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gotwind
Forum Admin
United Kingdom
755 Posts |
 Posted - 28/07/2007 : 14:31:57
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I have been asked to include a Frequently asked questions page (F.A.Q)
As you can imagine, this would be a huge amount of work for me as the subject is so broad, but very worthwhile for new visitors.
What I propose is: if any of the members on this forum can contribute a number of questions and answers to a 'typical newbie' question, please could they add it to this posting.
This would be the best way of getting a wide range of questions, and answers.
I will then check them all, edit if necessary and repost here, and on a page on gotwind.
e.g.
Q:Will a 100 watt generator be enough to power all my domestic electricity needs?
A: No,a 100 watt generator would typically be used for maybe powering small lighting requirements e.g. 4 fluorescent lights switched on for an evening.
The Futures Green - Getwind of it.
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ll81
Junior Member
124 Posts |
Posted - 29/07/2007 : 11:15:46
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I have been asked alot 'why do I need a 30 amp fuse to my inverter when the plug to my telly only has a 5 amp fuse in it.
And the answer (in simple form)
The inverter uses a technique that turns the battery DC to AC and passes it through a transformer. The current from the battery will be a proportionate to the voltage ratio of input to output. For instance a 12v-240v inverter multiplies the voltage 20 times so the current is divided 20 times. Every amp at the output needs 20 at the input. This is also why you need thick cable to the input and can't use normal 240v exstension cable to connect the inverter to the batteries.
For 12v inverters a good rule to follow is use
300w use 8 gauge 30 amp fuse
600w use 6 gauge 70 amp fuse
1000w use 4 gauge 120 amp fuse
If you are using more than a meter of cable use the next size up, IE 300w use 6 gauge but still 30 amp fuse. For 24v inverters the current draw is 1/2 so you can use 8 guage on a 600w inverter with a 30 amp fuse.
Try to use AGU type fuses and holders above 20 amps as the push in leg type (used in cars) do not handle sustained current draw and will melt the holder.
woo-hoo |
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spumanti
Starting Member
Denmark
4 Posts |
Posted - 03/08/2007 : 09:53:21
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Nicely explained there ll81.
Maybe it would be useful to inclyde something about Ohm's law as well:
P=U*I
P - power/effect (watt)
U - voltage (volt)
I - current (ampere)
Basically the formula explains the relationship between the three.
to get -say 10 watt- effect from a 12 V source, you will drain 0,833 A from the source. P=U*I => I=P/U => I=10/12=0,833 A
to get 10 watt from a 230 V source, you will drain 0,0434 A from the source. I=10/230=0,0434 A
there's no place like 127.0.0.1 |
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ll81
Junior Member
124 Posts |
Posted - 03/08/2007 : 17:13:46
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I was keeping it simple.
For the technically minded Ohms law is expressed as I=E/R. Where I = current in Amperes E = electro motive force in Volts and R = resistance in Ohms. It expreses that current, voltage and resistance are inveresly proportionate to each other. If one volt were across 1 ohm one ampere of current would flow and one watt of power would be dissipated. By knowing any two you can work out the others
E/I=R
E/R=I
E2/R=P
E2/P=R
I2*R=P
I*E=P
P/I=E
P/E=I
P/I2=R
P/R=I2
P*R=E2
They seem hard at first but they are simple really. We use these laws hundreds of times when designing circuits. They are the building blocks of electronics. Enjoy
woo-hoo |
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Liparis
Starting Member
Ireland
5 Posts |
Posted - 05/08/2007 : 16:16:00
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Hi,
I've just joined.
How about beginners and techno-idiots like myself put forward questions, I have thousands, and some of you experienced guys put up your answers? It would of course require answers in plain down-to-earth language that an eejit like me can understand. I know what I want, but haven't a clue how to work out what I need!
Earth is the insane asylum of the Universe.
www.species-specific.com |
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gotwind
Forum Admin
United Kingdom
755 Posts |
Posted - 06/08/2007 : 21:54:34
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Liparis.
Please put forward your questions,
I'm sure we will all try and answer them.
Ben.
The Futures Green - Getwind of it. |
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BushWhacker
Junior Member
Canada
254 Posts |
Posted - 14/08/2007 : 07:49:42
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Some good reading for anyone, but especially those just starting out.
Home Power is based in the US but the principals apply everywhere.
If you are new to the renewable energy path there are links on the left (scroll down a wee bit) called "Just Getting Started?"
http://www.homepower.com/
Cheers!
BW
Think about how stupid the average person is; now realize half of them are dumber than that.
- George Carlin |
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BushWhacker
Junior Member
Canada
254 Posts |
Posted - 14/08/2007 : 09:14:55
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VAWT design question.
At a given wind speed (say 15 mph) if you increase the diameter of a VAWT it will increase the torque available to the output shaft. I'd imagine that the RPM of the impeller would drop as well. Has anyone found data that would help one decide where the cross over point is for optimum power output?
