Ideal sized Inverter-?

Jock89

Jock89

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Hi all,
I've checked thru some previous threads on this but nothing seems to give me the answer I'm looking for.
I'd like to install a 12v-to-220v Inverter but 1500w seems a tad small. No idea what my future req'ts might be but 3000w seems OTT. What do you all have on board & why.?
I'm living on board alone at present but as I get into serious 'cruising mode' this figure could well double.!
Thanks...Jeff
 
Always found that an inverter ate my batteries big time, you'll need a large battery bank to cope with a 3k inverter and a serious amount of time to recharge them.

I live on board and have a portable 2.2kw generator which I use to power all sorts of power tools and bits and pieces,the only thing I ran on an inverter (was) a tv or radio. but found it very in effective.

what you planning on running off the inverter ?
 
I have nearly 1000Ahrs here. At the moment I can only think of TV/Hi-Fi/Laptop/small batt chargers/1.2 Kw hair-dryer/electric shaver/Electrolux fridge runs from shore-power only, but will change fridge soon for Waeco or similiar...but no idea what future needs could be.
2.0Kw seems about right but don't see anyone selling them. The 'name' brands seem to jump from 1500 to 3000 watts. Also, the latest types seem to use about 0.2w while on stand-by. Does that mean they now don't chew battery-power on stand-by.?
 
not sure about the more modern stuff mines about 4 years old and as i said it just munches through the batterys a couple of hours with the tv on and the screen starts to get smaller !!

try marlec they helped me out with the wind generator always good advise and friendly ... so far
 
If you are talking about a 1000Ah battery then a C/10 rate = 100A (for 10 hours) and a C/20 rate = 50A (for 20 hours) Check to see what your battery is specified for, it will be either C/10 or C/20, most likely the latter. If so, then your max sensible discharge rate is 50A which will give (out of the battery) W = A x V = 50 x 12.2 = 610W. You can discharge much faster which would be fine for things like power tools, vacuum cleaners, if only used for five minutes or so in which case a 1500 W inverter sounds OK. I have 600W inverter which is maybe a bit small but we manage fine. It is very important to go for a sine wave inverter as some equipment blows up with square or modified sine wave.

Generating electricity from diesel, converting it to chemical in a battery, converting chemical back to electrical again, then to 230V is horribly inefficient, expensive and environmentally unfriendly. Much better to use a generator for bigger loads such as vacuum cleaners, hair dryers, etc. and you'll appreciate a genny if you plan to liveaboard anyway.
 
I've posted several times on this issue - try over 1 year ago!

My House batteries are 1050Ah - 5x210 Ah Lifeline AGM's. The Inverter is a Phoenix Multi-plus from Merlin in Poole. This great unit is also the battery charger - at 120 amps - and it also supplies EXTRA AC amps to add to the shore power amps. So in a cheapo French marina which only has 6 amp breakers you can dial up 6 amps on the MultiPlus and it takes 6 amps from shorepower and synchronises itself to supply the extra from the batteries. When the load is reduced it switches back to recharging the batteries. There's a very good manual you can download with all the details.

Even here in Portsmouth in the winter with all the heating on we can set it to 16 amps and still go over a bit when we turn on the microwave for a few minutes.

The best piece of kit on the boat - and if you need loads of amps you can link five of them together!

Oh - and to charge this lot we use a Fischer Panda 12 volt diesel genny - which pumps out 280 amps. Much quieter and more efficient than an AC genny because it only goes at the speed necessary to delivery the load required.
 
I have a 3000w pure sine wave inverter from victron, they do a 2000w one. Lots of people do.
However I would go for the biggest you can afford, pure sine wave, you only need monstrous battery banks if you USE all of the 3000w for long periods, but in an emergency, it´s nice to have spare capacity from batteries and inverters.
You will here a lot of crap spouted on hear about this subject, only listen to those that have and use these beasts on a regular (ie all year) basis, living aboard. Lemain has a few years experience with them, as I do.
I would also advise getting a genny if you intend to use inverters at anchor, they will burn up a lot of battery amps.
 
That sounds like advanced, flexible and impressive kit, and very useful if used properly though the potential for abuse (battery abuse) is huge so you need to understand the technology.

For the record, what was the cost of the system and how long have you been using it for? Is this mainly weekend usage or liveaboard? If the batteries are often called on to supplement the mains I would have thought that they would have a fairly short life?
 
I have a new 1600w inverter and have been supprised at how little it seams to hammer batteries. Fitted this summer and so far it has only been used for fitout but will run sanders, drills etc all day and then only takes about 30min to recharge batteries. (no charge for electrics unless permenatly plugged in). Although rated at 1600w it will happily go to 2kw+ for a short time. Tend to agree with Leman that if you need more then the system costs for batteries etc make a gen an increasingly effective option. I would tend to approach it by starting with what the batteries/alternator will support and size the inverter for that. Then if you need more power and particularly if you plan to run high demand appliences for over 10/15min back it up with a geny. I am looking at getting a 1/2kw 'suitcase' style petrol geny that will do this and give power when dried out. Sailinglegands set up sound fantastic and big inverter plus installed geny can certainly give you house like power supply but its mega bucks. depends what you want it for but the rode to disaster is an inverter with inadequate battery/wiring/charger to support it.
 
