- Corrosion Layer 1 and 2 - Soaking - Formation - Tank Formation and Washing - Container Formation - Concept of Tank Formation Program - Inert Gas Oven - Enveloping - Assembling - Equilibrium Cell Voltage of the lead acid battery - Pourbaix Diagram - Chemical Reaction (Charging and Discharging) - Battery Container and Cover - Accessories - Safety Labeling - Sulfuric Acid

1. Lead-Acid Battery II
Bahtiar Yulianto
October 2016

2. Corrosion Layer 1 and Corrosion Layer 2
Detchko Pavlov Lead Acid Batteries Science and Technology

3. SOAKING
The diluted sulfuric acid used as electrolyte will penetrate into the pores
of the plates and immediately react according to equation (1) and
with the basic lead sulfates are converted into the neutral sulfate
PbSO4.
3PbO*PbSO4 + 3H2SO4 ↔ 4PbSO4 + 3H2O (6)
The acid penetrating into the pores due to reaction is diluted to almost
water. It is essential that the grid surface or, more precisely, the
oxide/sulfate layer on the grid surface is wetted with electrolyte of
sufficient conductivity. The active material in this stage is a
nonconductor and the electrochemical oxidation and reduction can
only take place at the grid surface where the electrons can flow free
in the metal.

4. SOAKING
Before :80% 4BS, 3BS, αPbO, SpGr 1.20
After 24 h : 50% Lead Sulfate, 20% 4BS,
20% 1BS, SpGr 1.16
Before : 50% 3BS, 40% 4BS, αPbO, βPbO, SpGr 1.20
After 24 h : >95% Lead Sulfate
Before :80% 4BS, 3BS, αPbO, SpGr 1.20
After 24 h : 50% Lead Sulfate, 35% 4BS,
10% 1BS
Before : 50% 3BS, 40% 4BS, αPbO, βPbO, SpGr 1.20
After 24 h : 60% Lead Sulfate, 15%3BS, 25% βPbO

5. FORMATION
The formation process is the conversion of the cured plated material into lead
dioxide at the positive plate and sponge lead at the negative lead.
Dissolution-precipitation mechanism where lead sulfate dissolves and bivalent
lead ions are reduced to lead (-) and oxidized to lead dioxide (+).
(R Wagner, MOLL Accu Elsevier 2009)
To begin formation positive and negative plates are inserted into diluted sulfuric
acid and connected to a rectifier. The rectifier acts like a pump removing
electrons from the positive plates and pushing them into the negative ones.
The following reaction equations are simplified showing only the essentials:
Positive PbSO4 + 2H2O ↔ PbO2 + H2SO4 + 2e- + 2H+ (4)
Negative PbSO4 + 2e-+2H+ ↔ Pb + H2SO4 (5)
The hydrogen ions (H+) traveling from the positive to the negative plates close
the electric circuit and leave the plates in an almost electrically neutral
status.
(Lead Acid Battery Formation Techniques – Digatron)

6. FORMATION

7. TANK FORMATION & WASHING
The cured plates are loaded into large tanks containing sulfuric acid solution
and electric current is passed through the plates (i.e., tank formation process). Spongy
lead forms on the negative plates and lead dioxide on the positive plates.
After formation, the positive plates are washed with water and dried at a temperature
<80 oC. The negative plates are treated in the same way, but drying is done in an
oxygen-free atmosphere.
Washed plates : Pb + 1/2O2  PbO + 52 kcal mol -1
Unwashed plates : Pb + 1/2O2 + H2SO4  PbSO4 + H2O + 93.9 kcal mol -1

8. WASHING
Positive plates with too much acid, used with dry-charged negative plates, would have a
tendency to take up water from the surrounding atmosphere and to pass some
moisture to separators and negative plates, which then causes the negative material
to be partly discharged.

