By Jay Yarow
Here's a weird one. Preliminary research coming out of Iowa State University is showing that peak wind speeds have been slowing since 1973 across the East and the Midwest.
The slow down in wind speeds is bad news for anyone hoping to get more electricity from wind turbines. According Jonathan Miles, of James Madison University (who didn't write the study), a 10% drop in wind speed is equal to a 30% drop in how much energy can be gained.
Strangely enough, there might be a relationship between the rising temperature of the planet and dip in wind speed. Wind races across ice much quicker than it does across water. On the Great Lakes, there is less ice now, which could be part of the reason for a slowing in wind speeds.
It's not just a local phenomenon. Wind speeds are slowing globaly, and a heating planet might be causing this as well. The temperature difference between the poles and the equator is shrinking, which means a drop in air pressure. That means wind speeds could decline.
The relationship between global warming and wind speeds is not definitive, but it's an idea that's floating out there.
Studying change in wind speeds is fraught with complications. The locations where wind information is gathered are victim to possible changes like trees growing to block wind, which could affect the data.
The full study will be released in August in the peer-reviewed Journal of Geophysical Research.
Thursday, June 11, 2009
Wednesday, June 10, 2009
Tal-Ya Water makes the most of dew
Karin Kloosterman June 04, 2009
The ancient Israelites used stones to collect dew from the air, now the modern ones are taking the idea further. A new Israeli company Tal-Ya Water Technologies, which launched in May, promises to squeeze dew from the air for watering crops where water resources are precious or scarce. This new invention has a number of ecological benefits that go beyond simple water savings. For about $1 a piece, per plant, a square serrated tray made from a special plastic composite sits directly on the ground. The reusable tray is fitted with a hole in the center for a plant to grow. Using non-PET recycled and recyclable plastic with UV filters, and a limestone additive, Tal-Ya's trays do not degrade in the sun or after the application of pesticides or fertilizers.
An aluminium additive helps the trays -- about 70 cm by 70 cm for a pepper plant -- respond to shifts in temperature between night and day. When a change of 12 degrees centigrade occurs, dew forms on both surfaces of the Tal Ya tray, which funnels the dew and condensation straight to the plant and its roots.
The trays are also made in larger sizes for trees, Avraham Tamir, the company head and inventor tells ISRAEL21c.
Weeds out weeds, uses less water and fertilizer
"Using our system has a number of benefits," Tamir says. Farmers don't need to worry about weeds because the trays block the sun, so weeds can't take root. "Farmers need to use much less water, and in turn much less fertilizer on the crop," he explains. Less fertilizers and pesticides means less groundwater contamination.
Locking together like pieces of LEGO, special sections of the tray make space for irrigation and watering equipment to fit into the solution.
Field tests in Israel with the Ministry of Agriculture suggests whopping water savings of up to 50 percent of irrigated water by using the Tal-Ya system.
"Dew collection starts at night," Tamir says. "The critical mass goes down below," he explains while pointing to the serrated edges of the trays. If it rains, we can amplify 1 mm of rain so that it equals 27 mm."
Protection from extreme temperature change
Water from dew and condensation is in effect distilled water. Adding this to the soil alleviates the salinity from irrigation, says the company. The trays also protect crops from extreme shifts in temperature, like in Canada or the United States where late and early season frosts put some crops at risk.
Of course, "the amount of water collected depends on location," Tamir points out. Humidity factors, temperatures and precipitation are important to consider.
Founded four years ago and based in the village of Gan Yoshiya in Israel, research collaboration to help build Tal-Ya which means "God's dew" in Hebrew, came from the Hebrew University, the Ministry of Agriculture, the Volcani Institute and Ben Gurion University.
Tal-Ya launched its new product at the Agritech exhibition in Tel Aviv. Tamir says he is now selling his product to Israeli farmers, and looking forward to international buyers from America.
The ancient Israelites used stones to collect dew from the air, now the modern ones are taking the idea further. A new Israeli company Tal-Ya Water Technologies, which launched in May, promises to squeeze dew from the air for watering crops where water resources are precious or scarce. This new invention has a number of ecological benefits that go beyond simple water savings. For about $1 a piece, per plant, a square serrated tray made from a special plastic composite sits directly on the ground. The reusable tray is fitted with a hole in the center for a plant to grow. Using non-PET recycled and recyclable plastic with UV filters, and a limestone additive, Tal-Ya's trays do not degrade in the sun or after the application of pesticides or fertilizers.
An aluminium additive helps the trays -- about 70 cm by 70 cm for a pepper plant -- respond to shifts in temperature between night and day. When a change of 12 degrees centigrade occurs, dew forms on both surfaces of the Tal Ya tray, which funnels the dew and condensation straight to the plant and its roots.
The trays are also made in larger sizes for trees, Avraham Tamir, the company head and inventor tells ISRAEL21c.
