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Inverter advice

scr0che

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Couple of inverter questions.

Planning a separate radial circuit for the inverter, 2x sockets - separate from the shore power circuit - sound reasonable?

Plan to have a switch at the chart table to turn it on/off - is there a way to do that to ensure the battery charger is NOT switched on at the same time when connected to shore power?

In terms of sizing, 1200w inverter - charging laptop, toothbrush, battery tools - all occasional - torquedo elec outboard in particular - is that big enough? I've 350w solar panels and 400Ah AGM batteries in the house bank.

Looking at a Victron Smart Inverter 12v 1200VA - any good?
 

pvb

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Planning a separate radial circuit for the inverter, 2x sockets - separate from the shore power circuit - sound reasonable?
That's what I did, dedicated sockets for the inverter, no chance of any problems.

Plan to have a switch at the chart table to turn it on/off - is there a way to do that to ensure the battery charger is NOT switched on at the same time when connected to shore power?
That's what I did; fit the switch out of the way so you can't accidentally turn the inverter on as there'll be a drain on the batteries. I don't understand your comment about the battery charger - if you have shore power, you wouldn't use the inverter.

In terms of sizing, 1200w inverter - charging laptop, toothbrush, battery tools - all occasional - torquedo elec outboard in particular - is that big enough? I've 350w solar panels and 400Ah AGM batteries in the house bank.
If that's all you want it for, 1200W should be fine. But laptops work well from 12v car chargers. The Torqeedo battery will also charge easily from the 12v house batteries. So do you really need an inverter? If you want to run other stuff (microwave, hairdryer, kettle, etc) you'd be better looking for a 2000W inverter.

Looking at a Victron Smart Inverter 12v 1200VA - any good?
Victron's website doesn't mention a Smart 1200W option - are you sure that's what you're looking at? Otherwise, Victron equipment is good quality, if a bit pricey. For your declared use, you'd probably find an inverter for less than half the price on Amazon.
 

scr0che

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Thanks, on the right track.

It's a Victron Phoenix Smart 12v 1600VA. The victron kit is quality, figure fit a decent inverter now so I have options if my power requirements change in the future. Lockdown projects preparing for a circumnavigation.

I'm told if you run a charger from shore power and accidentally turn the inverter on at same time it can make a mess of your batteries. Is there a device, and is it necessary, that can literally prevent both being on at the same time? May not be needed as you say, just put the inverter switch out of the way.
 

PaulRainbow

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Thanks, on the right track.

It's a Victron Phoenix Smart 12v 1600VA. The victron kit is quality, figure fit a decent inverter now so I have options if my power requirements change in the future. Lockdown projects preparing for a circumnavigation.

I'm told if you run a charger from shore power and accidentally turn the inverter on at same time it can make a mess of your batteries. Is there a device, and is it necessary, that can literally prevent both being on at the same time? May not be needed as you say, just put the inverter switch out of the way.
Can't see why that would happen. But, if you want to prevent it, fit a normally closed relay somewhere in the inverter remote wiring and connect the coil wires to the shore power, when shore power is on, you can't then use the inverter if shore power is on. Can't see the point though.
 
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Graham376

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I'm told if you run a charger from shore power and accidentally turn the inverter on at same time it can make a mess of your batteries. Is there a device, and is it necessary, that can literally prevent both being on at the same time? May not be needed as you say, just put the inverter switch out of the way.
I've wired our inverter into the normal ring via a double pole 2 way switch before the rcd so it can't be combined with shore power or feed the shore power socket.

P.S. Just have to remember to switch water heater & battery charger off.
 
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GHA

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I'm told if you run a charger from shore power and accidentally turn the inverter on at same time it can make a mess of your batteries.
That's a new one - how would the charger or batteries know? What sort sort of "mess"?
Unless it means the charger will get confused with where the power is going and switch to float too early, no different to running a fridge,laptop etc though
 

Graham376

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That's a new one - how would the charger or batteries know? What sort sort of "mess"?
Unless it means the charger will get confused with where the power is going and switch to float too early, no different to running a fridge,laptop etc though
Our 350w inverter knows if I've forgotten to switch high power items off, it sounds the overload alarm but no damage. I would think a larger inverter would just run the batteries flat after a while charging batteries by drawing more current than it's putting in.
 

pvb

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I've wired our inverter into the normal ring via a double pole 2 way switch before the rcd so it can't be combined with shore power or feed the shore power socket.

P.S. Just have to remember to switch water heater & battery charger off.
If you just have dedicated sockets for the inverter, you don't have to remember anything!
 

Graham376

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If you just have dedicated sockets for the inverter, you don't have to remember anything!
Used to just plug in to the two sockets on the inverter but got fed up with extension leads around the boat so wired it to the ring. Unless we've been in a marina, it's very rare for water heater to be used and I don't think we've had to use the battery charger for a couple of years.
 

PaulRainbow

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I've wired our inverter into the normal ring via a double pole 2 way switch before the rcd so it can't be combined with shore power or feed the shore power socket.

P.S. Just have to remember to switch water heater & battery charger off.
Sorry Graham, but this is a bad way to wire an inverter.

