BEST Autumn 2011 61

Longer life, long run times, better monitoring, faster charging. Is this snake oil or what? Shawn Kelly of Active Grid Technology explains how mechanical excitation of the lead-acid system can give so many benefits.

Active Grid Technology (AGT), Inc., a Massachusetts Corporation, is

introducing its Ultrasonic Power Boost Advantage (UPBA™) technology which will transform the way we view and use batteries. This technology is the subject of US Patent 7,592,094 as well as a new pending patent, and is available for immediate license.

We utilise an innovative ultrasonic technique to make the battery last longer and perform better. Application of our UPBA™ ultrasonic signals result in extended battery pack life, increased battery pack run-times, much faster charge times that require less recharge energy, increased cyclic efficiencies, significantly less gassing and dry-out conditions and a substantial reduction in the probability of developing a thermal run-away condition. Our novel techniques also allow us to offer superior

State-of-Health (SoH) monitoring capabilities with End-of-Life (EOL) prediction techniques, as well as advanced energy storage system control and management solutions.

This includes superior string equalisation and cell balancing, impedance matching control algorithms, overall system efficiency improvements and fast battery pack recovery. Wide-spread use of our UPBA™ concepts and strategies will result in a ‘step’ change in energy-storage system efficiencies which will reduce consumption of generated energy thereby reducing our country’s dependence on foreign oils.

Additionally, our solutions will give system designers the tools necessary to minimise the energy-storage infrastructure’s inherent shortcomings. Our methods will give battery manufactures the advantage with our formation charging solutions, it will give battery charger and monitoring

manufactures several layers of added functionality, and it will give battery users the piece-of-mind they deserve.

This article is about batteries in general and their inherent limitations and short-comings (i.e. problems), and how these same problems have eluded some of the world’s top battery engineers and scientist for decades. Certainly, they have made slow, small and incremental improvements by changing the material, design and construction of batteries, by figuring out how to get more chemically active material (i.e. lead) into a smaller volume, by developing new porous electrodes, by adding new additives and substances, and by continuously coming up with new and ‘next best’ battery chemistry.

However, these are all evolutionary changes and we are offering a revolutionary step change. In fairness, this has been one tough nut to crack!

Ultrasonic approach promises the earth forlead-acid batteries

62 BEST Autumn 2011

We mechanically excite the chemical reaction products within the battery and we make the battery last longer and perform much, much better. It is REALLY that simple.

While similar approaches have been tried before, often with mechanical excitations well below the frequencies required to make a real difference UPBA™ technology operates at frequencies in the MHz region. Our UPBA™ mechanical excitation waveforms are on the order of microns. So our signals are very localised. In contrast, previous attempts were using frequencies in the KHz region, in fact, these attempts were subjecting their test batteries to the same ultrasonic frequencies that are used in ordinary household jewellery cleaners.

The remainder of this article will be focused on solutions for lead-acid chemistries.

Re-Defining Energy Harvesting

Our method of harvesting energy is different to anything that is currently being explored or deployed in the market. Our new UPBA™ approach exploits the reverse property of this piezoelectric or similar material, i.e. the electrical-to-mechanical energy conversion

property, which in turn allows us to harvest once unavailable chemical potential energy from the battery. We can capture large amounts energy from previously unclaimed chemical potential and we can get it from all battery types and in all applications.

Our UPBA™ solutions add value since we can enhance the performance and extend the life of an existing investment in lead-acid batteries! New and so-called “disruptive” technologies and chemistries fail to win market share because their developers and supporters fail to account for incremental improvements and enhancements to the prevailing technology they are trying to displace or replace. This is especially true with utilities, because reliability, availability, and familiarity with the product (i.e. staff training, O&M characteristics, existing expertise, etc…)— in other words, predictability— is critical.

Our UPBA™ technology is nothing more than an add-on to an already proven technology that everybody understands. We just make it better and provide the following benefits:●● Extended●battery●pack●life

even if this battery is near the end of its mortal life regardless of its operating profile or history— Our

method and technique targets and eliminates the inherent ionic kinetic inefficiencies that plague all battery chemistries as well as keeps the bad, unwanted and non-chargeable substances in solution where they belong, rather than on the electrodes.●● Increased●battery●run-time●(i.e.●more●Capacity-AHrs) for the same foot-print and weight and at ‘all’ discharge rates and operating regimes—Our solution more effectively utilises the already existing chemically active material that is within the battery, i.e. we harvest once unavailable chemical potential energy and put it to use.●● Much●faster●recharge●times●that●require●less●recharge●energy●(i.e.●lower●voltages●required), our enabling technology maximises the charge acceptance at all charge rates and keeps unwanted and detrimental bonds from forming— Thus, our voltages will be lower than the typical voltages that you currently require to recharge your battery pack and we do not waste energy in order to overcome detrimental and unwanted bonds. Our system will work with your current charging system— In fact, our

Radio●Frequency●(RF)●amplifier●used●to●drive●PZT●actuators●in●MHz●region.●This●device●fits●in●the●palm●of●your●hand.●Device●is●designed●to●efficiently●drive●the●capacitive●PZT●loads.

