Jd 620 alternator not charging

[offroad23]

Noticed ever since I have had this 620, battery never seems to stay charged. Replaced battery once and then again under warranty 6 months later. It has a 4K4 12VNEG alternator ig came with when I bought it. Decided to check voltage and it isn't putting any voltage out. Has a 2 pin plug on it with one wire going to terminal on the alternator where ammeter wire is connected and 2nd wire is not connected to anything. Where should this second wire go?

 

[offroad23]

Alt pic

 

[Jim.ME]

Hard to tell from your picture but it looks like the plastic plug is in backwards. I can't tell for sure what the colors in your plug are, white and red are commonly in those positions, but different colors may be used depending on who made the plug. Function of the terminal is what is important, not color.

The sensing terminal is the one that is supposed to have the wire going to the battery wire post on the alternator. The excitation spade terminal should have a wire providing power to it from a switched source. If that source is tied to your ignition circuit you will need a diode, resistor or indicator light to prevent a back feed from the alternator, when the engine is running, which can prevent shutting the power to the ignition off.

The locking tab of the plug is supposed to be in the notch at the front of the slot. As for the wires in the plug this picture may help.

 

[offroad23]

Red sense wire is tied to post on alternator, white wire doesn't go any where currently, will run a wire to switched power in dash now. Thank you for your assistance.

 

[Jim.ME]

Red sense wire is tied to post on alternator, white wire doesn't go any where currently, will run a wire to switched power in dash now. Thank you for your assistance.

Be sure you tie in separate from where the ignition system is fed. If you sue the same switch terminal as the ignition you need an indicator light, diode or resistor in the excitation wire.

 

[used red MN]

If you sue(use) the same switch terminal as the ignition you need an indicator light, diode or resistor in the excitation wire.

You will need the above to be able to shut off the engine. One of those items will be needed to.. using a sort of nontechnical term- bleed out” the power from the excite terminal that will continue to feed the ignition when the switch is off. If you only used this tractor occasionally you were probably just using the power in the battery. If you don’t run lights and the tractor starts easy it will run a long time and a couple dozen starts easily on one charge of a good battery.

 

[offroad23]

Hooked up excitation wire temporarly to switched power and alternator is now functioning. Will try to track down diode tomorrow.

I think your right for no more then we had been using it we were running on battery only. Was using it for rakng hay ast year and was working great for a while and then lost power and I haven't trusted it much since. Knew it was charge related, but never took the time to dig into it till today. Will put it on rake this year and hopefully it makes the season with no more issues because we do enjoyed running it.