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)

Sale Items

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.



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    48 Discussions


    8 years ago on Step 2

    So, is there any good solution how to connect inverter directly to home power?

    2 replies

    Reply 12 months ago

    Unless you spend the big $ for a pure sine wave inverter, it best just to use direct connect extensions.

    I.E. Not using home wiring. Square wave inverters are not compatible with home wiring where neutral is tied to ground .


    3 years ago

    What was wrong with the built in generator or was the output to low. The problem with most alternators is that when your battery reaches 85% they drop back to a trickle charge

    1 reply

    Reply 3 years ago

    Responded earlier to the same Question...Here was the response

    The charger for a ride on provides very low charge current for such a small motor/battery starter requirement.(Some as low as .5 amp) The use of a car alternator is to be able to use the entire output power capability of the ride on mower (100 amp or more) under full load conditions.

    Keep in mind when under load the battery will supply (in this instance) up to 125 amps @ 12 volts of power to feed a 15 amp 120 volt circuit. The alternator will go into FULL charge mode as soon as the draw is large enough.The battery acts as a dynamic load balancer, as the motor can not respond instantaneously to varying loads.

    It is really 2 independent operations taking place. Battery supplying instantaneous response to changing load conditions. Alternator providing a constant charge current source to replace the battery drainage.


    8 years ago on Introduction

    Great article !!! My step-daughter REFUSES to turn off the computer when she is done, SO I want to make a pedal powered generator to get back at her. (If this seems cruel, I REALLY do need to lose my Molson Muscle !!! LOL) My wifes' car quite working right after I replaced the alternator :-(, so now I have a nice new shiny Delco Remy CS 130 series alternator I can't return. Would anyone be so kind to email me a wiring diagram of the circuit ? I'd hate to wire it up incorrectly and destroy it ! I've also stripped all of the relevant wiring & battery out of the car. Many thanks in advance. My eMail is : mpandersen@live.com

    1 reply

    Reply 3 years ago

    maybe convert an old singer treadle model to generate power?! I enjoyed operating the old machine without sewing as a kid... loved it. Something about getting it to start with say the large hand wheel and almost effortlessly getting it to "sing" out some high rpms....


    3 years ago

    thanks. .. I will investigate more. Question: I have a 04 crown victory police car. I might be removing the high-output generator because of parasitic drain within it's diode array. Would anyone know if the take-out unit might be useful in a similar project at the cost of the core charge?


    10 years ago on Introduction

    I have a Craftsman lawn tractor with a 19.5 B&S Twin-II I/C engine, that would work perfectly for the reasons that kflack stated. Driving a Delco CS-144 140A alternator should be NO problem!! Last year, I built a 1.5kW gen-set using a 6hp B&S Lawnmower engine, another Delco CS144, a Xantrex Prosine 1800 Inverter and up to 300Ah of batteries, for up to 5 hours of silent runtime before I have to re-start the engine.

    2 replies

    Reply 4 years ago

    I see 2 problems with this first car alternated only use full change up to 80% and then drop back to a trickle, 2nd I would have thought that your ride-on would already have an alternator built so why not use that one


    Reply 4 years ago

    Question 1 -(kflack Homebuilt Generator) I don't fully understand the statement your are trying to make but will take a shot at it.

    If you mean that car alternators start charging batteries at 80% and you are not getting the full use of Battery cycling then you are correct. The intention here is not to store and cycle the batteries but to use them as a constant current source for the loads that the inverter needs in real time. The alternator simply maintains the the battery charge status at as close to 100% as possible.As a mater of fact, using standard lead acid batteries, in this instance instead of deep cycle batteries is recommended. 

    In Gen-Set case it looks like he is manually charging up a storage bank and turning off his generator while cycling.In his case a Deep Cycle Battery would be applicable.

    Question 2 -The charger for a ride on provides very low charge current for such a small motor/battery starter requirement.(Some as low as  .5 amp) The use of a car alternator is to be able to use the entire output power capability of the ride on mower (100 amp or more) under full load conditions.


    4 years ago

    So I am a backyard tinkerer and have been playing around with making a wind turbine using an ac delco alternator. I know its not a great source of power, just playing around with it. The alternator model I am using has the pin connector with SLFP. I have a jumper wire connecting the S to the hot wire going to the battery. And the ground from the alternator bracket to the neg. terminal. But I am not getting any power generation. Is there another wire I should be connecting or something else?

    1 reply

    Reply 4 years ago on Introduction

    Car Alternators need about 3000 + rpm to generate power.

    Wind Gennie about 300 rpms is max....

    Look to upgrading to a permanent Magnet Core in your alternator and then maybe you will see something.


    8 years ago on Introduction

    cemb: asks; at what rpm does an alternator need to spin in order to produce its max output

    1 reply
    Josehf Murchisoncemb

    Reply 7 years ago on Introduction

    Maximum power is usually controlled by the regulator; it is more rpms and efficiency, usually 2 to 2.5 idle speed of the vehicle the alternator is for.
    An example a Mack truck’s idle speed is 400 to 500 rpm and max rpm is 1800 you might want to run the alternator at 1000 to 1200.
    A Chevy Sprint’s idle speed is 1100 and max rpm is 10000 rpm its alternator you might want to run at 3000 rpm.

    In reality house wiring has 220 across two live lines that go to ground at the neutral making 110 per side. Another little known fact is home hydro can fluctuate from 90v to 135v depending on where you are on the line and how modern the service is. If you are getting voltage from the neutral it is probably feed back in the lines finding a shorter rout to ground, I was shocked by a house circuit with the circuit breaker off that way.
    To connect to house wiring you need a 220 110-volt power inverter with a pure sine wave signal synchronised to the service. The output is kind of like a centre tap transformer. Service transformers have the windings hooked up in ether delta or Y configurations they’re essentially a centre tap transformer. This is a simplified explanation.
    I hope this helps.

    1 reply

    Absolutely Correct Josehf !

    My reference to using a (Non Bonded Neutral) for the switch panel is a non standard approach to temporarily use (During a power failure) for key switched circuits. By using a non bonded Neutral it is possible to use a less expensive inverter (Square Wave) versus True Sine wave as you mentioned above.They in reality do not use the same methodology for power generation (Center Tap transformer) and hence the need to have the Neutral (NOT Bonded) to the ground line. It is not an accepted standard for household wiring to have the neutral unbonded from the ground line, but is the only way possible to use a square wave inverter on household wiring via a switched panel.

    Your assessment above is absolutely correct and is a superior configuration (True Sine Wave Inverter) that meets existing legal wiring codes. In your instance above, with a True Sine wave inverter, the Neutral Line would remain bonded to the Household ground

    Oh, Hey! I made one of these last week!!! Min is made from a vintage 1980 Lawn Chief ride-on mower. The engine died, so i tore the whole thing apart and put in a 5hp honda engine. the new engine connects to the transmission, and also a 55-amp alternator. (I couldnt afford a more powerful one) it generatoe loads o power that run it's seven 55W halogen lights. i havent hooked an inverter to it yet, but i was planning on doing the exact same thing as you. I have it on youtube: http://www.youtube.com/watch?v=vK7WSZER9yI


    I was half thinking of rigging  an alternator on a treadmill type of devise and just chaining the  yard tractor up on it.  this makes much more sense