Inverter advice

[Ric]

Grateful for advice on a 12v inverter.

Uses will be to charge laptop and electric drill batteries. Perhaps also an electric kettle.

A nice luxury might be one that I can connect to the boat's existing 220v ring main which is normally only used for shore power.

 

[sailorman]

Grateful for advice on a 12v inverter.

Uses will be to charge laptop and electric drill batteries. Perhaps also an electric kettle.

A nice luxury might be one that I can connect to the boat's existing 220v ring main which is normally only used for shore power.

you will need a 3Kva inverter to run a kettle & Very large battery bank.
Some equipment requires Pure Sine Wave & these inverters are much more expensive than the modified sine wave inverters.
i think you need to decide what you want / need

 

[NB Willawaw]

The problem will be the kettle. This will need a large inverter and a good battery bank.

Otherwise you can use a small quasi sine wave one.

In terms of connecting to your existing mains wiring inside the boat, this is not so much a feature of the inverter as the way that you switch it in and provide protection.

Grateful for advice on a 12v inverter.

Uses will be to charge laptop and electric drill batteries. Perhaps also an electric kettle.

A nice luxury might be one that I can connect to the boat's existing 220v ring main which is normally only used for shore power.

 

[pvb]

Just to add an alternative view, it is possible to get low-wattage travel kettles, which can use as little as 650W. OK, they're small and take longer to boil, but do the job. So the inverter and battery bank don't necessarily need to be huge.

Of course, it's also possible to get 12v kettles for about a tenner, which also do the job, but are even slower.

But I agree that the OP needs to decide exactly what he wants to power before choosing his inverter.

For the laptop, I use a car charger lead which works perfectly from the boat battery.

 

[Mistroma]

These are quite extreme requirements, ranging from 100W- huge inverters. A kettle won't need a pure sine wave but I imagine that startup current will be massive. Heating elements draw very high current when cold and then drop quickly to normal level. So a 3kW kettle will need a 3kW inverter to just about run. That will draw around 240A when heating water. However the initial current will be much higher. I don't know exactly how high but know that some small 300W inverters can't run 100W hair tongs. So you'd need to get advice about correct size of inverter. Even a small travel kettle will draw about 50A with a much higher startup surge.

Another problem will be that the standby current for a large inverter will be quite significant. It will probably draw just as much on standby as it will when charging your small devices. So not very efficient use of battery power.

I'm actually wiring in a small inverter next year and have all the parts. I can share details if you like (parts, supplier,diagram etc.).

 

[rosssavage]

Just to add an alternative view, it is possible to get low-wattage travel kettles, which can use as little as 650W. OK, they're small and take longer to boil, but do the job. So the inverter and battery bank don't necessarily need to be huge.

Of course, it's also possible to get 12v kettles for about a tenner, which also do the job, but are even slower.

But I agree that the OP needs to decide exactly what he wants to power before choosing his inverter.

For the laptop, I use a car charger lead which works perfectly from the boat battery.

It takes 'x' amount of energy to heat 'y' mass of water, so you can take a smaller current for a longer time, or a bigger current for a shorter time, but your batteries will need to be just as big...

That said, the inverter could be smaller, ergo cheaper and easier to install

 

[Haven't-a-Clue]

Grateful for advice on a 12v inverter.

Uses will be to charge laptop and electric drill batteries. Perhaps also an electric kettle.

A nice luxury might be one that I can connect to the boat's existing 220v ring main which is normally only used for shore power.

Towsure do a decent 1kw/2kw inverter wot I use onboard the last 3 years for everything from 1200w m/wave to charging up laptop and phone, also 850w kettle. Use BIG cable to connect the inverter to the batteries and a length of 16amp blue cable with a 13amp plug on one end and the usual blue shorepower plug on t'other. You're all set to go......well it's what I have and works just fine. Jolly nice to be able to boil up for a cuppa as you sail (the inverter mounted just inside the companionway).

 

[pvb]

It takes 'x' amount of energy to heat 'y' mass of water, so you can take a smaller current for a longer time, or a bigger current for a shorter time, but your batteries will need to be just as big...

I guess you haven't heard of Peukert...

 

[rosssavage]

I guess you haven't heard of Peukert...

Um, bugger.. didn't think it would make that much difference at these w's..

Just did a bit of pretend maths and assuming 100Ah battery and 2kw kettle (167A) or 650w kettle (54.2A) and Peukert constant of 1.4 (flooded battery generalisation) there is a mahoosive difference.

Sorry. Corrected

 

[CAPTAIN FANTASTIC]

I have 5 x 110 amp batteries and I use a 1200 watts inverter which I bought from Maplins some 6 years ago cheap (~£65). The inverter, which is not a pure sine, will run all electrics via the main circuit including the recent addition, TV flat screen.

I also use a low wattage electric kettle, I think is 850watts. I have not tried to run a microwave yet but it may be able to run a 650w microwave. The inverter is permanently connected to the batteries.

