Lawnmower Power Generator With A Twist

This is a 500 watt power generator big enough to power tools, and home electronics.  If you try plugging in kitchen appliances, heaters, window AC units etc....it will shut down, you need a 2k-3k watt power converter for large power comsumption appliances..

 It's not difficult to build this project, if you know how to wrench things apart and have a basic understanding of how things work with engines and electrical components then you'll do just fine.  If you want to save money on the build, go to junkyards, recycling centers, and landfills which is where I got most of the parts.   You'll be surprised the stuff you can find for pennies or better yet FREE.   I spent $40 for all the parts needed for this project.  

There are a few optional parts not needed to run this little power jewel.   The lawnmower tires, enclosure, vehicle battery, handle, voltage meter, 120VAC outlet, light, and on/off switch for light.   I decided to go all out with this one by adding all those extra features, just took me longer to make, 3 months exactly.  A schematic diagram will show how to wire everything up.    The AC outlet you see on the panel is tapping from the power converter which already has AC outlets.  I just wanted to make an extension of it so I wouldn't reach around the back to plug in things....

Step 1: Parts, Where, Tools, How Much$$

Here are some links for the power tools I used.....http://www.sears.com/shc/s/p_10153_12605_00921914000P?blockNo=2&blockType=G2&prdNo=2&i_cntr=1292168781911,    http://www.sears.com/shc/s/p_10153_12605_00928223000P?prdNo=1&blockNo=1&blockType=G1,   http://www.sears.com/shc/s/p_10153_12605_00911543000P?prdNo=10&blockNo=10&blockType=G10,                                                                       (1)  WOODEN or METAL platform-   Helps bolt down the Alternator, Engine, and DC to AC power converter.  I used aluminum sheet metal with L-frame bars for a sturdy frame.  Got the sheet metal and L-bars for FREE from recycling center.   I used a JIGSAW with a metal cutting blade to get the job done easy.(NOTE)..Do Not Try Using the jigsaw to cut  IRON or STEEL...The blade will kick back and will break sending pieces flying...If you have better cutting tools for that kind of material then by all means use it.  

Other tools include a drill press, vise grip, portable hand held drill, hacksaw, and a hand held file.   If you have better tools to get the job done quicker and safer don't hesitate....It took me three months to build the crazy thing, and a few busted knuckles.
 
   The platform size varies with how many components you want to throw on it, the one I made is a  2'x3'  with a top shelf to hold vehicle battery.  more details about that later.

(2)  LAWNMOWER ENGINE-   Vertical or Horizontal, 3.5HP or bigger.   I got it for FREE from landfill (vertical shaft) with a key way slot, or you can buy a new one for $100+....

(3)   ALTERNATOR-   It's a delco part# CTBBB-7127-12 rebuilt, with internal voltage regulator, 65amp, two wire connector harness.  paid $23, auto parts store.    This is the heart of the system,  I recommend using this one, it's simple to setup and comes with an internal voltage regulator.

(4)  DC to AC POWER CONVERTER-  The one I used is a 500 watt converter, got for FREE from recycling center.    The bigger the better, pure sine wave is the best. 

(5)  VARIABLE RESISTOR-  Also know as a  Rotory Switch or POT.   You can get one from an auto junkyard for $2... look for an older vehicle, 70's through late 80's any model, also known as a light dimmer switch or dashboard, panel lights dimmer....you just turn the knob in one direction and the lights dim or brighten....you need a 2 wire pin switch....this part is used to control the amps coming from the alternator.....

(6)  ON/OFF Switch-  There are a few different kinds...rotory, toggle, rocker, and push.  I used a toggle with a built in green light.

(7)  PULLEY- 3" or 4" diameter, IRON or STEEL,   $3 from junkyard,   Make sure it has a key way to help prevent it from slipping on the engine shaft.  (NOTE) make sure the pulley is equal the weight of the cutting blade or greater,  if not the engine will not hold it's spin cycle.  Got mine for FREE from recycling center.

(8) BELT-  $12 at lawnmower repair shop or auto parts store.  If you want cheap try the  landfill which I got from, or recycling center, auto junkyard or neighbor throwing it away.  I recommend a belt from a self propelled lawnmower, makes a perfect fit.....which I used on this project.

(9) BOLTS with NUTS & WASHERS-  Paid $12 for nuts, bolts, and washers from home depot.  Try to get rust proof hardware.

Other parts are optional like the voltage meter, light, on/off toggle switch for light, and extra 120VAC outlet,  which are not required to operate a fully functional generator.
 

Comments

[kill-a-watt]

Nice, I'm looking at building one of these. I want to add a circut to recharge or jump car batteries and maybe add field control to convert mine to a light-duty welder.

The 3.5 HP engine is limited to maybe 2500 watts total.

You are using a GM Delco 10si alternator, which can only put out about 900 watts at 14volts times 63 amps. I assume the unit is self-excited, so if you pulled one out of a junked car, you would probably have to install a "one wire" kit. Although the 10si is  ubiquitous, with that engine I guess you have headroom to use a larger alternator.

Technically, that cooling fan on the alternator is running the wrong way, but I'll bet it works fine because it's not located in a hot under hood area of a car. The alternator itself doesn't care which way it spins.

"Battery" is not in your parts list. I'd recommend a deep cycle type. If you use the less expensive wet-cell type, get a battery box for the battery and bolt it down. Acid burns.

Good job with the safety-nazi stickers. No one could fault you there!

[kill-a-watt]

confirmed with a search: 7127 is "self-exciting" or "one-wire". The "-12" means that alternator is "clocked" at the "12 o'clock" position.