That little VAWT that Gotwind built
http://www.youtube.com/watch?v=fLKavEd3WgA
would probably spin like the dickens until you put much of a load on it.
If one were to space the same sized "blades" out farther (5 ft diam perhaps?) with more blades (12?) how much would RPM suffer? Would the increase in torque compensate to allow one to gear up the output shaft speed?
Things that make me go HMMmmm?
Cheers!
BW
Think about how stupid the average person is; now realize half of them are dumber than that.
- George Carlin |
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Peter Williams
New Member
United Kingdom
51 Posts |
Posted - 14/08/2007 : 10:42:00
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Got loads of basic questions so I'll try and list one regularly so it can be answered.
What are the fully charged and flat/fully discharged voltages for 12v and 6v batteries?
What sort of information will a multimeter give me about a solar panel/wind generator? (and how?)
If a higher voltage (eg 15v) is used to charge a 12v battery, how do I stop damaging the battery with excessive charge when the battery is fully charged?
I have a solar panel and a charge controller, will this regulate the charge from my wind turbine also if added to the system?
I have 2 12v 85amp/hr leisure batteries and want to link them, how do I do this and does it require a certain size cable for safety?
More to follow later. |
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ll81
Junior Member
124 Posts |
Posted - 14/08/2007 : 17:08:44
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10.5v is dead flat for a 12v and 5.2 for a 6v.
I am currently building a 'novice' buildable load controller that can be built on strip board for a couple of quid, should have pics and design on forum this evening.
A charge controller will regulate as two at once with one circuit if it is a consumption and not resistance type controller.
For batteries link Positive-Positve, Negative-Negative for more voltage link the positve of one to the negative of the other and draw current from the remaining nodes. For high current loads (1000 watt inverter) use 4 guage cable.
woo-hoo |
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gotwind
Forum Admin
United Kingdom
755 Posts |
Posted - 14/08/2007 : 20:40:59
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quote:
Originally posted by Peter Williams
What sort of information will a multimeter give me about a solar panel/wind generator? (and how?)
The multimeter will indicate voltage across the Solar panel or battery terminals and current through the positive wire to a load - DONT EVER TRY TO TEST CURRENT ACROSS A BATTERY - it will pop the fuse instantly..
If a higher voltage (eg 15v) is used to charge a 12v battery, how do I stop damaging the battery with excessive charge when the battery is fully charged?
At low current,(about a 10th of the battery's total capacity) it is not really a problem - e.g. a 10 amp/hour lead acid battery being charged by a maximum 1 amp of current.
A safer alternative and at higher charge currents requires a charge controller.
I have a solar panel and a charge controller, will this regulate the charge from my wind turbine also if added to the system?
No, wind turbines don't work with solar regulators, they just disconnect the power, and this allows the turbine to become unloaded, and can spin up to dangerous speeds, a bespoke regulator with the suitable 'dump load' is needed.
I have 2 12v 85amp/hr leisure batteries and want to link them, how do I do this and does it require a certain size cable for safety?
Thicker cable the better (Car battery thickness) connected in parallel for a 12 volt system.
More to follow later.
The Futures Green - Getwind of it. |
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Peter Williams
New Member
United Kingdom
51 Posts |
Posted - 17/08/2007 : 20:47:53
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Could I be harmed with a 12 volt battery bank system?
What does start up and rated speed mean when looking at wind turbines? and why is it alway meters per second?
Do I need planning permission to erect a small scale wind turbine?
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Phil Martin
Starting Member
23 Posts |
Posted - 17/08/2007 : 21:00:24
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Hi Peter
A few years ago now, I was testing one of the big 5000 watt Genny's at work and as I turned the key switch, one of the 160 amp batteries in the bank exploded, some guys close to the Genny house rushed in to find me dazed and confused but thankfully unharmed !! The explosion outside sounded like a shotgun being shot, I was told and the cause a build up of Hydrogen gas in one/two of the cells(check weekly your water levels).
Since this I am very wary of batteries.
See you Phil |
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ll81
Junior Member
124 Posts |
Posted - 18/08/2007 : 00:21:15
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Agreed, gasses given off by charging cells are highly explosive. 12v voltage wise won't hurt you. You can have serious burns if you happen to have a watch on that shorts the terminals or holding a spanner that gets shorted across the terminals.
woo-hoo |
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Peter Williams
New Member
United Kingdom
51 Posts |
Posted - 20/08/2007 : 12:26:44
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| car batteries are cheaper and easier to access than leisure batteries, would they be anygood for small scale applications? Can they be mixed with leisure batteries? |
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ll81
Junior Member
124 Posts |
Posted - 20/08/2007 : 16:32:42
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The ideal charging voltage for lead acid automotive is 14.4v and 15v for leisure. It is worth noting that although you can get leisure batteries at 70AH they are rated at low current draw over a long time. A 110ah tractor battery will give high current output if needed. On the flip side continual charge and discharge will soon damage it, but so will high current draw from a leisure battery. For small scale go with leisure batteries.
woo-hoo |
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Topic |
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FAQ page - help please
