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Lead Acid Batteries in VRLA/AGM Design Allen Xiang March. 2012

Basic principle of VRLA Battery

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Folie 1

Lead Acid Batteries in VRLA/AGM Design

Allen XiangMarch. 2012

1My curriculum lead acid battery technical infos not a sales talk my colleagues will do thisAs Brian has suggested questions at the end but then many

2 The VRLA/AGM revolution of 1971 Key VRLA/AGM features and outlook Essential technologiesTechnology Issues - The topicsPositive grid alloy and grid manufacturing technology Electrolyte management in the cell Positive active mass stabilization Plastic material and AGM stability Thermal management and RAPS applications Asset management with anti-theft GPS module

2Two parts this afternoon one basic concepts of the VRLA design so to give you and idea of wheer this technology coming from going to

3

What makes the world go round?

My favored characters doing desert driving and getting stuck asking life important questions3

4

Petrol ?

4

5 Tires ?

5

6

Batteries!

BSS

Linus aka Ahamed bringing it to the point6

7

1971

This invention concerns a maintenance-free type lead acid cell which is in a normally sealed condition. The cell is characterized by structurally free, non-self-supporting plates separated from one another with highly absorbent flexible separators containing electrolyte and constrained within a container such that mechanical integrity is imparted to obtain a unitary self-supporting structure. Means are provided for maximum recombination of evolved gases and for discharge of excessively high pressure gas. A centroid element allows for operation in any indiscriminate attitude.

7The last lead acid design revolution started - 1971 D cell - miners lamp Gates Rubber in Colorado

1971 Maintenance-free operation Electrolyte leak proof design Grid plates Electrolyte absorbed in glass fiber matrix Internal gas recombination Self stable battery case Overpressure vent valve Position independent operation

8

8Design features

1971 Maintenance-free operation Electrolyte leak proof design Grid plates Electrolyte absorbed in glass fiber matrix Internal gas recombination Self stable battery case Overpressure vent valve Position independent operation

9

9Beauty fell asleep patent disputes NOT_INVENTED_HERE

1971

1981

Maintenance-free operation Electrolyte leak proof design Grid plates Electrolyte absorbed in glass fiber matrix Internal gas recombination Self stable battery case Overpressure vent valve Position independent operation Prismatic cell design 2V cells and 6V/12V monoblocs10

10Two princes came and kissed the sleeping beauty Chloride BT- closer to electronics Gould MF fork lift motive power cell prismatic cell present when this happened

19711981

Today

11

Acme

MP

Eos

REX

HTB

11Once these tow biggies launched the trend VRLA then many followed sizes capacities - layouts

The official family nameVRLAAGM*Valve Regulated Lead Acid battery with Absorbent Glass Mat*

12

12Also the name was defined away from sealed maintenance free mentioning VALVE

What offers power, Pb/PbO2/H2SO4?

FLA

Pb+PbO2+2H2SO42PbSO4+2H2O+2e6 Kg

Dilution of acid11 KgExcess of acid13 Kg

Excess of active material26 Kg

Grids, case, cover, terminals 43 Kg166 Wh Kgtheory23 Wh Kgeffective

Materialfor 1 kWh13

13How much material for 1Kw and 1h 6Kg theoretical - 166Wh/kg Lithium 300Wh/kg unpacked

What makes the VRLA/AGM attractive?

VRLAAGM166 Wh Kg

6.0 Kg

Higheraciddensity

Lessactive mass perAh

Thinnercorrosion resistantlead alloy grids

Less electrolyteMore efficientmaterial use35 Kg28 Wh Kg

Materialfor 1 KW for 1h14

14VRLA optimization = getting out more from less

What is a key VRLA/AGM feature?

VRLAAGMInternaloxygen recombination

4H+H2O

4eH+

2H2O4H+

O2SO4--SO4--SO4--SO4--H+H+15_+H2OH2O

15Key game changer was internal gas recombination explain components of slide ion AGM pores plate then start

The valve of a VRLA cellO2 H2O2

16

VRLAAGM

16One component essential = valve allow excess gas (hydrogen) to escape prevent oxygen to enter = chemically discharge the battery

What is a key VRLA feature?Delicate charge balance due to internal oxygen recombination

100mA100mA4mA ?1mA ?O2 cycle

Pb corrosionSelfdischarge+_O2 venting/capturee2mA ?

