NOT WIND but WATER

Highland_FlingHighland_Fling Solar Expert Posts: 37
Looking to put a propeller shaft generator alternator on my yacht.

I have a few ideas but hate reinventing the wheel so here i am looking for advice.

There seems to be two or three options.

1. Is a small 12V 35A car type alternator

2. Is a 12V car type alternator when the stator coils are changed for 24V ones - this is something i dont understand but seems to give twice as much power - so if you understand how to do this and how it works i woudl love to hear about that modification.

3. Is a PMA something like this http://www.windbluepower.com/Permanent_Magnet_Alternator_Wind_Blue_Low_Wind_p/dc-540.htm

Controlling that i would use a Morningstar 60A MPPT controller - however i dont know how i can stop this generating electricity - if i used the PWM model i could divert to a 12V heating coil in the hot water system. controlling an 'alternator' is easy as i can put a switch in to activate/excite the coils.

4. Is to use the generator out of a marine wind generator or a small 24V DC motor

thoughts ideas suggestions?

thanks in anticipation

Comments

  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: NOT WIND but WATER

    You don't need the efficiency and low RPMs of a permanent magnet alternator, just a bog standard 24V alternator would do. 24V is typically used in trucks, no need to modify a 12V unit, you're sure to find some at the local vehicle recycling/scrap place.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,221 ✭✭✭✭✭
    Re: NOT WIND but WATER

    A boat is not the place (in my opinion) to play around with design. Here is a link to what I used for power on my boat in the 90's. The one thing that I found was that we often did not want to be where the wind was. The other was we did not want to be where the surf was (surfers). We had plenty of time in both places for 10 years! I finally built a bimini for the cockpit and went solar. Good Luck!
    http://www.fourwinds-ii.com/v2/?c=library&i=windGenComp
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BB.BB. Super Moderators, Administrators Posts: 30,634 admin
    Re: NOT WIND but WATER

    Here is an old thread about towed power and other options for a sail boat:

    Solar-only battery charging on Sailboat w/o an engine

    The towed generator/alternator will put something like a 50 lb drag on your boat--so that has to be taken into account.

    Regarding a 24 volt alternator output 2x the power of the unconverted 12 volt model... Remember power is P=V*I -- The limit on an alternator/generator is generally the maximum current. If you pull too much current they will overheat. But, if you raise the voltage (stronger magnets, turn it faster) so that the voltage doubles--then P=V*I will double the power.

    However, nothing is for free... The 24 volt unit outputting ~2x the power will have ~2x the drag as the lower power unit (has to spin faster and/or more torque).

    Converting to a permanent magnet does give you "more power" because you are not "wasting" a percentage of the power to run the electro magnets inside the spinning rotor.

    However PM rotors have their own issues... The rare earth materials are frequently very sensitive to moisture and rust very quickly if exposed to water (or sea water). So, the magnets require a very tough (epoxy or equivalent) water tight finish. But they are also very difficult to get paint to stick well.

    One other thing to consider--will the alternator bearings last a long time with 50-100 lbs of thrust (or tension) load? Generally alternators are designed with ball bearing for side loads and not so much for thrust loading.

    Anyway, sounds like an interesting project.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,221 ✭✭✭✭✭
    Re: NOT WIND but WATER

    Yep I missed that it is water!Sorry! If you tow it at night, always keep in mind "big fish eat at night" You have to protect that motor! The Four Winds link I gave has options for using the wind gen motor for water gen. Take a peak!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER

    here is what a want to do

    SAM_0337-1.jpg

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  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER
    stephendv wrote: »
    You don't need the efficiency and low RPMs of a permanent magnet alternator, just a bog standard 24V alternator would do. 24V is typically used in trucks, no need to modify a 12V unit, you're sure to find some at the local vehicle recycling/scrap place.

    so how do i get that down to 12V...............or will it only give me 12V if i run it slowly

    I am told the fix for a powerful prop driven system with a slowly turning prop shaft is 24V coils in a 12V alternator unfortunately the guy who did these conversions is deceased and his customers who have these are non technical - so are not sure what was done really - just that it worked :D:blush:
  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER
    A boat is not the place (in my opinion) to play around with design. Here is a link to what I used for power on my boat in the 90's. The one thing that I found was that we often did not want to be where the wind was. The other was we did not want to be where the surf was (surfers). We had plenty of time in both places for 10 years! I finally built a bimini for the cockpit and went solar. Good Luck!
    http://www.fourwinds-ii.com/v2/?c=library&i=windGenComp

    thanks but the last thing i want is a wind generator noisy and needs a pole etc and windy anchorages.

