Propulsion engine for generating electricity.

[Supermalc]

Reading the various recent posts regarding running engines in gear, and charging capabilities brings me to the thought.....why isn't the engine disconnected from the drive and connected to an alternator, be that 12v or 240v?

 

Because of shortage of space, and economics, it doesn't make sense to have a separate generating engine, but the common setups seem to be too much of a compromise. Why not have an alternator that works at full capacity for charging, that is connected instead of the propshaft when using the engine while moored up.

 

No doubt there are many systems that work perfectly and so no need to change, but if I were a liveaboard, I would certainly be looking at going down this route.......especially as the cost of oil has risen dramatically this last couple of years or so.

 

A couple of years ago I did a small bit of welding for someone with a newish livaboard. His generating capacity adequately supplied the needs of my little air cooled arc welder. He did not have an ancillery generating set, and I think he ran from an inverter. But with the engine running there was ample 240v power.

[John Orentas]

Reading the various recent posts regarding running engines in gear, and charging capabilities brings me to the thought.....why isn't the engine disconnected from the drive and connected to an alternator, be that 12v or 240v?

 

Because of shortage of space, and economics, it doesn't make sense to have a separate generating engine, but the common setups seem to be too much of a compromise. Why not have an alternator that works at full capacity for charging, that is connected instead of the propshaft when using the engine while moored up.

 

 

Hi Malcolm.

 

"Why isn't the engine disconnected from the drive and connected to an alternator, be that 12v or 240v?"

 

I think there is such a system available, it's called a gearbox. I know just what you mean though.

 

It always seems a bit silly to run a damned big engine just to spin round a little alternator. My case is not untypical, engine is rated at 33 KW (45 bhp) and my alternator is rated at 1 KW, an absurd imbalance. Even running at half power what are you going to do with all that power, even if you managed to turn most of it into usable electrical energy, a five bedroomed house on a cold February day will not use 16 kilowatts of energy on a continuous basis, storage isn't the answer either, how many batteries and hot water tanks can you live with.

 

So much as it goes against our instincts, the concept of a smallish efficient engine running at half of full power is not too bad.

Edited June 20, 2007 by John Orentas

[Hairy-Neil]

I think there is such a system available, it's called a gearbox. I know just what you mean though.

 

But if the gearbox isn't designed to run for long periods in neutral it will fail prematurely. Aparently some rely on the rotating components to 'splash' lubricate the bearings.

[Purple Fairie]

Reading the various recent posts regarding running engines in gear, and charging capabilities brings me to the thought.....why isn't the engine disconnected from the drive and connected to an alternator, be that 12v or 240v?

 

Because of shortage of space, and economics, it doesn't make sense to have a separate generating engine, but the common setups seem to be too much of a compromise. Why not have an alternator that works at full capacity for charging, that is connected instead of the propshaft when using the engine while moored up.

 

No doubt there are many systems that work perfectly and so no need to change, but if I were a liveaboard, I would certainly be looking at going down this route.......especially as the cost of oil has risen dramatically this last couple of years or so.

 

A couple of years ago I did a small bit of welding for someone with a newish livaboard. His generating capacity adequately supplied the needs of my little air cooled arc welder. He did not have an ancillery generating set, and I think he ran from an inverter. But with the engine running there was ample 240v power.

Its availible now Malc its called travel power

We have it on ours

Just turn engine on and 240v to everything at the same time as charging the batterys

All we need to do is run engine for 2 hours every other day for all our 240

[mayalld]

Its availible now Malc its called travel power

We have it on ours

Just turn engine on and 240v to everything at the same time as charging the batterys

All we need to do is run engine for 2 hours every other day for all our 240

 

A travelpower is just another alternator.

[Smudge]

A travelpower is just another alternator.

So is a generator

[Tony Brooks]

But if the gearbox isn't designed to run for long periods in neutral it will fail prematurely. Aparently some rely on the rotating components to 'splash' lubricate the bearings.

 

Which just means do not trust the marinisers of expensive yellow engines to get the specification right, look and see what hire fleets use. If a box stands up to a hire fleet it will stand up to anything.

 

We used Velvet Drives and hydraulic PRMs, both being hydraulic boxes have their own oil pump and they never gave trouble. (well one Velvet Drive did when its clutches wore out).

 

I have no idea how "ordinary" boaters are supposed to get reliable advice. I feel sorry for them.

 

Tony Brooks

[carlt]

So is a generator

True but it's attached to an engine matched to the alternator, not one designed to shove a boat about.

[Timleech]

But if the gearbox isn't designed to run for long periods in neutral it will fail prematurely. Aparently some rely on the rotating components to 'splash' lubricate the bearings.

 

I think you'll find that most or all 'mechanical' boxes in our size range use splash lubrication. Nothing wrong with that if it's done properly, but it's a bit poor if it relies on the engine being in gear for the input shaft bearings to get any oil.

 

Actually the size of alternator (including Travelpower) being frequently fitted now would make a sizeable dent in the power output of a 'properly sized' engine for a narrowboat. It's when you get into the 40+ hp commonly seen now that there's a big mismatch.

 

Another way of dealing with the issue is having an engine driving a hydraulic pump, and hydraulic motor on both the alternator - which can be a 'proper' mains voltage job as big as the engine output - and on the prop shaft.

Fairly expensive, though, compared with a mass-produced engine/gearbox/alternator combination.

 

Tim

[Smudge]

True but it's attached to an engine matched to the alternator, not one designed to shove a boat about.

