruise straight away, weather permitting. When moored, or stationary due to weather I assume that's when recharging batteries is key so are 4 x 140A Vetus AGM domestic batteries large enough to provide a robust 12V system, and easily rechargeable?

Other than the fridge, we'll have an under dinette 12V freezer and I believe the LED lights are 240V, which along with any other 240V appliances(toaster, tv, microwave, phone/laptop chargers) will be supplied by a Mastervolt Ultra 3000W inverter/charger; do you have a view on any of this spec in achieving an effective charging procedure?

Holy smokes, are you going to cruise four hours a day every day, if so you might be able to turn your lights in in winter. 

My power audit pre boarding was to measure the electricity I used in house, for three seasons, I excluded winter 'cos I used electric heating, and on a boat I would have a solid fuel stove.

My fuel bill excluding the diesel propulsion is the same as the house, (small flat)

Also my house was lit by a lampost nearby, so I often did not need a lot of lighting in winter.

PS what about the washing machine and tumbler dryer 🤣

PPS there are significant losses if you are determined to convert 12 v to 240 volt

PPPS go back to the drawing board, use the search engine, and go to Pacific Yacht Systems on you tube,  this will help visualise self sufficiency, there are loads of off grid vlogs, but I think you need to get your head round this before you spend any more money.

Bimble Solar has a power calculater.

Edited by LadyG
Link to post
Share on other sites
24 minutes ago, James Dunleavy said:

Thanks Tony,

Ours is a new build, currently at sailaway stage about to be fitted out. Should we have, or do we need a power audit? We plan to live aboard for at least a year from mid-Jan and cruise straight away, weather permitting. When moored, or stationary due to weather I assume that's when recharging batteries is key so are 4 x 140A Vetus AGM domestic batteries large enough to provide a robust 12V system, and easily rechargeable?

Other than the fridge, we'll have an under dinette 12V freezer and I believe the LED lights are 240V, which along with any other 240V appliances(toaster, tv, microwave, phone/laptop chargers) will be supplied by a Mastervolt Ultra 3000W inverter/charger; do you have a view on any of this spec in achieving an effective charging procedure?

Any lead acid battery is emphatically NOT easily rechargeable if you expect a decent battery life. The more the bank gets charged the lower the current that can get into the batteries so to all but fully recharging them takes many hours. I would suggest you need to charge for 3 to 4 hours every day and then 8 to 10 hours at least once a week to get them fully charged. However to know when the batteries are fully charged or when its important to stop using electricity and start charging ASAP you need some form of battery monitoring device(s). By and large it won't matter if you cruise or run the engine while tied up to charge the batteries but charge them you must until the late spring.

 

If you have not done a power audit how do you know your battery bank is large enough? How do you know you won't be regularly over discharging the bank and thus shorten their life?

 

An inverter/charger is no use in charging batteries unless you are connected to a mains shoreline. I get twitchy when I read things like mains powered toaster, tv, microwave, phone/laptop chargers via an inverter when no power audit has been done. Microwaves tend to demand about twice the power shown on the front, that's the cooking power, not electrical power. Someone far more qualified that I said that using electrotype from batteries (including via an inverter) to produce heat was stupid. I would add especially if you have not done a power audit. Phone chargers and such like are probably best charged via USB direct from 12V DC. The laptop by car charger, again direct from 12 DC.

 

 

Link to post
Share on other sites
57 minutes ago, James Dunleavy said:

Thanks Tony,

Ours is a new build, currently at sailaway stage about to be fitted out. Should we have, or do we need a power audit? We plan to live aboard for at least a year from mid-Jan and cruise straight away, weather permitting. When moored, or stationary due to weather I assume that's when recharging batteries is key so are 4 x 140A Vetus AGM domestic batteries large enough to provide a robust 12V system, and easily rechargeable?

Other than the fridge, we'll have an under dinette 12V freezer and I believe the LED lights are 240V, which along with any other 240V appliances(toaster, tv, microwave, phone/laptop chargers) will be supplied by a Mastervolt Ultra 3000W inverter/charger; do you have a view on any of this spec in achieving an effective charging procedure?

