Maintenance Free Types; High-Cycle Maintenance Free Types; Charge Volt And Amp Values; Definitions - Komatsu 930E-2 Shop Manual

Maintenance Free types:

Immediately after engine start, system volts are
lower than regulator setpoint with low amps.
15-30 minutes into charge cycle, still low volts and
low amps.
15-30 minutes into charge cycle, volts rise several
tenths, amps increase gradually then increase
quicker to medium to high amps.
20-35 minutes into charge cycle, volts rise to
setpoint and amps lower.

High-Cycle Maintenance Free Types:

These types respond much better than standard
maintenance free types. The charge acceptance
of these batteries may display characteristics
similar to standard, maintenance type batteries.

CHARGE VOLT AND AMP VALUES

Voltage and amperage levels are functions of battery
state of charge. If the batteries are charged 95% or
higher when the engine is cranked, the charge voltage
will be near regulator setpoint and the amps will taper
quickly from medium to low. True battery voltage is
obtained AFTER removing any surface charge from
the battery or after 24 hours of non-use.

DEFINITIONS

NOTE: Charge voltage and amp rates vary from bat-
tery type to battery type, based on battery construction
technology and physical size of battery.
Low amps are the necessary amps that a battery
will take continuously over a period of time without
damage to the battery when the battery is in an
operating system and is constantly cycling.
Batteries such as the Group-8D may accept rates
up to 15 amps over several hours without raising
their internal temperature more than a few de-
grees. Group-31 batteries may accept rates up to
5 amps over several hours with minimal tempera-
ture rise.
M13-8
Medium amps are defined as some multiple of the
low amp value, perhaps 30 amps for the Group-
8D and 10-15 amps for the Group-31. This rate
of amperage will cause a rise in battery tempera-
ture over a long period of time (4-8 hrs) and may
lead to an overcharge condition if temperature
elevates too high.
High amps would be 50 to 75 amps for a Group-
8D, and 25 to 35 amps for a Group-31 size. High
amperage rates over a short period of time (2-3
hrs.) can severely damage any battery by over-
heating the battery and causing thermal runaway.
The battery, in effect, forgets its state of charge
and will accept all amps offered. The electrolyte
solution is boiled off as the battery moves into an
excessive gassing stage.
Charge voltage is the voltage delivered to the
battery when the alternator and regulator are
operating properly. This charge voltage value is
the voltage regulator's setpoint. At times the
charge voltage value may be less than the regu-
lator's setpoint but it will never be higher than that
setpoint.
Battery voltage is the steady state voltage of the
battery. The value of this voltage relates directly
to state of charge.
B+ voltage is battery positive voltage, but does
not refer to a specific value as does battery volt-
age.
Surface charge is a higher than normal terminal
voltage a battery has when it comes off a charger
or after extended time in vehicle operation. The
surface charge must be removed to determine
true battery voltage.
24VDC Electric Supply System
with 220 Amp. Niehoff Alternator
M13002 2/99