PZT●actuator●(brownish●with●blue●connector)●attached●to●lead●paste●of●typical●2-Volt●lead-acid●battery●test●cell.●The●white●PZT●sensor●was●positioned●to●ensure●ultrasonic●energy●was●present●on●cell●during●test.

BEST Autumn 2011 63

Close-up●of●PZT●actuator●attached●to●the●positive●terminal●of●2-volt●lead-acid●battery●cell.●PZT●disk●which●produces●ultrasonic●energy●is●contained●underneath●alumina●housing●shown.

PZT●actuators●attached●to●the●terminals●of●2-Volt●battery●cell.●Actuators●bonded●with●military●grade●epoxy●and●then●torqued●to●top●of●battery●post●with●machine●screw●to●ensure●maximum●coupling●of●ultrasonic●energy●into●battery.

system will make your current charging system components last longer. ●● Increased●cyclic●efficiencies

that are kept high throughout the battery’s life based on enhanced energy conversion efficiencies (i.e. a result of substantially reducing the ionic kinetic inefficiencies that plague your current battery) and a significant reduction of unwanted and non-chargeable substances that typically build-up (i.e. tertiary substances/compounds) within and on your electrode surfaces.●● Significantly●less●gassing●and●dry-out●conditions will exist based on lower than typically required over-charge voltages— With our solution all of the cells in a battery string will on average experience lower voltages than they would otherwise be subjected to.●● Significant●reduction●in●the●probability●of●a●thermal●run-away●condition developing based on these same lower than typically required over-charge voltages— In fact, we will reduce this probability even more with our string equalisation and cell balancing control algorithms.The same base enabling

UPBA™ technology that permits us to offer the battery pack

lifetime and performance enhancements allows us to offer revolutionary and extremely accurate Electrochemical Impedance Spectroscopy (EIS) State-of-Health (SoH) monitoring. ●● Superior●EIS●SoH●monitoring

which provides a ‘true’ indication of the battery’s electrochemical health (i.e. age)— Our UPBA™ SoH monitoring technique eliminates the inherent limitations and uncertainties (i.e. flaws) with which our EIS competitor’s products are riddled. For decades there has been

considerable activity and debate regarding the use of internal “impedance” characteristics as a battery condition measurement. The interest reflects the desire for simple electronic means to replace discharge testing as a practical determination of residual battery capacity, particularly given the increased usage of valve-regulated lead-acid (VRLA).

It is widely accepted that the only way to truly know the true health of a battery is to periodically conduct test discharges. Conducting periodic test discharges of the plant’s critical battery back-up not only places severe operational restrictions on the plant, but, even more importantly it reduces the operating life of the battery

pack and results in premature battery pack replacement. If the utility tries to minimise the length of time that this necessary operational restriction is in place, by charging the battery at a faster than the recommended rate, then this will ultimately result in unwanted and premature costly battery pack replacement.

The goal of any EIS SoH monitoring technique should be to extract as much information as possible about the electrochemical health of the battery; however, the variability and uncertainties introduced by various battery types and conditions have caused the current EIS monitoring techniques to fall short in the market place. Our UPBA™ ultrasonic technique brings these techniques to a new and trusted level.

These game-changing benefits are made possible with use of our base UPBA™ excitation energies. We can control and exploit this enabling technology to improve on our solutions and benefits even further: ●● Superior●string●equalisation●and●cell●balancing is made possible with our impedance matching control algorithms. We can change our enabling UPBA™ excitation energy that is applied to any given cell in the string in real-time and on-demand. This allows us to change that cell’s complex

internal impedance response to the dynamic voltages levels that the string has subjected it to— Thus, we adjust our UPBA™ excitation energy in response to the voltages measured across any given cell in the string and we can automatically compensate and bring this cell back to a safe condition.

❍ Impedance matching control algorithms allow us to even further enhance the benefits that our base UPBA™ excitation energy provided, such as:

➢ Longer battery pack life— We keep our cells in check and keep the detrimental higher voltages at bay.

➢ Longer battery pack run-times— The weakest cell in a string dictates the string’s run-time (i.e. AHr capacity). Our cell balancing techniques will bring the weaker cells to a fully charged state in a fraction of the time; thus, our UPBA™ system will effectively fix the ‘weak link’ in the chain.

➢ Even less gassing and dry-out conditions— Since our charge voltages to each cell are kept in check with our string equalisation and cell balancing algorithms the electrolysis of H20 that cause excessive gassing and dry-out conditions are kept to a minimum.

➢ Even lower probability of thermal run-away conditions developing— For the same reason noted above coupled with our thermal run-away cell watchdog calculations being performed continuously in the background we significantly reduce the probability of these unsafe and unwanted events.

