Battery Equalizer - Komatsu 930E-2 Shop Manual

Battery Equalizer

The majority of the accessory and control circuits
operate at 24VDC. Several components however, re-
quire 12VDC (cab window regulator motors, cas-
sette/radio, cigar lighter etc.).
A battery equalizer (8) system is utilized to obtain the
required 12VDC and ensure that all the truck batteries
are charged and discharged equally.
A 50 amp circuit breaker (6) mounted in the box pro-
tects the 12VDC circuits.
Troubleshooting
Normal battery maintenance procedures should be
followed according to the intervals specified in the
"Lubrication and Service" section of this manual. Refer
to the "Battery" information in this section for detailed
instructions regarding proper battery maintenance and
service procedures. Prior to troubleshooting the bat-
tery equalizer system, inspect all battery circuit con-
nections for excessive corrosion, loose cables, ground
connections etc. Use the following procedure to check
the system if a problem occurs:
1. Check the 12VDC circuit breaker.
a. If the circuit breaker has opened, check circuits
and repair cause.
b. Reset circuit breaker.
2. Check other applicable circuit breakers to deter-
mine if one or more has opened. (Refer to Circuit
Breaker Chart in the following Section for a list of
circuit breakers and the circuits involved.)
a. If the circuit breaker has opened, check circuits
and repair cause.
b. Reset circuit breaker.
3. Check battery voltage with the battery equalizer
connected and the engine running.
a. Verify battery charging alternator output is 27.8
to 28.2 volts.
D02018
4. If alternator voltage is outside above limits, refer
to Section "M" for battery charging alternator
service information.
5. With the engine running, verify voltages at the
battery equalizer terminals.
a. Measure the voltage between the 24 volt and
b. Measure the voltage between the 12 volt
6. If the difference between the voltage measure-
ments above exceeds 0.75 volts, the battery
equalizer is defective and should be replaced.
Always open main battery disconnect switches
prior to removing or connecting any wires or ca-
bles on the Battery Equalizer terminals.
24VDC Electric Supply System
12 volt terminals.
terminal and ground.
D2-5