Connecting an Inveter

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dom

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I have purchased a 600W continuous/1000W peak PSW Inverter to work from a 12V system. I don't want to go to the hassle of adding another ring or wiring in a DPDT switch with a 12V coil allowing for remote switching.

I am considering a Heath Robinson effort whereby I take 240V power from the inverter and lead it directly back into the boat's shore-power connection. My main instrument panel has 3x active switchable circuits: "Internal Sockets", "Battery Charger" and "Calorifier" and the plan is only to leave the "Internal Sockets" switch activated. Clearly the inverter's fuse will blow if someone accidentally switches on the calorifier.

My question is: what would happen if someone accidentally turned on the Battery Charging circuit?

My guess is nothing much other than slowly draining the battery via inefficiencies through heat loss, etc; but I'd rather not guess when it comes to electrics! Tks
 
Interesting question - I have a similar set up with a domestic style distribution panel with the exact same circuit breakers as you. Never thought of connecting the inverter to it so as to be able to use the sockets around the boat. Could be a good idea depending what the experts say.
Apart from the problems that might occur (fuse blowing) if the immersion heater was on, what about the consequences if you connected to shore power with the inverter connected either on or off ?
 
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Storyline said:
Apart from the problems that might occur (fuse blowing) if the immersion heater was on, what about the consequences if you connected to shore power with the inverter connected either on or off ?
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My logic is that I could not connect shore power to the boat without first disconnecting the inverter from the boat's single shore-power connection. That would leave the inverter disconnected from any 240V circuits and only connected to the house battery bank via the 12V leads.

But as you say, only one of the electrical whizzos will be able to definitively answer these questions.
 
Perfectly valid system if a little clunky and safe enough if executed well and the inverter correctly installed. The flattened battery you mention is obviously a possibility should you forget to turn off the charger.
 
Many thanks ...two seventeen year old girls will now be vey happy that they can watch "whatever it is they watch" en route to Channel Islands next wk!

Much appreciated
 
dom said:
I don't want to go to the hassle of adding another ring or wiring in a DPDT switch with a 12V coil allowing for remote switching.

I am considering a Heath Robinson effort whereby I take 240V power from the inverter and lead it directly back into the boat's shore-power connection......
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You cannot "play" with AC, especially on a boat. If the shore-power and the AC are connected at the same time there will be a big BANG which could cause a fire. It would be illegal in your house to attempt something like this for very good reasons. AC is Alternating Cycles of high voltage - 50 times a second. If the shore-power and the Inverter are not perfectly synchronised when they are connected then huge currents will flow which at best will blow breakers - if they are fitted - at worst will spoil your trip to the Channel Islands.

If the battery charger is connected to the inverter then just think what is happening. You are trying to charge a battery at the same time as the battery is trying to charge itself. Perpetual motion if it worked! There will be a rapid drain on the battery, the lower the battery voltage gets the harder the charger tries to work and takes more current, so the battery voltage falls faster....and faster......and.....

A simple solution is to have just one isolated AC outlet from the inverter that AC loads used when away from shorepower.
 
sailinglegend420 said:
You cannot "play" with AC, especially on a boat. If the shore-power and the AC are connected at the same time there will be a big BANG which could cause a fire.
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On our previous boat the shorepower connection was inside a locker, thus I did what the OP is suggesting by plugging in the inverter to the shorepower inlet and ensuring all but the sockets were turned off. I couldn't physically connect the shore power without first disconnecting the inverter.
 
fireball said:
On our previous boat the shorepower connection was inside a locker, thus I did what the OP is suggesting by plugging in the inverter to the shorepower inlet and ensuring all but the sockets were turned off. I couldn't physically connect the shore power without first disconnecting the inverter.
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As with the OP, perfectly safe and impossible to have shore power without disconnecting the inverter and vice versa.
 
The only issue I see of concern in connecting the inverter to supply 240v to the ship's system via the shorepower connection is lack of earth - neutral link at the supply point. To overcome this I would add a link inside the inverter if one does not already exist.