 

11 minutes ago, Tony Brooks said:

Any lead acid battery is emphatically NOT easily rechargeable if you expect a decent battery life. The more the bank gets charged the lower the current that can get into the batteries so to all but fully recharging them takes many hours. I would suggest you need to charge for 3 to 4 hours every day and then 8 to 10 hours at least once a week to get them fully charged. However to know when the batteries are fully charged or when its important to stop using electricity and start charging ASAP you need some form of battery monitoring device(s). By and large it won't matter if you cruise or run the engine while tied up to charge the batteries but charge them you must until the late spring.

 

If you have not done a power audit how do you know your battery bank is large enough? How do you know you won't be regularly over discharging the bank and thus shorten their life?

 

An inverter/charger is no use in charging batteries unless you are connected to a mains shoreline. I get twitchy when I read things like mains powered toaster, tv, microwave, phone/laptop chargers via an inverter when no power audit has been done. Microwaves tend to demand about twice the power shown on the front, that's the cooking power, not electrical power. Someone far more qualified that I said that using electrotype from batteries (including via an inverter) to produce heat was stupid. I would add especially if you have not done a power audit. Phone chargers and such like are probably best charged via USB direct from 12V DC. The laptop by car charger, again direct from 12 DC.

 

 

 

There is no problem to having a lot of 230v equipment on board AS LONG AS YOU HAVE PLANNED FOR IT.

The planning needs to be "how do I put the amount used (+20%) back into the batteries"

 

I have (and use) 230v electrical kettle, toaster, microwave, satellite box, Twin-Tub washing machine, Air fryer, & Freezer, and,

12v fridge, lighting, TV, phones, laptop, kindle chargers, & water pumps

 

The 230v immersion heater, & oil filled radiator are only used when on 'hook-up'.

 

Set up is :

2x 70amp alternators

1x 170 watt solar panel

1800w Inverter

1000Ah FLA battery bank.

Link to post
Share on other sites
1 hour ago, James Dunleavy said:

Thanks Tony,

Ours is a new build, currently at sailaway stage about to be fitted out. Should we have, or do we need a power audit? We plan to live aboard for at least a year from mid-Jan and cruise straight away, weather permitting. When moored, or stationary due to weather I assume that's when recharging batteries is key so are 4 x 140A Vetus AGM domestic batteries large enough to provide a robust 12V system, and easily rechargeable?

Other than the fridge, we'll have an under dinette 12V freezer and I believe the LED lights are 240V, which along with any other 240V appliances(toaster, tv, microwave, phone/laptop chargers) will be supplied by a Mastervolt Ultra 3000W inverter/charger; do you have a view on any of this spec in achieving an effective charging procedure?

You do definitely need to do a power audit now, for your proposed electrical use.

As Tony says, it's not so much how much you use, but how are you going to replace what you use, today, for tomorrows use.

Fridges, are heavy electrical users, freezers are worse, microwaves are worse still(but only for short periods) toasters/electric kettles/hair dryers are all only for use, when connected to a shore line.  Much the same is to said about auto washing machines and tumble dryers.

Expect to replace the batteries frequently, till you learn to charge them properly, for your useage. (Your first set could be ruined within 72 hrs, if no attempt to recharge them is made.)

Smartgauge is one battery monitor, that will tell you when to start recharging, less good at telling when to stop charging.  For which you need an Amp meter gauge, that tell how many Amps the batteries are accepting.

Amp-hour counters, unless you know how to recalibrate them regularly, will give increasingly bad information.

 

Bod.

  • Greenie 1
Link to post
Share on other sites
16 minutes ago, Alan de Enfield said:

 

 

There is no problem to having a lot of 230v equipment on board AS LONG AS YOU HAVE PLANNED FOR IT.

The planning needs to be "how do I put the amount used (+20%) back into the batteries"

 

I have (and use) 230v electrical kettle, toaster, microwave, satellite box, Twin-Tub washing machine, Air fryer, & Freezer, and,

12v fridge, lighting, TV, phones, laptop, kindle chargers, & water pumps

 

The 230v immersion heater, & oil filled radiator are only used when on 'hook-up'.

 

Set up is :

2x 70amp alternators

1x 170 watt solar panel

1800w Inverter

1000Ah FLA battery bank.

 

I agree but what is clear to me is that the OP has not planned for it and what is more probably does not understand what that planning and the way to use the boat/equipment involves.

 

You are a very experienced boater who understands these things, I suspect the OP is not so I feel it is in his better interest for now to minimise his thoughts about mains equipment use while away from the shoreline.

