Help on selecting wattage output for Wind Turbine Generator to charge my Trolling Batteries
CC4ME Registered Users Posts: 4 ✭
edited January 2021 in Wind Power Generation #1
I'm looking for help in rightsizing the wattage for a 24 volt VAWT Lantern style wind turbine to charge my two 12 volt deep cycle marine batteries (flooded lead acid), in a 24 volt configuration, to power my Minnkota trolling motor. Each marine battery is rated at 85 AH. The VAWT (with MPPT) I'm looking at has the following specs: Rated power:800W, Maximum power:1000W, Rated voltage:12V/24V, Start up wind speed:2m/s and Rated wind speed:11m/s. Wind speed at my target location just off Lake Erie typically ranges between 5-14 mph but can go above 20 mph. I've been told by my battery manufacturer (and from other sources) to keep the max charging amps less than 25% capacity or a max 21 amps to avoid damaging the battery. I normally take my boat out on the water on the weekends and looking to charge my trolling marine batteries in between outings. Currently, I have to either move my boat down the road to an electrical outlet to charge my trolling batteries or yank them and charge them at home I have looked at solar panels but have ruled them out due to certain constraints.
Given the above information, can someone recommend a wattage (e.g. 500W, 1000W, 1500W, etc) to me that will meet my requirements? Any tips on reliable VAWT's I should be looking at that aren't too pricy?
Any help would be appreciated.
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I will start by saying that I am NOT a fan of small wind power. My recommendation is to use solar panels to start--then if you wish, experiment with a wind turbine installation...
To your specific questions... I have not seen any VAWT (vertical axis wind turbines) that generate any useful amount of energy--And are mechanically reliable. I will admit that I do not follow wind turbines, so there may be some out that are good...
Next, notice the wind speeds... 2 m/s to 11 m/s (starting and max rated output). 2 m/s = 4.5 to 11 m/s = 24.6 mph. And in reality, most turbines (HAWT--Horizontal Axis Wind Turbines) start to generate "useful" amount of power around 10-12 mph.
Wind turbines (of any time) need "clean" airflow to harvest power. That usually means >500 feet horizontally, and a minimum of 30 foot tall tower, to get into the good wind... If you have a house/trees/etc. nearby, then the turbine needs to be mounted above those obstructions.
Turbines can be relatively inexpensive, but the cost of a tower (and concrete if free standing), having a tilt tower/crane/lift to service the turbine once a year, as well as wiring because you (generally) do not want the turbine near homes/yards with children because of noise and possible flying objects/falling nacelles.
Looking at an MPPT type charge controller can be a very good idea--It allows better energy harvest from variable wind conditions (matches the alternator torque/RPM curve against voltage*current (think the equivalent of an automatic transmission between the alternator and the battery bank). Depending on the turbine selected, and the support equipment available--There needs to be a method to control the turbine speed (not usually a problem for VAWT, big issue with HAWT) and battery state of charge... Either need to shut down the turbine and/or have a "dump load" (resistor bank) and dump controller to get rid of excess charging current during windy conditions and full battery bank.
If you are in a location that is "miserably windy" when you want to harvest energy (many hours a day)--A turbine may work for you. And you may wish to look at a home built wind turbine system. If you are near water--Conditions that give you good wind--Would also seem to cause rough water...
Do you know of anyone that has built and operated a wind turbine system in your neighborhood for the last 1+ years (and it would be great if they can give you daily or monthly harvest numbers).
Here are some links from our FAQ to (now ~10 year old) discussions and test results for small wind...
Wind Power Links
www.otherpower.com (good forum for DIY Wind Power)
Hugh Piggott - Scoraig Wind Electric site for tons of info (from mike90045)
Scoraig Wind "Recipe Book" for DYI Turbines (from Chris Olson... From his 4/11/2013 post)
www.greenpowertalk.org (added from "russ"--Like here but more wind/less solar)
Small windpower a scam ? Survey says SO
Truth About Skystream & SWWP
Windmax HY-2000 2kW Wind Turbine (apparently, some vendors don't sell spare parts--just new turbines. However, the owner, Edward has been very happy with its performance from 2010-2012--BB. 5/31/2012)
The "Small windpower a scam?" link has a test of 10 or so small wind turbines and their test results... And most of them barely produced any power...
If you can tell us (roughly) where you are at and when you want ... We can look at available wind and solar energy and help begin sizing the system for you.
Just to give you a minimum sized solar power system (I understand you have looked at solar, and probably cannot use it do to some constraints--But as an example)... 85 AH @ 12 volt batteries (2x) recharge at 5% rate of charge (5%, minimum, 10% to 13% rate of charge typical):
That is assuming you drain the FLA batteries to "dead"--Don't really suggest that--Typically to 50% and possibly down to 20% State of Charge for "true" deep cycle batteries.
- 2 * 85 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.05 rate of charge = 160 Watt array minimum
- 2 * 85 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 320 Watt array nominal
- 2 * 85 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.13 rate of charge = 416 Watt array "typical" cost effective maximum
Of course, the amount of sun you can harvest (location, season, weather, shadows, etc.) will also affect the amount of harvest/sizing of the array.
For example, say you get 3 hours of sun per day (spring/fall typical), and use 50% of your battery capacity per day (or per weekend):
If you want to recharge over 3 days:
- 2 * 85 AH * 12 volts * 0.5 SoC = 1,020 Watt*Hours per day (same as 1 string * 85 AH * 24 volts * 0.5 SoC = 1,020 WH per day)
- 1,020 WH per day * 1/0.61 DC system eff * 1/3 hours per day so-so sun = 557 Watt array (3 hour sun "break even")
I would suggest if you can install some sort of tower for a HAWT, you may be able to rack mount an 160-416 Watt solar array just about the same/or less money and hassles.
- 1,020 WH per day * 1/0.61 DC system eff * 1/3 hours per day * 1/3 days to recharge = 186 Watt array "break even" @ 3 hours of sun per day
One thing to watch out for... Most wind and solar systems do not like to have their Battery Banks disconnected while wind/solar charging... It can confuse/damage the charge controllers (or for VAWT allow to "overspeed"). If you are moving the batteries to the boat, then you need to first "shut down" the turbine/solar array first, then disconnect the batteries from the bus.
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
gen: http://tinyurl.com/LMR-Lister ,
You would need to limit current. VAWT do not really need RPM control (they can free run in windy conditions)--But if you choose a higher wattage unit, you will have to regulate current from the turbine and/or have a dump load approximately equal to the turbine rating (battery will only take a fraction of the current when >80% state of charge--So you need to limit so that the battery does not over heat and/or "boil" (excessive gassing) of the electrolyte.
- 85 AH * 29.5 volts charging * 0.20 rate of charge = 502 Watts into battery bank