
28 | SAMLEX AMERICA INC.
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 Deep cycle service.
2. 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 discharged 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 measurement for electrical
current and is defined as a Coulomb of charge passing through an electrical 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. 21V for 24V battery 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 computer/ignition system. The assumed battery load is a constant discharge current of 25A.
Reserve capacity is the time in minutes for which the battery can deliver 25 Amperes at 80ºF (26.7ºC) till the
voltage drops to 1.75V / Cell i.e. 10.5V for 12V battery, 21V for 24V battery and 42V for 48V battery.
Approximate relationship between the two units is:
Capacity “C” in Ah = Reserve Capacity in RC minutes x 0.6
SECTION 7 |
General Information on Lead Acid Batteries
Содержание PSR-1200-24
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