Direct to 12 Volt generator - 'Modify' a cheap one perhaps????

Durcott

Durcott

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Direct to 12 Volt portable generator

Hi Forum Folk,

I've been trouble shooting an old cheap gennie - the usual grey import job of around 800 Watts that goes under a 100 different names.

I have a feeling the really cheap and cheerful bits need replacing - ie it's a write off....

That got me thinking ...

For battery charging (on a small yacht), why generate 240 Volts from a cheap nasty generator, just to run nasty car type battery chargers? The in-efficiencies must add up on each conversion.

What if I put a decent alternator onto the engine's crankshaft, via a pulley? The engine has a constant speed control, the alternator has a decent output, and a good regulator. I could even feed one of those 'clever' chargers.

While it's not practical on one of these cheap gennies (the generator is fully integrated with the engine) - I could see a typical Briggs or Honda motor rigged up in a frame with an alternator.

Granted - a wind turbine would probably be a more sensible option, but hey - I'm stinking of petrol and I want to play with my toys :rolleyes:

Is this today's winner for 'most stupid idea', or has anyone had the same thought and given it a go?

Cheers - Jeff
 
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Presumably your cheap generator has an alternator/diode set up to deliver around 380 volts DC. Just right for switch conversion to 240VAC equivalent. I wonder if it is not practical to rewind or remove windings on the stator (outside take off windings) and perhaps also remove or rewind the rotor (field coil) (also fit 6x high current diodes. The existing rotor field coil will be designed I think to run on a regulated DC of around 300 volts so I am guessing many turns of fine wire. You want less turns of heavy wire comparable to a car alternator with about 12 ohms resistance. The outer pick up coils will need to produce about 12v AC each of 3 phase coils at a current about 1/3 of expected output current. ie something similar to a car stator coil set.
Anyway probably a foolish idea but might be food for thought.
Yes obviously a car type alternator with a regulator designed for the job would be more efficient. So the regulator adjusts the field coil current about 1 amp which gives a higher voltage output which then pushes into the battery your maximum charge current. This all comensurate with the max power and ideal rpm for the engine and max power limitations of the alternator. So actually a manual regulator might be best certainly for experiment. good luck olewill
 
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