Inverter Size Compared to Your Boat Size?

[prv]

Ty , so it is a colorifier ( not wholly dependant on the electric element ) did you fit the system your self or did it come . ?

The boat came with the calorifier. Though I replaced all the original plumbing and electrics on board, so apart from physical mounting I essentially did the same work as installing it.

I also installed 420Ahrs of battery, and I did consider an inverter, but the simple fact is that there isn't any 240v equipment that I'd want to power from it.

The only thing I ever plug in to the sockets when on shore power is occasional power tools - but I bring those down as required for specific jobs, so I wouldn't be able to use them away from the home berth even if I did have an inverter. Otherwise, heating appliances like kettles and toasters are a waste of battery power when I could use gas instead, electronics are inherently low-voltage DC so there's no point going up to 240 AC and back down again, and as a holiday sailor rather than liveaboard I don't need domestic stuff like a washing machine and wouldn't have space for it anyway.

Just looking around me here at home, all the electrical stuff I see is either electronic, available in 12v (lighting, the fridge), or too power-hungry for batteries.

I suppose I'd find a small vacuum cleaner useful from time to time (most of the 12v ones seem to be pretty rubbish). But I've managed fine so far with a dustpan and brush and a damp cloth...

Pete

 

[cherod]

Are 12V immersion heaters not available?

Apparently ( google search ) they are available to run on both 12 and 240 , i suspect the 12 v element takes a bit longer . I suspect @ 10 / 15 mins for 5 gals , anyone know ?

 

[prv]

i suspect the 12 v element takes a bit longer . I suspect @ 10 / 15 mins for 5 gals , anyone know ?

How long they take will be determined entirely by the power in watts, not the voltage.

Pete

 

[PaulRainbow]

Apparently ( google search ) they are available to run on both 12 and 240 , i suspect the 12 v element takes a bit longer . I suspect @ 10 / 15 mins for 5 gals , anyone know ?

My calorifier is 30 ltrs and has a 1kw element. It comes on for one hour in the morning and in that hour probably heats the water up to 50c. Not sure exactly, but it's certainly less then the setting of he mixer valve, which is less than 65c.

 

[ip485]

This thread is nuts. Inverter size has nothing to do with boat size.

I have a 35 foot boat, what size shoes should i wear ?

That was my first reaction, and exactly what I was going to say.

.. but perhaps it does. I guess the point is on the whole the battery bank size is related to the boat size, not always, but there is a broad correlation maybe. In turn with a small battery bank there is probably little point having a massive inverter.

Of course I understand you could spec. a big battery bank on any boat, or even a smaller one with a big inverter realising it will only provide power for a short time.

Anyway, I have 800 AH on a 50 footer and a 4KW inverter which does me well. Using the A/C on the inverter which it will cope with of course hammers the batteries, as does even the kettle, so realistically it seems to me if this is your objective LIFPO4 is probably the only realistic answer to give any sort of sensible battery bank life, and then still the need for a big bank. If it is for the more typical lower load 240V appliances anything that doesnt heat or cool is probably neither going to have a huge draw or require these much larger inverters and battery banks.

I would add heating water with an inverter probably doesnt make much sense unless it is the only alternative. You are better of running the engine, or as I have done installing a dedicated hydronic heater which is utterly amazing at doing the job. As I said heating and cooling require significant amounts of power and would seem a poor use of all those hard won Amps.

 

[cherod]

My calorifier is 30 ltrs and has a 1kw element. It comes on for one hour in the morning and in that hour probably heats the water up to 50c. Not sure exactly, but it's certainly less then the setting of he mixer valve, which is less than 65c.

thank you , a bit longer than i expected ,, maybe a little boost from the 240 geny .
is that direct from 12 v battery or 240 throo an invertor ?

 

[PaulRainbow]

thank you , a bit longer than i expected ,, maybe a little boost from the 240 geny .
is that direct from 12 v battery or 240 throo an invertor ?

That's 240v from shore power. If i'm away from the marina it's engine heated or i use a gas kettle.

