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Old 19-01-2007, 16:17   #391
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Steve,

I did consider it, but didn't have any luck finding a 72V DC unit on the internet. Do you know who might make such a unit?
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Old 19-01-2007, 17:20   #392
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PS. When our Hull challenged friends laugh at how multihull's can't point and go slow, just remember that these Lagoon's and other's [ in OZ it's Multihaven and Elite] are the exact thing that they are talking about.

I for one and other's who have posted are doing our bit in an attempt to prove the mono boys wrong.

Dave
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Old 19-01-2007, 17:49   #393
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Quote:
Originally Posted by Quiet Riot 420
I did consider it, but didn't have any luck finding a 72V DC unit on the internet. Do you know who might make such a unit?
I just did a quick bit of googling. Not easy to find anything. I found this site Electric Car Company. It's a 72V eletrics car with aircon. I would imagine they take the power direct. One could ask them what unit they have.
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Old 19-01-2007, 19:48   #394
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Actually, it is not the air cond. that is the big 110V power drain. Its the standard 2000Watt (18 amps) water heater, and the 1500Watt hair dryers that I imagine my friends and charterers will bring.
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Old 19-01-2007, 20:04   #395
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The 50 amps for the batt chargers is current flow. Over a day that will supply 1200 Ahr. This is an enourmous amount of power for a small yacht. Typical well insulated frides should consume less than 50 Ahr per day. A 4A current drain, typical for a bd50, with a 50% duty cycle is 48 Ahr per day at 12V.

I presume the lagoon has a 12V house battery. Coupled with the charger 50A will give 14 kW hours per day. This is about 3/4 of what I use in my land house. I don't know how many Ahr the 72 V banks have but assuming 200Ahr they would be down to 20% in one day. This is the same as 1200 Ahr @ 12V, very substantial. I think it would be prudent to conduct an energy audit and find out your daily requirements.

The 72V inverters would be great, should see some increase in efficiency and I love the modularity. Have saved a link to them.

When mixing voltages I find it easier to convert everything back to watthours. The hair dryers are negligable probably less than 150 watt hrs per use.

Mike
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Old 19-01-2007, 20:39   #396
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Mike,

You have to remember that this is at 12V, so 50 amps at 12 volts is only 600 watts and that not near enough. Inverted to 110V AC this would be less than 5 Amps!

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Old 19-01-2007, 20:54   #397
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The motor battery banks of the 420 consist of 2 six battery banks that are connected in series to give a 72 V bank in each hull. Each 12V battery is
210 Ah, so at 12V you would have a total of 2520Ah, but at 72V's you would only have 420Ah, 210Ah in each bank. You can have 2 or 4 house batteries that are 140 Ah each for the DC needs of the boat. The big power users on the DC side will be the 2 fridges and the 1 freezer.
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Old 19-01-2007, 21:09   #398
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2520Ahr far out.

It may only be 600 watts but it constantly recharges the house bank which is the buffer for peak demand periods. Fridges cycle on and off, hairdryer would only run for maybe 5 mins, as does the anchor winch.

In this situation,which will be the same for me I think, the house battery needs to be able to supply enough current in case all devices come on together but the amp hour size is determined by the interval between recharges. 600W is the same as 6 substantial solar panels putting out full power and this is 24 hours per day. To get the same daily rate with solar you would need about 30 100W panels.
Check the power needs of the refidgeration I would think 150 Ahr per day for all three would be close to usage.
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Old 19-01-2007, 21:53   #399
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Mike,

When I made the comment about the 600W chargers being the bottleneck, I was mostly talking about the fact that you could not run much of a 12V to 110V AC inverter without running your house batteries down, as they (the house batteries) are now basically running the whole boat both AC and DC. The way my system will be set up, the house batteries will only have to handle the house & running lights, fridges, freezer, windlass, stereo, and nav station eq.

