Solar-Battery Load: Perfect Balance

[GILow]

Pps but fit a proper low speed pusher prop to the small engine otherwise you won't have the grip on the water that you need.


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[Matthew Dobrski]

Originally Posted by GILow

Ps. A64pilot is right. Ditch the big engine. My original river raft weighed 1. 6 tons and moved effortlessly with a 10 hp outboard and the raft pontoons were made from 44 gallon drums not lovely professional looking hulls like yours. We have friends with a 10 ton houseboat who move it around with a pair of 9 hp Yamaha engines no problem. Sheltered water makes life so much easier. I reckon a 6 hp would move your boat very easily.

Matt


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Whoa, my friend! This is not just a clunky floating house, she's making good 300-400 miles around during boating season. The weather is not always polite and sometimes I must push this toy against 50 km/hr wind and 3 ft. waves. In such conditions my electric engines (equivalent of 9HP at full throttle) will do not much, draining the batt in no time. Main 60HP Merc Big Foot engine does the job like a mad bull.

cheers,
Matthew

[Matthew Dobrski]

Dear dlymn,

... So your 40kw outboard drives you at 20km/h and you 1/2 kw motor drives you at 7km/h- amazing...

But true, If one can rely on build-in display with GPS measured speed and power consumption. The power/speed curvature is of relatively low climbing slope until some 8-9 km/h, after that it goes up like a rocket trajectory. The boat doesn't glide gracefully at 20 km/h like a slick clipper, it pushes a wall of water like a tug boat rather. The electric motor, however, is of 4kW power at full throttle, but most of the time it purrs at 10-15% to take the advantage of this particular property of my boat. And that's the whole idea ...

There is no such thing as a calm day. When you then put your dinghy in a 5 km/h heading breeze your 500w will be largely consumed countering this and so you will need to use more energy and so generate more power. If the tide is running against you, then more energy (if it's running with you, less) . If I am on open waters and floating, my GPS says I'm doing 1-2 knots on a "calm" day. That's current and breeze so light that you don't notice and not necessarily taking you in the direction you want to go.

Well, as you probably figured already, my boat never sees open sea. It's exclusively fresh water vessel, strong winds are avoided as much as possible, no tides, no currents. "Calm" water? Believe or not, on waters of my choice adrenaline rush is almost a welcomed attraction . About 75% of my boating season I will label as calm.

I would suggest that you do some detailed calculations on the cost/benefits of your project. We did this for the home system and found that the cost of batteries was greater than the savings made. This is not including the cost of panels and the risk of damage to them. Electricity storage has a very long way to go.

Indeed, one may wonder why bother. We all know that the enormous investment in home solar energy will never pay back, despite absurd advertising tales about selling the surplus. As for any mobile systems like mine, the cost of equivalent fossil fuel energy is ridiculously low, the weight of solar system to carry on the boat is plain stupid etc. But that's not the point.
See, anyone who ever experienced the joy of sailing in light summer breeze will understand the goals of my crusade. Personally I've found slow electric propulsion beneficial here and here only. Quiet, fumeless, peaceful ... And going, going, going like this Energizer Bunny ... Of course 400HP speed boat aficionados will never understand this philosophy .

Cheers,
Matthew

[Matthew Dobrski]

Originally Posted by dlymn

There is no such thing as a calm day. When you then put your dinghy in a 5 km/h heading breeze your 500w will be largely consumed countering this and so you will need to use more energy and so generate more power. If the tide is running against you, then more energy (if it's running with you, less) . If I am on open waters and floating, my GPS says I'm doing 1-2 knots on a "calm" day. That's current and breeze so light that you don't notice and not necessarily taking you in the direction you want to go.

Can't help but to post this pic. How do you call this weather?

Matthew.

[Matthew Dobrski]

[QUOTE=a64pilot;1682914]

Why such a big outboard? You do trim it out when under electric? Thought of selling it, losing a lot of weight with a smaller one? You would end up being faster on electric and use lots less gas when not etc. I think keeping your vessel as light as possible will go a long way towards making the electric thing work

Well, not really, dear a64pilot. See, the pair of Torqeedo Cruise 2.0 electric motors I have can push my boat efficiently at full throttle, but 4kW drain will empty no matter how huge battery bank in no time, 1 hour perhaps. In order to keep such system running on demand I will have to turn my boat into monstrous solar panels carrier. Which is no-no. That's why I keep my 60HP Big Foot Merc to provide strong push when needed. Again, the electric propulsion - in my case - is a relaxing alternative only and not the main drive. An outrageous luxury, one may say.

On the Chinese charger, just off the top of my head, I think the little Honda could run twice that size charger and LIFE batteries could accept the charge rate, but maybe it would be working hard and be loud, maybe 30 amp lets it purr along in Eco mode?

