Inverter-12v question

[Andrew B]

Unfortunately you don't seem to understand that the BSS does very little checking of electrical systems, and in particular 240 volt electrical systems on your boat.

 

If you don't believe me then go and download the guide - you will find almost no reference to RCDs, Circuit Breakers, AC earths, and all the things you need to know about when 240 volts AC is installed on a boat.

 

240 volts from an inverter can be just as lethal as 240 volts from a land-line, and the chances of getting it wrong are probably higher with the former. Very often people dfo get it dangerously wrong, even if all the wiring looks neat, with sensible cable types.

 

A BSS inspector has no right to tell you 240 volt AC systems are completely safe, as it is not within his remit to do enough inspection and testing to prove that.

 

I agree with those who say you need to get it looked at by someone who fully understands it. To me the fact that you imagine what you have must be safe totally justifies me thinking that, in my view.

 

EDITED TO ACKNOWLEDGE:

 

On reading your reply again, you do seem to agree to getting it looked at, which is good. My remarks that what the BSS man says does not guarantee it's safety still stand, though.

 

Hi Alan,

 

I understand your point and I agree on the basis it may look safe wired up but not physically. I also had my doubts to that only a qualified electrician could confirm and acknowledge the safety of the wiring and the power throughout the wiring itself.

 

Once I get it all sorted it will be inspected for my own and others piece of mind and safety. Through the help of people on this forum and post like yours have helped me put things more in perspective and what needs and should be done etc.

 

Im currently looking at a new silverline 2000w inverter on eBay to replace my sterling 1000w inverter.

 

Does anybody have any reviews on Silverline inverters?

[alan_fincher]

OK, It sounds like you are being sensible, and my reply maybe looks unduly harsh, on reflection, (although you have been polite enough not to say that!).

 

There have been countless examples reported of systems that look pretty, but don't pass muster, so it is very sensible to make no assumptions at all, unless you yourself fully understand all relevant elements of what you are looking at.

 

Stay safe!

 

Alan

[by'eck]

I am happy to report I have used these for 12v for many years without once becoming confused so it is possible Richard if you try. breathing helps so I hear.

 

You might not have been but I can attest to at least two novices who have come across them & wondered if they were 240 volt AC outlets. They are only rated for 2 amps AC - do you know what their DC rating is? What is the third pin used for?

 

Before households were wired with 13 amp square pin outlets around the beginning of the 60's, they generally had a mix of round pin 5 amp & 15 amp almost identical in shape but larger.

 

Using them for DC may not kill anyone but the concept of using bulky connectors for other than their design strikes a bad chord with me.

[Tony Brooks]

That's the question, I've never known because there isn't a light or anything to signal it's power also I cannot hear it running. I've had it running plugged into Marina mains through 240 but never on batteries as I worry constantly about it draining them.

 

 

If you can not hear it running when turned on it is broken, an absorption fridge, or you have a slight hearing problem. If it is a 12V fridge plugged into a mains socket I would not rule out the first option but I suspect the second.

 

For years the typical absorption fridge fitted on boats would run on gas, 12v DC or mains as you decide, select, and connect. The problem of these on 12V is that they draw about 8 amps with NO thermostat so battery life is short.

 

To identify the fridge you will need to get at the back. There should be a maker's plate there and I suspect it will say Electrolux but may have other names - let us know. Look at the back of the fridge or freezer at home and you will see a large, thin small pipe and wire grid like plate painted black. Compare that with what you have on the back of the boat fridge. If its similar (but smaller) then you have a compressor fridge and you need to find the data plate to tell you if it really is 12v or if its mains. You just might find a little fridge power supply down there allowing you to run 12V fridges from a mains supply. If the back of the fridge has fewer but much larger pipes then it is an absorption fridge which either needs to run on gas or mains (gas for preference whilst cruising) - or change for a modern 12v compressor fridge.

[Chris Pink]

Well I do have sympathy for those novices wandering around in baffled confusion after you said, slowly and clearly, "12 volt". I find the use of these obsolete connectors an elegant solution to the distribution of 12v. I don't particularly care what is done with the spare pin, it serves quite well as a polarity check.

 

And they look pretty.