●● Overall●system●efficiency●improvements from the same enhanced cell efficiencies (e.g. a reduction of the cell’s opposition to the flow of energy) are made possible with the presence of our base UPBA™ excitation energy and coupled with our new and novel UPBA™ impedance matching control algorithms will significantly enhance the overall energy storage system efficiency of our customer’s battery packs. In fact, battery packs equipped with our UPBA™ solutions will be much more viable candidates for integration with new and exciting renewable energy generation applications, such as wind and solar. Our solutions make possible the seamless integration of our equipped battery packs to these unpredictable and variable new energy sources.●● Faster●battery●pack●recovery●times to a 100% state of readiness in a fraction of the time that your current system is capable of. Fast recovery from an outage event without harming the weak, less energetic, aged and slower cells in the string. Therefore, the user of our system will be assured that their battery pack is ready if they experience a second power hit.It is our complete Battery Management System

(BMS) package. What makes it tick?

Hatboro, Pennsylvania, USAsales@cobrawire.com

215-674-8773www.cobrawire.com

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66 BEST Autumn 2011

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The UPBA™ Enabling Our device in Figure 1 below is

not the only device we propose to use, nor is it the only way to efficiently couple ultrasonic energy into your battery pack, however, it is one of our favourites. We have designed our UPBA™ widget like this for several reasons; however, ease of installation was in the forefront of our minds. Our UPBA™ enabling technology eliminates the root cause of the battery’s inherent electrical performance limitations. Our ultrasonic energy positively interacts with and enhances (i.e. speeds up) the electrochemical reaction at the electrode-electrolyte interface which is taking place everywhere within and on the surface of the battery’s electrodes.

The UPBA™ Effect Our ultrasonic frequencies,

amplitudes and duty cycles do not take away from the battery’s life. In fact, our accelerated

lifetime cyclic testing shown in Figure 2 indicates just the opposite… our mechanical excitation energy actually makes the battery last longer! We will focus on the extension of life in a fairly arduous cyclic operating environment and the superior cyclic efficiencies that are made possible.

In Figure 2, there are two (2) tests shown. These tests were performed on commercially-available lead-acid motorcycle batteries. In Test A, the vibrating cell is red and the non-vibrating cell is blue, in Test B, vice versa.

Some take-a-ways from the test results in Figure 2: The battery cell equipped with one of our UPBA™ devices (i.e. vibrating cell, cell under test) underwent approx. 62 cycles while the other cell (i.e. non-vibrating cell, control cell) only underwent approx. 41 cycles and died, we discarded the outliers. This taught us that the vibrating cell survived about 50% more cycles than the non-vibrating cell during the period of the Test A and B, notice the increase in charging voltage on the non-vibrating cell (red, Test B) this is a result of degradation and a corresponding steady decline in the cell’s cyclic energy conversion efficiency.

After Test B was complete (not shown) the UPBA™ device was deactivated, thereby removing the ultrasonic excitation energy, and the once vibrating cell started to show signs of degradation very similar to what the non-vibrating cell (red) showed in Test B and stopped taking a charge after about 25 additional cycles. If we

include the additional cycles the vibrating cell underwent to our calculations above then we can conclude that the cell under test (vibrating through Test A and B) underwent about 112% more cycles then the non-vibrating cell.

If you closely look at the vibrating cell’s charge and discharge waveforms you will notice that it did not show signs of degradation similar to what the non-vibrating cell showed and this was just another compelling reason to take a closer look at the UPBA™ effect. The following test is even more telling of the UPBA™ enhancements.

Figure 3 is a Cyclic-Voltammetry (CV) graph of one of our UPBA™ tests, which will focus on the following aspects of our UPBA™ enhancements: Increased capacity based on better utilization of the available chemically active material, faster recharge times, lower recharge energies, higher peak currents, and the UPBA™ ultrasonic effects on gassing:

In Figure 3, the red curve is the vibrating test condition and the black curve is the non-vibrating test condition (i.e. the control). The area under the vibrating cell’s discharge curve (the big red hump pointing down at around 1.10V) is about 75% greater than the corresponding area under the non-vibrating cell’s discharge curve (the little black hump pointing down at around 1.13V).

The area under these curves represent AHr capacity (i.e. run-time), so, our UPBA™ excitation allowed us to harvest 75% more chemical potential energy from

Figure●1

Batt

ery

Volta

ge (V

)Ba

tter

y Vo

ltage

(V)

0 500 1000 1500 2000 2500 3000 3500 4000

0 500 1000 1500 2000 2500 3000 3500 4000Time (min)

Time (min)

3

2

1

0

3

2

1

0

Batt

ery

Volta

ge (V

)Ba

tter

y Vo

ltage

(V)

0 500 1000 1500 2000 2500 3000 3500 4000

0 500 1000 1500 2000 2500 3000 3500 4000Time (min)

Time (min)

3

2

1

0

3

2.5

2

1.5

Figure●2● Test●A● Test●B

UPBA™ EnablerPZT Actuator/Driver/Sensor

PowerIn

V+- in

singlefrequency�rst/lastcell

V1+out

Powermosfet

OscillatorHeatsink

Max X

PZT

BatteryterminalPballoy

RTD in

-+ temp out

w1

-+

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the same area of chemically active material under test!