    I am looking at (more) solar as well BUT solar is ugly and expensive prob $3000+ for a decent system

    I have two small solar panels with a nice Morningstar 15A MPPT controller but i want some real power especially when we are sailing wind generators typically dont work well when sailing as well. And solar only works when you have the sun shining.
  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER
    BB. wrote: »
    Here is an old thread about towed power and other options for a sail boat:

    Solar-only battery charging on Sailboat w/o an engine

    The towed generator/alternator will put something like a 50 lb drag on your boat--so that has to be taken into account.

    Regarding a 24 volt alternator output 2x the power of the unconverted 12 volt model... Remember power is P=V*I -- The limit on an alternator/generator is generally the maximum current. If you pull too much current they will overheat. But, if you raise the voltage (stronger magnets, turn it faster) so that the voltage doubles--then P=V*I will double the power.

    However, nothing is for free... The 24 volt unit outputting ~2x the power will have ~2x the drag as the lower power unit (has to spin faster and/or more torque).

    Converting to a permanent magnet does give you "more power" because you are not "wasting" a percentage of the power to run the electro magnets inside the spinning rotor.

    However PM rotors have their own issues... The rare earth materials are frequently very sensitive to moisture and rust very quickly if exposed to water (or sea water). So, the magnets require a very tough (epoxy or equivalent) water tight finish. But they are also very difficult to get paint to stick well.

    One other thing to consider--will the alternator bearings last a long time with 50-100 lbs of thrust (or tension) load? Generally alternators are designed with ball bearing for side loads and not so much for thrust loading.

    Anyway, sounds like an interesting project.

    -Bill

    My friends who have this system - see pictures get 10/18A when sailing 5/7 knots with no noticeable decrease in boat speed they have an alternator with the 24V coils so can stop and start the charging to see how much it affects boat speed - they say it does not - so it is power for nothing.

    You could eat your dinner off the bilge in my engine room water in there will mean we are sinking!!!! :grr :blush: :grr

    I think it will take typically around 3A to power the coils so this 10/18A output has that consumption to be factored in. 10/18A is the output from the alternator into the batteries measured using a Link 10 so i am assuming this takes in the power required to excite the coils and we have a Net output of 10/18A charging the batteries.

    NO thrust loads on my system :D

    The PMA people sell a varnish that is supposed to be 'the business' for protecting these units from weather etc.....i appreciate i will be operating in a very salty air laden environment BUT the boat alternator seem to be happy there for a significant number of years so i cant really see any significant issues with this installation.
  • BB.BB. Super Moderators, Administrators Posts: 30,634 admin
    Re: NOT WIND but WATER

    The battery bank will actually set the output voltage pretty much...

    Once the alternator is spinning fast enough to generate >29 volts or so for charging--then any additional RPM just produces more current (up to the rated maximum).

    In reality, if you understand MPPT solar charge controllers (the controller adjusts the current from the solar panel and measures the output voltage--to optimize Pmax=Vmax*Imax ... You could do the same thing with the Alternator. Find the optimum voltage and current at any particular RPM (there is a new charge controller coming out in the future that does just that for Wind Turbines from Midnite Solar).

    Anyway, with a standard alternator, they regulate the voltage/current output by varying the field current. For a PM alternator--you have to either watch the battery charging and manually stop the alternator from turning when the battery is full, or use a "diversion or dump" controller that takes any excess power (once the battery is fully charged) and dumps it to a resistance heater of some sort (air heater, hot water heater, etc.) to prevent the battery from being over charged.

