| Created by |
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| Created | September 18, 2012 |
| Last modified | September 20, 2012 |
| Tags | power power-supply |
48v motor w/ 24v solar/wind charging system.
A single DPDT switch can create a Series/Parallel battery bank.
Any number of battery banks can be added to the chain.
Keeping things simple.
Any bank switched to “Parallel” will charge.
Any bank switched to “Series” will provide 48v to the motor
All banks in “Parallel”, will provide only 24v to the motor.
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I think I found one on ebay: 100A 220V/380V Four Pole Double Throw Knife Disconnect Switch Toggle Brand New |
September 19, 2012 |
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I can wire each double set the opposite; one as parallel/series and the other in series/parallel, so while one is running the motor, the other is charging and vice versa. |
September 19, 2012 |
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You may want them both charging when anchored. Or both powering the motor when starting out. Also be sure the battery bank to motor diode can carry the current, you may need 2 in parallel. |
September 20, 2012 |
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It looks like your 4PDT can have the handle cut in 2, making 2-DPDT on one block. That would look nice too. Let me know how you turn out. |
September 20, 2012 |
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Thank you so much for your prompt reply and input. You have no idea how many people I asked on the net as well as in real life about this. I'm not an electrical engineer, just an amateur mechanic who happen to put together an electric sailboat that actually works. On the net, they would give me an answer that I wouldn't understand and would intimidate me, in real life, they just wouldn't know what I'm talking about. Anyway, I'm not quite sure what you meant: "Also be sure the battery bank to motor diode can carry the current, you may need 2 in parallel". "2 in parallel"? The diodes I'm using are - Power Diode Rectifier 200V 40A 1N1186A International Rectifier 1N1186 DO5 DO-5. At 48V it should be able to handle 166A. I assume that's big enough, because my system doesn't use more then 100A DC at 48V. So, what do you mean "2 in parallel"? Put two of them instead of one side by side in parallel? How big do you thing their cooling plate should be? I have aluminum L 2"x2" for each diode. Is that enough? I hope I'm not asking too many questions, I'm really exited. Thank you. |
September 20, 2012 |
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I have added diodes to the drawing. Diode rating 200v 40a DO-5 DO-5 is the diode container design. 200v is the maximum reverse voltage they can withstand. 40a is the maximum current they can carry (like a fuse). Then they burn out. (like a fuse) 48v is much less than the 200v. So you should be OK (except for lightning). Two 40a diodes side by side, should carry up to 80a. Drawing any more would cause both to Open circuit, and you would get no current at all through them (like a fuse) An 75-80a fuse between each pair of batteries, should provide electrical safety. When you mount the diodes, keep them in thermal contact with your aluminum 'L', and at the same time, keep them electrical isolated from your aluminum 'L'. (that's why they come with the 'mica' washers, and such) Car alternators have high current rectifiers, but they have air cooling. |
September 20, 2012 |
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A diode drops about .5v (half a volt) across its connections while conducting, at 40a (40.5=20) that's 20 watts of heat per diode you have to get rid of (cool). Think of it like light bulb heat, in a small container. Heat can also burn out a diode. If you draw less current through it, it produces less heat (va=w). As for a cooling plate, a small computer fan (24v) blowing on your 2” aluminum 'L', will help. Be sure to use “white thermal compound” between the diode and the heat-sink, as is used in mounting computer CPU's (Radio Shack), and enough metal to carry the heat away. I hope I've made things clear and not to complex. |
September 20, 2012 |
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Thank you very much. I think I got it! |
September 20, 2012 |
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Also, thank you for a thorough explanation of the functions of diodes, the amount of heat they put out etc... |
September 20, 2012 |
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What does your motor rating plate say it uses. |
September 20, 2012 |
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I have an instrument installed called "Cycle Analyst " from "electricmotorsoprts.com. It tells me how much current I'm pulling and keeps track of how much I've used up. So at max. acceleration I use about 100A. I can increase it by decreasing my reduction ratio in the reduction belt, therefore increasing the speed of the boat, but for now I'm fine. I go about 3.5-4 knots. The motor is 8.5 hp and my sailboat is 30' sloop, "Albin Ballad". |
September 21, 2012 |
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I have seen attachments for wind generators that gear up a tow prop, while under sail. 30' hull speed should be around 7kts. My S2 has a 35hp "atomic 4", but reaches hull speed with 6 hp, I used a GPS to measure speed. Sailed on lake Superior. Since you're sure you've used 100a, and you may end up using one battery bank at a time, you may want to consider 3-40a diodes in parallel for each battery bank. That would give you a 20a margin for diode safety. |
September 21, 2012 |
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Right now my boat has a folding prop, but in the future, when I take the boat out of the water to service the bottom, I'm intending to change the prop to none folding, so my electric motor, when under sail, will become an electric generator. I figure, I'll just plug it in to a wind generator controller through the switch and a fuse. For now though, I'm using diodes that are 200V - 40A. "Power Diode Rectifier 200V 40A 1N1186A International Rectifier 1N1186 DO5 DO-5". So, at 48V shouldn't it handle 166.6A each, or it doesn't work that way? Thank you again for your time and sharing with me this valuable knowledge. |
September 22, 2012 |
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Hi Carl. How've you been. The reason I didn't fallow your diagram is that I'm stock in my own head and being too stubborn about it. I'm going to try few other things and if those fail, I'll go to yours. So, here is what I have lately. The idea is to have independent charging controls for each pair of batteries: https://www.circuitlab.com/circuit/n76j9m/off-shore-charging-system-for-my-electrically-propelled/ Read the description, I have my problem there. Any thoughts? |
November 18, 2012 |
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