Making best use of shore and passive power sources

Discussion in 'OnBoard Electronics & Controls' started by jamesgyore, Jun 10, 2013.

  1. jamesgyore
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    jamesgyore Senior Member

    Now, that is a very cleaver idea. Thanks for the link.
     
  2. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    No James, it is not that clever. After reading the specifications, it is a toy and cannot be used on a yacht with salt and wet condition. Also the power output, even by 6 of them, is in no way suitable for your ideal electric propulsion.

    You have to search further. You either have to go the folding sideways way, or going up. Maybe a second small flat boat being pulled by your yacht. But you need at least 6 - 8 m2 and that for a 25 feeter is a demanding brain teaser.
    bert
     
  3. BertKu
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    BertKu Senior Member

    James,
    I looked at your estimate to have a 25 Kwh bank. That is about right what one needs for calm weather and sea.
    If it is used solely for your electric propulsion, you should be fine. 25Kwh , means with 2 Kw (2 x 1kw motor) , 2,5 hp, you speed will be low, but you could do 12 hrs, then added your solar input of 1 Kw, (to be realistic 600 watt) you would all in all be able to do 16 - 18 hrs. Your motors should be such, that you could have an override for emergencies, let say 2 x 3 KW and for sure, your available battery time will be shorter.(with stronger wind or higher waves.) You should have to take that into consideration with selecting a battery.

    I looked at Hobby King what batteries cost at 25 Kwh (Lithium nano technology. i.e. high current withdrawal if needed.

    If needed, one could build up a battery bank, by buying every month a few battery packs and make one battery yourself.
    lets look at some of them.

    SKU-9210000016
    = 498 gram 7.6 Amperehour 2 cells = 2 x 3.3Volt x 7.6 Amph = 50.16 Watthour at $ 45.95 each , would cost 25000 / 50.16 watthour = $ 22901.00
    SKU-9210000061
    = 1068 gram 5 Amperehour 6 cells = 6 x 3.3Volt x 5 Amph = 99watthour
    at $ 129.99 each, would cost 25000/ 99 watthour = $ 32825.00
    SKU: 9210000063
    1842 gram 5 Amperehour 10 cells = 10 x 3.3 Volt x 5 Amph = 165watthour
    at $ 185.39 each, would cost 25000/ 165 watthour = $ 28089.00

    If you would use a Turnigy battery nano tech model SKU-9210000013
    = 409 gram 4 Amperehour 3 cell = 3 x 3.3Volt x 4 Amph = 39.6 watthour
    at $35.57 each, would cost 25000/ 39.6 watthour = $ 22455.00

    or
    SKU - N4000
    = 531 gram 4 Amperehour 4 cells = 4 x 3.3 Volt x 4 Amph = 52.8 watthour
    at $ 35.83 each, would cost 25000/ 52.8 watthour = $ 16964.00

    What I try to say is, I don't believe that the material used varies from the one pack to the other, but you could have twice the power by selecting a different pack. 25 Kwh is 25 Kwh. You may have some more wiring to do for the one and not for the other. But what I like to say is, shop around and see how cheap you could make a 25 Kwh with various batteries.

    Be aware, most electric cars have hunderds of batteries parallel/serial placed as a powerhouse. It depends what motor they are using. A 400 Volt AC or a 300 Volt DC or just a 48 Volt DC brushless motor. Why can't you do the same.

    Bert
     
  4. jamesgyore
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    jamesgyore Senior Member

    That particular product, perhaps not, but the idea of a panel that can track the suns path is rather cleaver.
     
  5. jamesgyore
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    jamesgyore Senior Member

    Both SEW and Toyota have some interesting offerings.

    SEW does not have anything particularly efficient by way of DC offerings, but Toyota has some applicable and interesting technologies from their forklift business.

    Should anything of note come from Toyota I'll be sure to post it.
     