    Many solar charger actually have a diversion/dump mode configuration option.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER
    BB. wrote: »
    The battery bank will actually set the output voltage pretty much...

    Once the alternator is spinning fast enough to generate >29 volts or so for charging--then any additional RPM just produces more current (up to the rated maximum).

    In reality, if you understand MPPT solar charge controllers (the controller adjusts the current from the solar panel and measures the output voltage--to optimize Pmax=Vmax*Imax ... You could do the same thing with the Alternator. Find the optimum voltage and current at any particular RPM (there is a new charge controller coming out in the future that does just that for Wind Turbines from Midnite Solar).

    Anyway, with a standard alternator, they regulate the voltage/current output by varying the field current. For a PM alternator--you have to either watch the battery charging and manually stop the alternator from turning when the battery is full, or use a "diversion or dump" controller that takes any excess power (once the battery is fully charged) and dumps it to a resistance heater of some sort (air heater, hot water heater, etc.) to prevent the battery from being over charged.

    Many solar charger actually have a diversion/dump mode configuration option.

    -Bill


    Surely i only need 14/15V for charging - i do have a 12V system?


    Yes i understand that with an alternator it is the field current that controls things and i can just switch that off whereas with the PMA i cant switch it off so will need some way of using its power when the batteries are fully charged Running the autohelm and a full set of Raymarine instruments including radar should keep me on the right side of this BUT yes a PWM controller and a 12V heater coil in my hot water tank would seem to be a good back up option if i am generating too many amps from a PMA.

    I would really like to know how to turbo charge a 12V traditional Delco 10SI alternator with 24V coils. I think letting the alternator perform as normal but turbo charged with a switch off facility is appealing. I can feed this alternator output into my three stage battery charging system. However the performance of these PMA's looks awesome and it is a not very expensive out of the box solution with a PMW controller and a dump shunt water heater element. correct me if i am wrong but an MPPT controller wont do power dumping it just disconnects the generation input (solar) and since the panels dont care no damage but the PMA is a different kettle of fish. I really dont want to think about belt tension (slackening the belt) options to stop the PMA being driven I am trying to keep this simple
  • mike95490mike95490 Solar Expert Posts: 8,814 ✭✭✭✭✭
    Re: NOT WIND but WATER

    Why not get a 24V Balmar alternator and regulator ?

    http://www.balmar.net/index.htm
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.BB. Super Moderators, Administrators Posts: 30,634 admin
    Re: NOT WIND but WATER
    Surely i only need 14/15V for charging - i do have a 12V system?

    You were asking about 24 volt alternator conversions too... So I was not quite sure which you were asking about.

    For deep cycle batteries, you want around 14.5 volts for charging and 15 volts for equalization (at 77F).

    If you are using solar panels--pretty much need around 17.5 Volt Vmp solar panels to account for panel voltage depression (when panels are very hot, their output voltage falls about ~20%), voltage drop in wiring, and voltage drop across the solar charge controller.

    For an alternator system--you only need the 14.5 volts need to charge the battery bank (alternators can output 100 volts or more very easily without sufficient load on their output).
    I would really like to know how to turbo charge a 12V traditional Delco 10SI alternator with 24V coils. I think letting the alternator perform as normal but turbo charged with a switch off facility is appealing. I can feed this alternator output into my three stage battery charging system. However the performance of these PMA's looks awesome and it is a not very expensive out of the box solution with a PMW controller and a dump shunt water heater element.
    I have not seen a PMA based alternator setup--so I don't know how they control battery voltage / state of charge other than how it is done with wind turbines--Using a dump/shunt/diversion type controller and load.
    correct me if i am wrong but an MPPT controller wont do power dumping it just disconnects the generation input (solar) and since the panels dont care no damage but the PMA is a different kettle of fish. I really dont want to think about belt tension (slackening the belt) options to stop the PMA being driven I am trying to keep this simple
    Backing up a moment... A PWM (plus width modulation controller) is really just an electronic version of an ON/OFF switch... Nothing fancy going on... To charge a battery, the switch is on 90%+ of a cycle and off 10% or so of the rest of the cycle... When the battery is near fully charged, the switch is OFF 90% of the time and on 10% of the time (duty cycle is just made up for this example--the controller will adjust duty cycle to meet battery voltage charging requirements.

