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Old 29-11-2013, 21:34   #1
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Electrical distribution question

I am going to rewire and add more electrical devices to my cat. However, main electrical panel does not have any spare breakers and some of the devices are far away for <3% voltage drop. There is an obvious solution for both problems (new electrical distribution panel and thicker wire), but these are so last century, expensive, sometimes inefficient and complicated. Instead, I designed and built a system where all devices are connected to a closest "power hub" using shorter, smaller wires. I plan to have several hubs strategically located around the boat.
Hub is fed from main distribution panel using larger wires. Hub is controlled by a microcomputer to which I can connect up to 16 devices (or various sensors). I can control each device separately: SWITCH (On, Off, Power) and CIRCUIT BREAKER (sustained max current, absolute max current, time response). This way, each breaker can be setup up as slow thermal (slow response time) or fast (short response time ~1ms) and anything in between (yes, it is a software circuit breaker, there is a glass fuse in series as a backup). POWER is implemented using PWM, so only certain devices can be power-controlled (some fans, LEDs, etc.). I can monitor and datalog power consumption of each device individually, set total power consumption limit over certain period of time, various conditions for turning ON/OFF (e.g. turn device ON only if battery voltage and available power is about set limits). I can also turn off/de-power/round-robin devices (in pre-set priority orders) if battery voltage falls below a limit or total power consumption of the hub is over a limit. By monitoring power, controller can also check whether device consumes as much power as expected and raise an alarm if not (e.g. light bulb burns or connector to a device falls off or is corroded,or simply does not work).
Power hub is controlled over TCP/IP, either wired or wireless from any device with web browser (computer, smart phone, tables, or, if I can get my hands on it, chartplotter). The best point, I think, is that it could be very cost-effective solution. All parts are off-shelf, I built hub controller for less than $40 (including web server) and new device can be added for about $5-10, depending on max allowed current (I did not try to go over 30A/per device).

My question is what do you think about this idea? What are the gotchas and things I should take care of/avoid (e.g. potential for electrical noise is an obvious one)? Or, on the other hand, what useful features could I add?
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Old 29-11-2013, 21:47   #2
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Re: Electrical distribution question

You are not the first to venture there. I used to hear quite a bit about distributed power with software controlled breakers, etc. Not so much lately. Google "marine distributed power systems" and you will get lots of hits.
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Old 29-11-2013, 21:55   #3
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Re: Electrical distribution question

Go have a look at PerfectSwitch.

It's on the shelf but if you want to do away with all branch Circuit Breakers, it's going to be expensive, especially in the low amp circuits.

Or you could use PS for the high amp loads and localized Cb's for zone circuits.

But that means you need run around and kill all non 24/7 circuits at each zone when you want to leave the boat.

How are you going to meet the AIC requirements. A UL listed AIC is going to be very expensive for a homebrew.

Lloyd

Quote:
Originally Posted by BambooSailor View Post
I am going to rewire and add more electrical devices to my cat. However, main electrical panel does not have any spare breakers and some of the devices are far away for <3% voltage drop. There is an obvious solution for both problems (new electrical distribution panel and thicker wire), but these are so last century, expensive, sometimes inefficient and complicated. Instead, I designed and built a system where all devices are connected to a closest "power hub" using shorter, smaller wires. I plan to have several hubs strategically located around the boat.
Hub is fed from main distribution panel using larger wires. Hub is controlled by a microcomputer to which I can connect up to 16 devices (or various sensors). I can control each device separately: SWITCH (On, Off, Power) and CIRCUIT BREAKER (sustained max current, absolute max current, time response). This way, each breaker can be setup up as slow thermal (slow response time) or fast (short response time ~1ms) and anything in between (yes, it is a software circuit breaker, there is a glass fuse in series as a backup). POWER is implemented using PWM, so only certain devices can be power-controlled (some fans, LEDs, etc.). I can monitor and datalog power consumption of each device individually, set total power consumption limit over certain period of time, various conditions for turning ON/OFF (e.g. turn device ON only if battery voltage and available power is about set limits). I can also turn off/de-power/round-robin devices (in pre-set priority orders) if battery voltage falls below a limit or total power consumption of the hub is over a limit. By monitoring power, controller can also check whether device consumes as much power as expected and raise an alarm if not (e.g. light bulb burns or connector to a device falls off or is corroded,or simply does not work).
Power hub is controlled over TCP/IP, either wired or wireless from any device with web browser (computer, smart phone, tables, or, if I can get my hands on it, chartplotter). The best point, I think, is that it could be very cost-effective solution. All parts are off-shelf, I built hub controller for less than $40 (including web server) and new device can be added for about $5-10, depending on max allowed current (I did not try to go over 30A/per device).