  6. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi James,
    I fully agree with you on, normal static, environment like a table etc. But on a yacht, which moves and dances, I doubt it that somebody will have great pleasure from it, except in a harbor.
    Bert
     
  7. jamesgyore
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    jamesgyore Senior Member

    At this point of my build project, the need to commit to a particular technology or method of power generation is a little way off.

    I greatly enjoy the freedom to think, debate, dream, wonder, and question the options available to me before I have to commit.

    So far from this thread I have enjoyed the benefit of:

    1) Determining, that while expensive, a single hydrogen fuel cell can power all essential electrical systems. Done... Just have to find quite a few thousand Euro's I might have forgotten about in a jacket pocket.

    2) That a battery bank of considerable density can in fact be installed on my boat... Not quite as large as I hoped for, but near enough.

    3) A combination of solar and turbine technologies may well be able to deliver sufficient energy to keep the batteries charged and on board non-essential systems powered.

    4) A generator may only be needed to placate a sense of assurance of redundancy.

    That interesting solar panel you shared with me has planted a crazy thought which may or may not prove viable.

    What if the panel assembly was gimballed or stabilised by some other means? It need not be complex nor heavy. Just sufficient to enable the panel to be self aligned optimally to the sun.

    Naturally the idea needs refinement and further thought, but none the less the idea has merit.

    Further, if such a contraption could become a reality, why not mount them on a hinged "thing" not unlike the odd little trampolines shown on the kit yacht I referred to earlier?
     
  8. BertKu
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    BertKu Senior Member

    Hi James,
    Here is even something better to mount on your yacht with wind still conditions. You just pop it out of your transom. It is a solar charger, made by Volvo the car manufacturers, to charge an electric car. To enable somebody to charge a battery for an electric car, it must have some Kw output, good enough to get some energy into the battery. The wind factor is a problem, but normally, if you have good sunshine, the wind is kind to you. Maybe it is in such a way constructed, that the wind just blow through the spiderweb, without too much resistance. (lets hope).
    Bert

    p.s. this is real science f(r)iction. !!
     

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    Last edited: Jul 19, 2013
  9. BertKu
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    BertKu Senior Member

    What had you hoped for ?? 100 Kwh?? can be done with lithium, only 900 kg
    true
    Keep on dreaming, James, nothing wrong with that. Something may come out of it.
    Bert
     
  10. BernardG
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    BernardG Junior Member

    My 2 cents...

    If I may, I think it all go wrong in this discussion because of this sentence! If you want to install an electric engine, it will be the most important piece of your whole electric installation, so, as such, you can't take it out of the equation.

    I am far from being an electric specialist, but I researched the Pop 25 quite a bit, as I a
     
  11. BernardG
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    BernardG Junior Member

    My 2 cents...

    If I may, I think it all go wrong in this discussion because of this sentence! If you want to install an electric engine, it will be the most important piece of your whole electric installation, so, as such, you can't take it out of the equation.

    I am far from being an electric specialist, but I researched the Pop 25 quite a bit, as I see it as being very interesting.

    So, why do I say you cannot take the engne out of the equation? Because, under sail, it will be your main SOURCE of energy, as it become a generator when the propeller make it turn. So all estimations about your need for solar panels must take this into account.

    See this page:http://greenstarmarine.se/en/greenstar-10/ and this one: http://greenstarmarine.se/en/teknik/. This swedish company offers full system with all elements needed, at a cost (about, or a little more, than twice as amuch as an equivalent diesel engine).

    To keep the batteries loaded at anchor, I would look at this: http://www.accastillage-diffusion.c...maintenance-Model-ATMB-500-12V-19W,10689.html, as this is the only kind of windmill I would let run while not on board.

    Also, remember that the plan says explicitly that batteries are part of the ballast, so, not only their weight is already taken into account, but it's mandatory. If you replace the classical deep cycle batteries with Lithium, you will have a VERY extended range for the given weight.