But, as PRV said earlier, 12v or 240v don't matter as far as time goes, it's the watts that count.

 

[RupertW]

I would add heating water with an inverter probably doesnt make much sense unless it is the only alternative. You are better of running the engine, or as I have done installing a dedicated hydronic heater which is utterly amazing at doing the job. As I said heating and cooling require significant amounts of power and would seem a poor use of all those hard won Amps.

Fair enough but I want to avoid using the engine except for motive power and even then prefer sailing if possible.

 

[PaulRainbow]

I'm not really seeing the battery bank as being relevant, to be honest.

I want to run a 1kw widget, so i need a 1.2kw inverter, just to allow a little wiggle room. My battery bank isn't up to running a 1.2kw inverter so, i'll fit an 800w inverter. Now my inverter won't run my widget.

My thinking would be, we need to fit the 1.2kw inverter. Then we need to increase battery capacity (if not enough) and lastly we need to provide adequate charging, again if not already enough.

 

[ip485]

RupertW of course, but (and I am not patronising) the rules of physics are bl**dy harsh and using battery power to heat water in any volume and to a good temperature is realistically not practical, so, if there are even say two of you on board, you are at anchor for a few days (even a day) and want a good hot shower then you have to consider alternatives. Of course if it is a little water for washing up or washing your face it may be more realistic, but you might just as well boil a kettle.

The alternatives are running the engine in idle, running a Genset or a dedicated water heater. All work, the first two have some disadvantages, I think third is by far and a way the nest option, but at a cost, and with the need for a little space for the hydronic heater if that is the chosen source. There are larger gas heaters as well.

Hydronics for anyone wanting to do this are well worth a look. I am so impressed with mine. It really is pretty much boiling hot water on demand with little noise or fuss.

 

[geem]

Quite comprehensive ?

I forgot to mention that we have a third inverter. This one is 110v. We use it to feed excess solar power to the 220v 1200w immersion heater. If you do this, you convert a 220v 1200w immersion heater in to a 300w immersion heater. The benefit of doing this if you have sufficient solar panel capacity is that the batteries will stay on float, deal with all the normal boat loads such as fridge and freezer loads, etc and still heat hot water. We have it switchable via a 1 hour timer. Its nice to get free hot water for washing up or a couple of showers. We have 720w of solar capacity connected to the domestic battery bank

 

[geem]

RupertW of course, but (and I am not patronising) the rules of physics are bl**dy harsh and using battery power to heat water in any volume and to a good temperature is realistically not practical, so, if there are even say two of you on board, you are at anchor for a few days (even a day) and want a good hot shower then you have to consider alternatives. Of course if it is a little water for washing up or washing your face it may be more realistic, but you might just as well boil a kettle.

The alternatives are running the engine in idle, running a Genset or a dedicated water heater. All work, the first two have some disadvantages, I think third is by far and a way the nest option, but at a cost, and with the need for a little space for the hydronic heater if that is the chosen source. There are larger gas heaters as well.

Hydronics for anyone wanting to do this are well worth a look. I am so impressed with mine. It really is pretty much boiling hot water on demand with little noise or fuss.

I am installing a hydronic heater this winter. This will heat domestic hot water and radiators. We already have an Eber 5kw air heater.
The addition of this system means we can heat water via the engine, the generator, the solar panels via 110v inverter of by shore power. I think we have it covered?

 

[PaulRainbow]

I am installing a hydronic heater this winter. This will heat domestic hot water and radiators. We already have an Eber 5kw air heater.
The addition of this system means we can heat water via the engine, the generator, the solar panels via 110v inverter of by shore power. I think we have it covered?

You don't have a kettle ?

 

[Plymsea]

I have a 26' sailing boat and a 6m RIB (mixing imperial and metric!)

Have had a 300w inverter for over 20 years and used it about 3 times.

All my power tools are either gas or battery, latter can be charged with a DC-DC converter, as can the laptop. The only exception is a mains sander, which I dont consider to be an essential when cruising.

