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Old 12-01-2010, 18:50   #1
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Electric Motor and a Honda 2000 Generator?

i like the idea of an electric engine, but dont like the idea of getting crazy with a million amp hour battery bank. what is the current draw on an engine needed to push a 30' 6.5ton full keeler? could a honda 2000 keep up?

even with a 600amp-hour bank i could probably run the engine for 1/2 hour in and out of harbor and just pull the generator out for extended runs. after all the goal is to motor as little as possible and some of you lot talk about a tank of diesel lasting 3 years. on addition benefit is carrying 2 fuels instead of 3..

am i delusion to think this could be done for about/under 2k? (500 motor, 900 generator, 600 odds and ends?) ohh yea 300 for batteries
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Old 12-01-2010, 19:11   #2
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If everything was 100% efficient, (which it won't be) then a 2kva generator could continuously run a motor at 1.6kW. Which is 2.133* horsepower.

Is 2 horsepower enough to push your boat?
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Old 17-01-2010, 17:26   #3
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I repowered my 8500# Southern Cross 28 using an Etek 15hp @ 48v. I sured enjoyed it, especailly as I eased up up a fully crewed Benatue in light air. Not to ruin their day, they were sure relieved when I told them about my totally silent engine. Anyway, I could motor sail forever (if necessary) and not use my batteries just by running my Honda 2000. The cost was over $8000 for just the parts including the gel batts. I could have saved $$ and effort, if I stayed at 36v max because yachtie stuff doesn't exeed 36v. With 48v I could burn a trough through a muddy bottom for a short spurt. I will post pictures and spec's as soon as I get an opportunity. There are hundreds of factors to consider, or the whole system will be a heart ache. I will also list them. 8500# seemed like a good maximum weight as the electrical current increases exponentially voltage and cost wise. I would not recommend electric for an average cruiser, contiuous heavy weather or strong current, but the system can work well for a weekend sailor. I know I did not pass on many facts at this time and I have no ambitions to make money on this and it is time for this 76 year old sailor to take his nap.
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Old 17-01-2010, 17:42   #4
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Capt Fred - thanks for the info, i look foward to more, as well as the pictures. the only questions i have now are, what was the current draw on the motor at about 5knots of boat speed?, and what size is your battery bank?, also does that motor have regeneration capabilities?

Thanks
Ben
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Old 17-01-2010, 20:41   #5
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A honda 2000 will not keep up with your power draw if you are pushing into wind and waves or trying to get somewhere in a hurry in calm conditions. One of the issues with an AC generator is that your batteries and controller(some take AC but then you can't use any batteries and you have a parallel hybrid) all take a DC input. Your efficiency will be approximately .95(charger)*.95(controller)*.9(motor)=81% efficient with well thought out components. This means that if you have a 2kw continuous output generator, you can put 1.6kw out at the shaft which is 2.2hp. I would think that you would want to be able to sustain closer to 5hp but it really comes down to what you need. What is the purpose of the system for you? Do you need to be able to motor off of a lee shore or just catch a mooring? Also, if you don't run for too long, you can draw more than the generator outputs and just discharge the batteries. The higher the voltage you run, the more efficient your system will be so it is generally best to run the highest voltage possible as dictated by your battery configuration. This also means that your wires can be smaller which will save a lot of cost, weight, and bulk.

An Etek motor/LMC motor can support regen when you are sailing. I have actually used one of these as a generator. The limiting factor is finding a controller that supports regen. The DCP controllers used to support it but they are no longer made. I believe that Zilla supports it but I would have to check on that. Kelly advertises that they do but as of a year ago, the feature didn't work. One of the biggest advantages of an AC system is that the regen capabilities are much better. When you purchase an AC motor, it usually comes with a controller since they need to be matched.
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Old 17-01-2010, 21:14   #6
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Hi Ben, Electric current to drive a boat at 5 knots depends on many variables, such as hull shape, voltage, wind, wave action, weight of vessel, condition of bottom, type of prop and water current to name most of them. My battery bank was 8 100Ah gels wired to 48v. I will have to look into my notes for this, but the reason the batts were only 100Ah is, because if I remember correctly, the charging unit rate must be at least 25% of the battery capacity. I really don't want to answer these questions until I find my notes in my storage shed if the roaches haven't eaten them. As far as regeneration goes, don't expect much, BUT if I leave the dock at a slow troll out of Roberts Bayou into Arnica Bay for 10 minutes at 5 amps, I can regen about .75amps @ 5 knots for about 75 minutes to top off the batts again. I gotta see my notes to verify that. See my website wwwdotbiophiliadotnet to see my former 50ft 23ton FG cutter ketch that I designed and hand built with my mate in '77. I have since owned a SC28 which I converted to electric and am now the proud owner of a Rob Roy 23, which I modified more efficiently to a tiny cutter ketch. I want to be closer to the sea, just to run my hand in the water.
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Old 17-01-2010, 21:33   #7
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I've never been on a sailboat that had it's motor going full-bore.

