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7.1 GENERAL
i
INFO
For complete background information on Lead Acid Batteries and charging
process, please visit www.samlexamerica.com > support > white papers >
White Paper - Batteries, Chargers and Alternators.
Lead-acid batteries can be categorized by the type of application:
1. Automotive service - Starting/Lighting/Ignition (SLI, a.k.a. cranking), and
2. Deep cycle service.
Deep Cycle Lead Acid Batteries of appropriate capacity are recommended for powering
of inverters.
7.2 DEEP CYCLE LEAD ACID BATTERIES
Deep cycle batteries are designed with thick-plate electrodes to serve as primary power
sources, to have a constant discharge rate, to have the capability to be deeply dis-
charged up to 80 % capacity and to repeatedly accept recharging. They are marketed
for use in recreation vehicles (RV), boats and electric golf carts – so they may be referred
to as RV batteries, marine batteries or golf cart batteries. Use Deep Cycle batteries for
powering these inverters.
7.3 RATED CAPACITY SPECIFIED IN AMPERE-HOUR (Ah)
Battery capacity “C” is specified in Ampere-hours (Ah). An Ampere is the unit of measure-
ment for electrical current and is defined as a Coulomb of charge passing through an electri-
cal conductor in one second. The Capacity “C” in Ah relates to the ability of the battery to
provide a constant specified value of discharge current (also called “C-Rate”: See Section 7.6)
over a specified time in hours before the battery reaches a specified discharged terminal
voltage (Also called “End Point Voltage”) at a specified temperature of the electrolyte. As a
benchmark, the automotive battery industry rates batteries at a discharge current or C-Rate
of C/20 Amperes corresponding to 20 Hour discharge period. The rated capacity “C” in Ah
in this case will be the number of Amperes of current the battery can deliver for 20 Hours at
80ºF (26.7ºC) till the voltage drops to 1.75V / Cell. i.e. 10.5V for 12V battery, 21V for 24V bat-
tery and 42V for a 48V battery. For example, a 100 Ah battery will deliver 5A for 20 Hours.
7.4 RATED CAPACITY SPECIFIED IN RESERVE CAPACITY (RC)
Battery capacity may also be expressed as Reserve Capacity (RC) in minutes typically for
automotive SLI (Starting, Lighting and Ignition) batteries. It is the time in minutes a
vehicle can be driven after the charging system fails. This is roughly equivalent to the
conditions after the alternator fails while the vehicle is being driven at night with the
headlights on. The battery alone must supply current to the headlights and the com-
puter/ignition system. The assumed battery load is a constant discharge current of 25A.
SECTION 7 |
General Information on
Lead-Acid Batteries
Summary of Contents for PST-1000F-12
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