Originally Posted by Captain Canuck
Electricity is like the sea. If you give it a chance, it will kill you. I'm pretty careful with my wiring, having learned it from a friend of mine who's been a professional electrician for over 30 years. He's helped me reno three of my homes. I've also had to go through the OSHA safety training course a couple time for various contracts I've worked on. I don't consider myself an expert, but I am extraordinarily cautious around electricity and am a firm believer in "too much safety is just enough". I will be testing the hell out of the system I build long before it gets on my boat. If anything is going to melt down, I'd rather it do so on my concrete workshop floor rather than inside my boat.
I think I'm not explaining myself well. Thrust dictates speed. Once the water resistance matches the thrust from the prop, acceleration stops and the speed remains steady. Whether that thrust comes at 800 RPM or 1200 RPM is probably irrelevant. I guess I'll find out. I can't put Khaleesea on the hard until some space frees up, so I don't even know how big my prop is right now. Probably 16x10 or thereabouts. Hopefully I'll be up on the hard soon so I can take measurements.
Point taken about overdriving the motor temporarily. The DC cables on Kahleesea are already 2/0. From what I've read, at 48V that's over 200A, more than enough for cruising speed. Since DC and AC systems converge in the starboard aft compartment, that's where I'll put all electric connections. Looks like the charger and the inverter are going to have to be separate, since I can't find an inverter/charger unit that works with lithium batteries.
Are you putting your genset where your old diesel was? I can't imagine there are too many places in a 29' boat where you can put something like that. I'd also be interested to see your wiring diagram if you have one.
I find it interesting that you're going with the Chevy Volt model of hybrid propulsion. If I needed a longer cruising range, that would be the direction I would go too, but with as much solar as I could cram overhead.
One thing to be aware of, is that while Ohm's Law pertains to every element of electrical theory, standards and practices vary widely between residential, commercial, industrial, aviation, automotive, and marine electrical requirements and good practices.
ie, an excellent residential electrician, may not know marine electrical standards and practices at all.
I see this all the time, often due to marine survey reported deficiencies, where residential standards and practices were applied to boat wiring.
I'm not suggesting that everything was not done properly in your particular case, I'm just advising that the possibility exists in this or similar cases, where the work may not have been competed correctly.
I had a Canadian community college education and 30 years of experience as an electronic engineering technician (with a wide range of experience in residential, commercial, and industrial electrical systems, HVAC, and process instrumentation, before studying marine electrical and electronic standards and becoming Raymarine and ABYC certified. I was shocked (har har) at how much I didn't know that I needed to learn, to perform marine wiring correctly.
I do recommend, that anyone who performs DIY marine electrical work, to have it inspected by someone who is duly skilled and certified, just as you would for mods to your home, even though this is not a requirement on boats.
It may be free, or it may cost a nominal fee, to have a sparky (pet name for marine electrical technician) to inspect something, that your life could depend on.
For example, about 90% of bilge pump and VHF installations I inspect are deficient in some way, that could render them inoperative at some crucial time in the future, even if they are "working fine" right now.