Jinma 354 alternator charging output?

[DonRina]

Just wondering what my alternator should be putting out for voltage. I get 12.24 volts at 1500 rpm which seems low. My battery always seems to have trouble turning the motor over. The battery is new. Maybe the alternator or regulator are shot? Any troubleshooting guides for this? I did take apart all the electrical starting and charging circuit and cleaned everything. Grounds were cleaned as well.

Don B

 

[piper184]

Most alternators put out at least 14 volts. It has to be higher than the target voltage for the battery which is usually 12.5 to 13.

I would first check to make sure the belt isn't slipping. Then probably go for a new regulator

Do you have an ampmeter? Does it show that the battery is being charged?

 

[DonRina]

Ok, had some time for this. At 1200 rpm I get 13.8 volts once I go past this rpm I don’t get any more voltage and it actually starts going down slightly. I did take off the selnoid and took it apart and found lots of age/use contact corrosion. I cleaned all the contacts and reinstalled it. The tractor does start better now but the low alternator voltage is most likely the issue. I notice my ammeter has a ticking motion and isn’t steady so maybe the regulator is suspect.

 

[piper184]

Sounds like you might have two problems, maybe three.
The "ticking" ampmeter indicates the regulator or alternator are doing something.
The 13.8 volts indicates that the alternator is putting out sufficient voltage. A low or bad battery could be what is keeping it from going any higher, but it should be fine at 13.8

Where were you testing the voltage? I would check it at the back of the alternator and again at the battery post. Use the same ground point for each test. If you see a difference it could be the cable. Cables can and do corrode internally, adding resistance and not showing any harm externally. A quick and easy way to bypass this is to put a jumper cable between the alternator and battery post. Of course all connections have to be clean and tight.

Basic electrical troubleshooting is required here.

Start with the simple and easy first.
Clean and tighten all connections between the alternator, battery, engine and starter. You can use an ohmmeter to test cables if you disconnect at least one end.
Remove the battery and charge it off of the tractor. Let it sit and test voltages. Use a load tester if you have one. Or take it to an auto parts store, most will test for free.
If the voltage regulator is external from the alternator it can be replaced with a known good unit to see if that stops the "ticking". Also check all the connections that go to the external regulator. On my 284 it was plugged into the fuse block. The terminals in the block were of poor quality and caused lots of issues with the regulator.

I don't know the details of your tractor but in most cases the starter is grounded though the engine casting. Jinma was known for painting the casting before installing the starter, leaving a poor ground path. For a sluggish starter, I would pull it from the tractor and get it on the bench for a good cleaning and lubing. Dry bushings in a starter can cause a lot of drag. Also there are internal contacts that can get dirty and add resistance to the circuit. These starters are NOT maintenance free, the periodically need TLC.

The alternator is likely a totally enclosed fan model and should be fairly dirt free inside. But brushes can wear or not move freely, which could be a cause for your "ticking". I would leave tearing into the alternator as a last resort as it is probably the least likely to fail.

It can be time consuming, but if you are methodical about your approach it shouldn't be too hard to sort this out.

Ask away if you have any questions.

 

[Roadworthy]

Just a thought here - alternators frequently have soft carbon brushes. If they wear down (and they do) the alternator output will decrease.

 

[DonRina]

I had previously cleaned all the contacts on the battery, all grounds, alternator, clutch switch, basically everything in the starting and charging circuit. The voltages I posted were taken at the battery as well as at the starter. I believe that there is no issue with the starter itself as well as the newly repaired selnoid.

It’s been noted on the net that the Jinma ignition switch can be-a problem as well as the regulator.

I noticed that the main power wire going into the regulator does get warm so that could be an issue.

 

[piper184]

Good, you have done all the basic stuff. Now to find the real problem. The warm wire may be a good starting point.

Over-all the size and quality of the wiring on these tractors is less than ideal. Most all of the wires are too small and the crimped on terminals, especially the flat female ends are of poor quality. What I find is that the metal is not strong enough to maintain the pinching pressure needed to hold onto the male end. The curls on the female side loose their grip with vibration and eventually cause problems. You can squeeze then down with pliers but they only hold for a while. Eventually one of the curls will break off.

If I remember correctly the regulator senses system (battery) voltage through the fuse box, which is powered through the key switch. Then it sends voltage to the alternator to "excite" the field coil. This then raises the output voltage which goes through the ammeter, to the starter connection and back to the battery.

I don't think there is a great deal of current that flows from the regulator to the alternator but a bad wire/connection could certainly lower the voltage that is actually seen at the alternator. You should be able to use an ohmmeter to measure the resistance of that wire between the regulator and the alternator. Be sure to remove both ends to insure you are not reading some other part of the circuit. Or you could always make up a temporary jumper wire to bypass the wire in the harness to go directly between the alternator and the regulator. Also don't forget that the regulator needs a good clean ground for proper voltage reference.