 

Rating? Interesting? A lot more than the ubiquitous cigarette lighters, they run my laptop psu at around 6a with no heating so that will do me. There's a lot of copper to copper contact inside. I would have thought the 2a at 240v was more a convention appertaining to the fused circuit than a physical maximum. I would estimate them good for at least 10a and that's what their circuit is fused at.

 

And your proposal for 12v distribution?

[Andrew B]

If you can not hear it running when turned on it is broken, an absorption fridge, or you have a slight hearing problem. If it is a 12V fridge plugged into a mains socket I would not rule out the first option but I suspect the second.

 

For years the typical absorption fridge fitted on boats would run on gas, 12v DC or mains as you decide, select, and connect. The problem of these on 12V is that they draw about 8 amps with NO thermostat so battery life is short.

 

To identify the fridge you will need to get at the back. There should be a maker's plate there and I suspect it will say Electrolux but may have other names - let us know. Look at the back of the fridge or freezer at home and you will see a large, thin small pipe and wire grid like plate painted black. Compare that with what you have on the back of the boat fridge. If its similar (but smaller) then you have a compressor fridge and you need to find the data plate to tell you if it really is 12v or if its mains. You just might find a little fridge power supply down there allowing you to run 12V fridges from a mains supply. If the back of the fridge has fewer but much larger pipes then it is an absorption fridge which either needs to run on gas or mains (gas for preference whilst cruising) - or change for a modern 12v compressor fridge.

 

 

I will look at the weekend and post back about this. I do wear hearing aids too so that is probably why I cannot hear it. Would the fridge be better running of 240 constantly on an inverter or a 12v constantly on an inverter?

[Chris Pink]

I will look at the weekend and post back about this. I do wear hearing aids too so that is probably why I cannot hear it. Would the fridge be better running of 240 constantly on an inverter or a 12v constantly on an inverter?

 

You are still not understanding, an inverter only produces 240v not 12v and it is a characteristic of the fridge which voltages it runs on. Given that there are losses involved in an inverter it is always preferrable to run an appliance on 12v when that is possible.

[Andrew B]

You are still not understanding, an inverter only produces 240v not 12v and it is a characteristic of the fridge which voltages it runs on. Given that there are losses involved in an inverter it is always preferrable to run an appliance on 12v when that is possible.

 

I understand that an inverter converts 12v to 240 but I confused myself on the last bit with regards to running it on 12v I apologise.

 

What I MENT to have posted is will it be better to run 240 from inverter constantly or just 12v? Which would have a slower impact on the batteries? Soon I'll have 3 leisure batteries instead of 2.

[Chris Pink]

12v if possible (is it?)

[WotEver]

12v if possible (is it?)

As Tony B posted above, if it's one of the old Electrolux 3-way absorbption fridges 12/240/gas then you'd be better off replacing it. If it isn't, then it's unlikely to be both 240V and 12V. I don't believe I've ever seen one.

 

Tony

[Chris Pink]

.

Edited May 12, 2011 by Chris Pink

[Tony Brooks]

I understand that an inverter converts 12v to 240 but I confused myself on the last bit with regards to running it on 12v I apologise.

 

What I MENT to have posted is will it be better to run 240 from inverter constantly or just 12v? Which would have a slower impact on the batteries? Soon I'll have 3 leisure batteries instead of 2.

 

 

If it is a 3-way absorption fridge then running it on 12v is all but a total NO on a boat. Running it on mains is better but it will be far less efficient than a compressor fridge.

 

If it is a mains compressor fridge AND it is A+ energy rated then there will be a small extra consumption over and above a similar 12V compressor fridge which many find acceptable and reliable given the cheaper costs of a mains A+ fridge over a dedicated 12v one. If it is a nondescript mains compressor fridge bought on price then you will have to add the extra consumption caused by the lower thermal insulation employed and I would defiantly say 12V will be better.

 

You must grasp there are two different types of fridge systems; absorption which is inefficient in energy terms (unless it is running on gas) and compressor which is efficient. However without another piece of equipment a 12v fridge can not run of the mains and a mains fridge can not run off 12v save via an inverter and despite what the manufacturers claim driving it through and inverter is likely to give you about a 20% boost to its electricity consumption.

 

If you are going into hire then I think a 12v compressor fridge is your best bet BUT you must do a power/energy audit plus the charging calculations(on my website & elsewhere) to ensure you minimise the risk of destroying the batteries by forever flattening them and never charging them.

