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Tinbasherdan
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i think youd be better off with a couple of solar panels trickle charging a pair of batteries myself
W.olly
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I doubt he would do that, for what they cost they are crap reason i havnt fitted any to mine. Now if we actually had some decent sun shine it would be worth it.
I guessed like me he wanted to use the 'freewheeling' prop while under sail, but he has a different use in mind.
Cons are noise from the box and more braking effect from the prop, but it does work. In these days of cheap solar panels and efficient wind generators it's not so popular.
if he wants to use the spinning prop to charge batteries while using those batteries to power the electric outboards pushing him along.... then he's onto a looser
the drag from the prop will use up more power (forwards motion) then he'll put into the batteries... otherwise it would be perpetual motion
I thought you meant he's be sailing with sails
he could add an extra alternator to the engine, with a magnetic clutch (like air con etc. uses) and gear it up (bit pulley on engine) - that way he could get a decent amount of power out at low revs
depending how big the boat is, more batteries would let him shut the engine down for a while... old forklift cells would be perfect (they're 2v, so 6 of them for 12v) - but batteries are heavy so I guess depends on the boat design, if it's small and light of big and heavy already?
the drag from the prop will use up more power (forwards motion) then he'll put into the batteries... otherwise it would be perpetual motion
I thought you meant he's be sailing with sails
he could add an extra alternator to the engine, with a magnetic clutch (like air con etc. uses) and gear it up (bit pulley on engine) - that way he could get a decent amount of power out at low revs
depending how big the boat is, more batteries would let him shut the engine down for a while... old forklift cells would be perfect (they're 2v, so 6 of them for 12v) - but batteries are heavy so I guess depends on the boat design, if it's small and light of big and heavy already?
I asked around the boat yards where I work and the general consensus is it's a bad idea.
If your wanting to have a 2nd Alternator that generates when the engine is running it's far better to drive it direct from the engine rather than off the prop shaft.
If your thinking of having the prop driving the 2nd alternator whilst you are wind powered then it is a bad idea because the prop is designed to push the boat along and if you have the water driving the prop all you get is a lot of drag and little power generated. If this is what you plan then a Watt&Sea hydro generator is the way to go but they aren't cheap.
I dislike wind turbines due to the noise, even the "silent" ones aren't and you really have to pay attention when installing one to minimise transmitted vibration which makes noise.
Solar is a good solution and can make decent power even in this country, the newer ones are sensitive to Ultraviolet rather than visible light so they make reasonable power even when it's overcast.
If your wanting to have a 2nd Alternator that generates when the engine is running it's far better to drive it direct from the engine rather than off the prop shaft.
If your thinking of having the prop driving the 2nd alternator whilst you are wind powered then it is a bad idea because the prop is designed to push the boat along and if you have the water driving the prop all you get is a lot of drag and little power generated. If this is what you plan then a Watt&Sea hydro generator is the way to go but they aren't cheap.
I dislike wind turbines due to the noise, even the "silent" ones aren't and you really have to pay attention when installing one to minimise transmitted vibration which makes noise.
Solar is a good solution and can make decent power even in this country, the newer ones are sensitive to Ultraviolet rather than visible light so they make reasonable power even when it's overcast.
W.olly
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He is on a wide beam barge not sale.
i reckon another alt of the engine would be best but i dont think he has the room. He is thinking on what to do, he likes the friction wheel idea i think.
@wookie When i made the canopy for mine i was going to fit solar but it wasnt worth it for what they cost, i reckon a back up genny would be best when the batteries are running low. Saying that i will be using more power than he is with his batteries for the out board.
i reckon another alt of the engine would be best but i dont think he has the room. He is thinking on what to do, he likes the friction wheel idea i think.
@wookie When i made the canopy for mine i was going to fit solar but it wasnt worth it for what they cost, i reckon a back up genny would be best when the batteries are running low. Saying that i will be using more power than he is with his batteries for the out board.
W.olly
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rtbcomp
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Do you mean the spring on the motor? That keeps the belt in tension, but I was thinking of something to stop the shaft bending away from the alternator drive. Assuming the take-off point would some distance from a bearing.
I like that idea on the compressor - no need to adjust the tension for belt stretch & wear.
I like that idea on the compressor - no need to adjust the tension for belt stretch & wear.
W.olly
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yes if he fitted the spring to keep the pressure on the prop. it is going to be fitted near a bearing or joint.
Reason o suggested it to him as the pressure will stay and no need to tighten and it can be disengaged when not needed by a bar welded to the bracket and a catch/hook to hold it back.
Reason o suggested it to him as the pressure will stay and no need to tighten and it can be disengaged when not needed by a bar welded to the bracket and a catch/hook to hold it back.
Why not just swop the original alternator for a higher output one ?
If you don't mind me asking how much where you looking for solar ? I like it as power source, it's effectively free power once it's installed and you should always come back to your boat with full batteries unless it's been overcast for days and your bilge pumps run a lot.