9. TANK FORMATION
(R Wagner, MOLL Accu Elsevier 2009)
• During formation, the concentration of the electrolyte increases because of the
release of sulfate ions from positive and negative cured material.
• 1st stage : formation with low current
• 2nd stage : formation with high current density – to reduce the amount of gas evolved
in the final stage when the conversion efficiency is low.
• Automotive plates of 1.5-2.5 mm thickness can satisfactorily be formed in about 20h.
Thicker traction plates may require 2 days or even more.
• Conversion process can be controlled by measuring the ampere hours input. The
completion of formation is indicated by the development of a uniform color overall and
the disappearance of white patches on the surface of the plates due to the presence
of unconverted lead sulfate.
• Temperature in excess 60 Deg C should be avoided.
• The presence of a small amount of lead sulfate and lead dioxide in the materials after
formation is accepted as normal.

10. CONTAINER FORMATION
Johnson Controls battery plant in
Ceska Lipa, Czech Republic

11. CONTAINER FORMATION
(R Wagner, MOLL Accu Elsevier 2009)
Two shot formation process
The plates are formed in cells in a battery filled with H2SO4 solution of 1.15-1.10 relative
density which serves as the formation electrolyte. After formation, the battery is set to
a high current test discharge for 20 s, then it is recharged and the electrolyte is
replaced with more concentrated solution of 1.30-1.32 relative density. This highly
concentrated solution is diluted by the residual formation electrolyte in the plates and
separators, and thus the required final electrolyte concentration of 1.28 relative
density is reached.
One shot formation process
The plates are formed in assembled batteries filled with sulfuric acid solution of 1.23-1.24
relative density. When the basic lead sulfates and PbSO4 in the paste are
transformed into active masses, H2SO4 is produced and the formation acid reaches
the required concentration for normal battery operation. The thus formed batteries
are subjected to a final test by passing a high current for 20 s and monitoring the
stability of the discharge voltage at that. The batteries are then recharged for 0.5e1 h.
The acid concentration is measured after the formation and adjusted, if necessary.
This is the least expensive manufacturing method, but the batteries will have a
somewhat shorter cycle life. These batteries should be stored at 20-25 Deg C.
Depending on the grid alloy used, they have a shelf-life of about 2-3 months when
with Pb-Sb grids, or 6-8 months when with Pb-Ca-Sn grids, respectively.

12. Concept of Tank Formation Program
Lead Acid Battery Formation Techniques
Step Task Remarks
1
Operator checks the circuits which are started
one time to see that connection are made
properly. Charge current at 5% of C20
Can be confirmed by a manual voltage
reading or reviewing voltage data at
computer
2
Pause - cooling (the charge current will create
more heat inside the plates).
The charge current will create more heat
inside the plates
3
Charge current at 10% of the capacity for 15
minutes
SpGr electrolyte increase significantly only
after approximately half of the active material
is converted electrochemically into PbO2 and
Pb respectively. This is equivalent to a
charge of the nominal 20 h capacity
4 Charge current at 12.5% of C20
Until the voltage rises again
High polarization and gas evolution are the
main heat sources from now on
5 Pause
Cooling down before charge is continued
with smaller current
6 Charge current at 7.5% of C20 for 16 hours
7 Pause
8 Charge current at 5% of C20 for 10 hours 100% conversion of the current into gas
9 Stop

13. Example of Tank Formation Program for battery 72 Ah
Step Task Nominal Switch Break Total
1 CHA 3.6A 0:15 > 216 V
2 PAU 2:45
3 CHA 7.2A 4:00 > 216 V 28.8Ah
4 CHA 9.0A 10:00 90.0Ah
5 PAU 0:30
6 CHA 5.4A 16:00 86.4Ah
7 PAU 0:30
8 CHA 3.6A 10:00 36Ah
9 STO
TOTAL 44:00 241.2Ah
Step Task Nominal Switch Break Total
1 PAU < 50C
2 CHA 7.2A 4:00 > 216 V 28.8Ah
3 CHA 9.0A 10:00 90.0Ah
4 PAU 0:30
5 CHA 5.4A 16:00 86.4Ah
6 PAU 0:30
7 CHA 3.6A 10:00 36Ah
8 STO
TOTAL 41:00 241.2Ah

