what to do regards a generator

[lanerboy]

I like the look of this inverter and having read the write up, it looks like it will do the job no problem and like you say much less mess than a genny. What sort of size batteries would you think I will need and how many as I would like a separate battery bank just for the inverter to run off

you say there may be a reason I would need a marine specific inverter does anyone know if this is the case or not

if I was to go down this route does anyone know anybody who could install it all for me on the south coast as it would all need to be fitted correctly so I could turn the inverter on / off from inside the boat / cockpit area as I wouldn't want to have to keep getting down in the lazerette where I would have it installed

 

[jimmy_the_builder]

I would go the portable route for a season and see how much you need one. Other consideration is if you want to take your boat to the med you'll need one there for sure.

I tried this exact approach with my Targa 40, I bought a Honda EU20i which (as mentioned by someone further up the thread) was fine when not under load, but did like to get noisy when working hard. It was too noisy, for example, to run sociably on the bathing platform when rafted up with friends on the river Dart.

I then fitted a Onan 4kw generator (this was before I'd decided to move the boat to the Med). Now that I'm there with aircon etc it is invaluable, but even here in the UK it was much more convenient and quieter than a portable generator strapped to the bathing platform.

So, with that experience in mind, I'd skip the 'trying a briefcase generator' step and just go straight to having the proper thing installed.

 

[rafiki_]

I like the look of this inverter and having read the write up, it looks like it will do the job no problem and like you say much less mess than a genny. What sort of size batteries would you think I will need and how many as I would like a separate battery bank just for the inverter to run off

you say there may be a reason I would need a marine specific inverter does anyone know if this is the case or not

if I was to go down this route does anyone know anybody who could install it all for me on the south coast as it would all need to be fitted correctly so I could turn the inverter on / off from inside the boat / cockpit area as I wouldn't want to have to keep getting down in the lazerette where I would have it installed

Shawn, in my old Sunline, I had 345 ah of battery power, with a 2.5kw inverter. This was fine overnight for us, running the microwave, kettle, TV, fridge, lights etc. you need to half the quoted ah for usable energy, as the batteries will not recover if you use them below 50% of their max capability, so 170 ah for me. So you need to tot up your requirement. If your BBQ has a 2 kw element, and you are using 12 volts, then the BBQ a will consume 2000/12 = 167 amps (volts x amps = watts) so my batteries would run the BBQ for 1 hour, before needing charging.

 

[lanerboy]

cheers for your advise jimmy and I must admit I have gone off the idea of having one on the bathing platform

on the other hand I cannot justify at the minute spending £1000's on a full diesel marine genny, yes I know this would be the correct way to go and it would do all I ask it to but just to power the kettle and the griddle a few times a year just does not add up to me I understand you med guys need it for air con etc etc but all I want to do is run the griddle, regards an earlier post regards changing the griddle again I don't want to do this as mine is a factory fit griddle that works very well and I don't want to change that

I am leaning towards the inverter method if this will do the job but would like to here from others that have a decent inverter fitted to see how they find it and what they power off it

cheers shawn

 

[lanerboy]

cheers paul that's some great info :encouragement: gives me more of an idea of what I will need

 

[Nick_H]

Shawn, in my old Sunline, I had 345 ah of battery power, with a 2.5kw inverter. This was fine overnight for us, running the microwave, kettle, TV, fridge, lights etc. you need to half the quoted ah for usable energy, as the batteries will not recover if you use them below 50% of their max capability, so 170 ah for me. So you need to tot up your requirement. If your BBQ has a 2 kw element, and you are using 12 volts, then the BBQ a will consume 2000/12 = 167 amps (volts x amps = watts) so my batteries would run the BBQ for 1 hour, before needing charging.

Isn't there an efficiency factor for the inverter that needs adding to the equation?

 

[Whitelighter]

you say there may be a reason I would need a marine specific inverter does anyone know if this is the case or not

Sorry Shawn, I was being flippant with that comment.

