General Information On Batteries For Powering Inverters - SamplexPower PST-300-12 Manuel Du Propriétaire

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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 the
powering of inverters.
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.
Rated capacity in Ampere-hour (Ah)
Battery capacity "C" is specified in Ampere-hours (Ah). An Ampere is the unit of meas-
urement 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")
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 Rate"
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 battery and 42V for a 48V battery. for example, a 100 Ah battery will deliver 5A
for 20 Hours.
Rated capacity 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 25 A.
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
16 | SAMLEX AMERICA INC.
General Information on Batteries for
Powering Inverters