    "Note: The two battery banks weighting approximately 90kg each are considered internal ballast and should not be omitted, not even partially. In case an electric inboard motor is not the auxiliary propulsion chosen, if the banks are intended to be reduced, an equivalent ballast should be put in place so the weight of the internal ballast is maintained."

    Hope this helps,
    Bernard
     
  12. BernardG
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    BernardG Junior Member

    Seems to me those calculations are way off.

    First, they do not take into account that electric marine engines are (should be) also generators under sail, with a folding propeller, so that, when there is no need to charge the batteries anymore, there is very little drag added.

    My calculations are showing that, with 6 100A 12 volts batteries, there is an estimated run time of 7 hours (at 5 knots), and 45 minutes at full power (15+ knots). Each one weight about 30 kgs. 30 * 6 = 180 kgs, which is exactly waht the designer recommend. That's very far from the 600 kgs you're talking about. Now, if we switch to lithium batteries, as each (for the same capacity) weight 18 kgs instead of 30, we would need 10 of them to get the same weight, and we would get 1000 Ah capacity, or 12 kW.

    I don't have the exact numbers on Amps generated under sail, but about 200 per day at 5 knots seems reasonable, if not under estimated. So, assuming totally discharged batteries, it would take +- 5 days to fully reload them, without any solar panel involved. Assuming you have AC/DC power available while not under sail, it's perfectly possible to envision e-propulsion without any solar panel. Solar panels would be a serious plus, to reload faster, and for those times where the wind is too light, but they don't need to be monstrous either.

    Regards,
    Bernard
     
  13. CDK
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    CDK retired engineer

    BernardG, think again.
    Only 50% of the battery capacity is available to ensure an acceptable life expectancy. And even then there will be loss of capacity after each charge/discharge cycle.
     
  14. BernardG
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    BernardG Junior Member

    That's relative to the battery technology. Modern lithium batteries accept to be 90% discharged. And life expectancy might even be BETTER if there is a good, deep, discharge, before being charged again. To my understanding (but I am not a specialist), 50% is the norm for lead batteries. Deep cycle batteries (NiMh) are purposely built to accept 80% discharge. Now I agree that life expectancy will be better if you don't go over 50%, at least not regularly, but I also think that on a cruising sailboat you are not going to motor for more than a couple of hours regularly either....

    Now, I totally agree that you can't have everything on a small boat. If you want to have a decent estimated motor runtime, you will not be able to both run the engine WHILE having a fridge, clim, water heater, water desalination running all together. But I guess that's true for all but the larger sailboats. It's all about compromise and choices.

    Still, it seems to me that an electric motor on a small sailboat is perfectly possible, even with a fridge and a water heater, plus navigation electronics, without sinking the boat due to large and heavy batteries and solar panels.

    I have not yet made a calculation spreadsheet to simulate this precisely, but it seems doable to me.

    regards,
    Bernard

    PS- If it is between my life and the life of the batteries, the choice is quickly made for me! :)
     

  15. jamesgyore
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    jamesgyore Senior Member

    Most interesting... Since I'm building a yacht I should think that sails and associated hardware would be most important.

    I'm going out on a limb hoping that you might be sober and agree and not argue that auxiliary propulsion is just that, auxiliary. In other words, a SECONDARY means of propulsion.

    So exactly why would I give an auxiliary means of propulsion such attention? It is the least of my concerns. Electric propulsion is only a convenience to get me in and out of a marina or harbour.

    I've read a few books... I know what that tall aluminium thing in the middle of my boat is for. Apparently it supersedes the need for a motor, something about wind and sails... Or so I read.

    It seems these sail things have been used for a great many hundreds of years to propel vessels. A convenient and controllable means of propulsion is however desirable in close quarters... Go figure!

    Were they talking about auxiliary propulsion? Surely seldom used and mostly an irrelevant auxiliary means of propulsion.

    Hang on... What was that tall aluminium pole for again?
     
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