Hook up boat engine to permanent magnet generator.

[Bob54_98]

A 3000w 110v generator from Walmart costs a few $ 100. Did anyone try taking the generator component and hook it up to the boat engine ? The idea being why have a portable generator engine when we already have a boat engine ?

 

[Scott Danforth]

generators run at either 1800 RPM or 3600 RPM only depending if they are a 2-pole or 4-pole alternator. unless the generator is an inverter duty.

3000 watts at 110 volts is basically a 45 amp alternator. however the portable generator is not SAE j1171 compliant, so you would be building a bomb

 

[Bob Sander]

Scott has a point there. With Direct current rpm's doesn't really matter because there is no frequency component. Household alternating current however demands a specific frequency of 60hz (50hz for Europe). This limits the genny to very specific speeds in order to pop out the correct frequency. You can alter speeds a little with some fancy electronics, but you can't go all the way up and down the scale with them the way you can an alternator rectifying to dc

Interestingly enough, the old VW's used to have magnet Genny's instead of alternators... rectified over to DC of course, but they were never very good at generating heavy loads at lower rpm's the way an alternator is.

 

[Bob54_98]

I don’t believe that Alibaba is selling bombs. Here is a low rpm 3Kw 120v generator. https://m.aliexpress.com/item/10050...&terminal_id=81724783f8dc43e595164495149e4181

 

[matt167]

I don’t believe that Alibaba is selling bombs. Here is a low rpm 3Kw 120v generator. https://m.aliexpress.com/item/10050...&terminal_id=81724783f8dc43e595164495149e4181

For these to work like your thinking, you would need to have a specific rpm met to produce the power. Then you will need an hz gauge and a voltage gauge so that you can set the boat's rpm to run at exactly that speed and match 60hz exactly between 110v and 120v. If you look at PTO generators for tractors, they have those gauges on the ends by the plugs.

BUT even if you went through that trouble, the generator heads are not marine rated, which means not spark arrested. Gasoline vapors are often in the bilge and you would be creating a bomb... A better idea is simply an extra marine alternator hooked to it's own battery and run an inverter from that

 

[racerone]

I used to be ( 30 years ago) involved in an " emergency response crew "------Vehicles we drove had a 120 volt system to run air sampling units.----The technology is out there.

 

[Scott Danforth]

I used to design generators for cummins between 20kw and 1.2mw. Yes the technology is out there. Simply add another battery and a 3kw inverter just like the emergency vehicles and many of todays boats and RVs

 

[Chris1956]

as Bob said, in the 60's automobiles had permanent magnet DC generators instead of alternators.

The advantage of the generators was that they did not need any voltage from the battery to charge the battery. So if you jump started (or bump started) a car, it would charge a completely dead battery. The disadvantage was the current limit on them. They were less than 30A charging rate.

Todays alternators are 65 Amps on a regular basis. They will not charge a completely dead battery, as they need some back voltage to energize the field, so bump starting is out. Of course, if you jump start the car and leave the jumper cables connected for a while, they will get the necessary back voltage to begin charging

On another note. There are lots of designs for perpetual motion machines on the Internet. They have electric motors turn generators and get excess power from them. Why not use some of them to power everything you need. (smile)

 

[flashback]

I may be way off here, (i usually am) but if you did have a genny set up to the main engine my first thought was the fuel consumption would be much more than a small separate unit.

 

[racerone]

Most folks are unaware of how much horsepower goes into the grid.-----I have often asked folks how much power it takes to turn just 1 ( there are 8 of them ) generator where I worked.-----The most common guess is 10,000 HP----When in fact it takes 1,000,000 HP.------When all the electric vehicles are plugged in , where will the power come from ?

 

[Chris1956]

Larger boats have generator sets for a reason...They use less fuel than running a propulsion motor. They do take up more space, which that why they are usually on 40 footers or larger. Some put the commercial gens on their swim platform. They are air cooled and air ventilated and cheap. That can work, with the right precautions.

 

[matt167]

I personally couldn't imagine running a 4cyl to V8 at anything about idle In neutral.. I considered a PTO generator for my tractor until I really thought about the 3cyl diesel screaming at 2000 rpm ( (540 pto speed ) for hours in a power outage.

 

[Scott Danforth]

An extra battery and inverter is what many boats are going to. Just ask @tpenfield

 

[tpenfield]

I wouldn't just go buy 'stuff' and put it in the engine bay of a boat, unless it was 'certified' to be there. . . (SAE J1171 as an example)

The idea of having auxiliary power would be so you don't have to run the main engines when you want/need power (AC or DC) . . . right?

So, if you were going to 'hang' a generator off the main engine, for the purpose of Aux. power, you'd still have to 'condition' the power (Volts/Hertz, etc.) . . . right? all the while still needing to run the main engine.

It may be better to have an 'approved' 90 (ish) amp alternator running off the engine to charge a battery bank and use a marine inverter to get the power conditioning.

If you are just needing to 'camp out' for the night, I've seen some folks use the small Walmart style generators on the swim platform. Not sure how entirely 'safe' that was though as far as electric shock and CO poisoning.

For the electrical engineers of the world, they can probably figure this stuff out. For the rest of us, there are the specifically purposed and approved solutions.

 

[shrew]

I have a 6 cyclinder Diesel Main engine. I also have a 3 cyclinder 8Kw Generator.

Possible and Practical can be, and often are, mutually exclusive. Why would I want to turn a 2-4Kw coil with a 6 cylindar engine, when I can turn an 8Kw with a significantly smaller engine that burns significantly less fuel over the same time.

Also, in North America we use 110V @ 60Hz. What Hz are these running at?

 

[Scott Danforth]

I don’t believe that Alibaba is selling bombs. Here is a low rpm 3Kw 120v generator. https://m.aliexpress.com/item/10050...&terminal_id=81724783f8dc43e595164495149e4181

in the bilge of a boat, that is a bomb

 

[tpenfield]

The fuel tank is the 'bomb' the non-J1171 generator is the igniter

 

[roffey]

First off I don't know much about this kind of stuff and likely showing my ignorance but.... how does Ford put in the 120 volt outlet in their F150? ... and I do understand sparks and a bilge don't go together.

 

[dwco5051]

First off I don't know much about this kind of stuff and likely showing my ignorance but.... how does Ford put in the 120 volt outlet in their F150? ... and I do understand sparks and a bilge don't go together.

I would guess with a power inverter like this;

 

[matt167]

Ford has offered inverters for a few years or so. The F150 powerboost uses the trucks EV system to power the outlets which is different.