Dont know about the technical electronic stuff but ours is attached to an electronic box to sort all the engine speeds and other stuff out

[Gary Peacock]

The best solution if you need lots of electrickery is to get a boat big enough to have a proper gen-set! There are some very good ones in the marine world these days.

[Carrie]

Hey, I have a question. It may well be a stoopid one, but I have no pride and really want to know, so here goes.

Electric propulsion. I know you can only go about 4/6 miles a day with the set-up I've been looking at BUT. You know how your diesel engine charges up your batteries as you go along - why doesn't an elecric motor do the same, if it's turning the propshaft in the same way? (Told you I had no pride!)

[BigRoj]

Hey, I have a question. It may well be a stoopid one, but I have no pride and really want to know, so here goes.

Electric propulsion. I know you can only go about 4/6 miles a day with the set-up I've been looking at BUT. You know how your diesel engine charges up your batteries as you go along - why doesn't an elecric motor do the same, if it's turning the propshaft in the same way? (Told you I had no pride!)

 

This is because the electric motor is using electricity from the same source you are trying to put electricity back into!

 

Thats as simple as I can make it without going all technical!!!!

[Carrie]

This is because the electric motor is using electricity from the same source you are trying to put electricity back into!

 

Thats as simple as I can make it without going all technical!!!!

 

Thank you and thank you for your tact!

So .... there's no way of creating a sort of loop system (going into a separate battery, to be used later), Can the turning propshaft generate energy separately (kinetic into potential?) (Should I stop digging now?!)

[carlt]

Hey, I have a question. It may well be a stoopid one, but I have no pride and really want to know, so here goes.

Electric propulsion. I know you can only go about 4/6 miles a day with the set-up I've been looking at BUT. You know how your diesel engine charges up your batteries as you go along - why doesn't an elecric motor do the same, if it's turning the propshaft in the same way? (Told you I had no pride!)

I do believe you've invented the perpetual motion machine!

 

I do a similar thing with my battery, inverter, charger setup. Connect them in a loop and the batteries charge themselves.

[Carrie]

I'll just slink away with my 'electrics afloat' book! It's got nice big pictures in....

[Djuwenda]

Wlliawaw has actually covered most of the points raised here, if you have a look at his build blog.

 

He has donne without a propulsion engine replacing it with a diesel engine which charges a bank of batteries which in turn provide power for the electric propulsion as well as domestic electricity.

 

Wonder if you get away with using red diesel on that set up?

 

another selling point is the ability to cruise in complete silence...

[Adam]

Hey, I have a question. It may well be a stoopid one, but I have no pride and really want to know, so here goes.

Electric propulsion. I know you can only go about 4/6 miles a day with the set-up I've been looking at BUT. You know how your diesel engine charges up your batteries as you go along - why doesn't an elecric motor do the same, if it's turning the propshaft in the same way? (Told you I had no pride!)

 

That would just be like powering a inverter with your batteries then plugging in a battery charger to charge your batteries again.

[Lesd]

Hi Carrie,

Im a begginner with electrics too but my take on your idea/question is; If you did rig a 'machine' to take power from the prop shaft moement on an electric powered boat and returned this newly generated power back to the source batteries (or a seperate one) then the extra power drawn out of the source batteries to run that 'machine' would be larger than the power generated and put back in. Thats because no 'machine' in 100% efficient.

Les

[magnetman]

If you say 'perpetual motion' quickly while drunk it comes out as 'petrol motion'. Internal combustion, it works.

 

If you say 'perpetual motion' quickly while drunk it comes out as 'petrol motion'. Internal combustion, it works.

[Jim Riley]

If you say 'perpetual motion' quickly while drunk it comes out as 'petrol motion'. Internal combustion, it works.

 

If you say 'perpetual motion' quickly while drunk it comes out as 'petrol motion'. Internal combustion, it works.

 

 

and when your drunk you repeat yourself

 

as for the free power - have you ever tried picking yourself up in a bucket?

[blueprince]

I've got this machine, it just keep's on generating electricity, my batteries are full, quick sale, only £1,000! and this bridge too, it just gets in the way when I'm heading out of the thames, tower or something, post for more details.

 

seriously, with solar panels, (wasn't there a thread about a solar boat for sale?), a wind gen. and possibly some sort of thermal gen. (see power from my stove?) you might be able to power a boat all year round with only a small amount of diesel. I wouldn't like to do without though. As for an altenator, yes, weld a couple of pulleys together, and run any size/phase you want, put in an intelligent(really thick) charging system, and run 230 when you need it and charge your batteries the rest of the time. Beware of the really thick though, if you want to be safe, just unplug the buggers.(batteries)

[Jason Wilson and Family]

another selling point is the ability to cruise in complete silence...

 

The pirate bones in my body tingle.

 

I have been thinking that I will go with Willawas setup. Get a diesel generator and have it run to the banks and a leccy motor. Make sure it is suitable for running your motor at cruising speed while providing all the power you'd want for inside and you have full power at all times.

[Chris J W]

Wlliawaw has actually covered most of the points raised here, if you have a look at his build blog.

 

I must be going nuts, cos I'm buggered if I can find that Blog!

[Supermalc]

Thanks for everyone's input ........ despite the extra expense, I really think if I were ever to live on a boat, especially an expensive new one, I would 'go the extra mile' and have a hydraulic setup. Motor on the back, so no holes in the boat, and engine dedicated to charging, or 240v generator if necessary.