B6200 not charging

[djg]

I have owned this tractor for about two weeks. Charge light on all the time, only battery voltage shows on multimeter when engine is running, "dynamo" has about 24 volts ac output across the two wires out of it. Is my regulator shot? As always, thanks for any help. I have owners manual, but have not yet purchased maintenance manual.

 

[KennyV]

Sounds like your rectifier diodes have shorted out, not a big deal to replace.
You might want to take it to an alternator/starter re-builder in your area, slip rings and bearings may also need replaced. In any case it is not very expensive to rebuild.

You will want to do this soon as ac voltage is not good for your battery /forums/images/graemlins/shocked.gif. KennyV.

 

[djg]

Thanks for your reply. I think this system may be a little different than the usual type. The owners manual calls out dynamo, not alternator. There are two identical wires coming out of dynamo, no polarity coding. No polarity coding on wiring diagram. When spun by hand, the dynamo has a very strong magnetic field effect, much like a magneto, only stronger. This made me check for ac output. I think this system sends ac voltage to the rectifier/ regulator box, which turns it to dc and so on. I was hoping someone on this forum was familiar with this older system, so I could get an idea of what's going on until I get a maintenance manual. Thanks for any help.

 

[btolle]

In some countries they call it a dynamo instead of alternator.

The Japanese probably learned their English from the British who call it a dynamo.

An alternator produces AC current which would be switching the polarity many times per second so there is really not a fixed polarity.

The rectifier has diodes in it. A diode is like a check valve, it only lets current flow in one direction to convert the AC to DC. The diode also controls the signal to the alternator light. I have seen lots of GM cars where the alternator light stayed on all the time but the system was charging as it was supposed to.

The regulator controls the voltage output.

The wires from the dynamo (alternator) should go to the regulator You need to trace the wires and check the voltage output on the other side of the regulator. The regulator could be bad.

The easiest way to check the charging system is to hook your voltmeter to the battery terminals with the key off and see what that value is. Start the tractor and run it up above 1,500 RPM's and measure the voltage at the battery terminals again. The second reading should be about 1.2 to 1.5 volts higher than the first reading. If it is not charging the voltage will be the same or a few tenths of a volt lower than the first reading.

The reason for comparing rather than trusting the meter is that unless you paid at least $100 for the voltmeter you will be lucky if it is within 5% of being correct.

The system is really not a different design, all altenators work the same way. The difference is that some have internal regulators and diodes (General Motors) and some used external regulators (Fords) back a few years ago.

Sorta makes me miss my old 8N. The 6 volt generator never worked and it had a 12 volt battery in it so it started a lot better than the 6 volt battery did. I used to put the battery charger on it for a few hours and then use it for several days and the battery never showed any indication of being weak.

Bill Tolle

 

[djg]

Bill, thank you for your nice post. My meter did cost a hundred dollars. One of the few advantages of being a mechanic is buying real nice tools. The system is defiitely not charging, and the "dynamo" is definitely putting out electricity. I will bug out the wiring and if all is good, buy a new regulator. I hesitated because a new one is 70 dollars at tractorsmart, and you know the signs you always see at parts stores: No Returns on Electrical Items. I guess I will bite the bullet and buy the expensive shop manual too. Thanks again.

 

[btolle]

Please let us know what you find. That information will be useful to someone else (maybe even me) in the future.

Bill Tolle

 

[djg]

Btolle asked for an update on my tractor. I bought and installed a new rectifier/regulator, and the charge light went out, so I guess that fixed it. I'm still not getting much of a charge when running. I'm waiting for workshop manual to arrive, will update further if I learn anything from it.

 

[btolle]

Thanks for letting us know what the problem was, it might help someone in the future.

The alternators on these tractors don't put out much amperage since the tractor does not normally have many electrical accessories. I think the alternator on my B7510 is only rated at 14 amps.

Now you can get back to work /forums/images/graemlins/grin.gif

Bill Tolle

 

[MadReferee]

</font><font color="blue" class="small">( The alternators on these tractors don't put out much amperage since the tractor does not normally have many electrical accessories. I think the alternator on my B7510 is only rated at 14 amps.)</font>

BTW, they are not alternators. They are 14.5 amp dynamos with a separate voltage regulator. There is a big difference between an dynamo and an alternator.

Technically, a dynamo (or generator) works just a like a motor in reverse. A coil is made to rotate in a magnetic field. A voltage is induced in the coil. The induced voltage produces a current in the coil. Slip rings and brushes are used to carry the current from the coil to an external circuit which charges the battery. An external voltage regulator is also used.

The same dynamo is standard on almost all B and BX series Kubotas.

 

[djg]

Mad referee, in this unit, the magnet rotates, and the coil is stationary, so there are no slip rings or brushes. So shows my parts catalog cd. Do you know what a typical good charge voltage would be? Thanks.