24v/12v Converter for Windlass

Discussion in 'OnBoard Electronics & Controls' started by SeaJay, Oct 18, 2010.

  1. Tim B
    Joined: Jan 2003
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    Tim B Senior Member

    Ok, so you have three (basic solutions)

    1) A switch controls a series of relays switching 2x 12v batteries between 12v parallel and 24v series, whilst isolating the charge lines and activating the windlass lines. Pretty simple but someone will forget to throw the switch.

    2) Use a PWM motor controller with a 50% duty cycle. This is basically an NE555 chip with a series of MOSFETS hung off the output. There are literally hundreds of examples of this on-line. Achieve required current-handling by adding more MOSFETS. This will halve the POWER into the windlass. If you run this at sufficiently high frequency, then the effect (as far as the motor is concerned) is very similar to changing the voltage.

    3) As suggested before, run both 12 AND 24 volt systems. Be sure to label them clearly. You can, of course, charge 12 volt from a 24v system (with the right charger).

    Tim B.
     
  2. Pandoras box
    Joined: Jul 2010
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    Pandoras box Junior Member

    A simple solution would be to run 10 gauge wire from the 12 V battery (winless battery) back to your 12 V charging system with a automotive headlight inserted. I would insert the headlight close to the 12 V source. If you feel the need you can put any relay so that it will disconnect from the starting battery when the engine is not running. He headlight acts like a resistor to control the current flow through the small wires. My two cents, Mike
     
  3. whitepointer23

    whitepointer23 Previous Member

    an even simpler solution would be to stop stuffing around with the 24 volt equipment and just have 12 or sell the winch and buy a bloody 24 volt and have all 24. unless you enjoy over complicating things. kenworth trucks used to run series paralell switchs, the truck was 12 and the starter was 24. it was a crap system that they eventually done away with.
     
  4. SeaJay
    Joined: Jun 2007
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    SeaJay Senior Member

    Whiterpointer - make me on offer on the windlass;)
     
  5. whitepointer23

    whitepointer23 Previous Member

    i have already got one, everything on my boat is 12 volt. why don't you advertise it and put the money towards the one you need. anchor winchs are overated anyway, i mostly pull the anchor by hand because it is quicker. if i had the new type with bowsprit i would use it all the time, but i have to go up the bow to use my capstan thats why i don't use it much. good luck with what ever you decide on. just remember the simpler you keep it the less troubles you have.
     
  6. Tim B
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    Tim B Senior Member

    Converting from 24 volts to 12 volts is quite easy. It involves a pulse generator, a switch (usually a MOSFET) and a damn big capacitor. Simplistically, greater power handling means more (bigger) MOSFETs. Going from 12 volts to 24 volts is somewhat more complex.

    There are a lot of 24 Volt to 12 Volt converters around from the humble LM-7812 to highly efficient switched-mode systems. You pay more for better efficiency, but it doesn't have to be prohibitively expensive.

    Tim B.
     
  7. Fanie
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    Fanie Fanie

    If you look at switching such high amps (up to 100) then building a reliable switching supply at 50% duty is not so easy. Sure it can be done, I have done something similar in the past, the possible high amps is the problem. The components capable of powering such currents are expensive. You will also have to carefully design to compensate for various factors. Possible reliable issues. My third choice.

    Lubbie had a good idea, that was to use one battery for the windlass. You will have to charge each battery with it's own alternator in any case - even if they supply equal power to whatever.

    The reason is that batteries in series usually doesn't last very well, the one becomes weaker than the other and then it begins to snowball because one is overcharged and the other one undercharged.

    The second alternator is a must have, my second choice.

    Switching to 12V would be my first choice. 24V is considered more of an industry standard, but everything 12V is so much more available and affordable, thanks to the motor industry.

    If no one wants to buy the 24V stuff, throw it away, you will still be better off in the long run.
     
  8. whitepointer23

    whitepointer23 Previous Member

    this is true but why would you bother. anyone that actually spends time on the water knows that keeping things simple as possible is the best. these ideas are good on trucks and machinery that are 24v, you need 24 to 12 reducers for radios , it is a necessity. why do it on your boat when you don't have to.
     
  9. rxcomposite
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    rxcomposite Senior Member

    There was an article in PB magazine about a 24V winch and 12V supply. Their reccomendation is to use 2X 12V batteries near the winch and charge it using a 24V alternator.

    It is cheaper and less complicated as you run only two small wires to charge the battery.
     
  10. Pandoras box
    Joined: Jul 2010
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    Pandoras box Junior Member

    Use the small 24 V to 12 V inverter most probably even one as low as 10 amps would be sufficient. The battery will supply the 125 amps that's his job. The inverter will charge at its 10 amps. You might consider putting a headlight bulb between the inverter and the battery. This will act as a high current resistor while the winless is pulling every amps but will allow the battery to come up to full charge without popping the inverter's circuit breaker. My two cents, Mike.
     
  11. SeaJay
    Joined: Jun 2007
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    SeaJay Senior Member

    People


    While this thread has some interesting discussion, some of the recent posters may have missed the fact that a simple solution was found some time ago.

    This device (Automatic Charging Relay):

    http://bluesea.com/viewresource/57

    is designed to do exactly what I need at a cost of 70 USD. Problem solved.

    There seems to be a parallal thread developing related to the pros and cons of 12v vs 24v systems. There are other good threads where we can weigh in with our opinions on that subject.

    I'm all for keeping things simple but reality has a way of interjecting itself into things. I have been purchasing equipment for my boat for several years and the 12v windlass (new in the box) was one of the first purchases I made. I got it for less than 50% of the original cost. Recently I came across a lot of 24v new equipment at similar savings (Vacu-Flush system, Fuel Polisher, IsoTransformer, bilge pumps, lighting, etc), and had to revisit the 12v vs. 24v question. There are pros and cons for both, but I felt the 24v system, (or more precisely a 12v/24v combo system) had the most advantage for my situation.

    The 12v windless is problematic as it contradicts the general concept of a 12v/24v combo system...heavy loads on the 24v side, electronics on the 12v side. Nonetheless, I have the 12v windlass and needed to find a way to make it work. As noted before, I contacted a real expert at Balmar who quickly directed me to a simple, inexpensive, solution (by the way, Balmar doesn't even make this item). I now have options. If anyone is interested in swaping me a similar 24v windlass for my 12v unit, let me know. Likewise, if I found a great deal on a 24v unit, I might be tempted to buy it and try to sell my 12v unit.

    The the ultimate solution is a 24v windlass but until I happen upon a great deal, I don't think the ACR adds a great deal of complexity and I'm still about 1,000 USD to the good.
     
  12. whitepointer23

    whitepointer23 Previous Member

    seajay, can you tell me what a fuel polisher is, is it a spinner that works on centrifugal force.
     
  13. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    There are different types of polishers, the Alfa Laval is centrifugal, there are plenty of cartridge types of fuel polishers too.
     
  14. SeaJay
    Joined: Jun 2007
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    Location: Sacramento

    SeaJay Senior Member


  15. whitepointer23

    whitepointer23 Previous Member

    thanks for the info, i hadn't seen one of those before.
     
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