How Much Energy Does Your Windgen Really Put Out?

[Dockhead]

I installed a Rutland 914i about a month ago for the purpose of keeping my batteries up on my new mooring on the Hamble. I have been quite disappointed in the real practical output from it and am wondering whether it is defective. What are you guys getting with yours in practical real-life use, and other wind gennies?

Last night it blew steadily all night -- average over 20 knots according to Bramblemet with gusts to 30. Which corresponded pretty well to what my instruments told me, although of course I am in a little more sheltered spot than the Bramblemet instruments.

In 8 hours of that my 914i only produced 8 amp/hours of power (at 24 volts), so an average of only 25 watts. At 19 knots, the old 913 was supposed to produce 90 watts; the 914i is supposed to produce 140 watts at 22 knots.

Is there really such a gap between theoretical and practical output of these devices? If so, I have to say, I wish I had gone solar instead. This thing, which was not so very cheap, won't even cover my refrigeration loads, and in a gale. During a typical summer with a lot of calms, I wonder whether it will even cover self-discharge and bilge pump.

 

[maxy]

Wind genny choice

Several wind genny manufacturers now quote monthly output for this very reason, as instantaneous readings are very misleading.

The Rutland seem good at producing small amounts in very light breezes, where the bigger brothers don't even start charging. The Rutland seems good for weekend sailing where the unit has time (say all week) to recover used amps.

If you want more substantial charging, my personal favourite is the Air-X, it has issues but produces the most power against cost. We also have an AeroGen4 which performs similarly to the Rutland, and we have a D400 which has proved less effective in practice than the Air-X

The German Superwind looks good on paper and uses a centrifugal controller rather than electronic, which I guess would be even more efficient.

 

[maby]

The (admittedly small number of) people I know with them all seem to be pretty disappointed, I'm afraid! They have a theoretical peak output that is high, but the amount of time they run anyway near that is small.

A couple of years ago, I bought a £50 solar panel from Maplins almost exactly the same time our neighbour in the marina purchased a Rutland costing many times that. Even throughout the winter months, our batteries were always better charged than his!

 

[Bosun Higgs]

the 914i is supposed to produce 140 watts at 22 knots.

Is there really such a gap between theoretical and practical output of these devices? .

I guess the answer is "yes". The manufacturers claims will be base on the instantaneous output at a certain speed and I doubt that they would tell porkies - that would be a quick way to shut the business. More likely your problem is sheltered location and the state of your batteries.

At 22 knots the charger should put 9 amps into your batteries provided they are at 12v which is 108 watts. Raise the battery voltage and the current drops off. Drop the windspeed and the output drops.

That said the difference between an output rate of 100 watts or so and your 25 watts is too big to be just wind shelter or voltage. Are you sure about the 8 aH? Do you mean 8 amps for an hour or an average of 8 amps each hour you were charging?

If it's any consolation, solar panels are no better at delivering their rates output. Just quieter.

 

[CreakyDecks]

According to this calculator
http://www.green-trust.org/windpowercalc/eindex.html
at the wind speeds you talk about you should get about 130W if the thing is just 25% efficient. Maybe it's not as windy as you think where you are?

As an aside:
When I spoke to an expert at the Centre for Alternative Technology about what the best thing to spend my money on in terms of "green power generation" he told me to forget it and spend the money on insulation, insulation and more insulation! Maybe you should improve the insulation on your fridge.

 

[ukmctc]

my jennies are producing 2.9 and 3.0 watts just now thats .29 and .30 amps, the solar is producing much more, 30 watts and 104 watts thats 2.9 amps and 8.00 amps.
my six 110 amp batteries are at 14.2v and stay there generally not going below 13.9v even under full load.
After talking to Lloyd West at Marlec I got both wind and solar , never looked back.

 

[Dockhead]

I guess the answer is "yes". The manufacturers claims will be base on the instantaneous output at a certain speed and I doubt that they would tell porkies - that would be a quick way to shut the business. More likely your problem is sheltered location and the state of your batteries.

At 22 knots the charger should put 9 amps into your batteries provided they are at 12v which is 108 watts. Raise the battery voltage and the current drops off. Drop the windspeed and the output drops.

That said the difference between an output rate of 100 watts or so and your 25 watts is too big to be just wind shelter or voltage. Are you sure about the 8 aH? Do you mean 8 amps for an hour or an average of 8 amps each hour you were charging?

If it's any consolation, solar panels are no better at delivering their rates output. Just quieter.

8 amp-hours over 8 hours, so an average of one ampere of usable power or 25 watts or so (since I am 24 volts).

 

[lw395]

You have to realise that the windspeed it sees is way less than a weather station, because it is lower, sheltered by a lot of other boats etc etc. Many are in the disturbed air from masts etc.
If you've ever tried sailing a small boat through a marina or around big moored yachts, you will see what I mean. It may work very nicely on a pole in the middle of nowhere, but function very poorly in turbulent conditions.