Weeds out weeds, uses less water and fertilizer
"Using our system has a number of benefits," Tamir says. Farmers don't need to worry about weeds because the trays block the sun, so weeds can't take root. "Farmers need to use much less water, and in turn much less fertilizer on the crop," he explains. Less fertilizers and pesticides means less groundwater contamination.
Locking together like pieces of LEGO, special sections of the tray make space for irrigation and watering equipment to fit into the solution.
Field tests in Israel with the Ministry of Agriculture suggests whopping water savings of up to 50 percent of irrigated water by using the Tal-Ya system.
"Dew collection starts at night," Tamir says. "The critical mass goes down below," he explains while pointing to the serrated edges of the trays. If it rains, we can amplify 1 mm of rain so that it equals 27 mm."
Protection from extreme temperature change
Water from dew and condensation is in effect distilled water. Adding this to the soil alleviates the salinity from irrigation, says the company. The trays also protect crops from extreme shifts in temperature, like in Canada or the United States where late and early season frosts put some crops at risk.
Of course, "the amount of water collected depends on location," Tamir points out. Humidity factors, temperatures and precipitation are important to consider.
Founded four years ago and based in the village of Gan Yoshiya in Israel, research collaboration to help build Tal-Ya which means "God's dew" in Hebrew, came from the Hebrew University, the Ministry of Agriculture, the Volcani Institute and Ben Gurion University.
Tal-Ya launched its new product at the Agritech exhibition in Tel Aviv. Tamir says he is now selling his product to Israeli farmers, and looking forward to international buyers from America.
Everybody Wants A Solar Panel On The Roof
Everybody Wants A Solar Panel On The Roof
Jay Yarow|Jun. 9, 2009, 5:28 PM|comment1
PHILADELPHIA (Reuters) - U.S. demand for residential solar power installations is surging despite an economic recession, thanks to government financial incentives, some easing in credit availability, and increasing public recognition of its environmental benefits, industry executives said Tuesday.
Companies represented at the PV America solar conference in Philadelphia said the volume of their installations as much as tripled in 2008 and they see further gains this year as more people recognize that they can cut their electricity bills by at least 15 percent with an array of solar panels installed on the roof of their homes.
Geogenix LLC, a New Jersey-based residential solar company with 20 employees, installed about 150 systems in the first six years of its existence until 2008, and expects to do about that number this year alone, said managing member Gaurav Naik. He predicted the company would install at least 300 systems in 2010 when it plans to expand into Pennsylvania and some surrounding states.
"There is unprecedented demand for residential solar systems," he said.
Faced with a cost of about $50,000 for installation of a 7-kilowatt system on a typical 2,500-square-foot house, a New Jersey homeowner can defray the expense with a $12,500 rebate from the state and a federal tax credit of $11,000, Naik said.
After the first year, the homeowner can also expect a refund check for about $3,200 from the local utility in return for installing the solar panels, Naik said. The owner can expect to save about $1,700 a year in electricity bills, and should recoup the initial investment within five to eight years, he said.
According to industry trade group the Solar Energy Industries Association, there was an overall 16 percent increase in solar capacity, including commercial installations, in 2008.
Jeffrey Wolfe, chief executive of Vermont-based installer groSolar, said the market has also been boosted by lower prices for solar panels due in part to an increase in the supply of the polysilicon, the raw material used for their construction.
Wolfe argued the industry is benefiting from a cultural change that is more accepting of the need to find alternatives to fossil fuels, in part because of last year's surge in gasoline prices to more than $4 a gallon.
"People have seen what energy prices can do, and they have come to the end of their rope in denying climate change," Wolfe said.
Companies are also getting creative in bringing the upfront costs of solar power down for customers. groSolar, for one, is providing financing to customers who are unable to front the $40,000-$50,000 price tag for a typical solar installation. Wolfe's company now operates a lease program requiring a down payment of $1,000 and then regular monthly payments for use of the system.
In California, Arizona and Oregon, SolarCity installs systems without any down payment from the customer, who then pays a lease fee which typically ranges from $25 to $60 a month, said David Arfin, vice president of customer financing. The company owns and maintains the system but the homeowner benefits from the reduced utility bills, he said.
Arfin said the company's business tripled in 2008, and it is hiring 100 new installers to help meet "massive" demand.
Naik of Geogenix said financing for solar installations has gotten easier for qualified borrowers since the first quarter of 2009. He cited one client with a high 740 credit score who needed to borrow $38,000 and secured a 10-year loan at prime plus 2 percent by working with a financial institution that had previously done business with the company.
Jay Yarow|Jun. 9, 2009, 5:28 PM|comment1
PHILADELPHIA (Reuters) - U.S. demand for residential solar power installations is surging despite an economic recession, thanks to government financial incentives, some easing in credit availability, and increasing public recognition of its environmental benefits, industry executives said Tuesday.
Companies represented at the PV America solar conference in Philadelphia said the volume of their installations as much as tripled in 2008 and they see further gains this year as more people recognize that they can cut their electricity bills by at least 15 percent with an array of solar panels installed on the roof of their homes.