    An MPPT charge controller is a "buck mode" power supply which efficiently steps down voltage from high voltage/low current from the solar panel (or some can even take the energy from a wind or water turbine) to low voltage/high current for the battery bank.

    And an MPPT charge controller acts just like a PWM controller as the battery becomes fully charged (simply drawing less current from the solar panels as the PWM controller does).

    There may be MPPT charge controllers out there with a "Dump Mode" -- But mostly the PWM controllers have the diversion option (from what little I have seen--I am certainly not the expert in charge controllers and their various options). MPPT charge controllers are more expensive and would not need the MPPT function for controlling dump loads (in most cases that I can think of).

    And, in any case, you would still need a dump load and controller to keep the battery from over charging. As you say, running your alternator without a load could damage the diodes and/or any standard in-line mode charge controller from over voltage.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,221 ✭✭✭✭✭
    Re: NOT WIND but WATER

    There really never has been "power for nothing" in my experience. For one thing the rear seal and rear transmission bearing is going to be subject to wear now.
    Before it was locked when your were sailing. The shaft cutlass bearing and seal also now are subject to wear.

    What you propose makes some sense if you are crossing oceans and need to conserve fuel. In the caribbean most all sailing is within easy range of refueling.

    I can understand how the loads of radar, navigation lighting, electronics and refrigeration start adding up at night but most of the sailors we were with were underway about 5% or less and 95% of the time were on the hook. It is not such a bad thing to run the engine on the boat as it keeps things from growing in the seawater cooling system. Dielsil like to run and be loaded.

    I did post a link to the towed four winds charging system and I think it is at least truly redundent and has none of the risk in messing around with your other propulsion system.
    Fair winds!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER
    There really never has been "power for nothing" in my experience. For one thing the rear seal and rear transmission bearing is going to be subject to wear now.
    Before it was locked when your were sailing. The shaft cutlass bearing and seal also now are subject to wear.

    What you propose makes some sense if you are crossing oceans and need to conserve fuel. In the caribbean most all sailing is within easy range of refueling.

    I can understand how the loads of radar, navigation lighting, electronics and refrigeration start adding up at night but most of the sailors we were with were underway about 5% or less and 95% of the time were on the hook. It is not such a bad thing to run the engine on the boat as it keeps things from growing in the seawater cooling system. Dielsil like to run and be loaded.

    I did post a link to the towed four winds charging system and I think it is at least truly redundent and has none of the risk in messing around with your other propulsion system.
    Fair winds!

    BUT we allow the prop to rotate all the time and please dont tell me that is the more draggy solution as it is not This is a ten year old boat now with 7000+ engine hours and 12,000 miles logged and yes we have replaced the cutlass bearing once BUT only because A N OTHER bent the prop shaft and while taht was out it was sensible to stick in a new cutlass bearing. The option is to put on another prop a feathering prop to get more boat speed but as we sail a lot i thought prop shaft generator - much more powerful than solar works every day you go sailing and motoring and is invisible unlike solar and unlike solar it wont affect the boats performance in a negative way (increased drag from the solar panels) and megga less expensive so bang for the buck it looks like a winner.

    What i was hoping far was to find someone who knew how to turbo charge a 12V alternator using coils from a 24V alternator - cant find anything like that online lots about PMA and DIY PMA.

    I did forget to add that we are about to change the fridge freezer system from an engine driven one to a dual 12V system so putting power back into the batteries without running the engine is my number one priority.

