User manual

The movement of oxygen from the positive electrode to the
negative electrode is facilitated by the use of highly porous
separators that allow the oxygen to diffuse within the cell
and cause the reaction defined by Equation 1. The acidic
conditions prevailing inside the cell is very conducive to the
reaction between lead oxide and the sulphuric acid to form
lead sulphate in accordance with Equation 2 below:
2PbO + 2H
2SO4 ➔ 2PbSO4 + 2H2O (Eqn. 2)
As the lead sulphate is deposited on a surface that generates
hydrogen, it (lead sulphate) is reduced to lead and sulphuric
acid as indicated by Equation 3:
2PbSO
4 + 2H2 ➔ 2Pb + 2H2SO4 (Eqn. 3)
Adding the three equations and cancelling out like terms on
either side of the equations, we obtain Equation 4:
2H
2 + O2 ➔ 2H2O (Eqn. 4)
These four equations show the reactions that form the
principle of recombination that is employed by the CYCLON
®
battery product line. By properly designing the cell,
recombination efficiencies in excess of 99% are achieved in
the CYCLON batteries.
3.6 Shock & Vibration Characteristics
The spirally wound plate element is compressed within a
polypropylene liner or case, minimising plate movement
in high shock or vibration applications. Movement in a
vertical direction is also limited by the polypropylene lid
design. Overall, the cell has excellent shock and vibration
characteristics.
3.7 Float Life Characteristics
As noted previously, life expectancy of CYCLON batteries is
not limited by loss of electrolyte due to the sealed design.
Instead, life expectancy is determined by long-term corrosion
of the positive current collecting grid. The corrosion effect on
cell capacity is minimal until the cell approaches end-of-life,
which is defined as the inability of the cell to provide at least
80% of its rated capacity compared to that of 50% from a
standard AGM.
3.8 Cycle Life Characteristics
The cycle life of the cell in an application will be a function
of the depth of discharge (DOD), temperature and charging
rate. Depending on the DOD, the cycle life available can vary
from 300 to more than 20,000. However, to get these cycle
numbers, the battery must be recharged effectively.
3.9 Fast Charging Characteristics
Efficient fast charging can be accomplished using a constant
voltage charger. With an initial charge current capability in
the 2C
10
1
range the cell can be recharged to better than 95%
state of charge in less than one hour. Applications using
fast charging must allow for periodic extended charging to
maximise life.
3.10 Storage Characteristics
The CYCLON battery cell and monobloc may be stored
for up to two years at room temperature (25°C or 77°F)
and recharged with no loss in cell reliability or performance
capabilities. The recharge may be accomplished without
resorting to special charging techniques.
When batteries are stored at or near 25°C (77°F) we
recommend conducting an OCV audit every 12 months and
recharging when OCV readings approach 2.00 volts
per cell (VPC). If storage temperatures are significantly higher
than 25°C (77°F), even for short durations, the frequency of
OCV audits must be increased.
4.1 Introduction
Discharge tables and curves for CYCLON batteries are
shown in Appendix A. The capacity available from a cell is a
complex function of the state of charge, temperature, the rate
of discharge and the end of discharge voltage (EODV). The
tables provide the discharge performance of these cells to
various EODVs. The graphs provide the same information but
only to three EODVs.
4.2 Discharge Voltage Profile
Figures 4-1 and 4-2 show the room temperature (25°C/77°F)
voltage profile of CYCLON battery cells when subjected to
four loads - C
10/10, C10/5, 1C10 and 2.2C10.
In all cases, the low internal resistance of the cells allows very
stable voltage profiles, regardless of whether the discharge is
moderate (C
10/5 to C10/10) or at a high rate (1C10 to 2.2C10).
1
The C10 rate of a battery is defined as the charge or discharge current in amperes that is numerically equal to the rated capacity of a cell in ampere-
hours at the 10 hr rate of discharge. Thus the 2C
10 rate for a 5Ah cell would be 10 amps.
Chapter 4:
Discharging CYCLON
®
Batteries
9
Publication No: EN-CYC-AM-007 - December 2008
www.enersys-emea.com