I see no reason why that wouldn't work on your boat, but I'm happy to be proved wrong.

 

[jrudge]

I have used ebay inverters before with no problems. A griddle is not going to be concerned re a perfect sine wave.


I have an electric griddle and just bear in mind that if you include heat up and cooking time you will run it for about 30 mins.

3000w via 12v assuming no efficiency losses is a draw of 250 amps. This is very big! As above a battery is good for about half its stated amp hours, so for 3 mins you would be using 125 amps + inefficiencies + other 12 v stuff so probably 150 / 170 amps. And need circa a 300 amp battery bank +

When I had mine for anything other than quick use I used to

1. Run both engines at fast idle ( 1200 ish?)

2. cross feed the batteries so all batteries ( I only had 2 at the time) and both alternators were feeding the beast.

This gives another 100 + amps from the alternator pair which slows down the drain significantly.

This is not 100% ideal but it will cost you peanuts and for occasional use will be fine.

I would keep the engines running for a good 15 mins after you are done as the batteries will have taken a total caning.

Jeremy

 

[jimmy_the_builder]

If it's just for very occasional use but is a relatively heavy load - what about a 240v alternator on one engine?

 

[henryf]

I can only add that a properly installed generator such as an Onan is an absolute godsend and something I would now see as a must. Having another source of power when out and about really adds to the sense of security and means you don't find yourself glue to marina pontoons and their associated shore power. If you flatten all your batteries you aren't stranded, just strike up the genny.

Obviously with things like air conditioning it becomes an essential and as the boats get bigger I would say generators also become a must have rather than a would like to have.

I do think having a brand name silent running generator fitted to your boat increases it's value. Not necessarily by the full cost of installing it but probably a fair proportion.

Henry

 

[scubaman]

When we were looking for our current boat it became down to choosing between two P43's with very similar specs. The other one had a genny but no passarelle while the other had a passarelle but no genny.

Having the generator was one of the deciding factors for us and it has been in regular use. It's just so convenient to fire it up from the button for the griddle/kettle/oven/hoover/whatever and it takes out all the power related worrying when anchoring out.

I would concur that it's one of those critical items on the spec sheet that will help in selling the boat when the time comes.

 

[rafiki_]

Isn't there an efficiency factor for the inverter that needs adding to the equation?

Yes, you're right, and I should be using kVA rather than W, but I was just illustrating in round numbers, to give Shawn a feel for the inverter option

 

[RogerRat]

I would keep the engines running for a good 15 mins after you are done as the batteries will have taken a total caning.

Jeremy

This is true, you need very good and very big batteries to run an inverter successfully if drawing anything over a kilowatt. Any weaknesses in a cell or two and the batteries will fail. If this happens the bad battery can take out a good one, I have been told.

The amount of batteries you will need are heavier and bulkier than the size of genny required too. An inverter for a griddle is not viable imho.
Get a real genny between 4-5 Kva or BBQ portably is the simplest route.

If the med' is really on for you in the future decide whether your taking Phantom 40 or not. If you are, then you'll need to spec. it for Air Cond. power requirement instead.

RR

 

[symondo]

interesting thread....

my 2p worth if it helps

I used to run car stereos of over 3.5Kw of power off of batteries. It can be done but it does come down to charging - so best to check your alternators for feed etc...


for higher discharge - dry cell deep cycle batteries should be better for larger hits of power for an invertor plus the deep cycle batteries can usually take a harder battering of drain without the same ill effects.

Also regarding a generator - we are looking into this currently too. we have a Suitcase style 3.5kVa sine wave generator still in its box at home. I had intended to have a box constructed from fibreglass with all of the relevant vents/ducts access to get at plugs and ventilation and then sound deaden it before fitting to the fly bridge.

The unit we have has remote start so technically id just need access to top it up or service it.
Under full load is say 88dB - which im sure can be reduced with a deadened box.

