We have a 89 W250 that does snow plowing duty. Even with the large tractor battery the stock ECM controlled alternator had a hard time keeping up when plowing after dark with lights, heater fan, emergency yellow light and reverse warning alarm when plowing.
Seeing we had a spare 60 some amp alternator using 77 360 alt brackets reversed to go where the air pump was and a BWD voltage regulator using a empty relay plug for the voltage sensing wire. We used a #4 to go from the alternator charging post to the battery plus terminal.
While this works really good for keeping the voltage at 13.9 or better at all times and rapid battery recharge, The amp guage reads discharge at times even though the voltage is close to 14v.
The question is by adding alternator 2 and routing its output direct to battery is it possible that I've reversed current flow "backwards" through the guage, and if so will any damage be caused to the other stock ECM regulated system.
Thoughts anyone?

 

Just run one high output alternator(100 amp minimum), Problem solved. Amp gauge? In 89 they only had a volt gauge or was it added? I never heard of Frankensteining in another alternator!

 

We tried that on our 99 2500. Worked great above 2000rpm but in the stop/start raise/lower snow plowing parking lot that's done at below that rpm you had to stop in the middle of the job and hold it at 2500 rpm to get enough battery to make plow work again.
Our 89 has an amp meter in the dash from factory. The plow control box has a digital voltmeter in it.




Prototype system without welded spacer to plate w/triangle brace and the shims to perfect belt alignment and extended tension arm

 

Any more ideas on why the factory amp guage goes to discharge even though my digital voltmeter says 14.4v at the same time?