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-   -   Portable Generator question (http://www.sailnet.com/forums/cruising-liveaboard-forum/38742-portable-generator-question.html)

SVGratitude 11-23-2007 10:11 AM

Portable Generator question
 
It seems a lot of cruisers are using portable generators to help charge their house bank while at anchor. I'm considering the purchase of a Honda 2000 to charge my house bank.

I have 55 amp alternator, a 30 amp shore power system, a house charger (120v, 25 amp), and a 450 AH battery bank. Can I plug the generator into my shore power input and charge up my house bank in this way?

The Honda spec's say it puts out a max of about 17 amps. Will my 25 amp house charger run OK with this setup?

We are 1/3 of the way into a 6 month trip to the Bahamas and back ( having a GREAT time BTW).

Thanks,
Mark

gc1111 11-23-2007 10:27 AM

The power available is the limiting factor. Power is voltage times current. As a first approximation, the 115 volt output from the charger is 10 times the 12 volt output of the charger. So 1 amp at 115 can give (more or less) 10 amps at 12 volts.
When you say the house charger is 120v, 25 amp, I assume that is 25 amp on the 12v side. Is that correct? If so, the Honda should easily power the charger.

PBzeer 11-23-2007 10:32 AM

I use a Honda 2000, plugged into my shorepower receptacle to power my TrueCharge 20 amp charger for a 315ah battery bank. If using much power and low to no wind (for wind gen), I generally run it for a couple hours in the am, then a couple more in late afternoon. If I stay off he computer, I need it far less :)

Glad to see you're still moving on.

sailingdog 11-23-2007 10:35 AM

SVGratitude-

Yes, you can plug your Honda into the shore power system...and your 25 amp house charger will probably be fine. Just remember the 25 amp charger is 25 amps @ approximately 12-15 VDC, which is 2.5-4.x amps or so at 110 VAC, not counting conversion losses.

Be aware that the generators are rated for resistive loads, and inductive loads should be doubled to get a good estimate of what the generator can handle. For example—a 100 Watt incandescent light bulb or 1500 Watt heater are going to use about what they say... and the Honda 2000 can handle about 20 of the 100 Watt light bulbs... but if you have a 1200 Watt microwave oven, the Honda 2000 will probably have some trouble feeding it—since it is mainly inductive loads, not resistive.

Highly recommend that you have a CO detector aboard and running, since the exhaust from the generator is a serious hazard.

NautiG 11-23-2007 10:49 AM

I have a cheapo 2 cycle generator that I bought from Northern Tools. It only cost me $150. It claims to put out 1200 watts, but I think that is an exaggeration. It will only get my 40 amp battery charger up to the mid 30s.

So far it works great. But I've only had it a month. It sounds like a moped while running. I anchor from the stern and place in on the foredeck. That way the exhaust blows off the boat, not over it.

Remember to ground your generator. I can't find a ground on my "fire sale" boat (thanks SD), so I just connected a wire to the generator ground and tossed it overboard. A little "trailer park", but it works. You might not want to be tempted to connect to the AC ground on your boat. On my boat, it appears that the only ground for the AC panel runs to the shore power line. So the only way you are grounded is if you are connected to shore power.

I run my computer all day, but besides that, I just run a few lights, electric start the engine, charge a few AA batteries and a cellphone. I only have to run the generator every other day, for about an hour or so before I run out of juice.

Scott
Gemini Catamaran Split Decision
nautib.blogspot.com

sailingdog 11-23-2007 11:12 AM

Quote:

Originally Posted by NautiG (Post 226980)
I have a cheapo 2 cycle generator that I bought from Northern Tools. It only cost me $150. It claims to put out 1200 watts, but I think that is an exaggeration. It will only get my 40 amp battery charger up to the mid 30s.

This may well be due to the fact that a battery charger is an inductive, not resistive, load.

Quote:

So far it works great. But I've only had it a month. It sounds like a moped while running. I anchor from the stern and place in on the foredeck. That way the exhaust blows off the boat, not over it.
Have you read Don Jordan's article on anchoring from the stern. I do that a fair bit with my trimaran...and she seems happy about it.

Quote:

Remember to ground your generator. I can't find a ground on my "fire sale" boat (thanks SD), so I just connected a wire to the generator ground and tossed it overboard. A little "trailer park", but it works. You might not want to be tempted to connect to the AC ground on your boat. On my boat, it appears that the only ground for the AC panel runs to the shore power line. So the only way you are grounded is if you are connected to shore power.
I would be wary of grounding to the water...since that is an excellent way of creating a galvanic corrosion problem, especially on the Sillette sonic drive leg that the Gemini's use. Until you are sure you're not creating a problem, I would highly recommend tilting the sonic drive leg up. Also, grounding the AC genset to the water may also create an electrocution hazard for people in the water... I'd check with the manufacturer about the proper grounding method for using it on a boat.

Quote:

I run my computer all day, but besides that, I just run a few lights and electric start the engine. I only have to run the generator every other day, for about an hour or so before I run out of juice.

Scott
Gemini Catamaran Split Decision
nautib.blogspot.com
This of course is partially dependent on how large your house bank is, what kind of computer you have and whether the lights are incandescent, cold cathode fluorescent, halogen or LED.

NautiG 11-23-2007 11:45 AM

Hey SD,

I prefer to anchor from the bow, especially in cold weather. Less wind in the cabin. I have an outboard on my old Gem, not a stillete. I don't think corrosion will be a problem seeing as how the generator is on the bow and the outboard is 30 feet away on the stern. I am careful that there are no swimmers, but I think it's better to ground to the water, than not at all. I don't want to electrocute myself by touching a charged generator. I don't know where else you would ground to while at anchor.

Scott
Gemini Catamaran Split Decision
nautib.blogspot.com

erps 11-23-2007 12:00 PM

Quote:

Can I plug the generator into my shore power input and charge up my house bank in this way?
That's what I do and I get between 60/70 amps from the battery charger.

RandyonR3 11-23-2007 12:06 PM

When searching for a generator, a good point is how much noise it makes.. Kinda strange subject to bring up but I have been in anchorages
that were peasefull, quiet, and our early morning coffee was shared with the birds and the noises of nature...
And then some idot comes in drops anchor and fires up his generator..
and the reason we were there has just disappeared.. The EU model of the honda is a pretty quite unit..dont opt for an off brand without noise reduction.. You'll make enimies in an anchroage really fast.........

Idiens 11-23-2007 12:07 PM

If you are feeling green and have a ready supply of methanol, how about one of these...

www.efoy.com


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