Intro: Homebuilt Generator (Riding Lawn Mower) 1Kw
Well like most of us, I was looking to find a way to minimize expenses in creating an alternate energy power source.
The easiest way to perform this task was to re-use existing equipment installed in my home, & power toys to minimize costs.
My favourite expression to utilize cross functional synergies.
Well, I was able to put together the following items
At Home items
a) 2 Batteries (Used for my Motor Boat) 140AH
b) Lawnboy lawn tractor 10 HP (1980s vintage)
a) Xantrex 1000 power inverter ($89.00) Cdn Tire
Regular Priced Items
a) Fan Belt 4L44 Cdn Tire $ 11.00
b) 12V Car Led Lamp Cdn Tire $ 2.50
c) AC Power Monitor (UPM Em100) Cdn Tire $ 25.95
d) Battery clamps Cdn Tire $ 5.95
e) Booster Cables Cdn Tire $ 20.00
Optional: Siemens Generator Panel Box (and Circuit Breakers) $280.00
Note: Extensions cords will do in a pinch!
Scrap (Yard) Items
a) Cadillac Alternator (120amp) with Built in Regulator $ 35.00
b) 4 Position Switch (Scrap from old Battery Charger)
c) 6 Gauge Wire (Old Battery Booster Cables)
d) Panel Mount (For Switch and light)
e) Tie Wraps (Keep all loose wires tight and away from Belts)
Total Cost *Including Electrical Panel $ 469.40
Without Electrical Panel $ 189.40
Step 1: Alternators
Of special note, when assembling this conglomeration of items special care needs to be taken to research the specific products selected.(I.E.)
The cheapest way to connect an automobile alternator is to select one that has a built in regulator. In many instances they are denoted as a single wire connect. If you have external sense lines coming from the alternator (As Below) , wiring can become a little more difficult as you may need a resistor value of approx 35 ohms leading from the Generator Light wire on the alternator to + DC voltage. You also have to have a Power Switch to disable the charging of the stator at initial power up time. I.E. The resistance of the alternator can generate enough force feedback to make it too difficult to start you engine.
Step 2: Power Inverters
Low cost power inverters (Modified Sine Wave) actually have power being generated on both the Live and Neutral lines. Typical home wiring has the Neutral and Ground wires tied together. Hence if you try to connect a (Modified Sine Wave inverter) directly to home wiring it will not work and short out the inverter. The neutral has approximately 60V on it instead of the usual 0V.
Step 3: Generator Panel (Optional)
Ensure that when you plan your implementation to purchase a Generator Power panel that supports a bonded Neutral. (I.E. the neutral line is also switched) and that you do not tie the neutral to ground at the panel
Step 4: Nice to Haves
a) Voltmeter (Monitoring your battery voltage as power is being drawn. If the voltage drops continuously, your alternator is not providing sufficient power to meet demand)
b) DC Shunt (Measure DC current coming from alternator. Note: You may be able to play with the resistors on the stator to increase power). Crompton 100 Amp Dc Shunt
c) UPM EM 100 Energy Monitor or (Kill a Watt). (Measures the AC power voltage current, Peak Current, and Wattage. Constantly monitor inverter output versus maximums)
Note: Can also be used in advance to determine average and maximum loading levels by appliances in your home to enable you to size your generator properly.
Step 5: Formulas
a) Fan belt sizing
Belt length = ((Alternator Pulley Diameter + Motor Pulley Diameter) *1.5708) + (2* Center to Center distance of Alternator and Motor Pulleys)
b) DC Power Shunt. Typically continuous running load on current shunts is in the order of 60-65%.
When purchasing, make sure you have a 50% factor above your expected maximum running load.
i.e. 150% of your maximum load factor.
Note: Some manufacturers build in a safety load factor of 1.2
i.e. Crompton 100 Amp Dc Shunt
c) Pulley Size Calculator. Yup thats right, you notice that when you purchase an alternator these days they may not come with a V Belt pulley, and the size of the existing pulley may not match that required for the Horse power rating / RPM for your engine.