The fast recharge time is evident from the very steep slope of the vibrating cell’s red charge curve close to the origin as well as

the start of its ascent and entrance into the gassing region at about 1.10V, versus the non-vibrating cell’s black charge curve slope close to the origin and its later ascent into the gassing region at

about 1.15V. Additionally, the area under

the vibrating red charge curve is less than the area under the non-vibrating black charge curve, meaning less energy in and more energy out compared to the non-vibrating condition. Data reduction for this test revealed an approximately 38% increase in the vibrating cell’s energy efficiency by measuring and comparing the ratio of Energy Out to the Energy In for both curves as compared to the non-vibrating cell.

The peak discharge current of the vibrating cell was about twice that of the non-vibrating cell. Since the entire red vibrating cell curve shifted to the left this means that all this was happening at lower voltages. Thus a battery pack equipped with our UPBA™ BMS will require less voltage to perform its duty and this means that gassing, dry-out and thermal run-away conditions are much less likely to occur.

EFFECTS of xMHz at 58Vrms Initial Acid=1.3123 s.g. @ 75.8ºFInitial RE13 calibration = +4.0mV rel. to std.Final RE13 calibration =n/m (-0.5mV rel. to std. the next morning)All scans performed 2/20/07 w/acid & W.E. surface from 2/13/07)

E (Volts)

I (A

mps

/cm

2 )

0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 1.45 1.50

0.0020

0.0015

0.0010

0.0005

0

-0.0005

-0.0010

-0.0015

-0.0020

-0.0025

-0.0030

-0.0035

-0.0040

AN70220A_Rp07.cor = 0 Hz (initial control)AN70220A_Rp16.cor = xMhz at 64Vrms (90Vp-p) 1st trial

AN70220A_Rp96.cor = xMhz at 64Vrms (90Vp-p) 2nd trial

AN70220B_Rp05.cor = xMhz at58 Vrms (81 Vp-p)

AN70220B_Rp12.cor = xMhz at 52 Vrms (73 Vp-p)

AN70220B_Rp17.cor = xMhz at 46 Vrms (64.6 Vp-p)

AN70220B_Rp25.cor = xMhz at 40 Vrms (56 Vp-p)

AN70220B_Rp28.cor = 0Hz at (�nal control)

Figure●3

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A Look into a lead-acid battery

In order to examine the UPBA™ effect closer we will use a typical and accepted model of a flooded type lead-acid battery as depicted in Figure 4 (right). However, we split the resistance, Rpaste, into two components, Re

paste and Rionpaste

, which takes into account electron (e-) and ion charge carrier flow, respectively, to aid in our description.

Where:Rm=Metallic Resistance (post, alloy, grid and gridpaste, paste (e))

Rel=Electrochemical Resistance (paste(ion), electrolyte and separator)

In Figure 4, the top depiction models the physical components that offer an opposition to the flow of energy through a typical lead-acid battery. The equivalent circuit (the bottom depiction) has grouped these components in order to better describe the

battery’s electrical behavior as it relates to different types of charge carriers. The capacitance symbol (Cb) represents the storage capacity of the battery. The metallic resistance (Rm) represents the opposition to the flow to electron (e-) charge carriers, and the electrochemical resistance (Rel) represents the opposition to the flow of

ion charge carriers. The most important thing to understand is that our UPBA™ ultrasonic excitation energy targets and defeats the battery’s inherent ionic kinetic inefficiencies and this has profound results for our users. Our ultrasonic signals do not notably affect the metallic resistance, Rm (opposition to flow of electron (e-) charge carriers),

Rpaste Relectrolyte Rsepion

Rpost Ralloy Rgrid Rgridpaste Rpastee

Rm

Cb

Rel

CbFigure●4

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in our frequency ranges, but it does effect, and in a BIG WAY, the electrochemical resistance, Rel (opposition to flow of ion charge carriers). You will see later that Rel is a significant contributor to the overall complex internal impedance, ZINT, response of the battery, and this is a big deal!

How does our UPBA™ excitation energy affect R

el?

For a lead-acid battery, our UPBA™ excitation signal frequency, amplitude and duty cycle is selected such that it physically interacts with and alters the porosity of the porous PbSO4 volume that coats the electrodes during discharge. The porous PbSO4 volume that forms during the discharge can be visualised as a film, a layer, or a cloudy material. PbSO4 is also classified as a crystal and during its growth pores are developed between the crystal formations and they take various shapes and sizes. Shortly into a discharge the PbSO4 will completely cover the areas of the electrode where a discharge reactions between the abundant electrode ions (i.e. Pb+2) and the electrolyte ions (i.e. SO4

-2 and HSO4

-1) have taken place. Once this semi-permeable

PbSO4 layer coats areas of the chemically active electrode material it acts as an insulator in those areas. It starts to impede the flow of the large and less-energetic electrolyte ionic charge carriers (i.e. SO4

-2 and HSO4-1).