    I understand the issues with the PMA and PWM controllers are realise taht a MMPT does not have a shunt feature.

    thanks again
  • BB.BB. Super Moderators, Administrators Posts: 30,634 admin
    Re: NOT WIND but WATER
    BUT we allow the prop to rotate all the time and please dont tell me that is the more draggy solution as it is not
    From when I used to fly light aircraft, yes even a spinning prop with the engine off is still quite a drag (with an aircraft engine, there are still significant losses from spinning a "dead" engine--so stopping a prop from "windmilling" saves those losses)... If we wanted a long glide (with the engine off for what ever reason), one would slow the aircraft until the engine stopped, then point the nose down for best glide speed.

    However, it is certainly possible in a boat that the drag from the spinning prop is not noticeable when you are at or near your hull speed anyway.
    The option is to put on another prop a feathering prop to get more boat speed but as we sail a lot i thought prop shaft generator - much more powerful than solar works every day you go sailing and motoring and is invisible unlike solar and unlike solar it wont affect the boats performance in a negative way (increased drag from the solar panels) and megga less expensive so bang for the buck it looks like a winner.
    I have to agree that if you have wind/boat motion--that some sort of water turbine/prop powered alternator is going to be a lot cheaper (excluding maintenance) and probably provide a lot more power power than solar panels.

    On a boat, solar panels have so many handicaps, that they are probably not much more than a trickle type power source.
    What i was hoping far was to find someone who knew how to turbo charge a 12V alternator using coils from a 24V alternator - cant find anything like that online lots about PMA and DIY PMA.
    I guess I am still confused about "turbo-charging" a 12 volt alternator into a 24 volt alternator... What is your battery bank voltage--12 volt or 24 volt with the T.C. 24 volt alternator?

    From what little I have read/understand, one way to get a "24 volt alternator" is to make new coils with twice as many turns and 1/2 the wire thickness (to fit in the same area). That doubles the voltage but cuts the current by 1/2... So Power=Voltage*Current is still the same (2x voltage * 1/2 current = 1x power).

    You can also increase voltage by changing air gaps, probably by installing very strong permanent magnets, and spinning the alternator faster. But if the alternator is still charging a 12 volt battery bank--the extra voltage is wasted as there is still the maximum current limit (which, if wound for 24 volts, would be 1/2 that of an otherwise identical 12 volt alternator).

    Now, there is a new charge controller (or two) in development that does MPPT type function between alternators and battery banks... It lets the alternator reach the maximum (Power=Voltage*Current) by allowing the alternator to run at a higher voltage (2x-3x or more than the 12/24/etc. battery voltage)--then using its internal switching regulator to efficiently (around 95% or so) to down convert high voltage / low current from the alternator to low voltage/high current used to charge the battery bank.

    The Midnite Solar Classic charge controller has not be production released yet, but there are a few posts here that discuss this MPPT for Wind/Water type function in general terms (and the increase in over all power generated from such systems).

    You are probably looking at $500-$700 or so for such a charge controller when it does become available (assuming that it will work for your setup--I am not connected in any way with Midnite Solar and know nothing more than I have read here over the last year or so--the rest is just my guess work--that and $3 will buy you a cup of coffee :roll:).

    In any case--Other than the normal methods to increase alternator output (generally at lower RPMs for better compatibility with direct drive wind turbines and using permanent magnets to save field coil losses)--I am not sure how Turbo Charging an alternator increases its overall energy output for a typical fixed voltage battery bank application.
    I did forget to add that we are about to change the fridge freezer system from an engine driven one to a dual 12V system so putting power back into the batteries without running the engine is my number one priority.
    A worthwhile goal... But with any energy conversion--there are costs and losses involved. Just trying to understand the whole set of issues that you are attempting to address.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: NOT WIND but WATER

    RE: alternator modification.

    What you're talking about is replacing the rotor (armature) windings with ones capable of taking higher Voltage so that as the alternator spins more slowly than it would in an engine-driven application the output is as high. Finding the replacement is the trick.

    Normally the rotor has fairly low Voltage applied to it (varies with exact unit) which creates the magnetic field spun within the field windings - typically at over 1,000 RPM. There is a ratio here designed to produce the desired output. If you simply up the Voltage to the rotor the alternator will put out higher Voltage at lower RPM, but the current through the rotor windings will be high and they will burn out. So the windings must be changed. The basic formula looks a bit like this:

    Standard: rotor Voltage 6 V @ 1000 RPM = 12 V charging
    Modified: rotor Voltage 12 V @ 500 RPM = 12 V charging

    But that is not precise; just an illustration of the general principal.

