What size inverter?

Suggest a small 300w pure sinewave inverter and forget the oil heaters. Your choice of inverter capacity is limited by your Ah battery capacity and more importantly your charging capacity. A 300w will do nicely for phone chargers, laptop, DVD, etc.

Inverter size is dictated by battery/charging capacity of the boat. Sure you can get a 1500w or 3000w but your flatten the batteries in minutes if you put an oil heater (1-3kw) or kettle (2kw) on.
 
At the risk of stating the obvious Watts=Volts x Amps so -

1500w through the inverter will use 125 amps and
3000w will consume 250 amps.

Your batteries will not like these loads for long.

I have a 1000w inverter used to run a microwave (600 watts = 50 amps) and nothing else.

Tom
 
One thing to consider during the installation that has caught someone I know out is how it is installed re the battery charger. It is possible for the charger to think it can see shorepower and try to charge the batteries when the 240v is coming from the inverter. Result - flat batteries! Worth thinking about.
 
Jez,

Just to put things into perspective - just running one 240v 1500w heater via an inverter will flatten your 4 x 140ah batteries in less than 4 hours. Obviously less with the other 12v bits running whilst at anchore, like anchore lights..

I think an inverter would be good for the odd kettle boil or to charge your phone (much cheaper to buy a 12v kettle and phone charger) but to keep the boat and bed warm is almost a no go.
 
ok, see the power of the forum!

I am not being picky, but I assume that is four hours of continuous running? My expereice with these type heaters is they tend to be powered for around 20 minutes in every hour, heating the oil rather than direct heat such as a fan heater.

But I take your point and it gives it some perspective. On another point, do you think the 4 140AH batteries are enough genrally? I have the option to upgrade to 200AH.
 
Velleman is simple, reliable and cheap
http://www.velleman.be/be/en/product/list/?id=341677
or
you could go for a more intelligent solution f.e. from Victron,
http://www.victronenergy.nl/inverters-chargers/multiplus-12v-24v-48v-800va-3kva/

I have good experience in my boat with the combined charger inverter Compact multi plus 1600W.
We use this succesfully in OB-Vans aswell.

Victron has a good website with general info on DC power' supply etc.., and a good service !
You as a boat dealer could become dealer or get better conditions on both brands I believe, as I am for my business.
If you have difficulties obtaining them, I don't mind to help you with it.

What size is just a question of calculating what you want to do with it, as mentioned in other posts, but don't forget to caculate how long your batterys will last at a certain consumption....
I use mine mainly for making koffie, for my Labtop and for tools when I am working on the boat. Planning to buy a small oven aswell.
 
I think 4 x 140ah batteries are more than enough for 'normal' usage ie a couple of nights at anchore leaving both fridges on and general lighting use. I only have 3 x 120ah batteries for domestic and have spent 4 days and nights at anchore using things normally (2 x fridges) without the batteries going flat.
 
Those batteries are plenty. Inverters on typical medium to small leisure craft should only be used for the lightest of loads such as mobiles, laptop, tv, dvd, etc, but high wattage stuff like hair dryers, kettles and heaters are generally a no-no.

Another common mistake is some folk upgrade to larger capacity battery banks, but fail to also upgrade the charging systems (inc Altenators and charger), which results in the banks never actually getting fully charged. So if anybody wants a big inverter for a heavy continous load, you need a) a big capacity domestic battery bank and b) a big capacity charging system inc altenator upgrade.
 
[ QUOTE ]
On another point, do you think the 4 140AH batteries are enough generally? I have the option to upgrade to 200AH.

[/ QUOTE ]

Jez, not being funny but get whichever is cheaper. Cos you are going to need to replace all 4 of them after about a week anyway, if you try to draw 100amps from them for a few hours continuously. And that assumes the boat doesn't burn up due to hot cables. This whole idea is a total non starter :-)
 
Jez,

I'm with jfm on this one, using an inverter/batteries for primary heating is really asking for trouble, I doubt if you will have enough power available.

Using electrical power to facilitate a diesel heating system is really the only answer if you want heat in the boat with the main engine shut down.

Tom
 
Jez. forgive me for asking in case this is obvious but whats wrong with shore power, I imagine most places you will visit will have power to the toons, tis what I do anyway just carry a rad in the aft cabin and plug it in when we get where we are going, if fact we rarely use the boat heating at all its always on the oil filled rads.

Yeah, yeah we are big girls and don't spend the night on the hook etc but unless its med bound and its nice and warm can't be doing with no facilities when its damp and cold and you can't get off to a nice pub or resturant nearby.

Agree with jfm anything over smallish ampage on an inverter from batteries will flatten them in jig time, 50 or 100 will toast them just nicely!.
 
Its not for primary heating, more of a back up really. Already said that but dont expect you to read every post.

Trev, some of the nicest places in this country dont have shore power - plus I am a tight git when it comes to marina fees!!
 
Have just bought a 1600W (3000w peak) inverter from "onboardenergy.com" - i would highly recommend chatting to them - I spoke to the guy for nearly an hour before deciding on the kit that i now have to install this weekend.

I went for 5 * 120 Ah batteries; roughly 6 KWH, so probably usable for 3. I plan to use this system for cooking via a little induction hob, or a microwave (neither likely to be on for more than 10-15 mins) and am going to see if it will live up to providing background heat via something like an oil filled radiator on a timer to come on 20 minutes or so before getting up or returning from the boozer.

The inverter i went for is a victron "easyplus" which is pretty much plug and play, built in charger for when on shore power, and will even split the charge from shorepower to whatever is being used and devote the rest to charging, or take (say) 1kw from the shoreline and draw from the batteries if you go over a 1kw, so if you wanted to have everything running at once you could. I was planning on carrying a little suitcase genny for emergencies.

It's an expensive piece of gear, but because it is all in one box, it would be easily transferrable to another boat if necessary.

Oh, and you would need pure sinewave for a microwave too.

This probably doesn't help because none of the kit is tested yet, but at 43 I don't get very exciting Christmas presents any more, so I am looking forward to it, and it is the result of a lot of research!

[edit] PS, Onboard energy also made up all the connector cables for me so they should be ok. They fit Narrow boats for a hire fleet near nuneaton, and whilst narrowboats aren't everyone's cup of tea (c: they do have a need for a "domestic" electricity supply [/edit]
 
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