Part 2 of this project is available here.
DIY Power Generator
Input: Fuel, in the form of petroleum
Output: 12v DC and 240v AC electricity!
While overseas in the Philippines I was very impressed by the way the locals improvised, modified and fitted existing engines inside their hand-made boats. The result is an inboard engine with an extended drive shaft (which comes directly off the crank shaft) with a [usually] twin blade aluminium or stainless steel prop on the end. A rudder is placed behind the prop and is controlled using either a pulley system or directly with a rod.
The engine would need to be fitted inside the boat on a slight angle so that the drive shaft extends down through the hull and could stick out from under the boat.
Inspired by their ingenuity I decided to think about what I could do with my old lawn mower. The engine is still in good condition but the chassis is broken. There is no cost benefit in repairing/replacing the chassis so the mower has been sitting idle for about a year after I replaced it with a newer mower.
Last year my plan with the engine was to create a hydrogen fuel cell and see if it would run on hyrdogen. I did some preliminary research on this and decided it would probably take too long to do complete research on it and even then with a chance that the mower engine was not a suitable candidate for the conversion.
So, while in the Philippines and with the clarity that you muster while on a relaxing holiday (in fact, it was during a trip on a boat to the underground river, a natural Wonder of the World, at Palawan that this thought came to me) I decided that I will use the engine to make a power generator.
I’ve always wanted a generator for emergency situations and also for the occasional camping trip, but decided against it as the generator I wanted would’ve cost closer to $1,000 and I couldn’t justify that sort of cost for something I will rarely use.
Plus, building this generator will refine my new skills at welding, and indeed it has!
Currently, I am about half way through the project and because it is such a large project and it is taking so long I am posting it up to this blog in stages.
The descriptions for each picture are simple, so if anyone wants me to expand on any of the information below please leave a comment and I will do my best to help.
The basic idea here is to leverage on complex components that are already built and require minimal modification to work in the capacity of a power generator.
There are four sub-systems, they are:
– Engine
This is the power source. A small engine is best (eg. lawn mower or whipper snipper). The engine uses petrol as a fuel source to create rotational force through the crank shaft. This force is transferred to the alternator using a belt from a car.
– Alternator
You can get one of these from a car wrecking yard. They are used in cars newer than ~1960 (previous to this a generator was used, which isnt as efficient for what we want). The principle here is the alternator converts mechanical energy in to electrical energy.
I wont bore you with details on how this works, you can read Wikipedia for that. But basically it initially needs a small amount of power (which creates a magnetic field around the rotator) to actually work. So a 12v battery is always needed in the generator even if you dont plan on using it as a alternate power source as I am. In this case, you could use a tiny sealed lead-acid battery which is very small and weighs little.
– Tank battery (car battery)
Any wrecking yard will have a second hand battery or you can buy a new one from just about any petrol station. To allow the generator to keep giving power even when the engine is off I have decided to put in a large car battery. This battery is used by the alternator to get its initial power for starting and is then subsequently charged by the alternator. Once the engine is off the inverter will pull its power from the battery.
– Inverter
You can grab one from any automotive shop. The alternator generates 12-15v DC power (well, its makes AC which is then transformed and regulated to DC). The inverter will convert this DC (which it pulls from the battery/alternator) to 240v AC power for use on your home appliances.
Technically, you COULD tap in to the AC power generated by the alternator before it is converted to DC. But the AC is rough and raw and I don’t care enough to bother doing this.
The inverter I am using is 2000 watt and produces a pure sine wave (which is slightly more expensive but better for my application).
Materials list (non-exhaustive):
– Engine
– Alternator
– Inverter
– Car battery (12v)
– Electronics (wire, house (240V AC) power point, switches, relays etc…)
– Metal! Heaps of metal for the chassis. I used galvanised steel and aluminium
– Spray paint
– Nuts and bolts
Tools used:
– Drill (with various sized drill bits)
– Impact wrench
– Spanner set
– Screw driver set
– Various hand tools (pliers, side cutters, g-clamps, etc…)
– Angle grinder (with grinding and cutting discs)
– Bench grinder
– Dremel (cutting and grinding bits)
– MIG welder
– Hammer (for when you’re angry!)
