Generac 86640 - Manual (Page 87)

Testing (Continued)
2, Disconnect the battery ground cable. Connect an ammeter
jin series at “BAT" terminal of DC alternator. See Figure 5.
' Reconnect the battery ground cable. Connect a carbon pile
across the battery. Operate engine at 1860 rpm and adjust
carbon pile as necessary to obtain maximum current output.
a. If ampere output Is within 10 amps of the rated output
stamped on DC alternator case, the alternator is good.
b. If output is NOT within 10 amps of rated output, ground
the field windino tab by inserting a screwdriver into the end
case test hole (Figure 6).
CAUTION; The field winding tab is within 3/4 inch
of the casting surface. Do NOT force screwdriver
deeper than 1 Inch Into end frame._____________________
c. With field winding tab grounded, run engine at 1860 rpm
and again adjust carbon pile to obtain maximum current
output. If output is now within 10 amps of rated output,
check the field winding and check DC voltage regulator
with tester. If output is NOT within 10 amps of rated output,
check field winding, diode trio, rectifier bridge and stator.
OVERCHARGED BATTERY;
Connect a voltmeter from the DC alternator's No. 2
terminal to ground. If reading is “zero“. No. 2 lead circuit is
open. If the battery and the No. 2 lead circuit test good, but
overcharge exists, overhaul the DC alternator. Check field
windings for grounds and shorts. If defective, replace rotor
and test regulator.
#
Figure 6. Grounding the Field Winding Tab
Insert Screwdriver And Ground Tab
To End Frame By.Touching Screwdriver
To Both Tab and End Frame
End Frame
Hole
Page 9.2-2