Looking at the back of the alternator, think of the field winding contacts as the hour hand and the pivot bolt hole (the unthreaded mounting bolt hole) as "12" on a clock. By assembly, the alternator can be in four positions. 3, 6, 9, and 12 o'clock. If you know how to restrain the brushes, you can take apart the alternator and "re-clock" it for different applications in different cars.

[cid2323]

I bought the alternator at a parts store with a 2 wire harness connector. I didn't mention the battery because it is not required to start the generator, it's just an optional feature.

[rairwin]

This would be a good aplacation for the geet fuel system and run the thing off of 85% water

[cid2323]

How would it run on water?

[cid2323]

Did a little research on H2O engines, that's a cool idea. Have heard about it before but never bothered to read more about it until now. Might be a future project.

[tedervlad]

Good

[cid2323]

Thanks.

[MACKattacksnipe]

Very nice and clean

[cid2323]

Thanks. Been away for awhile, working on some new stuff to post.

[cid2323]

Thanks. Working on a smaller compact gen. Once I'm done with it will post on here to pass on for future builders.

[cid2323]

Thanks. Happy Holidays.....

[dsandds2003]

This is a great idea. HOWEVER i did not see anything about NOT using this indoors. If you use it in a garage MAKE SURE you leave the door open. You WILL need lots of ventalation.
I love the portability of this, would be a GREAT item to use with my electric branch trimmer. GREAT job on the pics and diagrams.

[cid2323]

I'm working on a smaller gen using a weed eater which makes way easier to carry as far as weight issues. I've been out of the loop on instructables for a while.

[bigtreehouse]

More of a question... I want to do the same thing... but, I have a bunch of alternators (4 or 5). Would this be overkill or make more power? good? bad?

Thanks

[cid2323]

You just need one, alternators vary in amps and voltage, 65 amps to 100+, and voltage 14.3 to 26.5 depending what you want to hook up on it. If you need more power related to voltage don't forget to match the converter if you need A/C voltage. Some alternators can get pretty expensive if you buy them from store, if you get one from junkyard look for a military vehicle, they all have alternators that run on 24vdc or other military equipment such as generators etc.

[Aprositus]

Great project.

[NullLifeException]

I'm not surprised that it stalls out when you try to draw too much power. Most inverters would have a breaker or some kind of overload circuit, but the engine can't provide the peak power needed to overload the inverter. It probably could though, if you put a bigger flywheel on it.

The flywheel helps keep the engine spinning when its working hard, by providing extra momentum to keep the whole thing turning. Today's lawnmowers are built with a minimalist philosophy to make things cheaper, though, so they're using the lawnmower blade to help the flywheel do its job. So, when you take the blade off, the engine can't keep running when it starts working hard.

I'm surprised it actually runs without the blades, actually. A lot of them won't.

[paleotool]

Excellent work! It looks like a well thought out and explained instructable. I have been intending to make one from a junk lawn mower I have and this looks like a nice, neat design.

[tedervlad]

www.tender.pro

[Dr.Bill]

Looked at it.
Translated it.
Whatzit for?

[cid2323]

It's a power generator, DC to AC 120VAC. you can use it for electronics, some power tools, lights, etc. makes perfect for camping or light up a small cabin. Happy Holidays.........................

[Dr.Bill]

This would be good for ham radio field days.
Shore do wish I had more room to work on stuff.
I give you a 5.0

[cid2323]

would make perfect for ham or camping.

[ContraptionMaker]

Nice build, just a word of caution!!!! DO NOT RUN THIS INSIDE A CLOSED BUILDING!!!! I notice in one pic you show this inside your house running a TV. This is an internal combustion engine and produces carbon dioxide which can kill you.

[UncleBuild]

Carbon Monoxide is killer when running IC engines indoors or using BBQ grills for space heating purposes. DO NOT USE INDOORS, including a garage.

[cid2323]

Engine is not on, the battery on top is powering the converter without having to run the engine, that is one of the features I included within the circuit as a backup.

Was getting dark outside so brought GEN indoors just to take pics, at no point was the motor turned on....The battery is doing it's work, that's the beauty of it....

[cid2323]

No worries!! that yellow battery you see on top is what's running the converter as a backup....good catch though. Never would I run a gas engine in my home.

[possum888]

That is brilliant! Our lawnmower's frame disintegrated, so it's essentially useless, and this would be a cool project to try out.

[cid2323]

That would make a nice project, you can also modify the engine for a cool pressure washer.

[karossii]

I'm curious... have you any idea on the efficiency of this unit? gallons of gas per KWH, for example...?

[cid2323]

Almost forgot, with the battery as a backup will last 24hrs with the same load...

[cid2323]

I don't know the specs for the engine, it's something I picked out from landfill....I do know with a small load and the tiny gas tank it will last up to two hrs none stop, which can be upgraded with a larger fuel tank.....I recommend stopping the engine every hr to check up on oil levels, especially with small engines..

[ac-dc]

It's essentially one of their 300 series, here:
http://www.briggsandstratton.com/engines/push-mower/detail/?series=300+Series&id={0CBA2950-9AF3-4E9E-880A-68D471813041}#specifications

... but they're not going to provide a load vs RPM vs fuel consumption graph for it, nor is it likely you'd find a load versus output power graph for the alternator, the there's the small efficiency loss of the pulleys 'n belt and the conversion to AC and/or battery charging... you'd have to measure efficiency as a whole *machine* yourself.

While I'm thinking about it, the first thing to go on those engines is usually a carb diaphragm right above the fuel tank, if it starts sputtering out after some use try replacing that first (about $2 and 10 minute job). youtube videos of the repair:
http://www.youtube.com/results?search_query=B%26S+diaphragm&aq=f

[cid2323]

You're absolutely right, to keep cost low just kept it simple for builders, some folks won't dare mess with carbs do to cleaning out or fine tuning them.