They are just too big to fit in the pores and this makes it more difficult for them to find and react with the abundant electrode ions (i.e. Pb+2) in these areas.

This difficulty in finding their way to the electrode ions that are readily abundant in solution is an opposition to the flow of ionic energy and we have grouped this opposition into the electrolyte resistance term, Rel, in the equivalent circuit from Figure 4.

The pores within the PbSO4 layer, film or crystal volume have a finite dimension and this is based on the PbSO4 substance and its crystal and chemical properties. Yes, these pore dimensions are not that rigid, they are oddly shaped, they are a result of different crystal shapes and sizes, discharge rates, time into discharge and they are also dependent on the battery’s history.

For now, it is important to understand that our mechanical excitation signal is selected to optimally interact with and alter the pores of the PbSO4 formation to allow for the maximum passage of the larger and less energetic SO4

-2 and HSO4-1 ions

as shown in Figure 5 below. Our UPBA™ ultrasonic excitation is tailored to ensure that the minimum finite dimensions of

the PbSO4 pores are not exceeded. Therefore, the larger and less energetic reaction ions, i.e. SO4

-2 and HSO4

-1, for lead-acid case, are guaranteed passage into and through PbSO4 volume throughout the entire discharge.

It is known that the typical pore dimensions found on and within the lead-acid battery electrodes are in the order of 0.1 to 5 microns, so it should not be surprising that our MHz excitation frequencies and resultant micron level waveforms in the sulfuric medium, can interact with and alter these pore dimensions. It should be just as easy to understand why our predecessor KHz excitation techniques and much larger waveforms fell short because they were not capable of targeting and eliminating the battery’s root problems.

What this means electrically is that by application of our innovative ultrasonic mechanical excitation energies (i.e. good vibrations) we are able to reduce the opposition to the flow of the electrolyte ion charge carrier energy, thus we are able to reduce the magnitude of the battery’s electrochemical resistance, Rel. Recognize that Rel is the inherent battery limitation that our UPBA™ technology is targeting.

So, in summary, by applying our mechanical energy we are able to change the electrical opposition to the flow of energy through the entire battery. As you get deeper into the discharge, this opposition will show up as an increasing drop in the battery’s terminal voltage. We can change this voltage drop and suddenly

Region 1

Frequency too high

Region 2

Frequency just right

Region 3

Frequency too low

Minimum pore size to allow passage

MechanicalExcitation EnergyFigure●5

For now, it is important to understand that our mechanical excitation signal is selected to optimally interact with and alter the pores of the PbSO

4 formation

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our equipped battery’s discharge characteristics are no longer what we would expect. Conversely, the currently accepted charging algorithms that are used in the industry will see a dramatic, but beneficial, change on our equipped battery packs.

Since we can reduce Rel by changing our signal it should be clear that we can also increase its value as well. Meaning, we can increase or decrease the battery’s opposition to the flow of energy with our UPBA™ signals and we can do this in real-time and on-demand, specifically, we monitor or sense other battery or system parameters as they change and adjust our mechanical excitation signal in response. This is the basis of how we are able to exploit our base technology and are able to offer advanced energy storage system control and management solutions, such as superior string equalisation and cell balancing, impedance matching control algorithms, overall system efficiency improvements and fast battery pack recovery as we discussed above.

Figure 6 is a concentration gradient curve that is present at the electrode-electrolyte interface.

The primary reaction ions (i.e. Pb+2 and SO4

-2) will react with one another at a certain distance from the electrode surface (i.e. plate). The initial reaction rate is based on the concentrations levels of these ions in the reaction zone (i.e. the point at which they find each other). When these ions react they provide us with electrical energy at the terminals of the battery, any other reactions or reaction steps that take place inside the battery do not give us useable current (i.e. Amps).

Our UPBA™ mechanical excitation does not eliminate any reaction steps necessary to get to the primary reaction (i.e. the actual e- transfer step that we really care about), however, it does speed them up. The PbSO4 layer will start to form and grow at the reaction zone and it will grow at a rate that is dependent on the gradient of the slope of the concentration curves of the electrode and electrolyte ions.

In Figure 6, the non-vibrating battery’s initial reaction rate (i.e. Amps) is lower and the layer grows slower than it does in our vibrating battery as shown by the red PbSO4 layer and our newly generated concentration curve. So, what does this mean?

Since our UPBA™ technique increases the passage of the larger and less energetic electrolyte ions into and through the PbSO4 volume, their concentration levels are higher at distances closer to the plate and this is shown by the red electrolyte concentration curve being higher than the black concentration curve. Since their concentration levels are higher the reaction rates between the SO4

-2 and Pb+2 ions is also higher and electrical opposition to the flow of ions is lower (i.e. lower Rel). Notice how the red PbSO4 layer is actually thinner as well as it forms closer to the electrode plate surface (i.e. at distance red d).