My question is what do you think about this idea? What are the gotchas and things I should take care of/avoid (e.g. potential for electrical noise is an obvious one)? Or, on the other hand, what useful features could I add?
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Old 29-11-2013, 22:05   #4
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Re: Electrical distribution question

My first thought was about moisture condensing on the boards in winter and causing corrosion. Though sealing the boards with a waterproof plastic, might get around that.

Of course you would need breakers (hard or soft) protecting the main feeder circuits too (30 amps?) at the main panel, not so much at the remote boards. Just for when you drive a screw between +and - on that remodel project later on.

Depending on where your autopilot heading sensor is located, you'll need to keep the current and signal wiring (R232, 422, etc) away from it. Then test the remote boards with the VHF and or SSB mic, keyed and see if you pick up a bit of RF.
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Old 30-11-2013, 02:04   #5
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Re: Electrical distribution question

Hmm... first thought is what happens when it fails but I guess if you can make it, you can fix it. You might even enjoy fixing it

Second thought is what about noise; that's got to be generating a lot of EMI and perhaps also be affected by outside noise.

Third (& last) thought: it sounds great for your boat but I will keep mine "so last century" 'cause it has worked well for a long time. Good luck with the project.
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Old 30-11-2013, 02:36   #6
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Re: Electrical distribution question

The "easy" fix to protect the circuit board is to get an aerosol can of conformal coating, mask off connectors and switches then spray the board.

Future solder repair is more difficult but is a good trade off, IMO.
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Old 30-11-2013, 09:38   #7
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Re: Electrical distribution question

Quote:
You are not the first to venture there.
Looks like I re-invented a wheel . At least it is the wheel I can build and fix by myself. But I did googled what you recommended and it was an interesting reading. The main concern is reliability, but I have several solutions for that.

Quote:
It's on the shelf but if you want to do away with all branch Circuit Breakers, it's going to be expensive, especially in the low amp circuits.
Or you could use PS for the high amp loads and localized Cb's for zone circuits.
But that means you need run around and kill all non 24/7 circuits at each zone when you want to leave the boat.
I am not sure I understand your comments. I did not buy and do not plan to buy anything expensive. I do not need to run around to kill circuit in each zone, it is done remotely through an app on my tablet. But this comment gives me a good suggestion: I can create a list of 24/7 circuits and when leaving a boat I will just turn everything off except circuits on this list. One button on the app.

Quote:
How are you going to meet the AIC requirements. A UL listed AIC is going to be very expensive for a homebrew.
Why would I need that?

Quote:
Hmm... first thought is what happens when it fails but I guess if you can make it, you can fix it. You might even enjoy fixing it
There is not much to fix. Very few people do their own SMC soldering (I do not). It is pure board replacement, not much more difficult than replacing standard circuit breaker, and at about same or lower prices. Very simple. Main controller board currently costs less than $18 (that is for 16 channels zone), each channel costs $5-$10 depending on max current allowed.

Quote:
...get an aerosol can of conformal coating...
Of course, conformal coating is a must on every PCB in marine environment. Anytime I bring any non-marinized device on my boat (like TV, for example), I open/disassemble it and if I can get to it I coat every PCB with several coats.

