The battery thread...some facts please

To be clear, the original estimate on the 25kw system was for a system that produced 25kw in a days time.

The post just before yours was a system that would use 30kw an hour, times 24 hours in a day. Mirroring using the engine continuously, say during a delivery or while becalmed.

Sorry for any confusion, this is why I went to law school, and am not an engineer.

 

Oh,remember one thing... A big thing. The sun is a moving target. Unless you do something very mechanical/electronic moving of panel the best you get at any given time is about 50%, except when the sun is vertical. Any shadow or partial coverage greatly reduces output. So you really only get may be 50% of panel usage and only for about 6 hours a day. Make sure you figure these into yours calcs.

 

Kilowatts, abbreviated "kW", is a unit of power and is an instantaneous quantity.

Kilowatt-hour, abbreviated, "kWh or kW h", is a unit of energy. 1 kilowatt-hour is 1 kilowatt for 1 hour. It is also 0.1 kilowatt for 10 hours and 10 kilowatt for 6 minutes.

 

I feel like I wrote this: http://www.boatdesign.net/forums/hybrid/battery-thread-some-facts-please-41978-4.html#post536551 in vain...

 

Yes you did, but sometimes repetition facilitates learning.

 

I feel your pain.

Despite all the posts,on a regular basis someone comes on and asks the same questions about this electric yacht and "hybrid" foolishness that could be gotten with a 2 minute search on the site or google.


Maybe a sticky thread with all the pertinent posts?

 

Stumble
Great logic...can I ask you a favour...purely as a sample of one so not staking any claims on it...can you please record how much of the journey you do under wind power and how much you do under diesel power. Like I say...only a sample of one journey so I am not going to make a judgement based on that, but it's good to have real life example. The thing I keep saying to everyone about hybrid propulsion is that if you sail then it's hybrid propulsion regardless of if the engine is diesel, petrol, nuke, hydrogen, anything. That's the great thing about sail boats...we have the best hybrid powered vehicles on the planet. This from a Prius owner!
Appreciate everyone's input.

Mick

 

Mick,

We will have the sails up the entire way, and the generator on, so I don't think this trip is going to be a very good indicator of much. In my years down island though I would guess we sailed about half the time, and motored the rest, but most long trips were done with a combination of motorsailing and pure sailing. This is pretty common practice for cruisers, since often there are restraints on when you can cross channels, sand bars and the like.

Some harbors for instance are inside unmarked channels, which makes a night approach impossible for a sail boat. So you time it to arrive at the channel around 10am when the sun is overhead, and seeing coral heads through the water is easier. If you get there early you just have to circle the reef until the right time, and if you get there late, you have to spend another day at sea, since a lot of places don't let you anchor freely.

Personally I don't see hybrid propulsion as a realistic option for anything but cruise ships, or very specific designs, which exclude almost all cruisers.

 

So, could I spend thousands on a genset, more on a heavy battery bank and then engineer an electric motor with a speed controller in order to turn a prop?

-Tom

 

"I don't see hybrid propulsion as a realistic option for anything but cruise ships, or very specific designs"

Some harbor tugs are being converted , loiter with almost no power , added push when needed.

Until batteries improve by 100% or better 1000% their use on pleasure boats will be limited to the current roles.

FF

 

"current roles" good pun!

-Tom

 

Fast Fred,

Those harbor tugs are typically using two or more generators coupled to one drive motor. The small genet is used when the tug is just moving along, and the big one gets cranked up for towing. The advantage is that when just moving around these tugs use a fraction of the power they need when under tow, and can use a odor sized to that requirement.

Private boats rarely see such massive disparities in necessary power output. At least for long periods of time.

 

They also have massive propellers that need tremendous torque at slow speed. Typically they use big gears for reduction, but then they are inefficient at higher speeds. Hence another advantage of of Diesel/Electric in a tug.

 

Private boats rarely see such massive disparities in necessary power output. At least for long periods of time.

Yet folks want refrigeration ,music , TV and some need air cond , really minor loads compared to using an aux sail boat or small vessel underway.

Maybe a 4hp diesel in a sound box and AGM's for life aboard?

 

Thats how I roll