[ QUOTE ]
the road to disaster is an inverter with inadequate battery/wiring/charger to support it.

[/ QUOTE ] Agree 100% To put the finishing charge into a battery takes some time. You can get up to 60/70% charge quite quickly at high current but the last 30% or so goes in at over 13V and by that time chargers are tapering-off, even most 'fast' chargers other than some of the really vicious water-devouring alternator controllers.
 
We have lived aboard in UK for the last two years - spending summers in France. Hope next year to make the push to the Med. Yes we have spent a lot on the system - but when its your home then why not? A little more on a large battery bank has been worth it as we never have to worry.

The Victron Multiplus 2.5kva invertor was about £1700, the Fischer Panda genny about £5500. They also wanted £1800 to install the genny, but everything on the boat I have installed myself so when it goes wrong in the middle of Biscay I can fix it.

The worst case scenario of using the inverter is for half an hour to reheat the immersion heater - 750 watt - which might take 65 amps or just 32 Ah. With 5 x 210Ah bats thats only 13 amp out of each battery so I don't know why you are worried about overloading the Lifeline batteries. They are designed for a very much higher discharge than this. The inverter and the batteries are now 4 years old and still seem fine as we never cycle them below 75% of the max capacity.

One extra thought on the inverter - we run a 3.5KVA air con/heating unit which takes about 5 amps but has a starting current of over 25 amps - no problem for the Victron.
 
[ QUOTE ]
..... an inverter with inadequate battery/wiring/charger to support it.

[/ QUOTE ]

As a post script to my last posting the wiring and installation did add a lot to the cost. Each battery has 2/0 AWG (62 sqmm @ £16/m) Lifeline marine cable and 300 amp bus bars with a 150amp fuse at each battery terminal to protect the cable. The voltage drop along the cable when drawing 150 amps is less than 0.1 volts. It should last the life of the boat.
 
[ QUOTE ]
With 5 x 210Ah bats thats only 13 amp out of each battery so I don't know why you are worried about overloading the Lifeline batteries.

[/ QUOTE ] There are several different issues. I don't know the spec of Lifeline batteries but presumably you know the maximum permissible current? With batteries designed to start an engine that is give in Cold Cranking Amps but that's only for very short periods. A 2.5kW invertor would draw, at maximum output, at 12V terminal volts, around 220A. It doesn't matter whether you like to divide by five or not as long as you remain consistent but 220A out of 1050Ah battery is C/5. At C/5 you are not going to get anything like 1050Ah out of the battery. You'll probably only get 750Ah at that rate, or thereabouts. You'd need to check how long you are permitted to draw C/5 for in any case.

There are very definite over-discharge risks however, used by someone who understands the technology, with care and sympathy for the batteries, you have a lovely system. If it was my system I would not want the inverter to draw the higher levels for more than a minute or so, indeed, I would probably make the genny start automatically if that was the case, after, say, two minutes, unless locked-off when it is inappropriate.

I would never heat water or food from stored battery energy because of the poor efficiency except on very rare occasions when it was, on balance, the sensible thing to do. But that's me - it's your system and you are free to use it how you want. Obviously the deeper and more often you discharge your batteries, the more you will have to charge them and the shorter they will last, and it is energy inefficient - but you know that and it is your choice how you actually use the system.
 
By the way, I have toyed with the idea of load shedding and load reducing for limited supplies and would have done that but we found that we never had a problem. My idea was to make the water heater drop out first, then cut back the kettle and electric heating with phase or burst controlled thyristors, on designated sockets. Not rocket science and does not require you to supplement the mains electricity with battery power. But here in the Med the mains seems to be 16A in marinas and with the genny we have 6kVA to play with so I have never bothered to design and install the load shedding.
 
we live aboard our 32 COlvic Watson all year and have a washing machine 240watts, sindryer150 watts, tv,dvd,laptop, 30amp battery charger. when at anchor we run our 2kw honda generator for 4 hrs and charge all up and run all our 240v system. we have 2 x 170 ah domestic batteries and 1 x 100ah for the engine. we tested our system this summer in the rance with a 50 watt solar panel and the genny we charged all u to max and then spent 14 days on the batteries with no probs.
 
I've got a 140watt inverter which does most things I need. Li-ion battery charges off 12v, hi-fi works off 12v, shaver will recharge off 12v.
The only thing I use the inverter for is charging the laptop, and for that I have a solid state powerpack, but am missing the plug into the laptop, so I'd challenge the need for an inverter at all.
 
4 hours generator running every day, at anchor and a 50W panel? With a bigger battery charger and batteries you should be able to reduce the generator run time quite a bit - in the summer, anyway, in the winter it takes a lot of generator running to keep comfortable.
 
so that electrical system fitted would cost £9000.00 ...wow, think Ill stick to my voltage regulated generator that cost me £400... and spend the rest getting to and staying in the med /forums/images/graemlins/cool.gif
 
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