  • Greenie 1
Link to post
Share on other sites
1 hour ago, James Dunleavy said:

 I believe the LED lights are 240V, which along with any other 240V appliances(toaster, tv, microwave, phone/laptop chargers) will be supplied by a Mastervolt Ultra 3000W inverter/charger; do you have a view on any of this spec in achieving an effective charging procedure?

I can't imagine why any builder would be wanting to give you 240v lighting system. I have to assume your builder isn't a boater?

Whilst the inverter is decent,  it will use an amount of battery power itself. For such a set up you would need it almost permanently on, especially if you go with the 240V fridge.

My choice would be, by all means have your inverter, but keep things that run much of the time, or that you feel you will be reliant on, to 12v, especially such as lighting. Have the most flexibility you can at this stage. Have them put cabling in to accommodate both 240 and 12v fridges, so if you plump for 240, and later realise you should have chosen 12v, at least the cables are there ready. Minimal cost at this stage. 

Toasters and microwaves may become defunct while cruising.

Good choice of batteries, it is helpful to have the system limited so you cannot take AGMs below 11v. If you are having solar installed, this can be done through the controller. 

Edited by Ally
Link to post
Share on other sites

To the OP you are getting sound advice from many experienced people at present, take heed. I would also add that if budget allows a brilliant bit of kit is a Travel power that does all the hard work heavy jobs whilst the engine is running allowing all 12 volt alternater amps to go to the batteries. I wouldnt have a boat without one anymore.

Link to post
Share on other sites
Just now, Tony Brooks said:

 

I agree but what is clear to me is that the OP has not planned for it and what is more probably does not understand what that planning and the way to use the boat/equipment involves.

 

You are a very experienced boater who understands these things, I suspect the OP is not so I feel it is in his better interest for now to minimise his thoughts about mains equipment use while away from the shoreline.

 

Yes agreed, or learn how to use, and implement an electrical audit.

It may well be that he can have none / some / all of his electrical 'stuff' but will need to plan / alter his charging equipment and battery bank size.

 

I'll try and find examples of an audit for him.

Link to post
Share on other sites

James, send me a message with your email address and I'll send you a pro-forma Power Audit.

It is a Pdf and you simply 'plug in' your appliance, list the Amps it uses and the time it is run for.

 

It will add everything up and tell you how many AH per day you will use.

 

You can do similar for 230v stuff

 

Edit to add - I think @Tony Brooks has one on his training website. 

Maybe easier for you.

Edited by Alan de Enfield
  • Greenie 1
Link to post
Share on other sites
5 minutes ago, Alan de Enfield said:

James, send me a message with your email address and I'll send you a pro-forma Power Audit.

It is a Pdf and you simply 'plug in' your appliance, list the Amps it uses and the time it is run for.

 

It will add everything up and tell you how many AH per day you will use.

 

You can do similar for 230v stuff

 

Edit to add - I think @Tony Brooks has one on his training website. 

Maybe easier for you.

Yes, examples in both the mechanical and electrical notes. possibly the notes re charging & battery capacity may be better for the OP in the mechanical notes.

Link to post
Share on other sites
1 hour ago, James Dunleavy said:

 

Other than the fridge, we'll have an under dinette 12V freezer and I believe the LED lights are 240V, which along with any other 240V appliances(toaster, tv, microwave, phone/laptop chargers) will be supplied by a Mastervolt Ultra 3000W inverter/charger; do you have a view on any of this spec in achieving an effective charging procedure?

That specification is meaningless in terms of an effective charging procedure unless you have a shore mains connection. Other than the inverter/charger everything else you have listed is a consumer of electricity, as is the inverter/charger when it is not plugged into the mains.

Batteries are not a source of electricity, they are simply short term energy storage. Everything you use has to be replaced (and more, due to various system losses). And the only sources from which that energy can be replaced are the mains (so only when moored where there is shore power), solar (may be enough to be self sufficient in the summer months, a useful contributor in spring and autumn, but zilch in winter), or power you generate yourself from your main engine or a generator.

Having more batteries means you can go longer before recharging, but also means that recharging will take longer.

So unless you have a fixed mooring with power, then your first question should not be "can my system power all these appliances?" But "How can I reasonably minimise my power use to keep it within what I can generate?"

 

Link to post
Share on other sites
26 minutes ago, Sea Dog said:

Whatever happened to @WotEver ?  The battery charging implications of this apparently simple question are right up his street.

