Norfolk Broads - The Forum - More Inverter and Electrics Help!!

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dannyb1

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Hi all, I need some advice!

Boat has a 240volt shore supply with various sockets and seperate 12volt and 24volt battery chargers fitted to on/off switches on the consumer panel where main trip is. There is also the 2 polarity correct lights on the consumer panel.

What I want to do is wire in an inverter via a crossover switch through the main panel so all sockets will be live and use the trip allready there.

my questions are:

What do I do about earthing the invertor? does it need an earth? or is it just connect live and neutral to crossover switch? along with the incoming shore supply which is earthed?

What do I do about the battery chargers as I would presume they would then run off the inverter which I dont think sensible? or is it?

cheers
Danny

SOS247

Jul-31-2010 @ 10:12 PM

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SOS247

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Hi Danny

I will try & help you but I strongly advise that this equipment is
installed by someone qualified, so please be careful.

Personally in your particular instance I would just fit the inverter as per
the manufacturers instructions & keep it separate from the mains shore
power. You can then just add another 240v socket a label it 'inverter'
accordingly.

Please seek guidance on the Boat Safety issues as they cover this area
(mainly because accidents have happened on incorrectly installed
equipment!)

Note - It's not really viable using the 12v battery to power a inverter,
which is powering the charger, which is then charging the batteries!! As
you know running an inverter uses several amps, so it defeats the
object!

Its does however depend on the inverter type or model which you
purchase. I supply the Victron Multi which is a very good unit, but the
Waeco Mobitronic etc is still okay.

And its always best to work out a boats electrical  system - backwards!
- i.e. list the different items that you want to run 12v & 240v, then list
the items you need to run at the SAME time. Add up the watts or amps
etc.

The key thing is to make sure the system is 100% safe.
Basically 240volts & water do not mix, and because boats are normally
small, 240v equipment can easily get wet etc.
Please also remember that even though you will know how your boats
electrical system works, you could sell your boat one day in the future
so other people & families may not know how your boat electriacl
system works.  So it needs to be safe with all the RCD breakers to
protect the different circuits etc

If in any doubt, just get a marine electrician or even a household type
electrician and arrange for the system to be fully tested after you have
finished it.

Good luck, any questions or issues just ask.

Edited - Sorry I went a bit mad on the safety! But I nearly lost my life
from 240v electrics and once its got you it don't like letting go!!!!
Friends are a bit lost how to help you as well!!



They say that 'Hard work never killed anyone' however, sleepless
nights, stress, not taking breaks & not eating correctly may just get you
there early!!

This message was edited by SOS247 on Jul-31-10 @ 10:17 PM

kfurbank

Jul-31-2010 @ 11:36 PM

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kfurbank

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Hi Danny,

Firstly when working with electricity, if in any doubt then consult a professional electrician.

In answer to your questions, you will need to ensure that any changeover switch, will switch both the live and the neutral. An inverter is effectively an isolated power source and its live or neutral should never come into contact with your shorepower live or neutral. With regard to earth, just link all your earths together which should also be connected to any of your boats earth bonding.

Placing the changeover switch before the RCD will ensure that whether you are running on inverter or shorepower you are always protected and that the inverter can be used to power all the existing sockets without the need to install additional ones. Many changeover switches are 3 way so that you can switch inverter, shorepower or generator.

Battery chargers and inverters are inefficient devices, in other words they consume power in the provess of charging or converting electricty and therefore output power will always be less than the input power. Therefore using an inverter to power a charger that is being used to charge the inverter batteries is one of the quickest ways to flatten the batteries and should be avoided at all costs. You need to get into the habit of making sure that when you remove your shorepower lead and then change the changeover switch to inverter, that you turn the battery chargers off. You could use an automatic changeover switch. These often have the inputs in an order of priority, so that if shorepower is detected this is always used first, followed by perhaps a generator is that is running, finally selecting an invertor if no other source is available. The automatic changeover switches will often have a lockout circuit. This is used to isolate certain sockets in the event you are running on inverter power. It's main use is to isolate such heavy current drain devices such as an immersion heater, or battery chargers when running on inverter power. Sterling Power make very good manual and automatic changeover switches. Further info can be found here along with instructions for both types. http://www.sterling-power.com/products-230vcs.htm

Keith

Grendel

Jul-31-2010 @ 12:49 AM

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Grendel

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quote:"......
you will need to ensure that any changeover switch, will switch both the live and the neutral.
......."

