Doesn't seem like a 1000W is going to give you much on a boat that big. I'd go minimum 5kW and many would probably tell you that is grossly undersized. Consensus seem to be about 1 kW/ton. You can go much lower in a hybrid but if your electric is all you got, I think that's a good number.
I can't imagine a 1000W motor pushing you must faster than a mph. Even with 5 kW I think you'll be lucky to get 4 mph. Which is a bearable speed if you're not in a hurry. And if you hit any wave action at all it will be more like 2 mph.
I just ran most of the day today in the Atlantic ocean at about 70 amps on a 48V system, which is about 3.5kW. With just a 1-3 foot swell, a bit of a chop, and the wind at my beam I was barely making 3 mph. Add a 20mph headwind and it's more like 2 mph. Same setting in a calm ditch and I'd get 4+ mph., 5 mph with a good tailwind.
Although my motor at full throttle will put 7 kW to the shaft at 140 amps and give me about 5 mph in calm water, the batteries would be dead in an hour or so, even with the solar input. ( When I say dead I mean 50% DOD). I typically get about 45-80amps continuous in full sun, depending on the inclination of the panels to the sun. With that and my 8 Trojan T-125s starting with a full charge, I can run almost all day at 75 amps and usually do not exceed the 50% DOD.
Carter
On Saturday, January 25, 2014 4:02 PM, Mark F <mark.internet@yahoo.ca> wrote:
how do you limit the current going to the motor at the three settings?
I had an old golf cart that did something similiar, but they had big resistors attached and was not very efficient.
In my experience, if I connect a 96V motor to a 48 volt supply, I will smoke it from too much current.
I have used a 48Volt controller and 48 volt battery bank, and I get smoke if I push it too hard( greater than 15 amps continuously)
I haven't tried direct connecting the batteries though.
Food for thought.
Mark
I had an old golf cart that did something similiar, but they had big resistors attached and was not very efficient.
In my experience, if I connect a 96V motor to a 48 volt supply, I will smoke it from too much current.
I have used a 48Volt controller and 48 volt battery bank, and I get smoke if I push it too hard( greater than 15 amps continuously)
I haven't tried direct connecting the batteries though.
Food for thought.
Mark
From: "kcr@kcrproducts.com" <kcr@kcrproducts.com>
To: electricboats@yahoogroups.com
Sent: Saturday, January 25, 2014 10:11:11 AM
Subject: [Electric Boats] RE: 48 volt solar panel array
To: electricboats@yahoogroups.com
Sent: Saturday, January 25, 2014 10:11:11 AM
Subject: [Electric Boats] RE: 48 volt solar panel array
I have a hybrid system on a Hughes 35.5. Diesel and 48v electric motor. I choose to skip the speed control and instead use battery switching. I have a bank of 4 12v batteries; two batteries are connected using a double pole double throw switch. Creating 2 banks with 2 batteries each. Using the DPSDT switch, each back easily switches from parallel(12v) to serial(24v). Adding another DPDT switch, I combined the the 2 banks and can now get parellel(24v) or serial(48v).
So I have three speeds for the motor 12v, 24v, and 48v. Batteries are serial or parallel dependent on switching
I can chose to run electric, diesel, both, or diesel charge.
In the charge mode I set the system to 24v and throttle back the diesel; since the 48v motor (now the generator) can run much lower rpm generating 27v (charging 24v batteries) then it would have to run to generate 54v (charging 48v batteries)
Cost is cheap - Switches about $35 each, Motor 48v 1000w - $360, I'm not sure why everyone doesn't do this.
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