Geogenix LLC, a New Jersey-based residential solar company with 20 employees, installed about 150 systems in the first six years of its existence until 2008, and expects to do about that number this year alone, said managing member Gaurav Naik. He predicted the company would install at least 300 systems in 2010 when it plans to expand into Pennsylvania and some surrounding states.
"There is unprecedented demand for residential solar systems," he said.
Faced with a cost of about $50,000 for installation of a 7-kilowatt system on a typical 2,500-square-foot house, a New Jersey homeowner can defray the expense with a $12,500 rebate from the state and a federal tax credit of $11,000, Naik said.
After the first year, the homeowner can also expect a refund check for about $3,200 from the local utility in return for installing the solar panels, Naik said. The owner can expect to save about $1,700 a year in electricity bills, and should recoup the initial investment within five to eight years, he said.
According to industry trade group the Solar Energy Industries Association, there was an overall 16 percent increase in solar capacity, including commercial installations, in 2008.
Jeffrey Wolfe, chief executive of Vermont-based installer groSolar, said the market has also been boosted by lower prices for solar panels due in part to an increase in the supply of the polysilicon, the raw material used for their construction.
Wolfe argued the industry is benefiting from a cultural change that is more accepting of the need to find alternatives to fossil fuels, in part because of last year's surge in gasoline prices to more than $4 a gallon.
"People have seen what energy prices can do, and they have come to the end of their rope in denying climate change," Wolfe said.
Companies are also getting creative in bringing the upfront costs of solar power down for customers. groSolar, for one, is providing financing to customers who are unable to front the $40,000-$50,000 price tag for a typical solar installation. Wolfe's company now operates a lease program requiring a down payment of $1,000 and then regular monthly payments for use of the system.
In California, Arizona and Oregon, SolarCity installs systems without any down payment from the customer, who then pays a lease fee which typically ranges from $25 to $60 a month, said David Arfin, vice president of customer financing. The company owns and maintains the system but the homeowner benefits from the reduced utility bills, he said.
Arfin said the company's business tripled in 2008, and it is hiring 100 new installers to help meet "massive" demand.
Naik of Geogenix said financing for solar installations has gotten easier for qualified borrowers since the first quarter of 2009. He cited one client with a high 740 credit score who needed to borrow $38,000 and secured a 10-year loan at prime plus 2 percent by working with a financial institution that had previously done business with the company.
Monday, June 8, 2009
Only 6% Of Coal In The Biggest Beds Can Be Pulled Profitably
Only 6% Of Coal In The Biggest Beds Can Be Pulled Profitably
Jay Yarow|Jun. 8, 2009, 9:22 AM|comment3
There's a vast supply of coal in the United States, but only a sliver can be pulled from the ground profitably. Just 6% of the coal that exists in the primary coal beds in the U.S. can be extracted at prices even higher than today's, the Wall Street Journal reports.
What's it mean? For the nation at large, not too much. Individual power companies could be stung, though.
As it stands now, the EIA says that the U.S. has enough coal to power the country for 240 years. David Rutledge, a professor at the California Institute of Technology, who studies coal says it might only last 120 years. Projecting anything 100 years into the future is pretty silly.
In 120 years the mix of energy in this nation will be considerably different. So, unlike oil, there isn't a pressing need to change course quickly. The current plan to diversify through wind, solar and nuclear, should work well in the next 100 years.
As for the power industry:
In the field, challenges are becoming more apparent. Mining companies report they have to dig deeper and move more earth to extract coal from aging mines, driving up costs. Utilities have grown skittish about whether suppliers can ship promised coal on time. American Electric Power Co., the nation's biggest coal buyer, says it has stepped up its due diligence to make sure its suppliers can make deliveries after some firms missed shipments last fall. It even bought a mine to lock down supplies.
"We are very much concerned, and it's getting worse," said Tim Light, senior vice president for AEP.
Jay Yarow|Jun. 8, 2009, 9:22 AM|comment3
There's a vast supply of coal in the United States, but only a sliver can be pulled from the ground profitably. Just 6% of the coal that exists in the primary coal beds in the U.S. can be extracted at prices even higher than today's, the Wall Street Journal reports.
What's it mean? For the nation at large, not too much. Individual power companies could be stung, though.
As it stands now, the EIA says that the U.S. has enough coal to power the country for 240 years. David Rutledge, a professor at the California Institute of Technology, who studies coal says it might only last 120 years. Projecting anything 100 years into the future is pretty silly.
In 120 years the mix of energy in this nation will be considerably different. So, unlike oil, there isn't a pressing need to change course quickly. The current plan to diversify through wind, solar and nuclear, should work well in the next 100 years.
As for the power industry:
In the field, challenges are becoming more apparent. Mining companies report they have to dig deeper and move more earth to extract coal from aging mines, driving up costs. Utilities have grown skittish about whether suppliers can ship promised coal on time. American Electric Power Co., the nation's biggest coal buyer, says it has stepped up its due diligence to make sure its suppliers can make deliveries after some firms missed shipments last fall. It even bought a mine to lock down supplies.