The only time I've been on a sailboat that was going about 1/2 speed, was at times when the captain was in a hurry to get back before a specific time. It seems that after about 1/4 throttle, it just takes too much power to move the sailboat just a little faster. In fact 1/4 throttle always seems like a lot of overkill to me.

I tend to wonder about how very little energy I can use to get a sailboat moving at a couple of knots, rather than how much power I need to plow the boat at hull-speed.

To that end, I'm more interested in keeping an electrified sailboat moving at 2 knots(in duldrums) while renewing the lessor amount of used energy with a solar panel or something.

I'm sure there are times when a lot of power might be needed . . . but I, personally have never seen such a time.

I've grown tired of hauling smelly gasoline bombs with me just so I can enjoy the fun of fighting internal explosion motors.
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Old 18-01-2010, 06:17   #8
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klem - thanks for the good info. i will not be cruising for a year or two but when i do i plan to do it in the spirit of the pardeys, hiscocks, etc... the motor will be a last resort, strictly for picking up moorings, making it in and out of harbor. shooting reef pass's etc. i would like to say that i would never plan to run the motor for more then an hour. i choose the honda 2000 becuase i will have one anyways to run my power tools (that cant be run of the inverter/house bank - 7" angle grinder and miter saw). i would like the ability to make as close to 5 knots (not hull speed) as possible for an hour. (5 knots so that i at least have the ability to make head way against a current)

now just crunching the numbers. i see the etek is rated for continuous output of 110amps at 48volts. so 8 trojans t-105's will give me a 220amp-hr 48v bank, and i could run the motor for an hour and only discharge it half way. then with regen sailing will top it off for the ride into the next port... looking online it is hard to find good info about the regen capabilities. what can i reasonably expect? how long would i have to sail to top off my theoretical battery bank if it was depleted halfway?

while the honda would not run the motor out right, it seems it could provide a decent motor sailing range as well. no?

i currently have a 130 watt solar panel for my house bank. should i go the electric route i will add a wind gen for that bank and have the honda as well. seems like it could be a workable system, i will just have to be very conscious of power management.

now crunching the other important numbers. cost:
a motor with controller and regen capabilities is going to run $1700
batteries - $650
honda generator - $800
plus odds and ends say about $3500

then i could pull out the diesel and its associated parts and sell them for $1000

or i could pull the diesel (yanmar 3gm30f), rebuild it myself, and id be looking at about $2000 in parts....

decisions decisions decisions...
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Old 18-01-2010, 11:54   #9
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pressuredrop,

I think that you have the right idea for a battery bank size given your stated use. How much of an issue is weight and space to put all of those batteries? I ran the numbers for a similar sailboat trying to push into a stiff headwind for an hour or two (I can't remember) and came up with around 18 T-105's for that use. Your battery bank would truly be for when you are becalmed or need to maneuver a few hundred feet with moderate wind. Something to keep in mind is that it is often hard to get the rated power out of a motor. As your rpm goes up, your back EMF goes up as well limiting your torque. One of the disadvantages of DC is this lack of torque at higher rpm where AC motors have a more constant torque curve. This might actually not be too bad unless you are trying to push really hard at high speed.

Something that you haven't mentioned yet is how you will connect the motor to the shaft. You probably don't want to direct drive it due to the motor rpm band being too fast for your shaft. The Etek tops out at 3700rpm and your shaft most likely tops out around 1500rpm so you will need a gear reduction. You want to gear down as much as possible without limiting your boat speed. Since the reduction will be in the range of 2:1 or 2.5:1, you could do this with a belt but that would require at least 1 bearing on the inboard end of the prop shaft.

Regarding regen, the reason that there are not good numbers out there is that the effectiveness varies widely. The two limiting factors are your controller and your batteries. Some controllers have very ineffecient regen (~70%) and some have very efficient regen (~95%). AC controllers will tend to be much better at this than DC ones. The inefficient ones will not be able to sustain it for very long without overheating. Batteries do not like to be charged quickly and become less efficient when the current goes up. On the electric ford ranger that I built, regen is about 50% efficient but we regen at up to 200A.

You should look into keeping everything cool. DC motors are air cooled so you will need to exchange the air in the space. AC motors are often water cooled which allows you to remove the heat at a remote location. Controllers can be had of either type.

