B7200 charging light flashes on and off

[Trevor]

Hi Folks, I have done a foolish thing! I have a model with a 5 wire generator and external regulator (Cargo 130627). Last year the battery failed, I fitted a new one in the dark recesses of the shed, it started fine and cut the grass in the bright sun. But when I parked it in the dark I noticed the charging light was on. Finally I discovered that I had the battery in the wrong way, + to chassis earth. I suspected I had wrecked the generator and or regulator and have since replaced both. But I still cannot get it to work properly. The new gen and regulator cause the charging light to slowly flash on and off and the voltage output fluctuates as high as 18V. I have checked all the wiring and all seems OK. I would really be grateful for any suggestions and also a copy of the circuit diagram for this setup. My user and workshop manuals only cover the 3 wire gennie.

Thanks in anticipation
Martin

 

[Stumpy]

If the battery was hooked up in reverse how did you cut grass? If the starter functioned at all it would've spun backwards and your engine will start in the wrong direction. All the forward gears would've been reverse gears or for a hydrostatic the pedal would've been backwards, and your blades would've been spinning in reverse too. Check the inside of your air filter for a bunch of diesel smoke particles.

It sounds like the regulator isn't working. Having current pumped in the wrong direction may have melted some ground cables. I'd check start checking grounds with a multimeter in continuity mode and see if you can find a bad cable. Have you looked at the fuses?

 

[Stubbyie]

I'm with prior poster: start looking for bad wire.

If the flashing is regular, syncopated, I'd look for a thermal relay or fuse constantly trying to reset itself.

If the flashing is more in time with engine or machine vibrations then I'd concentrate on a frayed or melted wire resulting from when battery was backwards.

Check around your local alternator (dynamo?) shop. Seems like I remember sometimes alternators have to 'flashed' to reset their internal diodes after being exposed to cross-connection---which could be a hot wire previously melted now finding intermittent chassis ground. I think this is possible but low probability: I'd track down a wiring schematic and do a little detective work on the wire harness.

Please post back what you find and how resolved so we may all learn.

 

[Trevor]

Thanks Stumpie and Stubbyie,
Yes I am equally surprised that the starter spun the right way, but its a manual gearbox and everything ran like normal. I will definitely check all the wiring and see if I can locate any melted wires or duff earths and try some checks across the gen windings. Both fuses OK and flashing seems regular and unrelated to engine speed. I am very grateful for your suggestions and appreciate the power of such a large forum. I will keep you informed on the outcome.
Trevor

 

[Kubota Newbie]

If your model has an external recitfier (little black box in the wiring harness coming from the alternator, probably has fins on it for cooling). Replace it.
The intended purpose is to turn the AC current produced by the alternator into DC current (I know, I know, before somebody points it out, it's redundant to say "current" after AC or DC, yada yada yada). Anyway, if you ran it with the battery in backwards it probably fried it. Your wiring diagram may refer to it as a "silicon stack".
BTW, the old Farmalls are converted to 12 volt, neg ground from 6 volt positive ground all the time so a Delco alternator can be used. Never have to monkey with the starter, works fine either polarity.

 

[Trevor]

Thanks Newbie, The original regulator has been replaced and the new one is definitely under suspicion, I think the AC to DC is actually done inside this gennie as it has a split end plate with 6 diodes and they are also on my target list. If anyone out there has circuit diagram and/or figures for windings resistance for this 5 wire gennie I would be be very grateful for a copy. I have checked the wiring and all seems 100%.

Thanks all for help so far.