"We are very much concerned, and it's getting worse," said Tim Light, senior vice president for AEP.
Thursday, June 4, 2009
Fuel Cells Will Have To Slum It With Forklifts Now That The World Loves Electric Cars
Ten years ago, the centerpiece of any conference on fuel cells would have been the hydrogen car and its glitzy promise to replace dirty gasoline engines in the not too distant future.
Fast forward to 2009 to an actual fuel cell industry meeting in the West Coast city of Vancouver and sleek hydrogen cars are jostling for space and attention with the humble industrial forklift, and there is little talk of the imminent death of the internal combustion engine.
The "zero-emissions" cars remain a sexy drawing card -- a fleet of 12 arriving in Vancouver from California on Wednesday after traveling 2,700 km (1,700 miles) drew a large crowd. But their earlier massive promises have disappointed and forklifts are where the money looks to be for now for fuel cells.
Three years ago Ballard Power Systems Inc, for many years the poster child of the automotive fuel cell industry, did what many would have thought unthinkable during the hype years of the late 1990s when its stock rocketed to C$200 on the then-promising technology: it decided to get out of the business.
Instead of continuing to sink hundreds of millions of dollars into trying to develop an efficient, economical fuel cell for the car of the future it turned its eye to more pedestrian markets like forklifts and back-up power systems where the technology could find commercial use now.
"The problem that we came to grips with (was) ... what type of investment over what timeline would be required to bring down the cost of that new propulsion system technology to the point that it would be a commercial reality?" said Ballard Chief Executive John Sheridan.
"The reality seemed to develop pretty clearly from all sides that this was still a very long-term proposition," he said.
2015 TARGET TOO OPTIMISTIC?
Fuel cells are devices that convert the chemical energy of a fuel, like hydrogen, into electricity. In hydrogen cars, the electricity then powers an electric motor and water is given off as a by-product.
Supporters thus hail them as being the most environmentally friendly alternative to the tailpipe emissions of the internal combustion engine.
Car makers including General Motors and Toyota Motor Corp told conference delegates in Vancouver this week that they are targeting 2015 as the date for a small, initial roll-out of fuel cell cars to the public.
The automakers themselves acknowledge that major obstacles -- the same one that have been around for years -- continue to dog the hydrogen car industry.
First and foremost is the lack of filling station infrastructure, a massive cost if the hydrogen car economy is to succeed but a chicken-and-egg problem for the industry.
"Cars will arrive in relatively small batches but the stations need to be there or the vehicles will stop coming," said Michael McGowan, head of hydrogen solutions at Linde Gas North America and Chairman of the U.S. National Hydrogen Association.
Other troubling questions include where the hydrogen fuel will come from, where it will be stored and how it will be distributed. The high cost of fuel cells is another bugbear.
Ballard's Sheridan believes the 2015 target could well be optimistic, given the financial woes of recession-battered car makers in Detroit and elsewhere.
ENTER THE FORKLIFT
Instead, Ballard is now selling fuel cells to warehouse operations for use in forklifts.
Early orders are small but the Vancouver-based company believes these will ramp up as the materials handling industry sees the benefits of fuel cells over the incumbent lead-acid battery technology.
Fuel cell-powered forklifts can be refueled in minutes, according to John Tak, President and Chief Executive of the Canadian Hydrogen and Fuel Cell Association, unlike the hours it takes to recharge a battery.
Battery packs need to be stored somewhere taking up valuable space on the warehouse floor. Fuel cells also operate for longer and don't present the same disposal problems as a toxic battery at the end of its life.
Ballard's Sheridan says there are many in his company who were sorry to give up the automotive fuel cell dream.
"I would love to see the technology (work). The technology could do a lot at a critical time for the environment, but in terms of the commercial reality we just don't see it," he said.
Fast forward to 2009 to an actual fuel cell industry meeting in the West Coast city of Vancouver and sleek hydrogen cars are jostling for space and attention with the humble industrial forklift, and there is little talk of the imminent death of the internal combustion engine.
The "zero-emissions" cars remain a sexy drawing card -- a fleet of 12 arriving in Vancouver from California on Wednesday after traveling 2,700 km (1,700 miles) drew a large crowd. But their earlier massive promises have disappointed and forklifts are where the money looks to be for now for fuel cells.
Three years ago Ballard Power Systems Inc, for many years the poster child of the automotive fuel cell industry, did what many would have thought unthinkable during the hype years of the late 1990s when its stock rocketed to C$200 on the then-promising technology: it decided to get out of the business.
Instead of continuing to sink hundreds of millions of dollars into trying to develop an efficient, economical fuel cell for the car of the future it turned its eye to more pedestrian markets like forklifts and back-up power systems where the technology could find commercial use now.
"The problem that we came to grips with (was) ... what type of investment over what timeline would be required to bring down the cost of that new propulsion system technology to the point that it would be a commercial reality?" said Ballard Chief Executive John Sheridan.