Therefore, for the same amount of energy withdrawn from the battery, the resultant insulative PbSO4 layer will be thinner everywhere, will coat more of the electrode surface area, and this will allow for more and more electrolyte ions to actually reach the abundant electrode ions (i.e. Pb+2), and start dating. This is an increase in the active material utilisation efficiency that was so apparent in the test results shown in Figure 3 (i.e. a 75% increase in output capacity), and therefore we are able to harvest more chemical potential energy from the battery just by exciting it with our ultrasonic energy and this results in longer run-times (i.e. AHr capacity)!

Given that our excitation devices and their driving electronics are designed extremely efficient (i.e. resonant power supplies) we only consume small amounts of electrical energy (which is converted to mechanical energy) to get these extreme effects.

How does our UPBA™ excitation effect battery life, cyclic efficiencies and recharge time?

From Figure 6 it is clear that the electrolyte ion concentrations and their corresponding ionic reaction rates are higher at closer distances to the electrode surface. When Pb+2 ions dissolve away from the negative Pb electrode (positive

ElectrodeH2SO4[Pb+2]

[SO4-2] and [HSO4

-1] Electrolyte ionsPbSO4 Layerwith UPBA™ PbSO4

Layer

Distance from platedd

Figure●6

BEST Autumn 2011 77

electrode not discussed), within the sulfuric acid solution, they become readily more abundant for a reaction with the SO4

- 2 and HSO4

-1 electrolyte ions. However, if the electrolyte ions

are not present and positioned for a reaction to take place (i.e. not ready for their date) then it does not happen and we do not get our electrical energy (e-) out of the battery. So, it should be obvious that our excitation energy selection helps these ions get where they need to be for their important reaction date with the Pb+2 ions. Without our UPBA™ solutions there are many detrimental physiochemical processes that take place which reduce the battery’s life, reduce its cyclic efficiency and increase its charge time and the required charge energy and these effects are not obvious, or intuitive.

The electrolyte ions’ kinetic transport limitations have far reaching effects that reap havoc on the battery’s performance,

which is significantly pronounced during cyclic operations. In a typical lead-acid battery discharge reaction, large ionic flow imbalances are developed between the electrode and electrolyte ions. These flow imbalances are extremely detrimental to the battery’s overall performance and ultimately lead to its premature demise.

If you can envision a unit volume of the PbSO4 layer which contains pores, then envision the electrolyte ions (i.e. SO4

-2 and HSO4

-1) trying to make their way through the electrolyte-filled pores with the intent of finding a suitable Pb+2 partner, then this will help with the following description. Uneven ion flow levels between the reaction ions (i.e. Pb+2 and SO4

-2/HSO4-1) have

adverse effects on the electrolyte’s alkalinity (i.e. PH) within the pores of the rechargeable porous PbSO4 unit volume. This change in alkalinity is caused by the unit

volume’s affinity to maintain its electro-neutrality.

Typically the Pb+2 ion flow overcomes the SO4

-2 and HSO4-1

ion flow because of their inability to penetrate and travel into and through the unit volume of the PbSO4. Therefore, the unit volume becomes more positive; however, in accordance with the laws of science, this volume must maintain its neutrality.

The consequence is that the uneven flow imbalance causes the electrolysis of H2O (i.e. water). As the battery discharges the specific gravity of the H2SO4 electrolyte decreases as it is replaced with H2O. This electrolysis breaks the H2O molecule into H+1 and OH-1 ions within the unit volume.

Since the unit volume is now positive the highly energetic H+1 ions (5X as energetic then other ions in solution) migrate out of this unit volume in order to maintain its neutrality. This leaves behind the less energetic OH-1 ions and therefore the result

BEST Autumn 2011 79

is an increase in the PH within the pores of the unit volume.

With the increased PH the local conditions for tertiary compounds, i.e. lead oxides and basic lead sulphates (both tri-basic and tetra-basic), to precipitate out of solutions becomes much more favorable. Therefore, based on unfavourable ion flow imbalances these tertiary compounds (i.e. bad things) come out of solution and negatively interact with the very porous and once very rechargeable PbSO4 compound.

These unwanted and non-chargeable tertiary compounds interact with, and form unwanted covalent bonds with the rechargeable PbSO4 volume and with the chemically active electrode material and reap havoc during the subsequent recharge. Figure 7 below is an illustration of completely discharged electrodes without and with our UPBA™ ultrasonic excitation.

It should be clear that any compounds or substances, other than the easily-rechargeable ionic PbS04 compound, that are created and/or formed during the discharge, and their corresponding binding/bond energies, are NOT desirable. One should keep in mind that even if the battery pack is on a float charge it is still undergoing constant discharge and charge

cycles, otherwise, you would not see changing string charge currents.

Any additional compounds and substances that precipitate out of solution and interact with the rechargeable PbSO4 volume must be undone during the subsequent recharge.

Undoing these reactions, if they can even be undone, requires higher-than-necessary charge voltages. Additional charge time and energy is then required to recharge the once very rechargeable ionic PbSO4 compound.

So, the goal of our ultrasonic excitation is to maintain the PbSO4 as pure as an ionic

compound as possible during the discharge, so that the subsequent recharge will use lower amplitude voltages, happen much faster and use less energy.

