Audi 80 1.9 TDI diesel / Induction Generator
Repost from field lines from September 18, 2007
My last post was about my intention to build a diesel generator with a 5kw Chinese alternator but since then I have acquired a 15kw 3 phase motor and buckets full of motor run caps. This entry will cover the initial tests on the motor and mechanical build to date there will be a further update on output etc.
To build a multi-fuel generator as a back up charging source for my two battery banks
To recover heat from the engines cooling system as hot water directly into the central heating for the house
To add an additional 12v alternator to the engine to charge an extra Battery bank to run the oil fired boiler
Last but most importantly I want to achieve this for as little cash outlay as possible..well that's what I told the wife!
I have an unlimited supply of free fuel mostly in the form of waste veg oil but also waste motor oil and lard. I currently heat my home and workshop on a combination of these fuels almost for free I say almost as there is a 600w heating element in the burner. I have also converted my car to run on W.V.O. it’s a Land Rover 2.5 TDi and it runs lovely on it. A good friend recently retired his old Audi 80 to my care as it had a noisy gearbox. The car is identical to one I also own just a bit longer in the tooth but runs a treat. His last words where to do as I pleased with it! red flag and bull come to mind! So I guess that's going to be my engine for the generator sorted.
The motor I have is a 3ph 15kw beast that weighs in at 150 kgs and will be excited with motor run caps. I got the details on how to do this from a fantastic little book Motors as Generators for micro-hydro power by Nigel Smith it gives details on how to work out the caps and by luck it gives an example using a 15kw motor.
The first step was to test the motor with the caps but my lathe was not up to the job so I welded up a temporary frame on the Audi with a drive belt from the crank shaft pulley
The test went well with 400v at just over 1500 rpm and 50hz, more on this later!
The engine removal was easy enough but this wasn't going to be a simple build and a number of problems would have to be solved. These engines are drive by wire ie the injector pump is controlled via an ECU (brain) and a bucket full of sensors there is no throttle cable it is all electronic. I should mention I am a diesel fitter to trade but it was in days of a couple of wires and a pull stop industrial engines. My solution to the problem was simple in principle but tricky in practice. I completely removed the original wiring loom ECU and dash binnacle from the car, this took longer than it did to lift the donkey out!
Next job was to build a new chassis to hold the engine and to figure a method of coupling to the motor. The chassis was built from 2x2 box section with 2x2 x1/4 angle. I took pics but lost them! The original gearbox had 2 shattered gears but the spigot shaft was fine so rather than mess about trying to couple to the flywheel I just refitted the the clutch and removed all the shafts from the gearbox. The spigot shaft runs on 2 wet bearings so I replaced them with sealed units. With the end case removed from the gearbox it exposed the end of the spigot shaft to which I fitted a 30 hp cush drive coupling to the motor this would allow a little bit of movment. The shaft is keyed and pinned. The next pic shows the coupling but I have moved the motor side of the coupling back for clarity
So with the engine and motor now mounted and connected roughly it was time to start it! boy was I optimistic when I turned the key everything worked on the dash and she turned over the best and was even injecting but would it go not a bit of it. The following two days then involved a lot of cursing a lot of beer and an even bigger supply of tobacco. To cut a long story short I eventually found the fault, some idiot (me) had connected two wires ass about face and as soon as I swapped them she burst into life
More beer was then required to celebrate!
Now to make some sense of the wiring by giving it a severe haircut, all unused circuits where removed, cables rerouted ABS system and intercooler where removed.
The ECU, fuse box , dash, key switch filters etc etc where then mounted to the frame of the chassis, at last it is starting to look like a machine rather than just a mess of wires! The radiator has been fitted; I will be fitting valves to allow connection to the heating system of the house and a duct from the radiator to my workshop for hot air heating. The unit will be placed in a shed adjoining the workshop but this means the unit has to go through a 43 inch wide doorway, but it should be ok with the air filter removed the widest point is 39inches.
Marmalade is checking for leaks!
That's as far as I have got so far, I hope to get started on the generator part tomorrow by fitting the caps, build a control panel and give the chassis a coat of paint and try to make it pretty.
The engine is way too powerful as it is 90 BHP but on the plus side my fuel is free and at 1500 rpm it is very quiet, I also intend to fit a compressor and hydraulic pump for workshop use. The Audi engine should be very reliable, time will tell.
One quick question for those in the know! do the cables to the caps carry full load current? Do they need to be as heavy as the output cables?
Finally for now total cost to date including caps and steel and mig wire discs etc £35 ($70) everything else was at hand or borrowed from other projects!
My next entry will be about the generator with all the details of the caps ect. It's herehttp://www.anotherpower.com/board/index.php/topic,112.0.html