no output power after changing the alternator.

[Michel]

Hi there,

I had my home made hydro power system running for 2 years, but the ford alternator gave up a while ago. I changed it for an other one from a Fiat Punto car and now it will not work any more.

The Ford alternator gave me about 50 Watts at 200 rpm. When I applied 12 Volts to the rotor coil it drew about 1.8 amp and while turning the hydro wheel the same time I always noticed more resistance than without the 12 volts, so I assume the rotor field was there.

The rotor coil of the new alternator doesn't take almost no current and there is no resistance at all when I turn the hydro wheel. so I think there is no rotor field.

When the water is running there is no output current at all.

Now I have a few questions;

1. Do you feel always resistance while turning the hydro wheel when you put 12 volt at the regulator?
   
   
2. Can I check if there is a rotor field?
   
   
3. Are there big differences between car alternators? (can I use any type I want)
   
   
4. Does anyone have a suggestion to fix my hydro generator?
   

[Norm]

The carbon brushes that make contact with the slip

ring/s might not be making good contact, which

may be why the rotor coil isn't taking much current ....or the coil might be bad.

Did you really mean 200 RPM at the alternator shaft or the hydro wheel shaft?

 You really should get some resistance when you

apply 12 volts to the rotor coil, you should

feel some cogging as you turn it IMO

[Flux]

I am not sure how you are doing this. You need to get inside and feed the field directly to the slip rings. The internal regulator can be different between different makes. Some have one ring common to negative but most have one ring common to positive.

Some have the brush boxes as part of the internal regulator and you will need to get rid of the regulator and feed the brushes directly.

You should indeed see field current flowing and you will feel resistance when you turn it, it will probably cog and it will drag. From your description you have not got a field circuit. It may be brush contact or a faulty field as Hiker suggests but I suspect you have not got directly to the brushes.

Probably for hydro you would be better off reducing the field with a resistor but it should at least work with full field.

Flux

[Opera House]

You didn't provide a lot of detail.  Are you aware that many alternator regulators require the alternator light pin to be connected to 12V in order for the field to turn on.  A rather clever gimick to reduce the number of wires.  Use a small 12V lamp or 330 ohm resistor.

[tanner0441]

Hi

Just one quick comment, my wife has a Citroen Saxo and the alternator on that is controled via the engine computer. Could your Fiat alternator be a simular type?

I have tried several Ford alternators they are more basic but more reliable and easier to get inside to modify.  Also the ford alternators are nearly £100 cheaper.

Brian

[Flux]

If this is for hydro then I assumed he had discarded the internal regulator and was supplying the field direct.

If the internal regulator is still present it will almost certainly need the wanrning light connected that Opera House mentioned or it will need 5000 rpm to kick in. There may also be other links to computer on modern vehicles. For basic battery charging with hydro, get inside and get field directly to the brushes, the internal regulator will cause many problems.

Flux

[hydrosun]

Harris hydro's used a Motorcraft 70 amp alternator from 1970s cars with an external regulator. You can then put a rheostat from one pin which puts out 1/2 voltage (6 volts) to the other rotor input pin. This allows lower losses for field current. The rheostat only has to lower the voltage from 6 volts instead of 12 volts. The rheostat allows you to control the field strength to match the power available from the water and allow the pelton to travel at 1/2 the speed of the water to get the most power.

 You didn't mention the amount of head in your system. A car alternator works best to produce 12 volts at about 100 feet head. At different heads you want different windings in your stator. A automobile electric shop can get a 24 volt stator for the Motorcraft for about $80 for lower head sites. This all supposes you want to play with this hydro to get a bit more power out. Of course a permanent magnet alternator would be even more efficient.

Chris