17

1mA ?Selfdischarge

17Due to gas recombination it become more difficult to control 100% stuts of charge float charge current - explain slide components then run

VRLAAGMLess volume&floor surfaceoccupied

What made VRLA/AGM based power back-up so attractive?KW 1h m2

1KW x h x m218

18All VRLA design mode yielded interesting features- and now the mainstay of lead acid design for stationary application

32% lower weight per Ah 45% smaller volume per Ah 36 % better high rate performance Position independent operation Only 1/6 of air exchange volume needed No water top-up needed No electrolyte leakage Fast on site air freight capable No activation procedure needed > 1 year storage capability Low cost of ownership Worldwide availability Attractive form factors (H x W x L)

VRLAAGM

The additional benefits of VRLA/AGM batteries 19

19Next to weight also other features

32% lower weight per Ah 45% smaller volume per Ah 36 % better high rate performance Position independent operation Only 1/6 of air exchange volume needed No water top-up needed No electrolyte leakage Fast on site air freight capable No activation procedure needed > 1 year storage capability Low cost of ownership Worldwide availability Attractive form factors (H x W x L)

VRLAAGM

The additional benefits of VRLA/AGM batteries 20

20Next to weight also other features

32% lower weight per Ah 45% smaller volume per Ah 36 % higher 1h rate current capability Position independent operation Only 1/6 of air exchange volume need No water top-up needed No electrolyte leakage Fast on site air freight capable No activation procedure needed > 1 year storage capability Low cost of ownership Worldwide availability Attractive form factors (H x W x L)How did the stationary lead acid battery evolve?

VRLAAGMFLA21

21However such optimization also induced increased sensitivity

What makes a VRLA battery more sensitive?

VRLAAGM

Less coolingby air flow

Morewaste heat per cell675mW vs. 92mW

30%less electrolyte

High-techplastics

Reduceddiagnostics

DelicateweldsThinner grids

MoreKW power

Less skilledoperators

Acidstratification

22

22Where are these sensitivities

32% lower weight per Ah 45% smaller volume per Ah 36 % higher 1h rate current capability Position independent operation Only 1/6 of air exchange volume need No water top-up needed No electrolyte leakage Fast on site air freight capable No activation procedure needed > 1 year storage capability Low cost of ownership Worldwide availability Attractive form factors (H x W x L)How should the VRLA/AGM battery evolve?

VRLAAGM

23

23The industry is now correcting some to the excesses in claims - to go away from two F1 races cars to a more rugged design

VRLAAGM 32% lower weight per Ah 45% smaller volume per Ah 36 % higher 1h rate current capability Position independent operation Only 1/6 of air exchange volume need No water top-up needed No electrolyte leakage Fast on site air freight capable No activation procedure needed > 1 year storage capability Low cost of ownership Worldwide availability Attractive form factors (H x W x L)Narada Ranges of VRLA

24

OPzS HR Eos REX, HTBOPzV NV Acme, MP

24The industry is now correcting some to the excesses in claims - to go away from two F1 races cars to a more rugged design

Critical components and technologies for dependable service

Positive grid alloy and grid manufacturing technology

Electrolyte management in the cell Positive active mass stabilization

Plastic material and AGM stability

Thermal management and RAPS applications

Asset management with anti-theft GPS module

25

25Give you some insight about key technologies impacting VRLA performance and life mention itmes

PbPbCa

Sn Positive grid alloy and grid manufacturing technology

26

26Current collector = lead alloy two families Tin level is important

Positive grid alloy and grid manufacturing technology

27

27Ideally pure lead but problems of recharge when cycling and strength when manufacture higher cost

Pb as bulk material 99.996% Sn as passivation preventer >3000ppm Ca as hardener 600ppm Bi as cycle life enhancer 300ppm Ag as creep strength enhancer 100ppm Al as sacrificial element 300ppm PbPbSnPbCaSn

AgBiAl

Pb is too soft Sn enhances GB corrosion Ca enhances GB corrosion Ag enhances water loss Positive grid alloy and grid manufacturing technology

28

28The industry is using now for VRLA three alloy FAMILIES SHOWN ADDITIVES PPM LEVEL EFFECTS alloy is life

Positive grid alloy and grid manufacturing technology

PbPbSnPbCaAgBiAl

Continuous strip caster

400p.min-11.5mm

Continuous strip roller400p.min-12mm

Book moldcaster15p.min-15mm

Grid shapepuncher

+-0.2mm+-6%/g+-0.06mm+-3%/g29

29Manufacturing technologies casting or punching - speed tolerances equipment cost

Positive grid alloy and grid manufacturing technology

Pb99.997%PbSn0.3-2.0%PbCaSn2.0%

Continuous strip casterstructure

Continuous strip rollingstructure Book moldcast structurePbSnPbSn30

Pb

PbSnPbCaSn

30Lead is not lead is not lead explain structures - grains

GB

Positive grid alloy and grid manufacturing technology

PbCaSnPb PbO2

1mol volume Pb

1.39 mol volume PbO2

GBPb0.3%SnPbO231

31Corrosion by acid and charge penetrates via the grain joints pushing grain aside +39%

