Coastal Cruiser

go ahead and take his word on that one marko
I learned it the hard way

its not so hard to understand once its explained but until then its very counter-intuitive

 

I stand corrected in my previous post, Rick is right, providing the head on resistance is not too large.

I can answer the Q on expected life from a battery -

If you discharge a battery 100%, it may be recharged and used for 100 cycles
If you discharge a battery 50%, it may be recharged and used for 300 cycles
If you discharge a battery 10%, it may be recharged and used for 1000 cycles
If you discharge a battery 5%, it may be recharged and used for 2400 cycles

Just a hypthetical example, there are as usual a lot of facors that affect the life cycles of a battery, but you get the idea.
The battery manufacturer should be able to supply you with the specifics.

A car battery lasts so long because when you start it you use very little of it's capacity
The guy with a difficult starter that cranks a lot usually have battery problems also...

 

Marco, there are two "conservation of motion" laws: the conservation of energy and the conservation of momentum. Each of these has different consequences and together they determine the outcome of collision-type interactions. But there is no conservation of force law. You can increase or decrease force by use of levers, gears, screws, foils, pneumatic surface area, transformers, and other devices.

The problem of moving directly into the wind is a problem of force, not a problem of energy or momentum. There is no law that says "It takes X energy to move against the wind and you can only get Y energy out of the wind". The energy that it takes to move and the energy that you get out of the turbine are variables that depend on the design. You can't just "know" that the energy that it takes to move against the wind is greater than the energy that you get from the turbine.

This is a force problem. The wind produces a force against the vehicle and it also produces a drag on the turbine. In the other direction, the prop produces a force on the vehicle. All you have to do is find a design where the force of the prop is greater than total force of the wind. There is no conservation principle that says this is impossible. It is just a matter of getting the leverage right.

 

If you were after an economic solution for the next ten years I doubt you would consider solar seriously.

My interest is really to prove it not only possible but practical. It is an engineering challenge.

When you consider pleasure craft they get very little use. Even a motor car does not last very long in terms of actual operating hours. So mechanical life is not really a problem. On a boat, weathering is more significant. I would not have a boat I could not store under cover and preferably on dry land. More marinas now offer undercover storage for large boats even over the water.

I only have one 10W solar panel I play with. I do not have any on the house. From second hand information it seems that good ones give good life on boats. On the other hand I have read some sorry tails.

The lithium battery technology is in rapid development. Car manufacturers are putting a lot of money into them. I expect their life will not be in question once they are widely used in cars. If they do not make the grade then there will be something else. It is an area undergoing rapid development. The work cycle on a pleasure craft is likely to be quite low. For a boat that does 60 days a year cruising you could expect at most 60 deep discharge cycles. Will take a few years to get up to 1000 cycles.

With batteries most people relate their experience to car starters. This is horrendous duty compared with say the battery that keeps the watch going.

I have found the lithium batteries in computers are degrading over a couple of years. I do not know the cause of this. Li-Poly technology is not well regarded concerning life but there are other cell chemistries with better performance.

Rick W

 

Fanie
the batteries they use for home DC systems are large and very cost efficient pr amp hr of storage
might not meet the weight to storage capacity of some of the more modern ceramic or lithium or whatever batteries but kick the crap out of a car battery any day and actually cost about the same per amp hr

from thread located at http://www.boatdesign.net/forums/propulsion/these-turbine-alternaters-easy-make-26738.html


the gorilla of the battery world



3300 cycles 10 year life grantee 15 expected weighs 424 lbs costs ~$1200 each
8V
20 hour discharge available amps 820 41 pr/hr
12 hour discharge available amps 713 59.5 pr/hr
8 hour discharge available amps 640 80 pr/hr

 

Hi Fanie, I am interested to know whether this is the short circuit current, the few hundred milliAmpere you mentioned or the influx into the 12 V. battery ? If it is the short circuit current, the only way to have some pleasure from your panels is to switch panels in series to 48 or even 72 Volt (provided the MosFets or transistors in your regulator can cope with the higher voltage, when suddenly the sun breaks through and your electronic circuit is too slow i.e. milliseconds instead of Microseconds ) It is very easy done with a Microchip and a few good quality solid state relays or normal relays. By overcast, your paneloutput voltage drops below the battery voltage. Only by pushing up the voltage by placing them in serial will help you still to charge your battery somehow.
Will you let me know whether it was short circuit current or otherwise?. I need your input for my own project.

 

Fanie
a few dumb questions
are you keeping the panels clean
are there any overhead lines casting shadows on them
did the installers use antioxidant
braided or solid lines

your power output should be relative to candle strength so if you get a light meter and use it in conjunction with your volt meter you can check the health of your system relatively easily

B

 

I read what you say yet still don't get it.
Why is this possible yet it is not possible to recharge your electric car batteries with a turbine on the roof?

 

Who told you that you cannot charge the battery of the electric car with a turbine on the roof.

The turbine will produce a net benefit providing the apparent wind speed is greater than the vehicle speed divided by the turbine efficiency.

So lets say you have a turbine of 80% efficiency on the roof of the electric car doing 40mph. If the apparent wind is greater than 50mph then you will get a benefit. So you need wind over the ground from in front of the car of 10mph. If the wind is less than 10mph then the turbine will sap energy. The benefit will not be enough to keep the battery charged but the car will travel further on a charge.

If you go up to 60mph then the apparent wind needs to increase to 75mph or 15mph over the ground to get a benefit.

So the same physics apply with boat or car but a slow moving boat is likely to have favourable conditions more often than a fast moving car.

If you are happy to do 10mph in the electric car like the Aeolus racers then, in strong wind, a good size turbine could recover enough wind energy to actually charge the battery and propel the car.

Rick W

 

Hi Boston,

The battery voltage can only charge so high at 'ful' current, after that the battery draws what it wants. Then it is TIME over which the battery packs it's stamina in, and not the AMPS

I don't have battery or charger problems, sorry if I created that impression.



Any place where it is in the open to such an extent that you can sensibly use a wind power generator on a car, you can just as well just use sails. What is considered as moderate on water is very slow on land. The first wind generator propelled little car I find on the road crawling at 5km/hr is the one I'm going ti run over

 

I thought you were having a problem with the panels

my bad

B

 

Not really, I wanted them to supply 80 Amp for their size

 

Hi Fanie, May I have a reply to thread No 96. Much obliged.

Bert

 

dont do it Fanie its a trick

 

OK Rick, let see if I get this...if there is no wind at all, and my electric car/boat is chugging along on batteries (what else) and I erect a turbine, I am doing miself a disfavour, since the apparent wind is from my own production...right?
If I have a head wind of at lest 10 knts then I can charge batteries...makes sense?
Can I ask another question? a wind turbine that is 80% efficient, does it mean that it converts 80% of the wind energy into circular force and only transmits 20% to its structure?