About generators

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HarlenW

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I am contemplating adding a generator to my boat. Here in the Pacific Northwest, I would be using it mainly to recharge my house battery bank after being on the hook for a day or more. My other AC needs are short and sporadic, coffee maker, TV, microwave and my inverter can handle them fine.

I have friends who are on the hook a lot and don't have a generator but recharge their batteries by running their engine.

Is using the engine at idle to recharge batteries an acceptable practice? I have a 110 Amp alternator. I know I would burn more diesel but it would take a lot to make up for the cost of the generator.

A small 5.5 Kw generator is about as big as I could fit into my engine room. How long would it take to add 200 Amps to my house bank?

Thanks.
 
you're going to get two different answers to that one... those who will say that running one of your mains at fast idle will destroy them, and those who will tell you that thousands of truckers let their diesel idle while they sleep without any issues...

with a 110amp alternator, if you run at fast idle (usually over 1000rpm), it shoudl take you 2 to 2 1/2 hours to put 200AH back in your batteries depending on how much the engine uses (ECU, fuel pump, etc...)

with a generator, it will depend on your charger... typical chargers put out 20 to 40 amps, so that woudl be 6 hours to top off the bank. inverter/chargers have larger capacity chargers, as high as 150Amps, so you'd need 2 hours.

it really depends on how you use the boat. if you rarely stay in place more than a couple of days and will only occasinaly need to run the mains to charge, i'd skip the genset.

if on other hand you often spend 3 or 4 days in one spot, without moving, then a genset may be worth considering.
 
Heck a "fast idle" of 1000 RPM isn't that much less than my "cruise"...

There are ways to "fool" your alternator into "seeing" a lower voltage and stepping up the charge voltage; talk to your alternator shop about it.

What is the capacity of your current battery bank??? The simplest (and cheapest) method may be to just add a couple more batteries.
 
a genset is by far the more flexible choice if your budget will allow it. it will make the boat more marketable when it comes time for resale and also allow you to run the a/c-heat while being a whole lot more peacefull at anchor.

my own main engine mfg specifically calls for not idleing without load as the unburned fuel will wind up in the lube oil and dilute it. they recomend always having a load on the motors and raising a min of 200 rpms above idle. but you may wish to check with your engine mfg. first.
 
As Willie has eluded to, check out an alternator charge controller. And a stock alternator is not likely to make anything near full rated charging amps unless controlled. And even then a stock alternators may not be the best choice for fast charging.
 
Harlan,

IMHO, With a boat as new and beautiful as yours, do it right and put in the genset.

Bob
 
Hate to be the one to say it, but we have a Mainship 350 with a built in diesel 8kw and I usually use a little honda 2kw to charge my batteries. It is quieter and uses about 1/10th the fuel the big one does. For the heavy lifting, like cooking and A/C, the big guy comes online, but if all you need is to charge batteries, I'd go with a little honda.
 
I have two batteries on a battery switch. When I get to my anchorage, I plug in a 40 Amp solar tickle charger to help maintain one battery used as the house battery. The second battery is left off line until I'm ready to start the engine and head home.

I can last a full 48 hrs at anchor while watching football games, using fans for cooling, etc. I use separate lights with their own batteries because lights run down a battery pretty fast. And I use an ice chest for food and a butane Mr Stove for cooking.

This set up has worked quite well for me for many years. No generator needed!
 
What would a little 800 watt gen do? How many amps is that??

They got a little compact unit at harbor freight($99). Will it run a laptop and 15" LCD TV??
 
I think when Harlan is referring to A/C he means Alternating Current and NOT Air Conditioning! IN the San Juans you will probably need HEAT more often than you will need A/C! Even during our recent heat spell, it gets cold at night!

Can you add a second alternator? OR an Alternating Current Alternator to your setup?

As far as the 800 watt Harbor Freight generator, I would avoid it like the plague. It will run at full throttle without the ability to ramp the rpms up or down to match the load. It won't have the muffler capability that a portable Honda or Yamaha will have and YOU won't be able to stand the noise let alone the other people near you.

Pros and cons of Portable Generator discussion in 3...... 2...... 1
 
I also use only battery power for anchoring, and do not use it sparingly. Two deep cycle group 27 batteries can power us for two nights without starting the engines, with a third battery for starting up.
We run lights, kids watch a movie or two, electic head, fridge running the whole time, ran a fan for a bit, no issues.
I suspect another battery and we could do 3 nights without a problem.
 
