Battery Percent And Charge Time - Schumacher SC-7500A SpeedCharge Owner's Manual

This charger adjusts the charging time in
order to charge the battery completely,
efficiently and safely. The microproces-
sor automatically makes the necessary
decisions. However, this section includes
guidelines that can be used to estimate
charging times.
The duration of the charging process de-
pends on three factors:
1. Battery State – If a battery has only
been slightly discharged, it can be
charged in less than a few hours.
The same battery could take up to 10
hours if very weak. The battery state
can be estimated by using the built-in
tester (see page 11). The lower the
reading the longer charging will take.
2. Battery rating – A higher rated
battery will take longer to charge
than a lower rated battery under the
same conditions. A battery is rated in
ampere-hours (AH), reserve capacity
(RC) and cold cranking amps (CCA).
The lower the rating the quicker the
battery will be charged.
3. Charge rate – The charge rate is
measured in amps. This charger
provides charge rates of 2A, 12A
and 30A. The 75A rate is for engine
start only. The 2A rate is for charg-
ing smaller batteries such as those
used for motorcycles and garden
tractors. Such batteries should not be
charged using the 12A or 30A rate.
The 12A and 30A rates are for charg-
ing larger batteries. In the 30A mode,
the charger begins at a low charge
rate and increases the charge rate if
it is determined that the battery can
accept the higher rate. All charging
modes will decrease the charge rate
as the battery approaches maximum
charge. After the charging process
has started, the digital display can be
used to determine charging progress
by selecting the BATTERY % mode.

BATTERY PERCENT AND CHARGE TIME

There are some important facts to keep in
mind when charging a battery.
• When the display indicates 77%
charged, the battery has been charged
enough to start most vehicles and has
already been charged as much as by
many other battery chargers.
• When the display indicates 85%
charged, the battery has already been
charged at least as much as by most
other battery chargers.
• The battery % shown in tester mode
is an estimate based on the bat-
tery voltage and the Battery Council
International scale. The battery %
shown in charger mode is an estimate
of the relative charge in the battery
compared to the charge it should have
if the charging process is allowed to
complete.
• The battery % shown in tester mode
can be used to estimate the relative
charge time. The lower the % shown,
the longer the charge time for a given
battery.
• The battery % shown in charger mode
is an indication of the relative progress
of the charging process. The higher
the battery % displayed, the less
charge time remains.
• The more a battery is discharged,
the faster it absorbs charge from a
charger. That means that the battery
% increases faster at the beginning
of the charging process than at the
end. In other words, it takes longer
for the battery to absorb the last few
percent of charge than the first several
percent.
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