 

[ip485]

I am installing a hydronic heater this winter. This will heat domestic hot water and radiators. We already have an Eber 5kw air heater.
The addition of this system means we can heat water via the engine, the generator, the solar panels via 110v inverter of by shore power. I think we have it covered

Adding radiators is a big work up and I am not convinced of the benefit. it might be thought there is less noise, but a fan at each radiator will I suspect prove that theory wrong. In the end I decided it was better to keep the blown hot air system and have a dedicated hydronic for heating water. It also made the installation much more straigh forward.

I am surprised you have excess solar. I have 800 W; in the summer this just about keeps up with the DC load, but certainly doesnt in the winter or on less sunny days. The batteries happily take all those Amps and need some supplementary help from the Genset.

Running the Genset and a conventional 3KW fan heater does the job of taking off the initial chill on a really cold day combined with the Ebber.

As to the kettle although the Inverter will boil the kettle I usually revert to the gas kettle at anchor unless the Genset is running, and I have been working on my setup to reduce the Genset run time as much as possible because although it is pretty quiet, it is better without it.

with regard to the OP it is also worth noting that even in the marinas 16 AMP outlets which are often the norm. often prove inadequate.

 

[Mistroma]

thank you , a bit longer than i expected ,, maybe a little boost from the 240 geny .
is that direct from 12 v battery or 240 throo an invertor ?

Requirements are easy enough to estimate and as others have said it isn't practical to use a battery to heat water for a shower. Calculation is pretty simple if you assume insulation is perfect. It doesn't make a huge difference in practice and just means it will take a few minutes longer than shown by the theoretical figure.

A 1kW element will heat 30 litres from 20°C to 50°C in around 63 minutes or 74 minutes starting from 15°C. Obviously in line with the actual figures quoted by Paul.

I have a 1.2kW element in a 45 litre tank which would take about 79 mins. or 92 mins. starting from 20°C or 15°C. The 1.2kW element actually cuts off at about 65°C but the engine gets it up to a ludicrous temperature (probably 90°C). It certainly keeps warm for a lot longer after an engine run than after heating on shore power.

 

[geem]

You don't have a kettle ?

Yep, electric kettle of old fashioned kettle on gas hob or induction hob?

 

[geem]

Adding radiators is a big work up and I am not convinced of the benefit. it might be thought there is less noise, but a fan at each radiator will I suspect prove that theory wrong. In the end I decided it was better to keep the blown hot air system and have a dedicated hydronic for heating water. It also made the installation much more straigh forward.

I am surprised you have excess solar. I have 800 W; in the summer this just about keeps up with the DC load, but certainly doesnt in the winter or on less sunny days. The batteries happily take all those Amps and need some supplementary help from the Genset.

Running the Genset and a conventional 3KW fan heater does the job of taking off the initial chill on a really cold day combined with the Ebber.

As to the kettle although the Inverter will boil the kettle I usually revert to the gas kettle at anchor unless the Genset is running, and I have been working on my setup to reduce the Genset run time as much as possible because although it is pretty quiet, it is better without it.

with regard to the OP it is also worth noting that even in the marinas 16 AMP outlets which are often the norm. often prove inadequate.

We are normally based in the Caribbean so plenty of sun.
The hydronic will do domestic hot water plus a towel rain in each heads. We dont need radiators anywhere else since the Eber heats the rest of the boat, it just seemed nice to be able to dry towels as well. Not normally a problem in the Caribbean.
We only normally run the genset to make water but whilst it is making water we often use it for other things. We never use it to charge batteries

 

[mrangry]

I see no need for ac power on a yacht

 

[geem]

I see no need for ac power on a yacht

We have a vacuum cleaner, angle grinder, electric plane, hair dryer, iron, cordless drill charger, 240v drill, immersion heater, Dremel, induction hob, three sanders, electric toothbrush chargers, tv, laptop, hot air gun, multi tool, electric kettle, sewing machine, watermaker, two battery chargers and hair clippers. We definitely have a need for AC power?