Thanks, guys, good advice and info from all. Yes, I meant alternating current when I wrote “AC”. I have a diesel heater and we don’t need air conditioning here.

The alternator I have is a new upgrade installed when I added the inverter which has a “smart” battery charger.

My two 8D house batteries are three years old and once, last year, underwent a complete discharge due to my carelessness. Could they have lost a significant amount of their capacity? I have a battery monitoring system and according to that, I seem to have 200 amps of useable power from the two batteries; is that what they should be providing? I do have a third 8D for the starter and thrusters. Also, what is the life expectancy for 8D wet batteries?

Pascal nailed it when he said there is disagreement around whether one can run the main engine at fast idle for a few hours without harm. One mechanic chided me for running the boat at 8 knots, 1800 RPMs, saying it isn’t good for the engine and the engine “wants” to be run a 3000. He didn’t like it when I asked if he would help me with my fuel bill. Before someone comments, I do routinely take her up to 3000 RPMs to clean out the turbo as some suggest should be done but, again, it is hard to get specific data. I tried with my engine, Yanmar 370 but the manufacturer wasn’t forthcoming.

Flutterby, my electrician also mentioned solar panels but I am a bit hesitant. We have our share of sun in the PNW, contrary to common opinion, but this isn’t Florida. Besides, my wife and I can cruise year around and it is often cloudy during our “winter” months.

And I have no interest in dealing with a small gas generator. Too much hassle and I don’t want to deal with storage of gasoline on the boat (I have an electric dinghy motor).

Still thinking…
 
Do you cook with propane? The Honda can be run on propane.
 
quote:
Originally posted by KiDa

Do you cook with propane? The Honda can be run on propane.

Click to expand...
I didn't know that. I wonder how it would stand up to a marine environment. Have you or others used it with propane on their boat?
 
We know of several people who use the Honda style gensets to lcharge their batteries and/or run A/C accessories. NONE use them in the bilge!
Either on the swim platform, foredeck or dock.
They seem to be happy with them.

The 800 watt genset mentioned is on sale for four days in Fort Worth (Cabelas Outdoor)for $119.00.

The claim is for 1,000 watts PEAK,800 rated.
The advertised claim is for 120v 15 amps, but that is not the real story. 800 watts divided by 120v AC = about 6.7 amps. Note, check the duty cycle and your requirements.

Fred
.
 
Of course one would not run a gasoline generator in the bilge! But where do they store the generator when not in use? Seems the salt air here in the PNW would be very hard on a generator stored anywhere on the boat since it is not intended for marine use.
 
Harlan, if I were you I would replace all batteries with Lifeline AGM 8Ds. Then I would install a inverter/charger like Pascal and I have one that can put up to 130amps back into the batteries. I would use a Link2000 controller with it have the 4.5 or 5kw diesel generator power the inverter so it automatically goes to charger mode. It would replace the batteries charge as fast as you can throw current into them. That is the beauty of AGM's. Now there is another way one of the generator manufatures makes a 150 or 200amp DC only generator. You could install that with a good pair of 8D AGMs (255AH each) and you would have a killer system. This same generator also has a water maker option. I know I just gave you 2 expensive options but either will add value and safety to your boat. Do a Google on Marine DC diesel generator and you will see the unit I am talking about, it is small. Good luck I swear by my AGM's they can recover like no other battery and are true dual use batteries. I have fairly large loads on my 2 house banks the main is qty.3 8D Lifeline AGM's and I have not been able to run them down in a 24 hour period. The 2nd house bank is qty. 3 31 series Lifeline AGMs this handles the watermaker, bow thruster, the head, windlass and wash down pump.
Good luck. Bill
Bill
 
Harlen, I am not trying to push a portable on you, but to answer your question, yes, they hold up fine in the marine environment. I've had a Honda sitting in my cockpit 24/7 for 6 years now in rather brackish water, and it's fine. We take it offshore for a month each year in true saltwater, and it's fine. For one thing, many, many parts on the Honda units are plastic. And then considering when underway it's always covered and secured, I don't have a spec of salt on it. No experience with the propane conversion though. I hear it works quite well.
 
Bill, thanks for the idea about a DC generator; that was news to me. I did the Google search but didn’t see the unit you were talking about; who makes it?

My marine electrician has already been talking to me about AGM batteries and has me convinced that I will switch to those when the time comes.

I already have the upgraded charger/inverter and I think the Link system to control it.
 
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