[Sir Nibble]

Andrew, this question does of course need resolving but I think there is more to it than that. If you are going to hire this boat out then you will need to supply engineering support services. If the boat is out on hire and something, anything goes wrong you will owe it to your hirers to effect a prompt effective repair. With this in mind either you or someone engaged by you needs to be familiar with the boat and it's systems. If you are intending to enlist professional help as and when required then your chosen professional has to be able to fix any problem that arises fast. Bring them in now so that they can solve problems like this for you and be familiar enough with the boat to give a good service to your hirers should the need arise.

[RLWP]

When I purchased the boat I was told the fridge is 12v and it has a 3 pin socket on. That is why I was wondering regarding this.

 

Our fridge is 12v, and it also has a 240v 13amp plug on it. It's wired up to run off the 12v supply, so the 13 amp plug is just hung on the back out of the way

 

As far as I can tell, It's a 240V fridge with it's own 12v inverter built in

 

Richard

[WotEver]

Our fridge is 12v, and it also has a 240v 13amp plug on it. It's wired up to run off the 12v supply, so the 13 amp plug is just hung on the back out of the way

 

As far as I can tell, It's a 240V fridge with it's own 12v inverter built in

 

Richard

Oh wow - never seen one. I assume you got it from a chandlers?

 

Tony

[RLWP]

Oh wow - never seen one. I assume you got it from a chandlers?

 

Tony

 

I got it from Alvechurch - it came with the boat

 

Richard

[WotEver]

I got it from Alvechurch - it came with the boat

 

Richard

Harrumph :::looking for a harrumph smiley:::

[RLWP]

Harrumph :::looking for a harrumph smiley:::

 

If I remember, I'll look up the make and model for you next time I'm on the boat

 

Richard

[Sir Nibble]

Our fridge is 12v, and it also has a 240v 13amp plug on it. It's wired up to run off the 12v supply, so the 13 amp plug is just hung on the back out of the way

 

As far as I can tell, It's a 240V fridge with it's own 12v inverter built in

 

Richard

Probably more likely a 12V one with a transformer/rectifier built in.

[RLWP]

Probably more likely a 12V one with a transformer/rectifier built in.

 

I'm not clever enough to know the difference between a 12v DC to 240V Ac transformer/rectifier and a 12v DC to 240V Ac inverter, so you're probably right

 

Richard

[Proper Job]

My fridge is similar to Richards

 

There's a gizmo at the back (I've got the paperwork for it somewhere).

 

It can switch automatically between 12v and 240v.

 

If you switch the fridge off at the 12v switch on the 12v db panel it is off. However, if you plug the 240v circuit in to shore power/genny the fridge will come on.

[Tony Brooks]

My fridge is similar to Richards

 

There's a gizmo at the back (I've got the paperwork for it somewhere).

 

It can switch automatically between 12v and 240v.

 

If you switch the fridge off at the 12v switch on the 12v db panel it is off. However, if you plug the 240v circuit in to shore power/genny the fridge will come on.

 

 

Shorline sell them but it is an add on to the basic fridge as far as I know.

[Sir Nibble]

I'm not clever enough to know the difference between a 12v DC to 240V Ac transformer/rectifier and a 12v DC to 240V Ac inverter, so you're probably right

 

Richard

Naw naw naw gord bless ya guv'nor you do bring a tear to me eye and no mistake.

 

 

Sorry, slipped into a little 19th century street urchin there. Linguistically I mean!

Look this isn't going well is it, tell you what I'll go out and come in again.

[ditchcrawler]

As Tony B posted above, if it's one of the old Electrolux 3-way absorbption fridges 12/240/gas then you'd be better off replacing it. If it isn't, then it's unlikely to be both 240V and 12V. I don't believe I've ever seen one.

 

Tony

And I don't think you could use a gas fridge on a hire boat

[Sir Nibble]

I'm not clever enough to know the difference between a 12v DC to 240V Ac transformer/rectifier and a 12v DC to 240V Ac inverter, so you're probably right

 

Richard

Right.

What I meant is that it is most likely to be a 12V unit with a 240V 12V transformer/rectifier for when you can plug it in to the mains.