Mind you the absolutely best thing with a genny is you can always rely on it to recharge your batteries when you need it, where you thinking of petrol or diesel ?
normspanners
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A higher output alternator will only put an extra few seconds of power into batteries,as the batteries soon get up to voltage and the alternator reg shuts down the charge , to a similar amperage no matter how large the alt is, high output alternators are only for running high loads like loads of lights, motors etc what is required is an adjustable regulator to keep the alternator charging at optimum voltage to keep pushing the current into the batteries which a small alternator 30/40 A is quite capable of. Time is the enemy when charging batteries to optimum capacity. You cannot change the laws of battery charging.
more info http://www.mastervolt.com/products/alternators-charge-regulators/#
normspanners
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to be honest a 12v to 12v charger would be the best option for this application IMO, which would draw more power out of the standard alternator and deliver it to the outboard batteries at optimum rate without affecting the main start battery.
@normspanners part of the problem here is lack of information, we are both trying to offer advice based on an incomplete view of the existing setup and more importantly the desired end setup. Whether or not he needs to swop the alternator for a higher output one depends upon how many batteries and of what capacity he wishes to charge as well as other expected loads on the electrical system when the engine is running. Sometimes I forget what seems obvious to me needs such as using a smarter regulator on the alternator or using a shadow charger for example isn't obvious to others.
My main aim by suggesting changing the alternator was to make him consider an alternative to some heath-robinson contraption on the prop shaft. If he is adding extra batteries to his system that need to be charged when the engine is running he is more than likely to require a larger capacity alternator to cope (but that is really only an educated guess on my part without knowing more about the entire setup)
My day job is working on boat electronic & electrical systems, one recent refit on a boat to go blue water cruising entailed a new bigger domestic bank, reworking the engine start bank & its charging setup, adding an invertor/charger, solar panels, wind generator and an additional battery bank in the bow for the windlass and bow thruster via a shadow charger.
But all of this took some careful planning, a complete understanding of the customers needs and detailed knowledge of the existing boat setup.
Along the way we also had to rectify some wiring issues where people who didn't know what they were doing and wired things up wrongly, my favourite was that the shore power charger for the engine batteries was wired to the wrong side of the isolator so when the isolator was OFF the charger still supplied power to the engine electrics rather than the batteries.
My main aim by suggesting changing the alternator was to make him consider an alternative to some heath-robinson contraption on the prop shaft. If he is adding extra batteries to his system that need to be charged when the engine is running he is more than likely to require a larger capacity alternator to cope (but that is really only an educated guess on my part without knowing more about the entire setup)
My day job is working on boat electronic & electrical systems, one recent refit on a boat to go blue water cruising entailed a new bigger domestic bank, reworking the engine start bank & its charging setup, adding an invertor/charger, solar panels, wind generator and an additional battery bank in the bow for the windlass and bow thruster via a shadow charger.
But all of this took some careful planning, a complete understanding of the customers needs and detailed knowledge of the existing boat setup.
Along the way we also had to rectify some wiring issues where people who didn't know what they were doing and wired things up wrongly, my favourite was that the shore power charger for the engine batteries was wired to the wrong side of the isolator so when the isolator was OFF the charger still supplied power to the engine electrics rather than the batteries.
normspanners
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as the batteries are for electric outboards I doubt they are going to be massive and I agree if he has one alternator that should be enough because the start battery will only need topping up after the initial start, most average batteries dont like having more than 30A thrown at them for long and if they do they have had there fill of those amps during the shortish bulk charge period, then the current drops considerably for the absorption stage. After all it takes 12 14 hrs to fully charge most wet batteries thats a lot of cruising !
So having a12v -12v charger to charge the second battery should need no more than 10-20A bulk for a sort period and will naturally drop off to 3-5 amps absorption so IMO a standard alt at 30-40A would easily suffice, again IMO.
there is no possibility of damaging regulators etc during switch over as per a std straight alt charge set up because with 12v -12v you just switch it off as per a 240ac -12v charger. and the beauty is the 'house' electrics are still catered for.
So having a12v -12v charger to charge the second battery should need no more than 10-20A bulk for a sort period and will naturally drop off to 3-5 amps absorption so IMO a standard alt at 30-40A would easily suffice, again IMO.
there is no possibility of damaging regulators etc during switch over as per a std straight alt charge set up because with 12v -12v you just switch it off as per a 240ac -12v charger. and the beauty is the 'house' electrics are still catered for.
W.olly
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I cant remember now or find my workings out for what i needed from the solar panel but it was at least two 150w panels a kit was around £350 and a small Honda EU ( petrol ) genny will cost the same and more reliable than sun ( The genny will have its own bracket to sit on over the side or transom when in use)
All lighting will be LED but there is a 12v TV a few USB charge points for phones and laptop. Propex HS2000 drawing 1.4amp. Morco F-11 water heater run of an inverter for the 30w needed and ro run T`s bloody straighteners.
I dont have a great deal of space for a larger solar either, just enough for the two 150w.