– Soldering station
Part 2 of this project is available here.
- The lawn mower with broken [back axle] chassis
- Pulled the engine off
- Cleaning out the carby and checking needles
- Cleaning carby
- Cleaning and checking engine
- Muffler/exhaust. I may need to modify this later to muffle it further
- Because of the crank shaft sticking out the bottom it was cumbersome to keep the engine upright. I made a temporary bracket and legs
- Temporary legs to keep the engine upright
- Testing the engine. Al is OK
- Starting work on the actual bracket used to hold the engine in the chassis. Need this piece to be on rubber engine mounts
- Finished product. Due to the placement of the bolt holes being in the way, this is the best design I could come up with. Its solid and works fine.
- Making the main base
- My brother helped me considerably with this project. He is cutting the bracket to size
- Retro fit
- Adding the rubber mounts. These are generic mounts used for car exhausts
- Welding the nuts in place
- Engine mounted on the base. The rubber mounts work a treat!
- Got an old Mitsubishi Lancer harmonic balancer from the wreckers
- Original plan was to ask a friend to use their metal lathe and widen the hole in the centre large enough for the bracket on the crank shaft to fit in place, then weld them in place
- However, I noticed that there is a metal plate tacked inside the balancer, without that place the cranks bracket would fit perfectly in its place!
- So I set to work cutting through the plate. I ended up using a multi-tool to cut one side off, which reveals the tacks are very small, so I drilled out the rest
- Here you can see the finished product. Ive welded the crank bracket on the harmonic balancer, its perfectly centred and solid
- A friend of mine is a mechanic and he gave me this Mitsubishi Mirage alternator. Its 75A. Later on ill look in to changing it to a power rated one. So need to make its bracket adjustable to suit multiple types
- Three lateral adjustments. This is more than enough to accommodate future alternator replacements
- The alternator bracket needs to be removable. In fact, the entire generator is designed to be modular for each repair/replacement
- Here you see a threaded rod which is used for unlimited height adjustment of the alternator
- Adjusted and read to generator power!
- The added benefit here is that I could add another belt and another alternator if I wanted to. But then things would be very bulky. Nice to know the option is there though
- Welded a nut on the alternator which is used for adjusting tension on the belt. The original idea to weld the nut on the bracket wouldnt allow for future alternator replacement, so this will do for now until I can think of a way to avoid the need to weld another nut on the replacement alternator
- This is a mechanical and electrical mechanism used to switch off the engine. On the mower you would let go of a handle which is attached to a cable. This would snap closed a brake on the fly wheel and also send a signal to the coil to disrupt ignition
- Removal of the mechanism. I will be jamming the brake open so it never closes (no need for it anymore) and also tapping in to the electrical switch for generator on/off switch. This will eventually come off a relay
- Testing the switch to see how it works
- These two pieces are for the generator cover. At this point I realise a huge design flaw in my generator…. too much metal = much heavier generator! The bulk of the weight will be the battery, alternator, inverter and engine, but the large amount of metal used wont help 🙁
- Some doodling. I’m not much of a designer and find it difficult to visualise and sketch ideas, but with such a large project design is a must.
- Due to my limitations as a designer I am designing the entire project in stages and each stage as I get to it. The risk is I design something in an earlier stage which doesnt work out in a later stage, hopefully I wont have any issues.
- Building the bracket used to hold the inverter and the battery
- Where not needed im using thinner/lighter pieces of metal to reduce overall weight
- Just doodling ideas for how the electrics will work. I think I will end up using a 2 relay system controlled by just one switch. This will keep the engine, alternator and inverter electrics separate from each other. These are the 3 sub-systems that require on/off signals
October 28, 2016 at 1:41 pm
Thank you for the training. But please can’t you do it video for someone like me to watch how it is been build, because the photo do not fully explain how to do it. But if you perform it and explain it in video, someone like will learn it and can perform the same thing.
But with this information i understand how to build Power Generator.
But i will save this page incase you post anything else.
October 28, 2016 at 2:35 pm
A video if a great idea. I am not very good at developing videos just yet, but I am practicing. Hopefully, my newer project will have video tutorials also. Thanks for the suggestion.
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