 

[henryf]

interesting thread....

my 2p worth if it helps

I used to run car stereos of over 3.5Kw of power off of batteries. It can be done but it does come down to charging - so best to check your alternators for feed etc...


for higher discharge - dry cell deep cycle batteries should be better for larger hits of power for an invertor plus the deep cycle batteries can usually take a harder battering of drain without the same ill effects.

Also regarding a generator - we are looking into this currently too. we have a Suitcase style 3.5kVa sine wave generator still in its box at home. I had intended to have a box constructed from fibreglass with all of the relevant vents/ducts access to get at plugs and ventilation and then sound deaden it before fitting to the fly bridge.

The unit we have has remote start so technically id just need access to top it up or service it.
Under full load is say 88dB - which im sure can be reduced with a deadened box.

There is a very big difference between a supposed 3,500 watt (audio) sound system and a 240 volt appliance which requires 3,500 watts (electrical).


Audio watts are largely dictated by the marketing department and measured in a multitude of different ways, peak, rms, pmpo and so on. Do not confuse these numbers with watts used in the Watts = Volts x Amps formula for constant current calculations.

A 240 volt 3,500 watt or 3.5KW appliance will generally require that figure constantly whereas the audio device will have momentary peaks of high current but overall a much lower requirement hence a Citroen Saxo doesn't melt when you bung a couple of "1,000 watt" amps from Halfords in the boot and also why power or stiffening capacitors can be used to meet input power requirements rather than a more long lasting battery based solution.

I am not an audio engineer and so bow to superior knowledge but this is my understanding.

Henry

 

[symondo]

There is a very big difference between a supposed 3,500 watt (audio) sound system and a 240 volt appliance which requires 3,500 watts (electrical).


Audio watts are largely dictated by the marketing department and measured in a multitude of different ways, peak, rms, pmpo and so on. Do not confuse these numbers with watts used in the Watts = Volts x Amps formula for constant current calculations.

A 240 volt 3,500 watt or 3.5KW appliance will generally require that figure constantly whereas the audio device will have momentary peaks of high current but overall a much lower requirement hence a Citroen Saxo doesn't melt when you bung a couple of "1,000 watt" amps from Halfords in the boot and also why power or stiffening capacitors can be used to meet input power requirements rather than a more long lasting battery based solution.

I am not an audio engineer and so bow to superior knowledge but this is my understanding.

Henry

i know what you mean but it was also running a similar 300A. most 12v systems i find are generally limited by discharge and recharge capability provided the cabling is upto it.

my underlying point was high discharge 12v options were easily doable for an invertor of sufficent power

 

[rustybarge]

Just a thought, how about running two Honda suitcase genny's in parallel.
http://powerequipment.honda.com/generators/models/eu2000i-companion [halfway down page]
Light to carry one at a time, double up when you need extra power, run just one for battery charging etc....
Works on the smaller eu1000 as well.

 

[Nick_H]

Lanerboy, if it really is just for the occasional barbeque, then best to buy a gas one and stand it on top of the electric grill.

Something like this http://www.clickonstore.net/mini-portable-barbegrill-p-460.html

 

[Jack Haines]

+1 on the portable BBQ idea if that is the main reason for you wanting a gennie.

We keep one of these in the lazrette and then just pop it on a collapsible table in the corner of the cockpit when we want to cook: http://www.weberbbq.co.uk/product/q1000/ It's pricey but super reliable and cooks well, too.

The gas bottles can easily be found in chandleries/camping stores.

 

[kashurst]

+1 for going for a gas BBQ. I have an electric BBQ/griddle and gennie etc but I rarely use it at anchor because you can guarantee that the boat will roll at just the wrong moment. Also my griddle is on the flybridge but I have found on other boats that the best place is in the cockpit as any roll effect is reduced as you are closer to the water - so sausages stay put! Last summer I probably didn't use it at anchor more than 5 or 6 times. However I use the griddle nearly every day when I'm aboard (bacon butties in the morning cooked outside!) but I am usually plugged into shore power so often don't use the gennie either. If long term plans are potentially to come down to the med maybe consider a gennie then for running aircon at anchor.