"The reality seemed to develop pretty clearly from all sides that this was still a very long-term proposition," he said.
2015 TARGET TOO OPTIMISTIC?
Fuel cells are devices that convert the chemical energy of a fuel, like hydrogen, into electricity. In hydrogen cars, the electricity then powers an electric motor and water is given off as a by-product.
Supporters thus hail them as being the most environmentally friendly alternative to the tailpipe emissions of the internal combustion engine.
Car makers including General Motors and Toyota Motor Corp told conference delegates in Vancouver this week that they are targeting 2015 as the date for a small, initial roll-out of fuel cell cars to the public.
The automakers themselves acknowledge that major obstacles -- the same one that have been around for years -- continue to dog the hydrogen car industry.
First and foremost is the lack of filling station infrastructure, a massive cost if the hydrogen car economy is to succeed but a chicken-and-egg problem for the industry.
"Cars will arrive in relatively small batches but the stations need to be there or the vehicles will stop coming," said Michael McGowan, head of hydrogen solutions at Linde Gas North America and Chairman of the U.S. National Hydrogen Association.
Other troubling questions include where the hydrogen fuel will come from, where it will be stored and how it will be distributed. The high cost of fuel cells is another bugbear.
Ballard's Sheridan believes the 2015 target could well be optimistic, given the financial woes of recession-battered car makers in Detroit and elsewhere.
ENTER THE FORKLIFT
Instead, Ballard is now selling fuel cells to warehouse operations for use in forklifts.
Early orders are small but the Vancouver-based company believes these will ramp up as the materials handling industry sees the benefits of fuel cells over the incumbent lead-acid battery technology.
Fuel cell-powered forklifts can be refueled in minutes, according to John Tak, President and Chief Executive of the Canadian Hydrogen and Fuel Cell Association, unlike the hours it takes to recharge a battery.
Battery packs need to be stored somewhere taking up valuable space on the warehouse floor. Fuel cells also operate for longer and don't present the same disposal problems as a toxic battery at the end of its life.
Ballard's Sheridan says there are many in his company who were sorry to give up the automotive fuel cell dream.
"I would love to see the technology (work). The technology could do a lot at a critical time for the environment, but in terms of the commercial reality we just don't see it," he said.
Sunday, April 26, 2009
Sunday, June 1, 2008
Solar Charged Lawnmower
Contents
* 1 The Basic Idea
* 2 The Plan/Design
o 2.1 Motor and Battery Sizing
o 2.2 Solar charging station
o 2.3 Solar Panel and Charge Controller Sizing
* 3 Parts and Cost List
* 4 Stripping the Old Mower
* 5 Fabricating the Deck
* 6 Mounting the Motor
* 7 Mounting the Blade
* 8 Battery Mounting
* 9 Electrical
* 10 Solar Charging Station
* 11 Testing
o 11.1 Reserve Capacity Test
o 11.2 Fifteen Minute Mow Test
o 11.3 Testing the Charging Station
* 12 Conclusion
* 13 Project Credits
[edit] The Basic Idea
An electric lawnmower that utilizes solar power as an energy source will address a number of issues that standard internal combustion engine mowers do not. An electric lawnmower with a solar charger will be easier to use. There is no messy dangerous gasoline to deal with. It will eliminate those pesky trips to the gas station for fill-ups. Just plug the mower into the charging station when not in use and it will be charged and ready for your next mow! Most importantly it eliminates the emissions of an internal combustion mower.
The basic idea is to convert an older non-working gas mower into an electric powered mower by replacing the gas engine with an electric motor that runs from a 12 volt battery. This battery will be charged using photovoltaic panel (A.K.A. - solar panel). I chose to convert an old gas mower rather than just starting with an electric mower due to cost and so I could design the power output. I also planned on using as many used materials as I can. This will help to save these materials from ending up in our already over filled landfills.
[edit] The Plan/Design
I would like to claim that I came up with this solar charged electric mower idea on my own but the truth is I came across an article about one in a "Home Power" magazine (Issue 107) awhile back and have wanted to build one ever since. When the opportunity arose to use it as a project in my Engineering 305 class at Humboldt State University I jumped at the chance.
[edit] Motor and Battery Sizing
Motor
Motor
Battery
Battery
To start with I needed to design a mower that would fit my needs. I have a yard that takes about forty-five minutes to mow so it was important to size the battery accordingly. To do this I had to find out what kind of amperage the motor would be pulling for the forty-five minutes it takes to mow the grass. This is dependent on the type of motor used. Motors are rated in HP (horse power) and I wanted around the same HP as a standard internal combustion mower. The newer gas powered lawnmowers are about 4 to 6 HP and the older mowers are around 3 HP. According to the article in "Home Power" magazine 1 HP of an electric motor is equivalent to about 4 HP of an internal combustion engine. I was hoping to purchase a 1 HP motor but after pricing them I decided I needed to go with the least expensive motor that would get the job done. This turned out to be a 12 VDC, 3/4 HP, Dayton electric motor. (See below for details on parts and cost.)
