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

Hold tight for Part 2 of this project. I hope to complete it within the next month.