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asdf38 11-25-2010 05:57 PM

Custom Electronic Design
 
I know there are some other engineers out there so I'm wondering if anyone has tried any custom electronic design for their boats. I'm a hardware engineer with plenty of experience designing 12V systems, but no experience designing for harsh environments.

I've got a few ideas that would be fun to design and cheap to implement - until you consider the environment anyways:

-Design a small board for the electrical panel with a display for voltage and current draw. It would have a micro-controller so I imagine I could think of a couple other things for it to do (current/voltage history, averages, etc.)
Microcontroller with analog input and flash memory $3
Two character display $4

-Design a battery distribution board for the house/starter banks that could monitor battery current/voltage, implement a battery sensing relay and provide short circuit protection in addition to a regular fuse.
Current sensing (would need bi-directional) $1
High power mosfet, good for ~20A, several could be put in paralel $2
Mosfet driver $6

So, on paper its all real cheap (Fab the PCB at expresspcb.com) But how can it be designed to hold up? Waterproof enclosures I suppose. Protective coatings or epoxies? Any other thoughts? Anyone tried anything like this?

Chris

sailingdog 11-25-2010 06:06 PM

Why re-invent the wheel. Battery monitors that are designed for the marine environment and already made to deal with the harsh conditions aren't that expensive, come with a warranty, a shunt and are ready to go out of the box.

SVAuspicious 11-25-2010 06:06 PM

I've done odds and ends, but this guy is the bomb: Blog | Nomadness | Geek expressionism at sea

brak 11-25-2010 09:27 PM

I found that most marine electronic devices that are "made for the sea" are not at all different from devices not made for the sea, except may be the outer box is slightly more waterproof (and a few go as far as pouring epoxy over the back or front of the assembly). Most don't even bother to use tinned wires or stainless fittings.

So, I wouldn't worry about "marinization" too much. Whatever you do, would be no worse than anything that comes out of Blue Seas or Uniden (which is all chinese junk anyway, no offense to great power of the east)

mitiempo 11-25-2010 10:03 PM

Uniden maybe, but I don't consider Blue Seas products as junk. I install their products daily and have never had an issue with any of them. Their customer service is excellent and they answer the phone promptly - they are located in Washington State.

As far as the op's question, what he describes I don't think will actually do what a good battery monitor like the Victron BMV-600 will.

RobertKWFL 11-26-2010 05:01 AM

I'm an electronics hobbyist and do a lot of work with microcontrollers, mostly AVR/Arduino. I've been thinking a lot lately about ways to merge that hobby with sailing. How about battery monitor plus wireless remote control of deck and cabin lights? Not necessary cost effective, but that isn't always the point with hobbies.

sailingdog 11-26-2010 05:50 AM

Robert--

I would highly recommend keeping such projects off of the boat. They increase complexity and the chance of failure...and having your deck lights fail at the wrong time is a good way to end up dead.

nickmerc 11-26-2010 07:13 AM

Robert,

Why not avoid things like running lights for right now and start with less crucial items? Who know, you may develop something we all want. Isn't experimenting part of what makes a good engineer; learning how to do it yourself? Anyone can say "let someone else do it".

I like the idea of having a history of my voltage and current usage that I could chart and see trends in my usage. Maybe even download to my laptop via USB. I know I can do this over NMEA 2000, but then I have to install a NMEA 2000 network which I do not yet have.
________
Penelopa

brak 11-26-2010 07:56 AM

Quote:

Originally Posted by mitiempo (Post 670682)
Uniden maybe, but I don't consider Blue Seas products as junk. I install their products daily and have never had an issue with any of them. Their customer service is excellent and they answer the phone promptly - they are located in Washington State.

:) I brought these guys up at random - pick practically any marine elecronics company.

I also use Blue Seas products extensively, and agree that they do have good customer service.

I just had a chance to take apart a few of their analog meters and, in parallel, a couple of much cheaper no-brand analog meters from China (a bit of a custom project here). Inside I found exactly the same stuff. Quality of connections and components was very much the same.

Nothing wrong about that - not every user wants to muck with generic components from China. People do pay for a label, support and consistency in fit, connections, standards etc.

RobertKWFL 11-26-2010 08:28 AM

Yeah, by "deck lights" I meant courtesy lights for boarding at night, certainly not navigation lights. Sorry if I used the wrong terminology. Even for non-critical systems I would have a hard wired backup. I enjoy building things, but don't like taking unnecessary risks.


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