Myles: Thanks so much for that chart. It's exactly what I was looking for. It seems to correspond pretty closely to what I think is happening too. You are right it takes a good breeze to get that first amp. But, all amps are good if it's coming off the wind IMO. When I first hooked up the wind generator I used a 10 amp ammeter. But, could barely see the meter kick at low amps. So I swapped it out for a 5 amp and that helped a lot. Yes, I won't be able to see the max amps of 8.3 but, that happens so rarely I don't feel it's important. I have seen the meter peg one or two times but, only briefly and that was very rare and VERY windy.
Most times I see it kicking up to an amp or two sometimes three in a good blow. It's all good! I did have a wind energy Ephphiany a few weeks ago while riding out the gusts of Hurricane Earl. The wind was cranking but, my Marine AirX was stopped because naturally the 48 volt bank was topped up and the AirX senses this and stops. I thought what a waste to have all this wind energy going by the boat and I could not use it. Then I remembered the 48 volt to 12 volt Sevcon converter I bought with my electric propulsion system but, never connected. So I hooked it up to the 48 volt output of the solar solar controller in the cabin and used the wind energy (via the 48 volt battery bank) to power my laptop and save the 12 volt battery bank to keep the important things like the freezer operating. The solar panels do a good job of keeping up th 12 volt bank usually. But, the laptop draws as much amps as the freezer. By using the excess wind power to power the laptop means I don't have to run the Honda generator as much either to charge the 12 volt bank. I don't know why I did not think of this before. In fact it's working for me right now as I wait here at anchor for the winds to drop and change direction so I can cruise on. Again thanks for the wind vs current calculations. Now I can also use my Pak Traker current readings to get a feel for the winds without getting wet or cold venturing out into the cockpit to read the ammeter too! Capt. Mike
--- On Mon, 10/4/10, Myles Twete <matwete@comcast.net> wrote:
From: Myles Twete <matwete@comcast.net>
Subject: RE: [Electric Boats] 48 volt wind Generator current vs wind speed
To: electricboats@yahoogroups.com
Date: Monday, October 4, 2010, 7:10 PM
The power available from the wind is proportional to the cube of the wind speed. Here's a rough estimate for you then: | Wind Spd | Pwr (watt) | Curr (amp) | | 28mph+ | 400 | 8.3 | | 26.8 | 350 | 7.3 | | 25.4 | 300 | 6.3 | | 23.9 | 250 | 5.2 | | 22.2 | 200 | 4.2 | | 20.2 | 150 | 3.1 | | 17.6 | 100 | 2.1 | | 14.0 | 50 | 1.0 | | 11.1 | 25 | 0.5 | | 8.2 | 10 | 0.2 | It's interesting to me that one of the big sell points as I recall for the AIR-X vs the AIR403 was that it would put out power at a slower wind speed. The table above seems to indicate that there's not really much use in deploying the windmill under 14mph, so it's kind of funny that they'd talk about delivering power at 7mph. I recall that when I had my AIR403 on my boat there was one day when I was being blown upstream with a nice following wind, perhaps 12-15mph…looking at my Link10 Emeter, the current delivered to my 36v pack from the wind generator only ever reached between 0.5 and 1.5amps---i.e. only delivered about 50watts max…OTOH, it was free with the added benefit of getting some extra push from behind. -Myles From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of Mike
Sent: Monday, October 04, 2010 9:56 AM
To: ELECTRIC BOATS
Subject: [Electric Boats] 48 volt wind Generator current vs wind speed I just had a frustrating call to Southwest Wind Power technical support. Since I am laying at anchor waiting for a weather window in windy nasty conditions. I thought I would try and get some numbers regarding current vs wind speed for my 48 volt Marine AirX wind generator. Apparently Southwest Wind Power does not have these numbers. The rep did say that the generator would max out at 8.33 amps in 28 MPH winds. OK. But, I was looking for the approximate wind speed numbers for 1,2,3,4 and 5 amps. Am I asking too much in trying to cross reference the current readings on my ammeter to the approximate wind speed? |
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