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frangipan
frangipan

Posted: Mon Nov 01, 2010 10:17pm

Post Subject: Inverters

We have just moved on to our first narrowboat and we have an inverter and we also have an electric shoreline as we live on a marina. This may sound dim but could you please explain why do we need the inverter on if we have 240v coming through on the shoreline. Many thanks

alanclarke
alanclarke

Posted: Mon Nov 01, 2010 10:25pm

Post Subject: Inverters

you need an inverter on board other wise you would require a very, very long 240v extension lead to operate your 240v appliances if you ever leave the marina and cruise the canal network.

Tommo
Tommo

Posted: Tue Nov 02, 2010 7:00am

Post Subject: Inverters

Pleaseforgive me if I seem a bit dim as I am new to boating. But as I read your question I think you mean why do you have to have them both on at the same time. On my boat I dont, if I am on shore line I do-not have the invertor swithed on. If I am away from my mooring the invertor creates electricity from the batteries so you can run certain appliances, but it mainly depends on what size the invertor you have and what you are trying to run. Tony Brooks who answers peoples questions on this site has guidance notes on his web site which tells you just about everything you need to know about a boat, it will be worth you having some night time reading, it has really helped me.

Tommo
Tommo

Posted: Tue Nov 02, 2010 7:04am

Post Subject: Inverters

This is his web site, hope it helps. http://www.tb-training.co.uk/

Tony-B
Tony-B

Posted: Tue Nov 02, 2010 8:20am

Post Subject: Inverters

Dear Fran, Inverters convert battery power to mains power or in the case of a Modified Sine Wave Inverter into something approximation mains power but maybe not close enough to work all equipment so if its the latter then you may need the shoreline to work a washing machine or microwave etc. The second reason is that once you have an inverter with a significant output the variety of mains equipment many boaters put on their boat grows This puts excessive demands upon the battery so when shore based mains are available it makes sense to use that rather than discharging the battery. Many boaters leave a small thermostat controlled electric heater on all through the winter to combat damp, you MUST use a shoreline for that otherwise you will ruin the batteries. Some boats have an immersion heater and in most cases running that off the inverter WILL ruin batteries so using a shore line to power it in the marina gets you hot water (and possibly battery charging) without running the engine. A large inverter presents a significant extra load to the battery bank so it makes sense to use shore power whenever you can. Now some inverters are known as Combi-units which means they contain a battery charger and if yours is like this using the charger function. I am sorry about the cryptic reply someone chose to send, I do not think it was very helpful. If this has put you off asking questions on the forum please email me directly (tony@TB-Training.co.uk) or via the magazine. Tony Brooks

alanclarke
alanclarke

Posted: Tue Nov 02, 2010 4:06pm

Post Subject: Inverters

my comment was meant as a light hearted reply and not meant to be unhelpfull in any way, sorry foy any offence caused,

Tony-B
Tony-B

Posted: Tue Nov 02, 2010 4:34pm

Post Subject: Inverters

Alan, I know it was and I found it funny, as I am sure did many experienced boaters however when you see how new boaters get treated elsewhere I did not want Fran to be put off asking again. TB

alanclarke
alanclarke

Posted: Tue Nov 02, 2010 7:29pm

Post Subject: Inverters

Dear Fran, just to let you know i am fairly new to boating myself, owning my own narrow boat for just over 3 years, i am sorry to say i haven't a fat wallet so i have taken on most of my boating problems myself, this is where this forum Tony's own web site and subscribing to this magazine has been invaluable, DO NOT loose you sense of humour if you have one, if you haven't then get one because you will need it, there has been many times i have felt like throwing myself off the nearest canal bridge due to what seems like endless problems being thrown my way, also don't forget the many boaters out there either live aboards or recreational so don't be afraid to ask them as many qestions as you like, i am still doing so, there is plenty to learn. All the best Alan.

frangipan
frangipan

Posted: Sat Nov 06, 2010 11:29am

Post Subject: Inverters

Thank you all very much for your comments. I do have a sense of humour and the idea of having an extremely long shore line is funny and I think we would all get a bit tangled! It is a very big learning curve this boat business and we have asked many people many questions. I am still a little confused about the use of an inverter though. If our inverter isn't switched on none of our electrical sockets work. What are we doing wrong?

frangipan
frangipan

Posted: Sat Nov 06, 2010 11:29am

Post Subject: Inverters

Thank you all very much for your comments. I do have a sense of humour and the idea of having an extremely long shore line is funny and I think we would all get a bit tangled! It is a very big learning curve this boat business and we have asked many people many questions. I am still a little confused about the use of an inverter though. If our inverter isn't switched on none of our electrical sockets work. What are we doing wrong?

Tony-B
Tony-B

Posted: Sat Nov 06, 2010 1:46pm

Post Subject: Inverters

The problem is that we do not know the specification of your inverter and we also do not know how your boat is wired up for mains electricity. First we must consider a basic inverter - nothing else inside the case, just an inverter. Mains electricity keeps reversing its direction of flow every 1/100 of a second and that means that 100 times a second it turns itself off for a tiny fraction of time. Now if you had a simple inverter and the shoreline connected at the same time it is almost certain that the time the inverter supply and the mains supply had turned itself off would not be the same. This would result in your inverter trying to supply the whole locality and then when the mains was on and the inverter off the mains would flow through the inverter. Significant damage to the inverter would ensue. To overcome this with simple inverters the boat builder can fit some form of change over switch so the supply is either from the inverter or from the mains but never from both. So one answer to your question may be that you have not found the change over switch or whatever is fitted in its place. You can get automatic change over devices so it isolates the inverter whenever you have mains power so the second possible answer is that such a device may not be working. Moving up the scale some inverters have the change over device built in so they in effect turn their works off when the mains are connected but to power the device the inverter would have to be turned on. However I suspect you have a much more sophisticated inverter. The first level of sophistication is that whenever your on-board electrical demand exceeds that which the shoreline can supply the inverter will synchronise itself to them mains and supply the difference, obviously the inverter would have to be turned on to do that. What I now suspect you have is a combi-unit which is a battery charger and inverter built into one case. In this case turning the inverter off would also prevent the batteries being charged which with the sophistication of the charger is pointless so whenever mains power is available you turn the inverter on. AS long as your power demands are below the limit set by the socket in the marina the batteries will be under charge and and you will be drawing power from the shore line. When your power demand exceeds the supply capabilities the inverter kicks in to supply the shortfall. there would be nothing but disadvantages to operate this type of system with the inverter turned off so I expect turning the inverter off also isolates the mains supply form the boat wiring. Another thing to bear in mind is that with these systems the charger side of the inverter will be supplying all or most of your 12V needs as well as charging the batteries. I bet this has raised as many questions as it has answered but keep coming back as you need to. Tony Brooks

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