This is simple enough to check just check for closed circuit (0 ohms) between the earth and neutral connections. Providing there is no other take off between the inverter and the outlet female socket II do not know of any reason why the earth - neutral link cannot be within the socket itself.

My preference would be a 3 position switch SP - Off - Inverter providing a clear Break Before Make which completely rules out any possibility of inadvertently paralleling the external shoe supply. You definitely do not want to do that.

Do remember inverters simply convert one supply voltage source level to another, and will have losses as a result. They are not generators, nor are they batteries. 12 VDC to 240vac even at low output from the 240vac will use a lot of 12vdc current. 1amp @ 240v will require 20 amps plus losses current e.g. for 75% efficiency ~25 amps.
 
rivonia said:
When we fitted our inverter I simply routed cable and installed seperate sockets. A label stuck to them saying inverter power. Simple and NO RISK.
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As we have done. Nice and safe and no issues for us. I suppose that if someone came on board and tried to use a 'dead' socket they might think something was wrong but no one every does...
 
I am considering fitting a 2000w inverter as my boat is now in The Netherlands.There is a problem with the supply as my immersion heater is 1500w, and when I switch on, the breaker on the pontoon trips. My question is, can I use the battery charger (which runs OK on shore line) to charge the inverter supply battery, to run the immersion. Obviously only when shore line available as when I am out, the port engine heats the calorifier.
 
1.5Kw @ 12v = 125amps (at 230v it's only ~6 amps) so you'd need either a meaty battery charger to keep up with the discharge or a large bank that is fully charged before the immersion heater warms up the water.
It's not going to constantly draw 1.5Kw - it'll switch in and out as the thermostat requires.

I'd be questioning why your 1.5Kw heater is popping the pontoon supply to start with.
 
All was OK when I left the UK, I understand power supply in Netherlands is notoriously poor. It also works OK with the Genny running, but I don't want that thing disturbing the birdsong. By the way, I have 24v power for the inverter with 4 12v batteries linked so there is a large battery bank.
Sorry I seem to have hogged the original thread question.
 
One potential problem is that a lot of inverters have their neutral and earth wires internally linked. It is possible that this will result in the RCD tripping if connected as the OP intends. The only way to find out is to try it and see. When using any inverter on board you should take care to use only double insulated appliances if at all possible because in reality you have no actual earth connection except that as described above any current leaking to the earth wire is connected back to neutral.
 
Graham_Wright said:
I have such a system with a changeover switch - shore - off - inverter. It switches all the wires live, neutral and earth.

I am not sure what an earth connection achieves on a boat.
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It achieves its normal purpose of providing a safe path to earth whilst you are connected to shore power. Once at sea the only "earth" is the link in the inverter between the neutral and earth wires, hence my belief that only double insulated appliances are really safe for inverter use. I agree with your practice of using a three pole changeover switch, and will be installing one when I put my new inverter in to power the fridge.
 
Norman_E said:
It achieves its normal purpose of providing a safe path to earth whilst you are connected to shore power. Once at sea the only "earth" is the link in the inverter between the neutral and earth wires, hence my belief that only double insulated appliances are really safe for inverter use. I agree with your practice of using a three pole changeover switch, and will be installing one when I put my new inverter in to power the fridge.
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I would like to see this argued out.
An earth protection works by detecting the false path between live and a persons body to something connected to earth. On a boat, what is that? The cooker is probably the only candidate and once you start connecting the ships 0v line to earth, all sorts of other problems rear their heads. I guess a kettle with a live short to its body would not cause an RCB trip if there was no earth so maybe I have answered my own question.
 
Jonrob said:
All was OK when I left the UK, I understand power supply in Netherlands is notoriously poor. It also works OK with the Genny running, but I don't want that thing disturbing the birdsong. By the way, I have 24v power for the inverter with 4 12v batteries linked so there is a large battery bank.
Sorry I seem to have hogged the original thread question.
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Having lived there for a long time I suggest that Dutch power supply is at least the equal of UK's. Many marinas and campsites limit the amount of power that can be drawn from pillars by using low-rated breakers. My calorifier immersion heater, bought in Holland, is only 850 watts to allow for this.
 
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