The 3/4 HP Dayton motor is specified to pull 58A with a full load. I used this figure to help determine the size battery I needed. I knew I wanted a 12VDC battery, they are easy to find, use, and come in a variety of sizes. The next step was to figure out the amp-hours I needed to run this particular motor for 45 minutes. Amp-hours are a measurement of the length of time it takes to discharge a battery at a certain amperage. For example; a 35 amp-hour battery should give 35 amps for an hour before being discharged. I know I want to run my mower for 45 minutes but I'll just round it to an hour to be safe. Although the motor is rated for 58A, that amperage is with a full load and typically while mowing I will not be running a full load. While just spinning the blade (not cutting grass) the amps will only be about half of the full load or 30A. So a 40 Amp-hour battery should allow me to mow moderately tall grass for about 45 minutes to an hour. It just so happens that I had a 40 amp-hour deep-cycle battery from a past project. (See below for details on parts and cost).
[edit] Solar charging station
Charging Station
Charging Station
After the grass is mowed I'm going to need a way to charge the battery for the next mow. Luckily, my grass only needs to be cut once every week or two. This allows plenty of time to charge the battery with a solar panel. I had originally planned to build a structure that would house the entire mower then mount the solar panel on the roof. Due to time constrains, lack of yard space, and lack of good stationary solar access I decided to build a small portable solar charging station. This will allow me to easily store the mower in the garage while placing the charging station in direct sunlight.
[edit] Solar Panel and Charge Controller Sizing
Charge Controller
Charge Controller
I have an 11Watt solar panel from a past project that I am using to charge the battery. It is rated at 16.5 operating voltage (Volts) and .62 operating current (Amps) in full sun. (See link below for details on parts and cost)
To figure out how long it takes to charge the battery I use this calculation I found in the owner's manual of a DieHard Battery Charger:
(Amp Hour Rating * % of charge needed / Amps) * 1.25 = hours of charge time
Say my battery is discharged down to 50%, according to my systems setup the calculation would look like this:
(40 Amp-hour battery * .50 charge needed / .62 solar panels Amps) * 1.25 = 40 hours total charge time.
I also have a 12V 4.5A charge controller from a past project. This is wired between the solar panel and the battery. The controller stops the battery from discharging through the solar panel when the sun is not out and the panel is not creating electricity. It also regulates the voltage to the battery. Varying voltage to the battery can significantly shorten the battery's life span. (See below for details on parts and cost).
[edit] Parts and Cost List
Quantity Materials Source Cost ($) Total ($)
1 used lawnmower yard sale 5.00 5.00
1 electric motor (Dayton 3/4HP, 12VDC) part #: 6ML04 Graingers 312.00 312.00
1 solar panel (UniSolar 11 Watt) Affordable-solar.com 120.00 120.00
1 charge controller (Morningstar SunGuard 4.5A, 12V) Affordable-solar.com 39.00 39.00
1 voltmeter Kragen Auto Parts 22.00 22.00
1 ammeter Kragen Auto Parts 16.00 16.00
1 battery (Sun Xtender 40 AH) windsun.com 90.00 90.00
misc. electrical (wire, etc.) local electric store 25.00 25.00
misc. hardware (nuts & bolts) local hardware store 20.00 20.00
1 switch (70A) Industrial Electric 50.00 50.00
Total Cost 699.00
[edit] Stripping the Old Mower
After searching various yard sales I found and bought this old lawnmower for $5.00. (You can't beat that price!) As you can see it needed a lot of work. I was hoping to remove the internal combust engine by loosening the bolts that attached it to the mower deck. No such luck. They where rusted to the deck so I spent a large amount of time cutting the deck with a rotary tool to allow the engine to be removed. I used some spray on paint remover to remove a majority of the red paint. Then I used a wire brush to remove all the rust. After that I sprayed the rust spots with a rust retardant to stop the rust from spreading.
This mower was in pretty bad shape, if I took on this project again I would try to find a mower in better shape. It may cost a little more but that money could be easily recouped by the savings in time and effort.
Old Mower Deck
Old Mower Deck
Old Mower Deck
Stainless Steel Patches
[edit] Fabricating the Deck
After stripping the mower and removing the engine I was left with a mower deck with a huge hole in it. I went to a local scrap yard and found a couple of small sheets of stainless steel about 1/16" thick. I then cut the steel to the proper size to cover the hole in the deck. Before welding the new stainless steel deck to the mower I drilled five holes; one in the center to allow the shaft of the motor to sit under the deck and four more around the center hole to allow the motor to be mounted to the deck. It was important to make sure the center shaft hole is centered on the mower. If the shaft is not centered when the blade is mounted to the shaft it could rub against the sidewall of the mower. After the holes were properly measured and drilled I carefully welded the steel over the existing hole in the mower. There were still a few spots where rust had eaten through the mower so I cut some additional pieces of steel to weld over the smaller rust holes. These patches can be seen in the image on the lower left. The 1/16" stainless steel worked well for this application. It is thick enough to support the motor and fairly easy to work with when the proper tools are used.