    You would need the specifications on the alternator you intend to modify, especially its resistance, intended input Voltage, operating RPM, and output Voltage in order to determine what to change. Finding new "innards" that would both fit and provide the higher resistance needed is a challenge.

    Keep in mind most alternators actually put out quite a lot more than 15 Volts. If you don't need the full 100 Amp or so charge rating you could possibly modify the regulation instead to get your charge Voltage, providing you have the certain minimum RPM needed to produce output.

    Sorry not to be any more specific, but there are so many variables in alternators!
  • mike95490mike95490 Solar Expert Posts: 8,814 ✭✭✭✭✭
    Re: NOT WIND but WATER

    Easier is to just change the gear ratio. Any alternator needs to spin at least 3,000rpm to produce power. You have to increase the pulley size on the shaft, and decrease the size on the alternator, to get the RPM's up. Too slow, and the intergral fan on the alternator will not move air, and then you just burn up the alternator.
    Get an optical tach, and measure the shaft RPM while under sail, and then most hot rod sites have gear ratio caculators to help you figure out what size pulleys you need. You may have to use a 2nd shaft to get enough gear ratio. And then what happens when you load down the prop shaft ? Will it stop spinning ? All that work, and then no power. Looking at micro-hydro turbine charts should give you an idea of what can be harvested. You may have to go with a duct on your prop, to have it spin the load of an alternator.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Dave AngeliniDave Angelini Solar Expert Posts: 5,221 ✭✭✭✭✭
    Re: NOT WIND but WATER

    I still do not see the logic here if you are now tied to 12V refrigeration. It seems the first thing to do after going from engine driven refrigeration is address how you will replace the energy when 95% of the time you are anchored???

    Maybe this is not true and you sail around every day? I just remember that boats that went from engine refrigeration to 12V were changing batteries every 2 years because of really deep cycling. I spent quite a bit of time in this area of marine electronics so keep in mind, we are trying to help you! Adding a bimini of solar won't work on every boat. It does however add enough solar space to keep from deep cycling! Bill, you should see a bimini of (5) 215 watt Sanyo's giving shade in the cockpit of a sloop! A stainless steel frame that is designed for 60 knot chubasco's in the Sea of Cortez. It is the rage down there right now BTW. There are quick disconnects for removing the panels for storms but most just leave them up full time.

    Mike is right! You need to find the shaft rpm. Is the picture similar to your boat?
    We do not know, and that is why I mentioned locking the shaft undersail as many transmissions are damaged by letting it spin. We always locked our propeller shaft for the 10 years we cruised to reduce maintenance.

    What many here do not know is that your not going to get much rpm as a marine transmission is also a reduction of output rpm of near 2/1.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER

    OK here is what i know.

    the pictures i posted is of my friends boat

    we both have 12V systems

    he had a 12V alternator on his boat and that worked fine but it was not super efficient.

    he met 'someone' who is now deceased who turbocharged his alternator by replacing some of the innards by parts from a 24V alternator and the output almost doubled.

    he has no idea what parts were changed.

    we both have similar sized boats and both have large three bladed props He can get up to 20A out of his set up when he is at hull speed and he has switched the alternator off and noticed no decrease in boat speed We both have speedometers/logs and GPS that will show boat speed to two decimal places.

    I cruise at 2000/2500 RPM - the gearbox has a 2.5 reduction i think

    2000 RPM is an easy 6/7 knots in flat water 2500 is over-driving the boat 8/9 knots

    So at 6 knots the prop is doing 800RPM

    Sailing i am assuming - and yes i want to get a portable RPM counter to measure this - say 200/300 RPM.

    I think that set up is an 8- 1 ratio speed at the alternator 1600rpm with no load say 1000 RPM when it is generating.

