Foton 40hp not charging

If you can get 18v out of the alternator by shorting battery to field, the alternator is good. Sounds like you have a bad regulator.

With the key on, check the battery voltage and field output at the regulator.

If you don’t see battery voltage at the regulator, you have a problem in the wiring/ignition switch.

If you don’t see field output voltage, the regulator is bad. The engine may need to be running for this to work, so check that too. If still no voltage on the field connection, bad regulator.

If you have field output voltage at the regulator but not at the alternator there is a wiring problem.

Without seeing a wiring diagram I don’t know if there are any fuses or other switches in the circuits.

I just went through this kind of thing with my Jinma 284. Regulator was bad. For a little more $ I was able to install a reman Delco 10si with only a slight modification to the mounting bracket. This is a “one wire” alternator so I sacrificed the charging system “idiot” light, which is now always on. The amp meter still works and now I can run all the lights and charge the battery at the same time!

Are you sure that’s the battery charging light and not just the “key on” light?

There should be a red LED on the voltage regulator that indicates field excitation when the key is on. If that LED does not come on then there is a problem with the key switch/wiring circuit, or the regulator is bad. Regulators are cheap.

I would go with a bad voltage regulator. Make sure ALL of your ground connections are squeaky clean. There are several caveats about going with the Si alternators, but most people I’ve seen ignore them anyway so I won’t bother.

Yeah, the biggest worry is the undersized wiring. The Delco puts out way more amps than the original alternator and can easily burn up the wires. However, the battery can put out more than the alternator, so…

In my case I have a new aftermarket fuse block on hand and I can rewire the tractor all at once if I have to, or more likely, a bit at a time as things fail. So far, no problems and the Delco is not overcharging.

The other weak point of the 285 series was the ignition switch. Going on 10 years and 500 hours with lots of cold (below 0) starts and all is well after I replaced the glow plug fuse and got it out of the cheap fuse block that melted.

Not familiar with the key on light. The 284 had an idiot light that was wired through the regulator that turned on when the battery was discharging and it also had an ammeter. When I removed the original regulator the idiot light stays on all the time. I just ignore it because I can see the ammeter working. Some day I may either figure out a way to make the idiot light work, or maybe a way to replace it with a digital voltmeter.

BTW, I had heard about the regulators with the indicator LED. Mine did not have that feature so it was down to troubleshooting with a multi-meter.

In my case the regulator shipped to me was $30. The reman alternator from NAPA was $60 with a new regulator and more output. My old alternator (14A)is just fine and laying on a shelf as a spare. I got lucky on the bracket as all I had to do was flip it over and add a 2″ bolt on extension made from some flat iron. Easily reversible if needed.

YMMV

Best of luck and let us know what you do to fix it.

Oh, one last thing, on the 284 the connections to the back of the regulator had a habit of coming loose. I would have to pull them out of the block and squeeze the tabs down a little to get a good connection. After a few hours they would shake loose again. Another reason for me to eliminate the regulator in the fuse block.

Sounds like you may have more going on than a regulator/alternator issue.

Things that come to mind are bad switch, bad wiring, bad connections, bad ground (same thing really).

I would start by checking the fuses and the battery. Remove and test it. Clean connections.

Start testing with a test light to see where there is power.

Make some jumper wires so you can by-pass questionable items like switches.

A wiring diagram is going to be a big help. Start tracing circuits. What works and what doesn’t? What do they have in common?

Well, aside from the tractor wiring being undersized for an 80 amp alternator, consider that you are also giving up the safety of having the OEM TEFC alternator. I know it doesn’t matter to most of you because you don’t understand the importance. With the exception of only a few, the Delco Si alternators are open frame and draw their cooling air through the front, which is fine for their intended purpose on on-highway vehicles. On tractors they sit right behind the radiator cooling fan and get blasted head on with chaff and dust. Enough chaff buildup can, and has, caused fires. There are several Delco Si alternator models that have a closed face fan and draw cooling air in from the rear. This is a compromise on having a TEFC alternator. Virtually all high-end Ag equipment has TEFC alternators. Aftermarket TEFC alternators are available from Prestolite/Leece-Neville or Motorola.

http://www.prestolite.com/pgs_products/alt_search.php

So not having a TEFC alternator is synonymous with the guy that’s not going to lash his tractor to the trailer because he’s not going on a thousand mile trip.

Don’t worry, I’m not going to mention this again.

In the case of my Jinma 284, the OEM was not a TEFC unit. In fact it had a fan and airflow identical to the 10Si that replaced it. I went from a 14 amp to a 63 amp alternator.

If I did field work or extremely dirty work, that would be a consideration along with probably not having a 284.

John’s problem remains, what is causing the alternator to not charge? We know the alternator works when “full fielded”, so for some reason the field circuit is not getting the voltage it needs. It very well could be the regulator but the fact that gauges don’t work may be a clue (or completely unrelated). At least it is “cause to pause” on the condemnation of the regulator.

If you have a known good regulator, the test is a simple swap. Bear in mind that new out of the box is no guarantee of a working unit. Known good unit means having proved itself on another tractor.

After that, it comes down to tracing the circuits and testing connections/continuity as you go.

John, do you have a schematic?

Also, just curious, what is the output rating of you alternator?

If you have part numbers for the regulator and alternator, please post them. We may be able to scare up some more information for you.