The same three electrical rules apply to trailers and tractors:
Check your grounds
Check your grounds
Check your grounds ~ Francis Robinson aka: Farmer

Thinking about the whole thing, it is probably much more common for the regulator to fail than the alternator. I fought the bad terminal/small wire thing on my 284 for quite some time and eventually the regulator failed. A replacement was half the cost of a re-man Delco alternator that put out way more amps and had an internal regulator. The down side of that conversion is that the Delco was not a totally enclosed fan design so on the rare occasion that I am working in dusty conditions I have to be vigilant about blowing the dirt out of the alternator.

The key switch could play a minor role in this but if you put it in run and get full battery voltage at the fuses, the switch is probably fine. The most common failure mode of the key switch is the glow plug circuit is fully fed through the switch contacts. That puts a 30A load on the switch and can burn the contacts. Also the glow plug wire is too small. The best solution for that is to install a solenoid so that only the relay current goes through the switch and full plug current comes from the battery directly (through the solenoid).

 

[DonRina]

Good, you have done all the basic stuff. Now to find the real problem. The warm wire may be a good starting point.

Over-all the size and quality of the wiring on these tractors is less than ideal. Most all of the wires are too small and the crimped on terminals, especially the flat female ends are of poor quality. What I find is that the metal is not strong enough to maintain the pinching pressure needed to hold onto the male end. The curls on the female side loose their grip with vibration and eventually cause problems. You can squeeze then down with pliers but they only hold for a while. Eventually one of the curls will break off.

If I remember correctly the regulator senses system (battery) voltage through the fuse box, which is powered through the key switch. Then it sends voltage to the alternator to "excite" the field coil. This then raises the output voltage which goes through the ammeter, to the starter connection and back to the battery.

I don't think there is a great deal of current that flows from the regulator to the alternator but a bad wire/connection could certainly lower the voltage that is actually seen at the alternator. You should be able to use an ohmmeter to measure the resistance of that wire between the regulator and the alternator. Be sure to remove both ends to insure you are not reading some other part of the circuit. Or you could always make up a temporary jumper wire to bypass the wire in the harness to go directly between the alternator and the regulator. Also don't forget that the regulator needs a good clean ground for proper voltage reference.

The same three electrical rules apply to trailers and tractors:
Check your grounds
Check your grounds
Check your grounds ~ Francis Robinson aka: Farmer

Thinking about the whole thing, it is probably much more common for the regulator to fail than the alternator. I fought the bad terminal/small wire thing on my 284 for quite some time and eventually the regulator failed. A replacement was half the cost of a re-man Delco alternator that put out way more amps and had an internal regulator. The down side of that conversion is that the Delco was not a totally enclosed fan design so on the rare occasion that I am working in dusty conditions I have to be vigilant about blowing the dirt out of the alternator.

The key switch could play a minor role in this but if you put it in run and get full battery voltage at the fuses, the switch is probably fine. The most common failure mode of the key switch is the glow plug circuit is fully fed through the switch contacts. That puts a 30A load on the switch and can burn the contacts. Also the glow plug wire is too small. The best solution for that is to install a solenoid so that only the relay current goes through the switch and full plug current comes from the battery directly (through the solenoid).

Yup, I did install a relay circuit for the glow plugs. I’ll check the charging by by passing the fuse connection to see if I get better charging.

Had to boost the battery today again to start it.

 

[piper184]

Is your battery loosing charge while it sits?
Have you done a load test on the battery? I know you said it was new, but it just might be a defective one.
Here is what I would do if it were sitting in my yard, keep in mind I have an el-cheapo HF load tester. It only puts a 100 amp load on the battery, but it will definitely show a bad battery. Also you can put a load on the system while it is running to test the alternator output. Very handy device and not too expensive.
1- Check battery voltage. If under 11, put a charger on it and wait until it reads at least 12.5
2- Let it sit an hour or two and check the voltage again.
3- Check it again the next day. It shouldn't go below 12 after sitting a day. If it does there is a draw somewhere, either in the tractor or inside the battery.

To test that theory remove the battery and do steps 1 through 3 again on just the battery with nothing else connected. If voltage drops, bad battery, if not, electrical drain in the tractor is the most likely suspect.

Put the battery back in the tractor and connect the ground cable. Put an amp-meter (multi-meter) in the circuit between the positive battery post and the positive cable. With everything turned off you should see a reading of zero. If there is any current flowing start pulling fuses one at a time to see if you can isolate the drain. If nothing is found that way, disconnect the battery wire from the alternator. If that stops the current flow, there is likely a bad diode in the alternator. Usually when they go bad they go "open" but in some cases they can short to ground. Then when the alternator is working it overcomes the minor short and will charge but at a lower rate than expected. But once you stop the engine, that leaky little diode goes right back to draining the battery.

If disconnecting the alternator does not stop the current, don't forget to unplug the regulator to test that as well.

I have seen all kinds of different failure modes in batteries, alternators and regulators. You just never know what the problem is until you track it down. You have eliminated a lot of the stuff, just gotta keep going until you find it.

 

[stevem5215]

My advice ? Replace the alternator and regulator with a GM all in one unit. Get a 3 wire alternator so it'll charge at low RPM's too. I put one of those on our Jinma/FarmPro about 15 years ago and it worked fine till we sold it a few years back. If you search for my name you'll probably see my posts on it from back then and how i did it all.