 

[sailorman]

I have 5 x 110 amp batteries and I use a 1200 watts inverter which I bought from Maplins some 6 years ago cheap (~£65). The inverter, which is not a pure sine, will run all electrics via the main circuit including the recent addition, TV flat screen.

I also use a low wattage electric kettle, I think is 850watts. I have not tried to run a microwave yet but it may be able to run a 650w microwave. The inverter is permanently connected to the batteries.

my microwave would not work with a mod sine wave, so i have a Struder 1200 pure sine wave. i do run the engine when its running for more than a couple of minutes. i have 345Ah domestics

 

[Ex-SolentBoy]

Surely the electric drill and laptop would be better charged directly from 12v? I am no electrical expert, but going from 12v to 220v and then back to 18v or whatever the need must be inefficient.

I have adapters on my boat for the drill and the laptop so they plug directly into 12 v sockets.

You can get very nice small kettles that draw way less than 2kw so a simple small inverter will cover that job.

 

[sailorman]

Surely the electric drill and laptop would be better charged directly from 12v? I am no electrical expert, but going from 12v to 220v and then back to 18v or whatever the need must be inefficient.

I have adapters on my boat for the drill and the laptop so they plug directly into 12 v sockets.

You can get very nice small kettles that draw way less than 2kw so a simple small inverter will cover that job.

a gas hob is more efficient for a cup of tea

 

[GrahamM376]

I use a quasi sine-wave Sterling 350W inverter. Runs TV and laptop, as well as SWMBO's small galley appliances. No problem plumbing it into the boat circuit, install a double pole two way switch before the RCD, DON'T just wire it into the back of the nearest power socket. That way you have the choice of using either shore power/genny through deck socket or, the inverter, without any conflicts.

 

[William_H]

Inverter

The OP has obviously not realised the problems of using an inverter. You can not just wire it into the ring main for use instead of mains power. If you inadvertently get the 2 AC supplies running at once you will get huge currents and CB popping every where. Hence Graham M367 points out the need for dual pole isolation switch that can not allow both. Secondly a user needs to understand the nature of the device he wants power from 240vac. As said the power used by AC gadgets in our home varies by about 1000 to 1.
heating devices are easily driven but use huge power. This needs huge batteries or a generator on line and very big wiring for 12v system. Indeed most real inverters run on 24 v system for this reason.
So Op is far better off to buy a small inverter for his chargers but keep the outlet as just one hidden from other crew so it can not be confused with AC power of our homes.
As said some electronic devices don't like the non sine wave output of cheap inverters. They may be damaged or just run very inefficiently. Certainly syncronous AC motors of refrigerators small fans etc must have pure sine wave.
So to the OP "it ain't as easy as it seems to run stuff off an inverter". good luck olewill

 

[TQA]

For the lappie get a 12 volt converter. Much more efficient.

As for the rest you are on your own.

 

[duncan99210]

We have a 1000w inverter from Maplin that is NOT wired into the boat's mains cicuit for exactly the reasons given above. We use it mainly for low wattage demands though occasionally use it for power tools. Its a simple one that cost less than £90 but I have a second 150w one which I use for charging laptops - I found it uses less power than the 12v charger I bought from Maplin. As to using battery power for boiling kettles - makes no sense to me at all; that's what the cookers for.

 

[Maine Sail]

Please keep in mind that with many MSW inverters items such as cordless tool, camera or other "battery chargers" may not work properly when powered via an MSW inverter. This can destroy the batteries. Some MSW inverters have a better wave form than others and the real elcheapo's are usually the worst. Pure sine has come down in price recently and made it more affordable.

I personally destroyed 3 very expensive 18V DeWalt batteries plus two very expensive Nikon DSLR batteries all with a Xantrex MSW inverter. I did not know why I was chewing through batteries until one day I noticed that after 4 hours my drill battery was still seeing "full charge" and the charger had not shut off, after about 30 minutes, as it does on a pure sine wave.

These batteries alone cost me more than the darn inverter was worth. I converted our boat to a pure sine unit and never again had these issues. I have since had many of my customers with MSW inverters notice the same, especially with power tool chargers. These power tool, batteries can get VERY expensive....

For the computer I would suggest considering a straight 12V adapter or DC/DC converter as it is much more efficient than DC/AC/DC. For the drill batteries use a small pure sine inverter. For the kettle try the stove top...

Unless you want to get into an expensive install I would suggest keeping your inverter isolated from the rest of the ships AC and using just the inverters dedicated outlets. This allows you to avoid transfer switches etc. etc.. If you truly need 3000W then a true marine inverter with auto transfer switch would be the way to go but you'll likely need to address your battery bank as was mentioned above. Old man Peukert does not like high loads on typical deep cycle high Peukert exponent batteries. If adding a monster inverter you'll likely want a good battery monitor that corrects for Peukert in the % Charged screen.. The Victron BMV-600 fits this bill well.