2008 Foton 254 Generator to Alernator Swap

   / 2008 Foton 254 Generator to Alernator Swap #1  

D0TC0M

Silver Member
Joined
Jan 31, 2015
Messages
147
Location
NB, Canada
Tractor
Foton TE254A
The previous owner had a **** of a time and butchered the wiring. I'm fixing what the previous owner did and install it right. I've included the original wiring schematic and I modded the diagram to show the new one wire delco SI alternator. I think I've got it right but if someone wants to double check it I'd appreciate it. The only thing is the alternator has a larger amperage so the ammeter in the dash might be undersized. I will probably tee off before the ammeter to separate the 30 amp fuse at the fuse box. That way I won't be clipping my ammeter and I turn on my aux circuits. The first image below is that of the original schematic with generator. The second is with the alternator. The third is with an alternator and with the 30 amp circuit at the fuse box fed from the battery via an aux relay. Of course the wiring size will increase to handle the extra current from the alternator and also the ground wires.

Original Schematic with Generator
1ze819w.jpg


Schematic with alternator
29ndnus.jpg


Schematic with alternator and Aux Relay
5lav5x.jpg
 
   / 2008 Foton 254 Generator to Alernator Swap #2  
You don't use an ammeter with the Si alternators. Use a voltmeter.
 
   / 2008 Foton 254 Generator to Alernator Swap
  • Thread Starter
#3  
I'm fairly sure the its an ammeter that came in my tractor otherwise the alternator wouldn't charge the battery in the circuit above. Its supposed to act the same as it was stock.
 
   / 2008 Foton 254 Generator to Alernator Swap #4  
The alternator that came with your tractor was nominally rated at 14 amps, if I'm not mistaken. If you are installing a System Integral (Si) alternator, especially of a higher output, you cannot use the factory wiring because it is undersized and you can't use the factory regulator either. The most expedient way to install a "one - wire" Si alternator is this:
(Notice the origin of the sensing circuit at the battery. This allows accurate voltmeter readings as well as accurately relaying voltage to the regulator ) You can obviously omit the indicator light. Wire gauge should be sized appropriately for the anticipated load.
DelcoWiring 1.jpg
 
   / 2008 Foton 254 Generator to Alernator Swap #5  
Are you using a self exciting alternator? The "One-wire" Si alternators actually have three wires.
 
   / 2008 Foton 254 Generator to Alernator Swap #6  
I'm fairly sure the its an ammeter that came in my tractor otherwise the alternator wouldn't charge the battery in the circuit above. Its supposed to act the same as it was stock.
You replace the stock ammeter with a voltmeter.
 
   / 2008 Foton 254 Generator to Alernator Swap
  • Thread Starter
#7  
Thanks for all the replies fellas. Its much appreciated.

The alternator that came with your tractor was nominally rated at 14 amps, if I'm not mistaken. If you are installing a System Integral (Si) alternator, especially of a higher output, you cannot use the factory wiring because it is undersized and you can't use the factory regulator either. The most expedient way to install a "one - wire" Si alternator is this:
(Notice the origin of the sensing circuit at the battery. This allows accurate voltmeter readings as well as accurately relaying voltage to the regulator ) You can obviously omit the indicator light. Wire gauge should be sized appropriately for the anticipated load.
View attachment 410361
You are correct. The factory regulator is disconnected (refer to my 2nd and 3rd schematics) and I have to and will upgrade all my wiring. That includes not only the "70" and "1" positive wires but also the negative wires. As far the previous rating of the generator, 14 amps seems low because this tractor had come with headlights and cab lights plus a cab heater blower motor which in themselves would draw more than 14 amps and the battery would never charge.

Are you using a self exciting alternator? The "One-wire" Si alternators actually have three wires.
Yes its a 3 wire SI alternator. I'm assuming its modded internally to self excite because it did charge with only one wire and the small 2 wire connector in the alternator is filled with silicone from the show where it was bought.

You replace the stock ammeter with a voltmeter.
Its integrated into the dash cluster and cannot be replaced, at least not easily. I'm trying to stay with stock.
 
   / 2008 Foton 254 Generator to Alernator Swap
  • Thread Starter
#8  
Ok looking at the schematic again, separating the aux load doesn't reduce the alternator current from flowing through the ammeter. Well it does but only when the engine is off. When it is started all the load and charging current would still pass through the ammeter and its only a +/- 30 amp scale. The fusebox technically can haul 60Amps so instead I'm going to use the ammeter to measure glow plug current only and install a voltage gauge to monitor the alternator. Of course the wiring will be upgraded to a larger size. Thanks for the heads up guys :)
 
   / 2008 Foton 254 Generator to Alernator Swap #9  
Thanks for all the replies fellas. Its much appreciated.


You are correct. The factory regulator is disconnected (refer to my 2nd and 3rd schematics) and I have to and will upgrade all my wiring. That includes not only the "70" and "1" positive wires but also the negative wires. As far the previous rating of the generator, 14 amps seems low because this tractor had come with headlights and cab lights plus a cab heater blower motor which in themselves would draw more than 14 amps and the battery would never charge.


Yes its a 3 wire SI alternator. I'm assuming its modded internally to self excite because it did charge with only one wire and the small 2 wire connector in the alternator is filled with silicone from the show where it was bought.


Its integrated into the dash cluster and cannot be replaced, at least not easily. I'm trying to stay with stock.

Very well, do what you will. Good luck.
 
   / 2008 Foton 254 Generator to Alernator Swap #10  
Leave your ammeter connected like it was originally. The 30 amp meter will work fine with your new alternator.

Connected correctly, the ammeter measures current flow in and out of the battery, not the output of the alternator. The electrical loads ( lights or whatever) will be on the same side of the ammeter a the alternator. The ammeter will swing to the + when some of the alternator output is charging the battery, and to the - when the alternator cannot keep up with the current needs, and the battery is making up the difference.

The 60Amp rating of your alternator is the maximum amount of current that the alternator can supply, usually at it's maximum RPM. Unless your tractor has a very large crank pulley, and a very small alternator pulley, it will not spin fast enough to produce the full 60 amps.

A correctly wired ammeter will give you far more information on the health of your electrical system, than a voltmeter will.

Stan
 
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