    PLUS when i am motoring i dont expect the Big Yanmar Diesel to notice that it is driving another alternator then of course the alternator will be rotating at 6400 RPM that could be an issue :grr

    There does not appear to be a cooling issues with the set up on my friends boat.

    We will have around 200/300W of solar and this will be on the aft end of the boat angled into the sun - luckily the trade winds keep the stern into the sun from mid day onwards. With the very small solar panels i have they are charging the batteries until 6PM or later Sunset being 7PM

    To put on 4 x 185W panels is going to destroy the look of the boat and add a lot of air drag and the panels wont be mounted in the most efficient way they will need to be facing directly upwards. Then i will need a bigger MPPT controller some serious changes to the bimini mounts plus panel mounts and cables then the cost of the panels plus the not so insignificant cost of shipping down to the Caribbean. - it quickly gets silly and that expenditure buys an awful lot of diesel.
  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER
    RE: alternator modification.

    What you're talking about is replacing the rotor (armature) windings with ones capable of taking higher Voltage so that as the alternator spins more slowly than it would in an engine-driven application the output is as high. Finding the replacement is the trick.

    Normally the rotor has fairly low Voltage applied to it (varies with exact unit) which creates the magnetic field spun within the field windings - typically at over 1,000 RPM. There is a ratio here designed to produce the desired output. If you simply up the Voltage to the rotor the alternator will put out higher Voltage at lower RPM, but the current through the rotor windings will be high and they will burn out. So the windings must be changed. The basic formula looks a bit like this:

    Standard: rotor Voltage 6 V @ 1000 RPM = 12 V charging
    Modified: rotor Voltage 12 V @ 500 RPM = 12 V charging

    But that is not precise; just an illustration of the general principal.

    You would need the specifications on the alternator you intend to modify, especially its resistance, intended input Voltage, operating RPM, and output Voltage in order to determine what to change. Finding new "innards" that would both fit and provide the higher resistance needed is a challenge.

    Keep in mind most alternators actually put out quite a lot more than 15 Volts. If you don't need the full 100 Amp or so charge rating you could possibly modify the regulation instead to get your charge Voltage, providing you have the certain minimum RPM needed to produce output.

    Sorry not to be any more specific, but there are so many variables in alternators!

    THAT sounds like it :-)

    100A output in my dreams 10 - 20 would be awesome
  • Highland_FlingHighland_Fling Solar Expert Posts: 37
    Re: NOT WIND but WATER
    BB. wrote: »

    I guess I am still confused about "turbo-charging" a 12 volt alternator into a 24 volt alternator... What is your battery bank voltage--12 volt or 24 volt with the T.C. 24 volt alternator?



    -Bill

    It is a 12V system somehow putting in 24V coils in the stator or the rotor - i dont know which

    I am assuming it was not both as you might as well just get a 24V alternator and be done with it.

    Changing the coils turbo charged it so its effective output was doubled

    A PMA looks so like what i need IF i could just switch off the magnets:grr........ooops :blush:that is what a normal alternator does switch on electro-magnets
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,221 ✭✭✭✭✭
    Re: NOT WIND but WATER

    A standard 12V high output alternator from Ample Power or Balmar will output 15 amps at 2000 rpm. If your shaft is spining 200 rpm you need a 10 or 20 to 1 increase in RPM. Who will do the machine work and remove the propeller shaft. Sounds like you will still be burning diesil alot so are you sure you can't fit some more solar. The turbo thing I beleive is just the standard things that are done on high output alternators to protect from heat, including changing sheave diameters to match rpm requirements BTW.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: NOT WIND but WATER
    THAT sounds like it :-)

    100A output in my dreams 10 - 20 would be awesome

    I know what you mean.

    A "100 Amp" alternator - that would be peak output at probably 3000 RPM.
    If you modify the internal wiring as above you'd lose at least 50% of its capacity right there, so we're now down to 50 Amps peak. Again, at 3000 RPM.
    But you wont be driving it that fast. According to your data, it is likely to be slightly less than 1/3 that speed so there goes more power. All told, your figure of 10 - 20 Amps is not unrealistic.
    The issue of heat is a non-starter; alternators don't produce heat unless they are "working". The less load, the less heat. The less RPM, the less heat. I seriously doubt heat would be an issue here (as opposed to under the hood of a car stuck idling in traffic in the middle of August in downtown LA).