Again, not really. The charger delivers 30A max current, draining 11.5A off 13.5A rated output of Honda gen. Probably after bulk charge I will switch to ECO mode, but not when battery is drained to the bottom.

Cheers,
Matthew

[SunDevil]

Originally Posted by Matthew Dobrski

As for any mobile systems like mine, the cost of equivalent fossil fuel energy is ridiculously low, the weight of solar system to carry on the boat is plain stupid etc. But that's not the point.

If you need to move your boat everyday I bet it would be a better deal to invest in the solar/electric motor system after a few years. You at least have a good guess as to what your running costs will be in 10-20 years. The minimal maintenance and lack of needing to refuel are also two big advantages.

Originally Posted by Matthew Dobrski

See, anyone who ever experienced the joy of sailing in light summer breeze will understand the goals of my crusade. Personally I've found slow electric propulsion beneficial here and here only. Quiet, fumeless, peaceful ... And going, going, going like this Energizer Bunny ... Of course 400HP speed boat aficionados will never understand this philosophy .

I met this boat owner, and he sounds just like you. Cruising on calm days down rivers, lakes, and canals is the way to go. This concept can work on many different waterways around the world however. I just wish there were some boats that were designed for solar and electric motors instead of just adding them to existing boats and hoping they work well. Eventually, I would like to see a boat that can handle the Great Lakes and Gulf of Mexico that is a solar powered cruiser in lots of different conditions that could occur in Summer in Michigan and Winter in Florida, but that is getting off on a tangent.

[Pauls]

I like your boat. Your concept makes perfect sense for what you want.

As others have said, there is no firm target here for solar cell output. The more cells the more power. In bright conditons you'll go faster, when its cloudy you'll go slower. I'd just fit as many as you think is practical. Your .5 factor for rated to actual is probably a good basic assumption, you already know that actual is going to vary based on time of day, weather, etc.

I like canoes myself. I made a 500 mile trip down th Yukon river once, a great trip. I'm sure you have a lot of fun on your boat.

[Matthew Dobrski]

Originally Posted by SunDevil

I just wish there were some boats that were designed for solar and electric motors instead of just adding them to existing boats and hoping they work well. Eventually, I would like to see a boat that can handle the Great Lakes and Gulf of Mexico that is a solar powered cruiser in lots of different conditions that could occur in Summer in Michigan and Winter in Florida, but that is getting off on a tangent.

IMO this is "mission impossible", at least for now. The physics and chemistry of photovoltaic phenomenon is known for quite some time and there's no sign of radically new, way more efficient technology for sun energy harvesting. Yes, exclusively sun driven experimental vessels have been developed, some even cruised around this planet, but they're anything but boats as we know, and certainly not a family cruisers. The bottom line: unless you'll willingly compromise the sea-worthiness and the beauty of the cruiser, there's is no way to install enough PV modules to provide the power able to compete with diesel or gas propulsion. So, at this moment only an electric solar/diesel hybrid seems to be the way to go. Some nice boats are making a lot of buzz at the shows http://www.guyharveymagazine.com/topics/green-boating-products/first-real-solar-boat

[mitiempo]

Originally Posted by Matthew Dobrski

IMO this is "mission impossible", at least for now. The physics and chemistry of photovoltaic phenomenon is known for quite some time and there's no sign of radically new, way more efficient technology for sun energy harvesting. Yes, exclusively sun driven experimental vessels have been developed, some even cruised around this planet, but they're anything but boats as we know, and certainly not a family cruisers. The bottom line: unless you'll willingly compromise the sea-worthiness and the beauty of the cruiser, there's is no way to install enough PV modules to provide the power able to compete with diesel or gas propulsion. So, at this moment only an electric solar/diesel hybrid seems to be the way to go. Some nice boats are making a lot of buzz at the shows http://www.guyharveymagazine.com/topics/green-boating-products/first-real-solar-boat

The Greenline will travel only 20 miles @ 4 knots under electric power. Much longer @ 3 knots. In a reasonable current in my area that would mean travelling backwards, often at more than 3 knots.

[GrowleyMonster]

If you are okay with 3kt or less in calm water, solar electric can be quite practical, especially if the boat gets used a lot. For only occasional use, solar panels cost too much to use for propulsion, though they are great for trickle charging a house bank.

My boat is 27' and 7600lbs, and 500w gives me about 2.6kts. Well, 10a at 48v.

If you will continue to use the boat a lot, just get all the solar you can mount. And afford. And a cheap 2kw portable generator as a backup. And you might consider a large windcharger as well, to keep harvesting energy even at night.