If anyone else is reading this, please do not connect an inverter, with plug in sockets, in this way. Inverters connected to the vessels consumer unit must have the neutral and earth bonded at the inverter and this is not a job for the average DIY person.

If an inverter is suitable to be connected to the vessel systems it can be connected so that some circuits are not powered by the inverter. Some systems are best suited to a split consumer unit, but a simple way of doing it is to fit a 3 way double pole changeover switch if you want to isolate the charger when using the inverter, or a 4 way if you don't want the inverter and water heater on with the inverter.
 

PaulRainbow

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Used to just plug in to the two sockets on the inverter but got fed up with extension leads around the boat so wired it to the ring. Unless we've been in a marina, it's very rare for water heater to be used and I don't think we've had to use the battery charger for a couple of years.
This was a better way of doing it. PVB has wired some fixed sockets in, that connect to the inverter sockets only, saves the extension leads.
 

Graham376

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Sorry Graham, but this is a bad way to wire an inverter.

If anyone else is reading this, please do not connect an inverter, with plug in sockets, in this way. Inverters connected to the vessels consumer unit must have the neutral and earth bonded at the inverter and this is not a job for the average DIY person.

If an inverter is suitable to be connected to the vessel systems it can be connected so that some circuits are not powered by the inverter. Some systems are best suited to a split consumer unit, but a simple way of doing it is to fit a 3 way double pole changeover switch if you want to isolate the charger when using the inverter, or a 4 way if you don't want the inverter and water heater on with the inverter.
As it happens, my back-up inverter has bonded earth and neutral but the Sterling in use doesn't. All inverters come with sockets for plugging in appliances, tools etc., and an isolated boat circuit is no different to using a multiple socket extension lead, which would be perfectly acceptable use.
 

PaulRainbow

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As it happens, my back-up inverter has bonded earth and neutral but the Sterling in use doesn't. All inverters come with sockets for plugging in appliances, tools etc., and an isolated boat circuit is no different to using a multiple socket extension lead, which would be perfectly acceptable use.
Remind us, what electrical qualifications do you have ?
 

RupertW

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Remind us, what electrical qualifications do you have ?
Careful, your factual responses are (with your one blind spot excepted) spot-on and with way more experience than I have, but playing this card just shuts down discussion without adding to our mutual knowledge
 

scr0che

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Can't see why that would happen. But, if you want to prevent it, fit a normally closed relay somewhere in the inverter remote wiring and connect the coil wires to the shore power, when shore power is on, you can't then use the inverter if shore power is on. Can't see the point though.
The only reason I asked was because I had read somewhere that it could ruin the batteries if they were charging from shore power whilst your inverter was on. I'll try and find the source of that statement! If it's not an issue then I won't add the relay, but thanks for the info anyway, good to learn about all these things.
 

Graham376

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Remind us, what electrical qualifications do you have ?
Around 60 years of surviving!

This was a better way of doing it. PVB has wired some fixed sockets in, that connect to the inverter sockets only, saves the extension leads.
Tell me what the difference is between what you say is acceptable above - to wire the inverter direct into a couple of dedicated sockets and wiring it into an spur protected by fuses and isolated from shore power?
 

PaulRainbow

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Around 60 years of surviving!
Sorry Graham, that doesn't count. Try sticking your fingers into a 24v supply with no RCD protection.

Tell me what the difference is between what you say is acceptable above - to wire the inverter direct into a couple of dedicated sockets and wiring it into an spur protected by fuses and isolated from shore power?
If the inverter has neutral and Earth bonded at the inverter, which is required by every regulation in existence that relates to such installations (generators included), (just because you are not bound by those regulations doesn't mean it's a good idea to ignore them), the installation will behave exactly the same as if it was connected to shore power, or if it was your house electrical system. Your RCD will still protect you. Note that the vessels Earth circuit must be connected to the grounding circuit, anode, metal hull etc, as applicable.

Inverters with sockets on them come in a variety of flavours. Some can be bonded (see above), so no problem. Others cannot be bonded, lest the go bang. Some are centre tapped, others are pseudo centre tapped, not all of them will trip the RCD to protect you. Some cheap ones with sockets don't even Earth the metal case, if they do, where will you connect it ? Will it trip the RCD ? Some have their own built in protection, others don't. A lot of cheap inverters with sockets are only suitable for double insulated devices, which might be fine to plug your drill into, but not so good with other fixed equipment that may be found on a boat.

So, if fitting an inverter to the vessels onboard system, it has to be neutral/Earth bonded and the Earth connected as above. There are plenty of budget inverters on the market that don't have sockets and can be bonded.

If it has plugs, i would suggest it has no place on a boat, i would absolutely refuse to fit one for a customer. If someone really wants to use one and cannot be 200% certain neutral/Earth is bonded, only use the sockets and take particular note of the inverters Earth connection, the vessels Earth circuits and any mention in the inverter documentation regarding double insulated equipment.
 

Graham376

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PaulRainbow

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The only reason I asked was because I had read somewhere that it could ruin the batteries if they were charging from shore power whilst your inverter was on. I'll try and find the source of that statement! If it's not an issue then I won't add the relay, but thanks for the info anyway, good to learn about all these things.
I can see where you'd think that, but as you can see, despite a much more detailed response, i'm still wasting my time, may just as well have stuck with the short version :)
 
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