14. Example of Tank Formation Program for battery 72 Ah
Step Task Nominal Switch Break Total
1 PAU < 50C
2 CHA
25A
60C
192V
155Ah >216V
3 CHA 187.2V 3.6A
4 CHA 3.6A 180Ah
5 STO
TOTAL

15. Factors that affect battery voltage during charging
Variable are
- The electrode potential of the reactants
- The kinetics of the charging process
- The rate of diffusion of reacting species through the plate and separators
- The product design
- Processes used in the construction of the battery
- Temperature
- Impurities in the system

16. SEM image of NAM
L : Sulphation R : Healthy
(Ptr Krivik & Petr Baca)

17. DRYING
(R Wagner, MOLL Accu Elsevier 2009)
Too intensive drying of positive plates can result in significant problems on high rate
discharge performance after the cells have been filled with electrolyte.
If the drying time is around 8 h, a typical duration in many plants, it starts to be critical at
a drying temperature of about 70 Deg C and the higher the temperature is above this
point, the more likely this problem will appear. In order to avoid this problem and to be
on the safe side, the temperature during the drying of positive plates should not
exceed 60 Deg C.
The latent danger of the higher temperature is a thermopassivation effect.
The negative plates when removed from the formation tanks must be immersed
immediately in water and kept there until the plates are put into a drying oven. The
water restricts the access of atmospheric oxygen to the material. The water is also
used to wash out sulfuric acid that is absorbed in the material. Later, in the drying
oven, the plates must again be protected against air.
Sometimes plates are treated with boric acid as an impregnator to keep oxygen away
from the surface and to avoid much oxidation during storage of the battery before
use.

18. DRYING
Detchko Pavlov Lead Acid Batteries Science and Technology

19. DRYING - INERT GAS OVEN
to improve the “deficient” dry-charging efficiently, especially for the
negative plates of lead-acid battery manufacturer. And it can also reduce the non essential
manpower; improve the efficiency of drying with better quality.
Loading door
Steel Frame
Ignition gas burner
Gas burner
Machine Control Panel
Cooling Water Line
Burner’s air line

20. Enveloping
Enveloping Machine

21. Assembling
Dried plates are stacked in active blocks, so that positive and negative
plates alternate with separators in between. Plates of like polarity are interconnected
into semi-blocks by welding together through the plate lugs. The active blocks are then
introduced into battery containers, the cells are connected and the batteries are covered
with lids and tested for air-tightness. The vents are closed to eliminate access of air
from the surroundings, and the batteries are packed and ready for delivery

22. Thermodynamics of the lead acid batteryPavlov – Lead Acid Batteries, the electric energy (Q) :
Q = nF (E1-E2)
F & n are numbers that determine the quantity of electricity.
The electric energy depends on the different between the potentials of the two
electrodes made of different substances.
Lead Sulfate Electrode (Pb/PbSO4) Potential – Negative Electrode
Pb2+
(aq) + 2e-  Pb(s) E0 : -0.126 V
Nernts equation:
EPb/PbSO4 = E0
Pb/PbSO4 + (RT/nF)ln K
Lead Dioxide Electrode (PbO2/PbSO4) Potential – Positive Electrode
Pb4+
(aq) + 2e-  Pb2+
(aq) E0 : +1.8 V
EPbO2/PbSO4 = E0
PbO2/PbSO4 + (RT/nF)ln K
This potential different generates one of the highest electromotive forces (EMF or DE)
of all electrochemical power sources based on aqueous solutions.
DE = EPbO2/PbSO4 - EPb/PbSO4
DE = 1.683 - 0.118pH – 0.059 lg a H2O + 0.029 lg a SO4
2- - (-0.358 – 0.029 lg a SO4
2- V)
DE = 2.041 – 0.118pH – 0.059 lg a SO4
2- - 0.059 lg H2O