    As for the maximum speed, most automotive alternators will stand 6000 RPM without trouble, especially as it won't be sustained. Likewise over-current/Voltage shouldn't be a problem as that's what regulators are for; gets too high, rotor windings are shut off (actually to "low feed"). The biggest problem is probably salt air corroding things, but you're familiar with that!:p

    Sounds entirely doable to me. Just a matter of finding a 12V alternator that has a corresponding 24V equivalent that can donate the rotor windings. This might involve buying two new, expensive alternators.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: NOT WIND but WATER

    http://sailmagazine.com/boatworks/engines-and-systems/hydroelectric_power_cruising/

    "For this application, Don Street recommends the Electrodyne low-rpm alternator, which is specially made for vehicles such as delivery vans that spend a lot of time idling their engines."

    http://www.electrodyne.com/


    Apparently Balmar also makes low speed alternators for use on putt-putt diesels:

    http://www.balmar.net/



    http://www.sailnet.com/forums/miscellaneous/22098-propshaft-alternator.html

    "We chose an Australian unit, especially wound to achieve high outputs at low speeds."

    "All of the components used in the alternator are readily available from local auto electricians. Bearings, brush holders, and slip rings in the unit are interchangeable with Bosch and Ingram alternators both of which are commonplace here and abroad."


    http://thefishingmaster.com/fishing-lures/prop-shaft-generator-1411112.html

    "The yacht has a 24 V DC electrical system. 24 V alternators are expensive. A used car alternator was chosen. A regulator was made to make the alternator produce 27.6 volts although the minimum speed of the alternator had to be doubled. Also the regulator had to limit the field coil voltage to about 14 volts to prevent overheating of the rotor field."



    http://books.google.com/books?id=j3B_0y_hVbsC&pg=PA88&lpg=PA88&dq=prop+shaft+alternator&source=bl&ots=71b7gJNjQ-&sig=NJu1P5HhAvd0gBh5AHyav3AFBRc&hl=en&ei=lb-GTJLjD5G4sAPVraSFCg&sa=X&oi=book_result&ct=result&resnum=9&ved=0CEYQ6AEwCDgK#v=onepage&q=prop%20shaft%20alternator&f=false

    "Prop shaft are either traditional alternators with prop shaft gearing to achieve rated output, or alternators wound to achieve outputs at low speed."

    Output. The maximum output will generally be in the region of 5-10 amps. The Lucas unit has a maximum output of 12 amps, with an approximate output of 1 amp per knot. Cut-in speed is 600 rev/min and requires a shaft-pulley ratio of 5:1."



    I found a pic of the Lucas here:

    http://www.practical-sailor.com/marine/madeineurope.pdf
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,221 ✭✭✭✭✭
    Re: NOT WIND but WATER

    Nice DWH ! Makes me want to put one on my wife's bicycle! I dug up the Ample Power price page from my old boat. They had 5 models that were fairly high output at 2000 rpm starting with model 4024 that was 42A cold and 31A hot.

    The large case #4059 was 98A cold and 87 hot. Ample in the late 80's introduced the 3 step voltage regulator to the commercial marine world. Before it was space and defense.

    DWH have you seen a picture of Don Streets BTW? It was nice to read a Nigel Calder article again. I got to spend some time with him in the NW Caribbean in the mid 90's. He is now in his 4Th addition of the Boat owners mechanical/electrical manual. (an 8 pound book) A perfect gift for anyone who needs to fix anything related to boats or anything for that matter. So I ask Calder about his maintenance schedules one night, his answer, "when it breaks I have my sons fix it"
    Anyway thanks for the link!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: NOT WIND but WATER
    DWH have you seen a picture of Don Streets BTW?

    I didn't see one on his site. I myself know nothing about sailboats, but I've been told I could pick up beer money hiring myself out as a researcher. :)
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