Transcript Battery Basics-Cell Chemistry Optima

Battery Basics-Cell Chemistry
Additional Reactions of Significance
C
•
Oxygen Reaction Cycle::
½O2 + Pb
PbO
C
PbO + H2SO4
PbSO4 + H2O
Note: Oxygen reaction cycle is a benchmark characteristic of VRLA batteries. It is more
pronounced with AGM than with gel constructions.
•
Severe Overcharge Reaction: 2H2O
C
O2 + 4H+ + 4e-
Note: This results in water loss due to venting of O2 and can be life limiting.
•
Positive Grid Corrosion: Pb + 2H2O
PbO2 + 4H+ + 2e-
C
Note: This results in water loss and can be life limiting.
Optima AGM Battery Construction
Optima has lower internal
resistance compared to flat plate
batteries
•Optima has less internal parts (~30)
vs traditional batteries (120+)
•Optima has over the partition, solid
lead connectors vs through the
partition inter-cell welds
Element Characteristics
• Factors affecting internal resistance of the battery
– Size of lead conductors
– Plate surface area
– Plate spacing
– Separator resistivity
– Electrolyte type
• Gel has higher resistance than flooded or
AGM designs which negatively impacts high
rate and cold performance
– Electrolyte concentration
– Temperature
Container/Cover Design
• Cylindrical cells provide superior
mechanical structure to battery
– Eliminates cell bulge
– Permits higher valve
pressures, 7-8 psi, compared
to flat plate, 1-5 psi
• Flat plate batteries can
experience end wall bulge when
pressure builds up on charge
resulting in loss of performance
Gassing Characteristics
• Gassing
– Less than flat plate/prismatic design
• Why?
– Higher purity materials – 99.99% pure lead
– Alloys – Optima uses a binary tin lead alloy
compared to a flooded battery that uses a multi
component alloy (silver, tin, calcium, aluminum,
etc… less impurities)
– Oxygen reaction cycle
Source: AGM Development Team
The Optima Advantage
Longer run time
Discharge Monitor of Optima Group 31 vs. Competitive Group 31 Lead-Acid Batteries
0
0.6kW to 10.50V Discharge Monitor - Ambient: 22 C
Voltage (V)
14,0
13,5
75Ah, Optima - 27.2kg
13,0
130Ah, Flooded - 30kg
12,5
98Ah, Gel - 31.4kg
12,0
11,5
11,0
10,5
Voltage cut-off: 10.5V
10,0
0
10
20
30
40
50
Time (minutes)
60
70
80
90