I have taken the AC duties away from the house batteries, and have all AC running off the 4000W--72V inverter drawing its input directly from the 2520 Ah motor battery banks. Thus the waterheater, the AC outlets (7) for such things as a microwave, and hairdriers, and the air conditioning do not tax the house batteries at all. If you know that for instance, everybody (8) will be taking showers and using hair driers just before going out to dinner or something, the you could always shut the inverter down and switch the AC duties back to the 21.5Kw genset for this intense power usage time. It is plenty big to handle everythig, and you could leave it running while out to dinner, so that when you got back the batteries would be up to 100% and the genset would not have to come on again as the inverter would now be switched (lockout switch between inverter and genset) back on for the rest of the nights entertainment.

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With this separation of chores, I hope that the 600watt charges due indeed keep the house batteries up above 80% most of the time.
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Old 19-01-2007, 22:33   #400
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FWIW, the 420 is constructed of Polyester and Vinylester FRP, with foam core hulls that are solid glass FRP below the waterline. The deck and bridge deck are balsa cored composite. Solid or felt core composite interior hull & roof liners, and FRP reinforced marine plywood bulkheads, tabbed or glued to hull.
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Old 19-01-2007, 23:48   #401
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FYI,

I just looked in Wikipedia, and it states the 1 HorsePower = .746 Kw for electric motors. If this is correct then the 10Kw motors listed in the most recent letter from Nick would come in at a respectable 13.4 HP. Lets hope this is the case and not just a typo that should have read 10 HP. Waypoint only has 12 HP Solomon motors.

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Old 20-01-2007, 04:11   #402
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I've opted for the standard electrics with the bigger genset and the 12V to 110V inverter from the house bank. I get all the Ah from all the batteries on the boat but my peak 110V load will be 1.8 kW. I'm not too concerned about this except for the fact I cannot realistically power an electrical compressor for my scuba gear. Given that the genset is going to have to be used from time to time, I have decided to fill my tanks on an opportunistic basis - maybe even get a few more tanks so I can get ahead if motoring for an extended period. This keeps it simpler for me.

However. Quiet Riot - you are very generous to your future guests - very admirable.

I am pretty sure the 10kW ekectric motors is not a typo. I became aware of this discrepency when I looked at the materials we picked up in Annapolis. I asked them directly and they confirmed the motors have been enlarged. Since then, it's been a case of documentation catch up.

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Old 20-01-2007, 06:18   #403
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Quote:
Originally Posted by ess105
I just did a quick bit of googling. Not easy to find anything. I found this site Electric Car Company. It's a 72V eletrics car with aircon. I would imagine they take the power direct. One could ask them what unit they have.
After this post I found an 72V electric truck with aircon. I emailed them inquiring about the part and who the manufacturer is. If I get a response, I'll share.

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Old 20-01-2007, 09:25   #404
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Steve,

My concern with Lagoons standard setup as you describe is again the 72V to 12V battery chargers at .6Kw, and their 1.8Kw standard inverter. As you can see you need to be very careful about how long someone runs your inverter, as it will be drawing 3 times more current than the chargers can replace. I ask Lagoon how long you could remain in this negitive current drain state before the house batteries were down more that 20%, and they did not answer my question. (no one else has either!) You have to remember that the genset will not come on to protect your house batteries from over discharge and possibe damage, that only happens for the motor batts.

You probably should make sure your 1.8Kw inverter doesn't have to power the standard 2Kw AC water heater, as you can see that this would be a mismatch also.

Anothe way for you to help reduce the bottleneck, is simply to add 2 more 25 amp chargers to the 2 they installed, and double the charging capacity up to 1.2Kw. (from my pic of them they look fairly inexpensive) That is what I was originally planning, but even after doubling the chargers, I felt 1.2Kw would not be enough, and have opted for the big 72V to 110V AC 4Kw inverter.

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Old 20-01-2007, 09:43   #405
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BTW-- Is anybody going to the Miami show?

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