One thing to keep in mind is parts availability if you are going distances. I have had good luck with getting suppliers to ship things to me promptly but they are often shipped long distances. I think that you will find yanmar parts to be more readily available.
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Old 18-01-2010, 18:45   #10
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Quote:
Originally Posted by SURV69 View Post
To that end, I'm more interested in keeping an electrified sailboat moving at 2 knots(in duldrums) while renewing the lessor amount of used energy with a solar panel or something.
Pretty difficult with current technology. Even if just 1kW (1.3 horsepower) was enough to keep your boat moving, have you seen how big a 1kW solar array is?
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Old 18-01-2010, 20:58   #11
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if you put flexible solar panels on your sails, you could do it. 500ft of sail area is roughly 5kW of solar panels. I know of solar panels that would work but they cost $20 per watt, so it would cost $100,000 for enough, and that is only one side of the sails (we want both sides)

If you covered your deck with solar panels, and also had ones that fold out all along the sides, you could get probably 2kw or so, but some of it would always be shaded, therefore a 1kw output may be realistic. My fear is the solar panels would not make a good deck (be slippery and crack if something falls)

Maybe instead you could heat water from the sun, and run a stirling engine direct drive to propel the boat. This would be 3x more efficient than solar panels. It could be electric hybrid if you wanted to get fancy. You could even deploy large inflatables which are towed behind giving huge surface area for water to circulate on. This has the added benefit of being able to run in reverse to act as both a heat pump and air conditioning unit when under sail power.
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Old 19-01-2010, 07:37   #12
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Having a few electric cars with solar panels, I have found that solar panels do not work well in this application. Some of the problems are: partial shading, cloudiness, incorrect panel aiming etc. Solar works well shoreside because you can aim the panels in the correct direction and use the grid as a buffer because you only output close to max power for a few hours in the middle of sunny days. We have solar panels on the electric cars for competition purposes(you get awarded points for solar miles) but in truth they don't do much whereas the ones on the house actually make a big difference.

Also, a wind generator was mentioned. This will only really work as a way to recharge the batteries when the boat is at anchor or sailing. If you are underway and there is no wind, the only wind will be apparent wind so a wind generator would actually decrease your range slightly because it would be capturing energy that was originally created as kinetic energy from the electric motor moving the boat. To get anything out of this would violate the basic principals of thermodynamics. If there was enough wind to get anything out of the wind generator, then you should be sailing.

You could always turn your whole boat into a heliostat to run that sterling engine.
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Old 19-01-2010, 08:36   #13
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I don't doubt that sailing on inland lakes, but we have needed full power from our little 18hp diesel on several occasions. the last was in October, coming out from the Ocracoke Channel against wind and waves. It is amazing how 6ft close waves with 25 knots of wind will slow you down.

I love electric and all things solar and alternative energy, but if you want safe reliable power for extended ocean cruising, unless you have the space and $$ for a diesel electric setup, I have found that it just is not possible yet given the state of current technology. When LIFEPO4 bateries, or the next generation after that come down in price, and boats are made with these as ballast, then we are close.

If your cruising is on sheltered waters, then I think it makes perfect sense.


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Quote:
Originally Posted by SURV69 View Post
I've never been on a sailboat that had it's motor going full-bore.

The only time I've been on a sailboat that was going about 1/2 speed, was at times when the captain was in a hurry to get back before a specific time. It seems that after about 1/4 throttle, it just takes too much power to move the sailboat just a little faster. In fact 1/4 throttle always seems like a lot of overkill to me.

I tend to wonder about how very little energy I can use to get a sailboat moving at a couple of knots, rather than how much power I need to plow the boat at hull-speed.

To that end, I'm more interested in keeping an electrified sailboat moving at 2 knots(in duldrums) while renewing the lessor amount of used energy with a solar panel or something.

I'm sure there are times when a lot of power might be needed . . . but I, personally have never seen such a time.

I've grown tired of hauling smelly gasoline bombs with me just so I can enjoy the fun of fighting internal explosion motors.
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Old 19-01-2010, 09:27   #14
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It would be nice if it were true, but electric drive systems for a given horsepower and range are still not as cost effective or as simple as a good diesel engine.
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Old 19-01-2010, 10:42   #15
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Pressuredrop,

I move my Freedom 32 (with a 48v motor from Electric Yacht, Inc.) at 3.5 to 3.8 knots using a Honda 2000i and a Zivan 18 amp, 48v charger that keeps up my 4 - 100 amp AGM batteries.

I also have regen that starts at about 4 knots of sailing speed with .5 amp and builds to 1.6 amps at around 6 knots of sailing speed.
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