Basic features of the corrosion attack of lead and lead alloys

Pb0.4SnPb0.9Sn0.01Ca4 G2 G1 G

Pb pure32

32An alloy is not an alloy is not an alloy - Fine tuning the microstructure

In VRLA compatible alloys, the corrosion attack proceeds predominantly via grain boundaries At the same alloy composition, the least grid damage occurs in the alloy with the smallest number of grain boundaries per volume of alloy Single or large grained alloys perform thus the best and fine grained the worst Only pure lead is immune to a predominant grain boundary centered attack Grid alloy stock manufacturing plays a key role with the corrosion resistance decreasing from book mold cast to continuous cast to continuous rolled material

33 Basic features of the corrosion attack of lead and lead alloys

33Results = grid growth loosing contact with mass loosing capacity splitting battery cases

Electrolyte management in the cells a delicate equilibrium

Assure a maximum of available H2SO4 for capacity Assure a maximum of available water for life Assure 3-4% open pores for gas transport Assure maximum absorption of the acid on the glass fibers Prevent gravity induced acid movements (de-wicking) Prevent density gradient induced electrolyte movement Balance acid storage in AGM vs. in active mass

H2O

+-

Dil. H2SO4H2SO4H2SO4

34

34Next battleground is electrolyte distribution explain AGM show AGM sample paper

Electrolyte management in the cells

Impact of acid quantity

dosing of life acid

density of life acid

formation efficiency

35

< 2mmO2

Horizontal

O2> 200mmVertical

35Acid movement impacting cell design and desirable operation orientation small plateau of optimum operation do it in the factory!

Positive active mass stabilization

36

Pb++Pb++Pb++Pb++Pb++Pb++SO4- -SO4- -SO4- -SO4- -SO4- -SO4- -Pb++Pb++Pb++ e

Pb++Pb++SO4- -SO4- -SO4- -SO4- -Pb++

SO4- -SO4- -PbSO4 (sol)

PbSO4

Schematic view of the dissolution-precipitation reaction in an active mass pore during the discharge of the positive mass in a lead acid battery

ePbSO4PbSO4

SO4- -SO4- -SO4- -SO4- -SO4- -SO4- -SO4- -SO4- -

Pb++

36Next challenge is active mass stabilization not only stand-by but charge discharge explain slide and discharge curve - coup de fouet we will see more details in my 2 talk

Positive active mass stabilization

PAM volume50% PbO250% pores

PAM volume50% poresPAM volume30% PbO2 38% PbSO432% poresPb PbO2+39% volume needPbO2 PbSO4+92% volume needPbSO4 PbO2-92% +X% volume gain Y% volume loss

PbPbPb37

37

Plastic material and AGM stability

+--

100%73%

100%

38 The AGM (Absorbent glass mat) in a VRLA cell has to be compressed in thickness by about 25 to 30% to assure adequate electrolyte continuity between the plates

This compressed AGM exercises, not unlike a spring, a force of about 40KPa or 70 to 110Kg on the interior walls of a 100Ah cell

Two factors, AGM shrinkage and plastic deformation by heath, destabilize this assembly and can led to dramatic cell capacity losses

38Battery cases and the AGM have a compression = vise function loose compression loose capacity

39 Plastic material and AGM stability

35C

39High tempertures = new challenges AGM fiber structure weakening plastic softerning VICAT

Coolstar

40 Thermal management and RAPS applications

Focus on not only cooling down, but also cooling management and temperature uniformity.

40Some solution is : localized battery temrperature managment not the cooling the building but cooling battery only low power consumption

Adapting the positive plate design to achieve a lower Pavlov factor and increased active mass loading

41

1.34 0.77 Thermal management and RAPS applications

= g PbO2 / cm2 grid surface

0.7717.7g.Ah 1.3414.3g.Ah

41

Capture and recombine oxygen with hydrogen on a Pd-on-Carbon catalyst bed Decrease the oxygen recombination duty of the negative active mass and thus polarize the negative plate stronger Increased negative plate polarization reduces the float current and associated internal heating

42

Thermal management and RAPS applications

140mA

200mA

42Additional features full charge with oxygen capture and recombination with catalyst have shown charge balance previously thermal excursion brake

43 Asset management with anti-theft GPS module

Anti-theft GPS module

43Logistics in battery life - manufacture OEM end-user recycler traceability Discussed on IEC level

44 Asset management with anti-theft GPS module

Anti-theft GPS module

44Logistics in battery life - manufacture OEM end-user recycler traceability Discussed on IEC level

45

In power need?.call onVRLA/AGM batteries!

45So this concludes my first part covenring technology issues the second part will then go imto the nitty gritty issues and cover themes Brian has asked me to deal with

Thank you for your attention!46

46An now questions