Ultimately, in a typical lead-acid battery application, these unwanted tertiary compounds win, creating a cyclic build-up of unwanted and non-chargeable compounds/masses everywhere on and within the surface of the electrode, as shown on the left depiction of Figure 7.

Figure 8 below is an illustration of electrodes as soon as the charging voltage is applied to the terminals of the battery.

In Figure8, the UPBA™ equipped electrode on the right has been set-up for success while it was being discharged. The resultant PbSO4 layer is mostly of ionic content, the layer is thinner and it is spread out evenly over the electrode, therefore the layer easily goes back into the electrolyte solution.

As shown on the left, the PbSO4 layer is not pure and has both ionic and covalent bonding, it is also preferentially located and piled up on the plate, therefore, it does NOT easily go back into solution and this is why the user has to apply higher-than-necessary voltages to recharge the battery. More than likely, that stubborn mass will not go back into solution and

Discharged CellPbSO4 only layer

PbSO4 layer & tertiary compounds

ElectrodeWithout UPBA™ With UPBA™

UPBA™device

Charged CellPbSO4 only layer

PbSO4 layer & stubborn, unwanted, non-chargable tertiary compounds

ElectrodeWithout UPBA™ With UPBA™

UPBA™device

Figure●7 Figure●8

So, the goal of our ultrasonic excitation is to maintain the PbSO

4 as pure as

an ionic compound as possible during the discharge, so that the subsequent recharge will use lower amplitude voltages, happen much faster and use less energy.

80 BEST Autumn 2011

therefore it suffers a premature decline in cyclic performance and it eventually wins out and leads to premature battery pack replacements.

Application of our patented UPBA™ ultrasonic energy allows easy passage of the stubborn, larger and less energetic electrolyte ions and this significantly reduces the detrimental ionic flow imbalances. Therefore we prevent, or substantially reduce, these bad and unwanted tertiary compounds from coming out of solution. Thus, batteries equipped with our UPBA™ BMS will last longer, have high and sustainable cyclic efficiencies, charge quicker and use much less energy in the process.

We would also like to offer our solutions to battery manufacturers themselves but not for the same reasons we approach battery users. We believe that UPBA™ devices can be developed that will clamp onto the battery terminals as the batteries are lined up in your

factory, taking up critical space and time, while undergoing the long and tedious formation charging process. We believe that we can cut your formation charging times in half, and we also think that the resultant formed electrodes will be far superior based on our UPBA™ ultrasonic treatment program.

Essentially, we are suggesting ultrasonic treatment before the battery leaves your battery plant whereby your customers will receive a much better product. The benefit to you is that you can actually form better batteries faster, and potentially obviate the need to expand your plant.

Back to the terminals of the battery—What we designers see!

Let’s take a look at the battery’s complex internal impedance, ZINT, in Equation 1 below.

Where; ωe= Electrical Excitation Frequency

Equation 1 represents the internal complex impedance of a lead-acid battery based on a simple AC analysis of the equivalent circuit modeled in Figure 4. The battery’s complex internal impedance, ZINT, determines the battery’s dynamic response to the systems around it and it represents a response

Equation●1

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BEST Autumn 2011 83

to both DC and AC excitation voltages felt on its terminals. Of course this is a simplified expression of a lead-acid battery and it is based on our choice of the battery model, however, it is sufficient to describe our novel UPBA™ enhancements.

From Equation 1, it should be clear that the battery’s complex internal impedance response to DC and AC excitation voltages will be very different. It should also be clear that its response will be different for different electrical excitation frequencies, ωe. Also notice that Rel is a very dominant factor in both the real and imaginary parts of the equation. Given that we have shown that the battery’s complex internal impedance response is sensitive to the electrical excitation frequency a brief discussion on the current high-frequency chargers is warranted.

These chargers claim to take advantage of the electrical frequency response of the battery. They claim fast charge times, because they electrically excite batteries with high-frequency electrical excitation (i.e. high voltages and currents), and as shown in Equation 1, ZINT will behave differently to different electrical excitation frequencies, ωe, so it is not surprising that they get better results than DC algorithm charging. But do they? They do in fact get short-term benefits. However, we believe this victory is short-lived, because these “brute force” methods of actually pounding energy into a battery to get the bad stuff off the plates actually accelerate the degradation of the battery pack and eventually sends your pack to a premature burial. These techniques apply large stresses (i.e. voltages and currents) to make the battery behave, and we all know what prolonged stress does! This is not what AGT is promoting; we want to reduce

your stress by reducing your battery’s stress.

Various EIS SoH monitoring techniques

Where;

θe=Phase angle due to electrical frequency excitation

Equation 2 represents the phase relationship between Voltage (V), Current (I) and ZINT. This is merely Ohm’s Law rearranged and in its complex form. It should be recognized that if a sinusoidal V is applied to the terminals of a battery at an electrical excitation frequency, ωe, then the resultant sinusoidal I, its magnitude and returned phase difference response, between the excitation V will be dependent on ZINT.