As mentioned in the stripping the old mower section, the whole process of fabricating a new deck could have been avoided by purchasing a mower in better condition. One that allows the engine to be removed without taking part of the deck with it.
[edit] Mounting the Motor
Dayton 3/4HP, 12VDC Motor
Dayton 3/4HP, 12VDC Motor
When mounting the motor to the mower deck the most important thing was to make sure it was centered and properly secured. I made sure it was centered by measuring an equal distance from the sides of the motor to the outside diameter of the mower. I secured the motor to the deck with four 3/8" bolts with washers. Adding washers between the motor and the deck allowed me to raise different sides of the motor to level. I needed to place two washers on the front two bolts to bring the motor up to level.
I struggled with the decision to the way I should mount the motor. Should I face the terminal studs toward the back of the mower to protect them and to allow easy access to the battery or toward the front to allow the battery mount to attach to the motor base? After trying the different variations I realized that the battery must be mounted to the motor base to provide the proper support to the battery. (See battery mounting above for more info.)
This method of battery mounting is working out well. I have had no issues.
[edit] Mounting the Blade
Detached Blade Mount
Detached Blade Mount
Unfortunately, when removing the old blade from the old mower I was unable to salvage the piece that attached the engine shaft to the mower blade. This meant that it was necessary to fabricate my own blade mount. I found a piece of metal rod about 3/4" in diameter in the scrap pile in the HSU metals lab. I bored a hole into the rod at about 3/8" in diameter (the motor shaft diameter). This would allow the rod to slide over the motor shaft. Next the rod needed a key way milled to allow a key to be inserted. The key connects the rod to the shaft and keeps the rod from slipping while the shaft is rotating. Then I cut the rod to length and welded it to an 1/8" thick metal plate that the mower blade will be bolted to.
After the blade mount was finished being fabricated I inserted it on to the shaft. Then to make sure the mount was supported vertically I drilled a small hole completely through the mount and shaft. This allowed me to insert a bolt as an added safety measure.
When the blade mount was securely mounted I bolted the mower blade to it using two 3/8" nuts and bolts with washers.
All in all the fabrication of the blade mount went well. The parts were free (except the nuts and bolts) so the only true cost was the labor and it seems to be doing its job well. The only thing I would change is the lengh of bolts I used. I used about a 1-1/2" bolt for both the blade and the blade mount. They really only need about a 1/2" bolt.
Drilling the Mount
Milling the Mount
Blade Mount
Mower Blade Mounted
[edit] Battery Mounting
Once the motor was mounted I needed to find a place for the battery to sit. As I mentioned in the mounting the motor section, the base of the motor was facing the rear of the mower and would provide a solid mounting surface for the battery mount. To get the proper weight distribution I wanted to mount the battery as close as I could to the back wheels. This would allow the handle bars to serve as a lever and allow the mower to easily pivot when on its back wheels.
Using a piece of stainless steel I purchased from a local scrap yard I fabricated the battery mount. I started by placing the battery in the center of the square piece of stainless steel. Then I marked the outline of the battery on to the steel. Next I cut the corners to allow the sides that extend beyond the battery to be folded up. After folding up all four sides I welded them together for support. The battery fits tightly into the mount so no excess strapping is needed.
I then added a small piece of steel to the front side of the battery mount at a ninety degree angle. This piece extended from the battery mount to the deck of the mower to help support the battery when bolted to the motor base (see bottom right image). The other end of the battery mount rests on the raised back of the mower.
Folding stainless steel
Partially complete mount
Finished battery mount
Placement of battery mount and motor
[edit] Electrical
Ammeter and Voltmeter
Ammeter and Voltmeter
The electrical was one of the more complicated parts of this project. I had originally thought it would be rather simple, just run some wires from the battery to the motor add a switch and that would take care of it. As I started to do so I realized it wasn't that simple. I needed to have gauges to measure the volts and amps of the battery, the wires needed to be correctly sized, and a switch for a 12V 60A system can't just be picked up at the local hardware store.
Lets start with the wire sizing. Wires are sized by gauge, the smaller the gauge the larger the wire. The Dayton 3/4HP motor pulls 58A according to the spec sheet. It turns out that a #6 wire is rated to handle 75 amps so that's what I used to connect the motor to the battery through the amp meter and switch (see wire diagram below). I used a 16 AWG wire to connect the voltmeter to the battery and a 16 AWG medium duty extension cord to connect the battery to the charging station. According to the extension cord label it could handle up to 13 amps. This should be more than enough for the .63 amps the solar panel puts out.