23. Thermodynamics of the lead acid batteryThe value of E0 depend on the crystal modification of PbO2 formed in the active
material.
a PbO2 Orthorhombic : 1.697 V
 PbO2 Tetragonal : 1.687 V
Bode and Voss  the different ~30mV, β having more negative potential.
Reutschi
a PbO2 Orthorhombic|PbSO4 : 1.7085 V
 PbO2 Tetragonal|PbSO4 : 1.7015 V
With respect to Pt|H2 ref electrode at 25oC in 4.4M H2SO4
a PbO2 Orthorhombic|PbSO4 : 1.698 V
 PbO2 Tetragonal|PbSO4 : 1.690 V
At pH 1-2.

24. Equilibrium Cell Voltage of the lead acid battery
Electrochemical Energy Storage – D Berndt
The equilibrium cell voltage depends only on the acid concentration

25. Three electrode systems form during the anodic polarization
of a Pb electrode in H2SO4
PAVLOV page 46

26. Stationary Voltage/Current curve of a lead electrode in 1 N
H2SO4
PAVLOV page 46
J.P Carr & N.A Hampson :
PbSO4 potential Region : -0.97V to -0.40V
PbO potential region : -0.40V to +0.95V
PbO2 potential region : > +0.95V

27. Electrochemical & Chemical reactions that proceed in the system
Pb/H2SO4/H2O

28. Pourbaix Diagram (Pavlov & J.P Carr)
Potential/pH Diagram for the Pb/H2SO4/H2O

29. Potential/pH Diagram for the Pb/H2SO4/H2O

30. Chemical Reaction - Discharging

31. Discharging Process

32. Charging Process

33. Chemical Reaction : Charge and Discharging
Discharge : Increase volume the solid phase by 164%
Discharge : Increase volume the solid phase by 92%

34. Battery Container - Cover
FLOODED BATTERY VRLA BATTERY HEAVY BOX
VRLA LID WITH 4K SYSTEM &
INTEGRATED FLASH ARRESTOR
KAMINA LID FOR HEAVY DUTYK2 DOUBLE LID WITH
INTEGRATED FLASH ARRESTOR
FLAT LID FOR HEAVY DUTY
MAINTENANCE FREE BATTERY
LID
DIN KAMINA LID WITHOUT
FLASH ARRESTOR
DIN KAMINA LID WITH 4K SYSTEM &
INTEGRATED FLASH ARRESTOR

35. Accessories
M18 KAMINA VENT PLUGS
WITH CO INJECTED O-RING
M18 KAMINA VENT PLUGS
WITH O-RING
M18 VENT PLUGS FOR K2
DOUBLE LIDS
MAGIC EYES FOR K2 DOUBLE
LIDS
M18 VRLA VALVE PLUGS M27 VENT PLUGS FOR HEAVY
DUTY BATTERIES
HOLD DOWN ADAPTORS FOR
DIN CAR BATTERIES
POLE PROTECTOR FOR CAR
BATTERIES
CORD HANDLES FOR HEAVY
DUTY BATTERIES
ELBOW FITTING FOR BATTERY
GAS OUTLET

36. Vent Plug
The caps are designed to the sulfuric acid
mist to condense and drop back into the
battery and allow hydrogen gas to escape
through the vent holes to the atmosphere.

37. Safety Labeling
DIN 50342-1 Safety Labeling are :
Red : No Smoking, no naked flames, no flash
Yellow : Battery Acid
Blue : Shield Eyes
Red : Keep away from children
Blue : Note Operating Instructions
Yellow : Explosive Gas

38. Sulfuric Acid
Mixing : 1.40 gr/ml at 20 ⁰C
Formation : 1.04 gr/ml at 20 ⁰ C
Flooded Battery : 1.26 gr/ml at 20 ⁰ C
VRLA Battery : 1.33 gr/ml at 20 ⁰ C
Laboratory Test : 1.28 gr/ml at 20 ⁰ C

39. Sulfuric Acid