battery discharging when engine running

[emmafabre]

hi guys,
I have a problem that I do not manage to sort out.
when I run the engine the battery is discharging very very quickly (10mn).
I believe this is or an issue of the starter/generator or the regulator. what do you think?
I check the wiring and I do not have anything badly earthed.
I raised the rear wheels of ground and while the engine in running and clutch in forward position I measured the voltage between the green wire out of the starter/generator ( i think this is the DF output) and the negative post of the battery.
I do not measure anything.
I thought my starter/generator was dead thus I replaced it with one known to work. but I have the same problem.

does my trouble shooting was good?
what do you think it is? how to progress further?

thanks for your help

[gaminde]

hi guys,
I have a problem that I do not manage to sort out.
when I run the engine the battery is discharging very very quickly (10mn).
I believe this is or an issue of the starter/generator or the regulator. what do you think?
10 Minutes is very short time for just having the motor running.

I check the wiring and I do not have anything badly earthed.
nothing is shorted that's good
I raised the rear wheels of ground and while the engine in running and clutch in forward position I measured the voltage between the green wire out of the starter/generator ( i think this is the DF output) and the negative post of the battery.
this is your field wire and the regulator should vary the voltage on this wire and this will cause the voltage to be output from the generator.
I do not measure anything.
I thought my starter/generator was dead thus I replaced it with one known to work. but I have the same problem.

does my trouble shooting was good?
what do you think it is? how to progress further?
yes troubleshooting was good
when you replaced the starter generator did this come with another regulator or not I would suspect the regulator. I would take a resistor of 1k ohms and connect it to the green field wire and touch the other end to the battery + terminal quickly and see it the generator output goes up this is done for a couple of seconds maybe 5 seconds if you get a voltage out of the generator replace the regulator.

thanks for your help

Hope this helps let us know what you find

[emmafabre]

thanks Gaminde,

sorry I do not understand how to do the test that you recommend in your last part?
Could you give me more detail?
how to find a resistor of 1khom?

regards

[gaminde]

Ok I now see Mexico for a location so Radio Shack is out. Use a light bulb from a house or automotive bulb, this bulb is wired in series with the green wire this is just a current limit device, I used to touch the green wire to the + battery but the generator will put out high voltage and I cannot recommend this.

also if you disconnected the green wire from the regulator and tried to read voltage you will see none! the regulator applies voltage to this wire to tell the generator to put out voltage, it regulates this output to match the generators output by sensing the generators output.

[emmafabre]

I did what you said.
I earthed the green wire but tension is not above the battery tension. just after start with battery at 12V it drop around 11.5-11.4 and even with the green wire earth this is the same reading.
I decided to open the generator to check the brush. everything oK. they are in very good shape.

I am not sure now what could be my problem.

[gaminde]

You must read the voltage out of the generator not the output of the regulator