12v Or 110/220v Generator - Help - Please

[Swagman]

Hi All,

Need some input please and hope someone can help.

I want to fit an small aircon unit plus a small freezer to our 46 foot yacht and wonder if anyone else has done anything similar and what way they went?

It's longer term cruising that dictates the freezer need but it does not need to be a big one. It's spouses need thats dicated the aircon for hotter climates - and I'm not arguing!

The big question I'd appreciate practical input on, is deciding twix a 220v or a 12v generator to fill my needs.

I've read the 220v is a more conventional route. But it is heavier, noisier and uses more fuel.

It would allow us to power a 220v freezer plus obviously run the aircon - but would need to be running for the units to work.

A 12v generator is lighter, smaller, and uses less fuel.

But it means we'd probabably best buy a 12v freezer - and add an invertor to run the aircon. Biggest upside is aircon and freezer could run from batteries and the genset kick in only when they get low.

If anyone has experience in doing something simialr and happy to share that, it would be much appreciated.

JOHN

[imagine2frolic]

GREAT SHOT doing 16 knots on your site. What conditions allowed that speed?

I bought a 110v freezer with 2.1 cubic feet. It draws 1.47 amps, and run it off of an 1500w inverter in the middle of the day. It works great, and after repackaging all the meat you can get in about another 50% of food.

Can't help you on the a/c unit. Although I do have a window unit of 8000btu, and a small insulated box that covers a hatch. I can run it with shorepower. I have successfully ran it off of the inverter this past summer when the electricty was knocked out in a thunder storm. That meant one of the motors running. This year I will experiment with a small gas portable generator, and the a/c unit.

[Trim50]

What power genset are you looking at? Do you have a water maker..if so, what type AC or DC? What is your battery capacity?

[Swagman]

Originally Posted by Trim50

What power genset are you looking at? Do you have a water maker..if so, what type AC or DC? What is your battery capacity?

Hi Trim,

Have yet to get specs for a/c unit and freezer so genset amp output not yet clear. But first decision is to go 12v dc or 110/220v ac? Most feedback so far seems to support the second choice.

We do have a small watermaker already - Pure 80E, a 12v dc unit.

Total battery capacity (excluding 120 amp starter battery) is 560 amps.

Cheers

JOHN

[Swagman]

Originally Posted by imagine2frolic

GREAT SHOT doing 16 knots on your site. What conditions allowed that speed?

Mid Atlantic with 30-35 knots solid from aft quarter / behind.

Full main and a scrap of headsail poled out.

Averaged 10.1 knots over 100 miles. Some surfing, but basically lucky enoough to maitain high speeds over that period with peaks like that caught on the photo.

JOHN

[Trim50]

John,

Normally I would always suggest going with an AC genset for efficiency reasons associated with making water and charging batteries. However it seems that you are strongly a DC vessel at this point and therefore it would probably make sense for you to get the smaller DC genset. However….

The bigger question is where will it be installed, how much room for sound proofing do you have, and will you be doing the install yourself? I installed my own NextGen 3.5kW AC unit. Unit cost around $4000. With me doing the install, it cost about $8500 once all was said and done with materials. I had to shoe horn mine in under the cockpit...I also installed automatic fire extinguisher system, stainless steel fuel lines, dual AC vent fans, double layer of sound proofing. When the system is under heavy load, it is still quite noisy. As such, if you have the room for a larger genset with two or three pistons, I would recommend getting the larger unit to reduce noise levels. I have found that just because it is smaller doesn’t mean that it is quieter. A highly loaded single piston Kubota diesel produces a lot of vibration and noise. I believe they report their sound levels based on a 50% load. A 2 or 3 cylinder genset will have far less vibration and noise. Unfortunately I didn’t have room for a larger unit.

NextGen

http://www.nextgenerationpower.com/

The system is noisy and vibrates a lot at 70-80% load. After only 50 hours of use, the stainless steel exhaust manifold started leaking from a weld joint. NextGen would not warranty the $350 part which was obviously a bad weld. As such, I can not recommend buying NextGen.

Cheers,

Ken

[Trim50]

John,

This DC genset looks promising...I wish they had been around when I was looking.

http://www.polarpowerinc.com/products/gene...genset_lomb.htm

Ken

[Jon D]

The real issue is do you need AC power for the air conditioning? Most A/C units want either 120/220V not 12/24v DC. If that's the case then you know you need a regular generator not a small DC unit. I would size it so that most of the time it is 70-80% loaded. Generators really do not like to be run with minimal load.

We have a Panda 4200 FWC and overall are happy. Had some issue initially that required the original generator to be replaced however since replacement [ under warranty] we now have about 450 hrs on the unit with no real issues. You have to pay attention to the impeller and belt that drives the raw water pump [those are service items] and we had one solenoid fail [5 minute fix]. All in all happy with the unit and would buy another as long as we get reasonable longevity out of this one. Unit gets very regular use as we are full time cruisers.

[Swagman]

Hi,

Others have recommended Breezair as a simple 12v DC aircon sytem. If that proves suitable then it might be we opt for a 12v water cooled freezer and 12v genset.

Anyone here had actual practical experience with Breezeair and can provide input?

Anyone smart enough to calculate aircon BTU output to chill off a 15'x15'x6 saloon from say 35 celcius down to 25?

Really appreciate all the advice and views given so far.

JOHN

[Trim50]

John,

Give this a try...I think you will need at least a 10,000 -15,000 BTU/hr system depending on insulation an sun exposure.

http://www.csgnetwork.com/acroomsizecalc.html

Ken

[steelfan]

'Aircon and feezer could run on batteries' - have you done the calculations ? We have 670 amphrs house batteries (golfcart type) and I would not dream of running the aircon without the generator going.

John

[richardwatson]

Hi John,

If you are going to want to run an aircon unit at anchor you will need to have an AC generator running. If you have a small generator then you can buy a cheap 'window fit' aircon unit from a diy store and mount it temporarily over your deck hatch. If it gets corroded, throw it away and buy another. Have seen them as cheap as $100.

If you build in a DC aircon unit (compressor belt driven by a DC motor), the motor is likely to be 1HP or so, and the current draw will soon drain your battery bank, so it would still be better to have a generator running.

When our DC freezer was playing up a few years ago, I bought a small domestic fridge and ran it off an inverter. When it was fully turned up it would freeze. Not pretty but it worked.

If you don't need aircon at sea, or at anchor, a small petrol generator is a good thing to have, and can save the day if your batteries go flat.

Fair winds