I tried to point that out to the OP. Maybe @WotEver is a bit fed up with repeating the same thing almost week in and week out. However until we get that power audit and proposed charging regime from the OP not much more than warnings can be given.

Edited by Tony Brooks
Link to post
Share on other sites
2 hours ago, Leggers do it lying down said:

There is an interesting discussion on the subject here:

https://forums.whirlpool.net.au/archive/2192148 

I have a 24 volt system and a 240 volt fridge, I did post my figures some time ago but here they are again

 

I have been running another set of tests on our 240 volt fridge.
The fridge runs via a Mastervolt Mass Sine 24/1500 and all current readings are take from a Sterling Battery Management unit.

The inverter + Fridge + fans =3.5 amps
The Inverter + Fridge = 3.4 amps
The Inverter = 0.4 amps  

        

I have connected a RS hour meter across the refrigerator compressor to record compressor run hours.
The refrigerator is a LEC Elan and sits under a work top with 25mm air gap each side and 50mm between the top of the refrigerator and the
underside of the work top. The air space behind the refrigerator is well over the recommended space as the hull side slopes from the floor to 

the gunwale.  There are ventilation holes drilled in the floor behind and below the fridge. Also there are 4 computer fans mounted in the floor connected in
series parallel that when running blow cool air from under the floor up the condenser. All readings were taken with the fridge in normal use. 

The fridge thermostat was set at 3 and had been running for a couple of days to allow things to stabilise before readings were taken at 1700 hrs
each day. The thermometer inside the fridge was reading at the top of the acceptable range.

At the end of the first day with the fans off and the fridge running as normal the hour meter recorded 7.6 hrs in 24 hrs.
On the second day the fans were switch on and the reading at the end of 24 hrs was 7 hrs.
The next day the fans were switched off and the hours run were 7.1 This indicates to me that the fridge was adequately ventilated as installed.

That night I insulated the fridge on both sides and the top with sheets of 25mm close cell insulation foam covered on both sides with aluminium foil as used in the building trade.

At this point things got interesting which I can't explain. The running hours were slightly less but the internal temperature of the fridge fell.

Over the next 2 days I adjusted the thermostat setting to bring the internal temperature back to its original level. This resulted on it now being set at 1.5 as
opposed to the original 3. I don't know why this happened as in my book the thermostat should keep the inside of the fridge at a constant
temperature. I suspect it is a timer and not a stat.

Once this had settled down I started recording readings again which run between 6.3 and 5.7 hours per day
11/8/06 1700hrs  1170.2
12/8/06 1700 hrs 1177.8        7.6
Fan on
13/8/06 1700hrs 1184.7        6.9
Fan off
14/8/06 1700hrs 1191.8          7.1
Insulation added and fans on
15/8/06 1700hrs 1198.5         6.7
reduced stat setting
16/8/06 1700hrs 1205.0          6.5
17/8/06 1700 hrs 1211.3         6.7
18/8/06 1700hrs 1217.0          5.7
19/8/06 1700hrs 1223.6          6.6
20/8/06 1700hrs 1230.0           6.4
21/8/06 1700hrs 1235.5           5.5
22/8/06 1700hrs 1241.2           5.7
-- 

Link to post
Share on other sites

Batteries are like a leaky bucket, what you take out has to be replaced and a bit more. Undercharging is the fastest battery killer known. Do not think your 100 amp + alternator will put 100 amps + in to the batteries all the time, if you allow for about 1/3 of its rating you will be nearer the mark, a good battery monitor will tell you when you have full batteries, with volts over 14.2 and current down to 1 or 2 amps per battery. 

 

Solar charging is free after the initial outlay, but negligible in winter.

Shore Power charging should  be  under 20 pence for about 80 amp hours.

Generator (petrol) probably about 80 pence for 80 amp hours.

Main engine about 1 pound per 80 amp hours on red diesel, when we have to use white it will be 1.5 pounds for 80 amp hours. 

Power on the cut is very expensive and it really pays to use as little as possible.

Most boaters use between 90 and 140 amp hours a day. Do the power audit, and think.

One thing that helps, when you are moving or using the engine to charge the batteries, as the batteries get nearly full they will only accept 20 or so amps, the alternator can provide more so that, so it is the time to use a washing machine or toaster and electric kettle (small one)  before you moor up and stop the engine. That way most if not all the power has come from spare alternator power and not the batteries.

 

  • Greenie 1
Link to post
Share on other sites

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 account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.