Quote:
Third (& last) thought: it sounds great for your boat but I will keep mine "so last century" 'cause it has worked well for a long time. Good luck with the project.
Of course, I would not just go in and replace what is working, I am talking about new work.
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Old 30-11-2013, 09:43   #8
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I guess the other question would be why? I miss the upside of such a set up.
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Old 30-11-2013, 10:00   #9
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Re: Electrical distribution question

Until such a control system is "commoditized" (eg made up of packaged, encapsulated, modular, off-the-shelf, and hopefully marinized components), my gut feeling is that it would still be preferable to stick with a simpler, proven way to distribute DC power - wires, breakers/fuses, etc.
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Old 30-11-2013, 10:11   #10
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Re: Electrical distribution question

I love distributed systems. The idea of much shorter runs combined with large trunk lines that reduce the required size of wires on the boat just makes things easy. I am not sure why the marine industry has been reluctant to get rid of home running everything, but it's about time.
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Old 30-11-2013, 11:22   #11
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Re: Electrical distribution question

A couple of manufactures have just that. I remember a few years ago a few of big expensive CATs had the systems installed from the factory.

At one time all three boats were dead in the water shortly after delivery. It took months to a year to get it sorted. I quit following the saga, and do know what the final outcome was.

Calder, did a couple of mag stories touting the benefits.

BEP had a partial system called the C-Zone System. I don't see them advertising that anymore.

Carling Technologies has the OctoPlex System.

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Until such a control system is "commoditized" (eg made up of packaged, encapsulated, modular, off-the-shelf, and hopefully marinized components), my gut feeling is that it would still be preferable to stick with a simpler, proven way to distribute DC power - wires, breakers/fuses, etc.
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Old 30-11-2013, 15:20   #12
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Re: Electrical distribution question

Quote:
Originally Posted by BambooSailor View Post
..........
There is not much to fix. Very few people do their own SMC soldering (I do not). It is pure board replacement, not much more difficult than replacing standard circuit breaker, and at about same or lower prices. Very simple. Main controller board currently costs less than $18 (that is for 16 channels zone), each channel costs $5-$10 depending on max current allowed..........
I don't think your concept is a bad idea and I am sure you can implement it but as you have asked for our thoughts, let me say also:
There is always something to fix, especially any electrical device on board.

I am possibility (probably) influenced by too many years around wet wooden boats but everything electrical from the battery and main bus wiring right though to the reading lamp in the fore-peak starts deteriorating from its first night spent on-board. Your Cat is no doubt much much drier and environmentally well protected in comparison but all this means is that the decay is just going to be slower. You are however clearly going to be using more devices and thus increasing the number of potential failure points.

If you are planning to cruise, you will need to take more than a fistful of spares because those items are not going to available in many third world ports and even in first world ports, will be difficult to obtain near shoreside outlets. Sure you can get anything a western city with a population over 1 million but can you get it near where you are moored or anchored without local knowledge and transport. Of course, you can wait for it to be delivered in a first world port but again not always in third world port.

Wire and a glass fuse are usually available anywhere and even if the type one needs is not, some simple equivalent will be available than can be pressed into service. Your system does not allow for that aspect so readily.

I can toss a few coils of wire aboard, a pocket full of glass fuses, some crimps and crimper ( or even a soldering iron) and I have all the spares I will ever need. Heck, I can not even worry about carrying spares because I can get enough of those items in any village that has a general store. I really only need to carry them for running repairs at sea or at a isolated anchorage (my favourite place BTW).

How will you control this system with a smart phone app where this no phone connection. Yes, I realise you will still be able to control it on-board but my point is that the technology it relies on is not universally available. This may not be an issue for you as depends on where you are planning to go.

Let me restate, your system is not a bad concept and you sound like someone who would enjoy putting it together; just make sure you enjoy keeping it going when away from the comfort and certainty of your home port. However, it wouldn't work so well for the cruising I have undertaken in the past. You of course, will be cruising in a new future and that may be different...

Again, the best of british luck to you.
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Old 30-11-2013, 17:46   #13
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Why not consider publishing the circuit diagrams. Make a nice Open Source Hardware ( OSH) project


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Old 30-11-2013, 17:48   #14
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I built a prototype electronic central breaker panel a few years ago. Using E.T.A. Electronic switches. Similar idea but not distributed. I think distributed systems in under 50 footer don't make sense.

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Old 30-11-2013, 18:04   #15
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Re: Electrical distribution question

I'm going in between the two extremes. I have added a sub fuse panel up forward. One big pair of wires to the forward panel and split everything out there. Of course if you want to turn on lights, stereo, or heater in the front of the boat from the back of the boat what I've done won't work. Not a problem for me though.
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