Battery and motor schematic
I found the gauges at a local car parts store. I wired the ammeter in series and the voltmeter in parallel. The ammeter helps to give me an idea as to the amount of amps I'm pulling when mowing the grass. This in turn gives me an idea as to how long the battery is going to last before needing a charge. The voltmeter tells me when I need to recharge the battery. According to the battery manufacturer the battery is fully charged when the voltage reads 12.7 V. When it reads 11.75 V the battery is down to 30% and needs recharging.
I originally wanted to use a breaker for the on/off switch but after searching for awhile I noticed that a 60A 12V circuit breaker is not readily available. Luckily I found a switch that could handle 60A at a local industrial electric supplier. I also added a 100A fuse between the battery and motor.
Solar charging station electrical:
I also used 16 AWG for the connections between the solar panel and the charge controller. I put a 1.5A fuse between the solar panel and the charge controller as specified by the manufacture.
Solar charging station schematic
[edit] Solar Charging Station
After the mower was assembled and ready to go I needed a way to charge it. A used a 11 Watt Uni-solar panel that plugs into the mower when not in use. This panel is made to charge a 12V battery at .62 amps in full sun. I screwed a couple 4' long 2x4s to three cross supports to serve as a mount for the panel (see picture at top of page "Charging Station"). This makes for a light portable sturdy structure. I needed something I could easily move to the best solar access.
I also mounted a Morningstar SunGuard charge controller on to one of the cross supports. It is hidden behind the solar panel to protect it from the weather. (see picture at top of page "Charge Controller")
Although this solar panel is able to charge the battery I would have liked to get a larger one (if I had the money). As stated on the Home Page it takes about 40 hours of direct sunlight to charge the battery from 50%. Here in Humboldt County direct sunlight is not always prevalent. In optimal conditions we may get 5 hours a day in the winter. This means it would take eight days to charge the battery from 50% to 100%. On the bright side, the grass can't be cut when it's raining and it is usually raining if it is not sunny in the Pacific Northwest.
[edit] Testing
Testing the mower proved to be more difficult than I had anticipated. Wouldn't you know it, the only time I have ever been excited about mowing the lawn and it rained for a week straight? I did manage to get some tests done in my garage and even mowed a little grass when the rain let up.
[edit] Reserve Capacity Test
I bought the Sun Xtender deep-cycle PVX-420T over two years ago and have never used it. The manufacturer recommends running this test if the battery has gone unused for over 6 months to ensure the battery is capable of providing the necessary capacity to perform properly. After the battery is fully charged (12.7V) you are supposed to discharge the battery at 25 Amps until the voltage reads 10.5V. Luckily the mower pulls 25 Amps when running (not cutting). So I turned it on and timed how long it took to go from 12.7V to 10.5V. This ended up taking well over an hour. The PVX-420T was rated to do this in 61 minutes. So the battery passed this test with flying colors. If it would have taken 49 minutes or less, the manufacture recommends replacing the battery.
[edit] Fifteen Minute Mow Test
I was anxious to get out and try the mower so during a break form the rain I did just that. The wet grass didn't provide ideal mowing conditions but I will take what I can get at this point. I measured the battery voltage to be 12.5 (about 90% capacity) prior to mowing. I had the mower deck set to the second to highest position and the grass was moderately long and wet. I watched the ammeter while mowing and it was pretty consistently pulling 45-60 amps. I mowed for about fifteen minutes (about 1/3 of my yard) and when I finished the battery voltage read 12.25 (about 60% capacity). Not bad considering the grass was wet. I figure that in ideal conditions (moderately long dry grass) the mower should pull between 40 and 50 amps. At that amperage the 40 amp-hour battery should last about an hour before becoming completely discharged. Completely discharging the battery is not good for it so I will only run the mower for 45 minutes which is about how long it takes to mow my lawn. This should leave the battery at about 11.75 (about 30% capacity).
[edit] Testing the Charging Station
Once again the rainy weather did not provide the ideal conditions for testing the solar panel charging station. Therefore, I had to use a battery charger to recharge the battery to a safe level. I used the 2 amp setting on the charger. This gives the battery 2 amps at a constant voltage in until it reaches about 80% (12.4V) capacity. It then starts to vary the voltage and this is not good for the battery. At this point I take the battery off the charger and plug it into the solar charging station. In a full winters day sun it raised the battery from 12.4V (80%) to 12.5V (90%) so I know its working. I plan on using the charging station at greater lengths when the weather allows me to do so.
[edit] Conclusion
Over all I really enjoyed completing this project. It was a lot of hard work but most things worth doing are. In retrospect there are only a few things I would change. First, I would find a mower that could be easily disassembled or at least able to be disassembled. This would save time and labor on the fabricating portion of this project. Next I would invest in a larger solar panel, at least 50 Watts this would allow the battery to be charged quicker and require less sun between mows. I would have also used a breaker rather then the switch I installed or mount a fuse between the battery and motor. This would help to make the system safer and protect the motor if the amperage rose to an unsafe level. Besides that the mower runs great and I'm looking forward to quiet pollution free mowing from here on out.
If you have any questions feel free to e-mail me at createfreedumb at hotmail dot com
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