Equation 3 below represents the complex internal impedance of an

ideal capacitor. As you can see it is much less tedious than that of ZINT in Equation 1 above.

Figure 9 below is our baseline and it provides insight to the novelty and inventiveness of our UPBA™ EIS SoH monitoring method. The phase relationship is depicted between V and I when applied to an ideal capacitor. A very small amplitude sinusoidal voltage is applied across the terminals of the capacitor and the resultant phase difference ϴe of the current response is measured. In the case of an ideal capacitor this phase difference ϴe is exactly 90º.

The only charge carriers involved in an ideal electrolytic capacitor are electrons (e-). There are no chemical reactions happening within this type of capacitor and there are no inherent ionic kinetic deficiencies.

Clearly, if this same excitation voltage signal is applied across the terminals of a lead-acid battery, which does undergo several chemical reactions, reaction steps, and has inherent ionic kinetic deficiencies, the

Equation●2

Equation●3

Figure●9

Figure●10

Phase Relationship between Voltage (V) and Current (I) in an Ideal CapacitorV or I

0

I

V

Phase Differenceis 90º

Degrees (º)

Phase Relationship between Voltage (V) and Current (I) Single Frequency TechniqueV or I

0

I

V

Phase Differencefor IdealCapacitor 90

Degrees (º)

Phase DifferenceSingle FrequencyTechnique

86 BEST Autumn 2011

phase difference ϴe between V and I will be different than that of a ideal capacitor.

Any differences in the phase angle response between V and I in a battery, as compared to that of a capacitor, assuming the electrical excitation frequency ωe is the same, and assuming Cb and C are the same, will be due to the magnitude response of the Rm and Rel components of ZINT in Equation 1.

Figure 10 is the phase relationship between V and I applied to a conventional battery using the single electrical excitation technique.

In Figure 10, the green shaded region is comprised of the magnitude response differences of both Rm and Rel, at the electrical excitation frequency ωe, which as we have discussed is a measure of the opposition to the flow of both e- and ion charge carriers, respectively.

However, there are other factors that affect Rm and Rel as well, such as: aging, State-of-Charge (SoC), the battery’s

internal Temperature (T), the battery’s material and design, and the battery’s manufacturing tolerances and processes.

So, this green-shaded area contains many unknowns and the current EIS SoH manufacturers systems can not differentiate what is causing what, they just know something is different. This is why this product at best can only be safely used to determine imminent cell failure.

But, somewhere amidst the vast green shaded area there is a contribution by the battery’s age (i.e. its true electrochemical health). However, with this single electrical excitation technique there is no way to pull this valuable SoH information out so that it can be used by the battery user to aid in making costly battery pack replacement decisions.

Figure 11 is yet another attempt to reduce the green shaded area to provide useful electrochemical health (i.e. aging) information. In this case, two electrical excitation frequencies, ωe

1 and ωe2, are used

and then one takes the difference of

the two returned phase responses and attempts to gather better electrochemical health information.

This approach successfully reduces the area of the green shaded region, so it does in fact remove some of the unknowns (indicated by red shaded region); however, one still does not know what part of the green shaded area is actually due to the electrochemical health (i.e. the age) of the battery.

In this case one is able to remove the contribution to ZINT (in Equation 1) that was attributed to Rm by taking a difference in measurements very close in time. Since the metallic resistance, Rm, is very sensitive to temperature then that uncertainty is successfully removed, however, Rel is also sensitive to temperature and this does not remove that unknown uncertainty.

If you mathematically take the difference of ZINT with two different excitation frequencies you can verify that the contribution from Rm is eliminated (i.e. trust but verify). The magnitude of Rm is also very dependent on the battery’s material, design, manufacturer tolerances and processes, so by removing it these types of uncertainties are also eliminated from the green shaded region. However, Rel is also dependent on these factors, as well as the battery’s SoC, and this does not remove these uncertainties from the green shaded area.

Figure 12 is a phase diagram of our UPBA™ EIS solution and as you can see the green shaded area is very, very small. In fact, our green shaded area now represents the ‘true’ electrochemical health (i.e. age) of the battery. We●urge●you●to●consider●

licensing●these●technologies●which●together●increase●the●energy●efficiency●and●life●of●your●energy●storage●devices,●enable●you●to●accurately●monitor●its●health●(i.e.●age)●and●its●remaining●useful●life,●and●it●allows●you●to●communicate●with●and●gain●control●of●your●device. Contact: shawnkel@gmail.com

Figure●11

Figure●12

Phase Relationship between Voltage (V) and Current (I) Ultrasonic TechniqueV or I

0

I

V

Phase Differencefor IdealCapacitor 90

Degrees (º)

Phase DifferencefromUltrasonicEnergy

Phase DifferenceSingleFrequencyTechnique

Vwm

Phase Relationship between Voltage (V) and Current (I) Dual Frequency Technique

V or I

0

I

V1

Phase Differencefor IdealCapacitor 90

Degrees (º)

V2

Phase Differencefrom V2

Phase Differencefrom V1