Diesel generator

Things 12V and 24V
Trev
Posts: 160
Joined: Thu Jan 15, 2009 2:56 am
Location: Moruya NSW

Diesel generator

Post by Trev » Tue Dec 27, 2011 4:54 pm

Hi builders
I am at the stage now when I am seriously looking into the electrical system for our boat. We intend to eventually live aboard and therefore would like some creature comforts, plenty of refrigeration, washing machine, water maker, etc. maybe even a small air con unit? then I start thinking about how am I going to supply power to these luxuries, starting with solar panels, wind generator or 2, a back-up portable petrol generator, inverter and all the associated cabling and control equipment. It all starts to add-up in money, weight and complexity? It all sounds very complex to me!
My question is, has anybody done the exercise of comparing the type of system I have just described or using a diesel generator and a battery charger?
I like the thought of power provided by solar and wind, but worry about it inefficiencies? I like the reliability and simplicity of a generator, but not real keen on the noise and fumes etc.
does anyone have any advice?
Cheers
Trev

sea_bee
Posts: 107
Joined: Sat Jul 09, 2011 6:09 pm
Location: Pillar Valley NSW

Re: Diesel generator

Post by sea_bee » Tue Dec 27, 2011 9:27 pm

Hi Trev

I have only just work on building my catamaran, but never-the-less can provide you with some practical answers to your questions.

I have been living on stand-alone power now for well over 20 years. At first, I have 4 small solar panels and a couple of car batteries for lights, and used a petrol 1.5KVA genset for running the washing machine.

Over the years, the comfort level has increased as I have moved from the first bush camp into a house. Now I have 10 more big panels and the genset is a 8KVA diesel. Off the batteries, we run 12V refrig, computers, tv, power tools, washing machine, pump water to a header tank and when the batteries get to float during the day, I turn on the pool pump to drain off some of the excess power.

The only time we have run the diesel since buying the last lot of extra panels was to warm it up to change the oil!

On a cat, you should have the space for enough solar panels and a wind gen, and maybe have a small petrol genset for backup. The only reason I would consider a bigger diesel genset would be to run electric motors!

dazza
Posts: 116
Joined: Sat Apr 02, 2011 9:12 am
Location: sunshine coast

Re: Diesel generator

Post by dazza » Thu Dec 29, 2011 6:39 am

Hi Trev,

From the little research ive done , the water maker will use the most power to make a reasonable amount of water for live aboard,so start there and work backwards.Chances are youll have enough power for the creature comforts.

Dazza

mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Re: Diesel generator

Post by mahnamahna » Thu Dec 29, 2011 9:56 am

I have never lived aboard a boat so I cant speak with any authority. But I would have thought the fridge would draw the most power. It runs 24/7 albeit in cycles, watermaker runs when you need water but that may only be every couple of days during peak solar power times. You would also supplement your water needs by catching rain water, and filling at docks (especially when refuelling) whereas you may only be on shore power to run the fridge or recharge the batteries much less frequently.

Trev
Posts: 160
Joined: Thu Jan 15, 2009 2:56 am
Location: Moruya NSW

Re: Diesel generator

Post by Trev » Thu Dec 29, 2011 11:58 am

Just trying to get my head around all this electricity stuff, so just simply, If I used an average of 100 amps (12v dc) total per day and I have a 50 amp battery charger, I would have to run a genset for 2 hours a day to replenish my batteries?
Trev

44c
Posts: 1148
Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Re: Diesel generator

Post by 44c » Mon Jan 02, 2012 7:22 am

In reality at 50 amps you'd need to run your genset a bit longer. As batteries get close to being fully charged they accept charge slower.

But if you had a diesel genset you'd go for a much bigger charge rate than 50 amps. A small genset would be around 5kva, so would be able to produce more like 400-500 amps

We run all the luxuries you describe, except the aircon. At least 80% of the time on solar power. We have 590 watts and an MPPT charge controller.

We don't have a wind generator. Don't like the noise they make. Also saw one chop a seagull to peices....

Our watermaker makes nominally 30 litres per hour and uses 18 amps while running. We seem to use around 30-40 litres per day.

So on alternate days we'll make water for 2-3 hours. On the other days we make bread with an electric breadmaker.

As a backup we have a 1kva invertor genny, which can run a 50 amp charger fine.

If you can live without aircon, you can manage without the genset. But if you must have aircon, you will need the genset to run it.

Trev
Posts: 160
Joined: Thu Jan 15, 2009 2:56 am
Location: Moruya NSW

Re: Diesel generator

Post by Trev » Mon Jan 02, 2012 4:57 pm

I am probably leaning towards the genset at the moment? I have to do some serious research into costs, size and weight of these units, they may just be too expensive or too big or heavy?, but it seems like the simplest and most practical option? but one down side to the genset is the ongoing running and maintenance costs.
The system would still be 12v but things like the fridge and freezer would run on AC when available, it would heat the water heater and charge the batteries. I would also have some solar to provide a maintenance charge to the batteries if we are away from the boat for any time.
Any thoughts on the use of electric hot plates and oven? this will keep the LPG outside the boat, just in the cockpit for the BBQ
Anyone have any opinions?
Trev

44c
Posts: 1148
Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Re: Diesel generator

Post by 44c » Tue Jan 03, 2012 5:12 pm

If I was going to go that way, I'd have a BIG inverter, and all household appliances, ceramic cooktop, electric kettle, household fridge/freezer....

The genset would be 24 volt, or even 48 volt as would the inverter. Currents would just be too big on a 12 volt inverter.

The reason I'd do this is because I wouldn't want to have to fire up the gebnset every time I wanted to just make a cup of coffee.

You could just hook a DC-DC converter and one 12 volt battery to the 24/48 volt bank for the 12 volt stuff.

Our friends on "School's Out" have this typ of set up, and it works well for them. They originally went 48 volt because they had electric drives which were 48 volt. They turned out to be unsatisfactory, so they have now outboard power, but the rest of the system works pretty well.

However, it's not a cheap excercise - the genset and inverter cost a fair whack. And there's a weight penalty, even with Lithium batteries which they now have.

Lithiums would be the way to go with this set up too, because they can absorb high rates of charge right up till they are nearly full. And they don't mind being left part discharged. They cost more, but weigh less.

Anyway, that's how I'd do it if I were going that way, because I've seen that it works.

BTW you can get 48 volt solar panels and also 48 volt wind generators.

rexd666
Site Admin
Posts: 157
Joined: Tue Dec 15, 2009 7:15 am
Location: Melbourne, Vic

Re: Diesel generator

Post by rexd666 » Tue Jan 03, 2012 8:17 pm

What about Flywheel generators on the existing engine? Yanmar and Nanni have them, haven't looked at others. The only thing I have thought about is one engine would get more hours generating power, I guess you could get one on each side to have redundancy.

Jim
Posts: 691
Joined: Fri May 19, 2006 8:25 am
Location: Cairns

Re: Diesel generator

Post by Jim » Wed Jan 04, 2012 11:49 pm

Hi Trev, I wouldn't get all hung up about a gas system blowing your boat to bits because if it is installed correctly it is a safe as. I have had gas in my house for 30 years and never had a single problem, and that is with 30 plus year old technology and whatever safety systems they had back then. My boat has gas hot water, stove and BBQ and I wouldn't have it any other way. The only thing I ever have any concerns about is power, so the more things I can have operating that aren't connected to the battery, the better. If I could have gas instruments and auto helm I would be a much happier man.
Jim.

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