In electrical language this is called a double pole changeover switch, this will switch both live and neutral.
Grendel

SOS247

Aug-01-2010 @ 1:51 PM

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SOS247

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Just for interest the Victron muli units that we supply have the
automatic change overs already in, so when adding up the costs you
need to take this into account.

On our new boats which we recently built the inverter, charger & shore
power system is idiot proof! Its just plug & go...... We can run 2000kw
240v equipment on-board constantly, whilst plugging in/out of shore
power etc. If the shore power is on the unit will just automatically
switch to charge batteries OR supply inverter or visa versa, plus you
can control/limit the power. This is the key benefit of using the
Victron units.

Copying what the commercial hire fleets install its a safe option, over
the years 'everything' has been tested and if it constantly fails it no
longer get used!

They say that 'Hard work never killed anyone' however, sleepless nights, stress, not taking breaks & not eating correctly may just get you there early!!

dannyb1

Aug-01-2010 @ 6:48 PM

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dannyb1

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Thank you for all the very helpful advice, I have been looking at the Sterling Pro Combi 24volt Charger / 1600kw inverter as it seemed so I thought quite straighforward. It already has a 12volt Victron Charger fitted and whilst they are excellent units it is cost as always.

What I wanted to do was fit the pro combi which has an automatic changeover as part of it, but would have problems with the 12volt charger and the immersion (which I hadn't considered) as being on the same circuit they would be live via the inverter unless I switched them off manually which I would prefer not to do and was hoping I could make this happen automatically in some way. maybe the procombi isn't the product I need.

However, I think I will go for the easy option and keep my existing 12 and 24 volt chargers as they are and do what I think Jason suggested and go for a seperate cicuit, now this raises a few more questions I would be grateful for more advice on!!

I would go for a sterling inverter probably only 1000w as its really only for TV's and laptop chargers, now in the instructions it says to fit the recommended fuse on the live power input from the battery which is fine but says nothing about an RCD, is it sensible to fit one of these in anyway and is just a case of putting in on the live output before any sockets? what rating RCD would be best?

Can I run a radial type circuit off the inverter ie, wire it a double socket in saloon and then on to a double in the aft cabin (and if possible then go on forward to a single socket in the bow cabin and end the circuit there? (37ft boat)

The earth for it, Another boat I have seen with an inverter had an earth bonding system that seemed to go back to the big metal pipe where the weed filter lives, now I dont think my boat already has anything like this (but could be wrong) so could I just take the earth back to that or is that wrong? Also would every metal object on the boat need to be bonded back to the same place or I am getting confused here?

Last question, I have 3 battery banks, 1 24v consisting of 2 12volts connected as 1 24v, this does fridge, heater and I think the thruster, and I also have a 12volt bank of 2 for domestics and 1 12v engine start......should I go for a 12volt inverter or 24volt and would I need to increase either bank size or would it be fine as is?

I am quite competent with electrics but inverters are something I am not clear on, best to get as much advice as I can before I decide If I am capable or not!

Greatly appreciate your help!

Cheers
Danny

This message was edited by dannyb1 on Aug-1-10 @ 7:35 PM

dannyb1

Aug-02-2010 @ 3:34 PM

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Ok been doing some reading and would I be right in thinking you would earth the RCD for the inverter output to the boat chassis...ie to where the battery negatives go? does that then mean that the shorepower earth should do this also as at the moment I think it takes its earth from the shore feed only? Havent opened it up to find out yet but cant see anything visible to point toward it being earthed to boat chassis/engine block at present

Cheers
Danny

gallopinhairpin

Aug-02-2010 @ 4:12 PM