 

[maby]

You have to realise that the windspeed it sees is way less than a weather station, because it is lower, sheltered by a lot of other boats etc etc. Many are in the disturbed air from masts etc.
If you've ever tried sailing a small boat through a marina or around big moored yachts, you will see what I mean. It may work very nicely on a pole in the middle of nowhere, but function very poorly in turbulent conditions.

Exactly - I've stood in the cockpit of our boat watching the masthead anemometer show fifteen to twenty knots while the neighbour's windmill just ticks over at a very leisurly pace.

 

[chasroberts]

Exactly - I've stood in the cockpit of our boat watching the masthead anemometer show fifteen to twenty knots while the neighbour's windmill just ticks over at a very leisurly pace.

This could be because the batteries are charged and the system controller then reduces the speed of the turbine to avoid overcharging the system. As a Rutland owner I'm interested in the thread but never done a specific test on output instead relying on what the controller says. Don't seem to remember much of a problem with it though although I too have gone down the solar/wind combo path.

Chas

 

[catalac08]

I have had 2x913's for a few years now. I should really have bought an AIr-X or one of the other high output generators but I was concerned about the swinging radius of the bigger gennies being a safety hazard on a small boat. I rarely see anything like the claimed output from either but being relatively low down on poles at the stern this may be expected. The main thing is that the wind at stern level is about half of that at mast head, from simple measurements. One is linked to battery bank 1 via an HRSi regulator which has been fine and the other is linked to both banks via an HRDX regulator which also has been good. The whole setup works fine and kept the batteries at approx 12.9 year in year out except when we were on the boat when after about 10 days the batteries would start to suffer a little if the re was not much wind.
A year or so ago I fitted an 80W Solar Panel (e bay cheapo then £140 now £100)routed through the HRDX and most of the time this panel provides more charge than both the wind generators together. Even when it is overcast it often shows 2 amps and when at all sunny gives 4-5 amps much of the time. The batteries are maintained at 13.6V much of the time and we are now energy self sufficient however long we are on the boat at anchor etc.
I think from my limited experience that even in the UK solar is more cost effective than wind generators and for a boat a mix of both should be considered, depending on space and cash available.
If it was not such a fag taking off one of my generators I would sell it and buy another solar panel!

 

[CreakyDecks]

The internal impedance of the generator will be very small, maybe two ohms. That means that the resistance of the rest of the circuit has to be MUCH smaller than that, if it is one ohm the current will drop by a third. Possible causes of high resistance in the circuit are wires that are too thin for their length, dirty or loose connectors and partly sulphated batteries.
Apologies if this is stating the obvious.

 

[Marvyn]

I installed a Rutland 914i about a month ago for the purpose of keeping my batteries up on my new mooring on the Hamble. I have been quite disappointed in the real practical output from it and am wondering whether it is defective. What are you guys getting with yours in practical real-life use, and other wind gennies?

Last night it blew steadily all night -- average over 20 knots according to Bramblemet with gusts to 30. Which corresponded pretty well to what my instruments told me, although of course I am in a little more sheltered spot than the Bramblemet instruments.

In 8 hours of that my 914i only produced 8 amp/hours of power (at 24 volts), so an average of only 25 watts. At 19 knots, the old 913 was supposed to produce 90 watts; the 914i is supposed to produce 140 watts at 22 knots.

Is there really such a gap between theoretical and practical output of these devices? If so, I have to say, I wish I had gone solar instead. This thing, which was not so very cheap, won't even cover my refrigeration loads, and in a gale. During a typical summer with a lot of calms, I wonder whether it will even cover self-discharge and bilge pump.

I'm having the same problem! Had it 8 months and it hasn't produced more than 0.7amps per hour yet. It's not my location. Tried everything. I have to send it back though it seems that's just the way it is. Haven't seen a good post yet. The marlec team are always reluctant to give me answers. I've been very patient but now I feel I may have to complain!

 

[yatch lover]

marine wind turbine V400 output

Sailors tend to think in Amps and Knots. Many wind generator companies are focused on land-based applications, and give performance charts which are based on "average annual windspeed" or "lab results" or similar jargon which can be confusing to us sailors. Sailors want to know what to expect on a real yact on real water. So, what kind of performance can you really expect with our unit? Our real world observed figures, below, are taken aboard a 44' sloop, at anchor, with a 400 Amp-Hour battery bank in a discharged state, and a continuous load from various on-board systems:

V400 output according to wind speed:

• 5 knots - <1 Amp
•10 Knots - 7 Amps
•15 Knots - 14 Amps
•20 Knots - 19 Amps
•25 Knots - 24 Amps
•30 Knots - 27 Amps

You can get more info from www.newmeilwindturbine.com