Servato - Battery Power 2016

Steven A. Mulawski, Dorion Carr, David P. Boden and Alex Rawitz
Presented by Alex Rawitz
Servato Corp
Adaptive Charging:
A Further Development of Intermittent Float for Charge Maintenance of
VRLA Batteries in Telecommunications Standby Systems

Issues with Continuous Float Charging of VRLA
Batteries
Shortcomings of Intermittent/Periodic Charging as
Improvements to Continuous Float
Adaptive Charging
► Overview
► Principles
Case Studies: Examples of Adaptive Charging’s Ability
to Enable Battery Life Extension, the Identification of
Bad Batteries, and other Equipment Issues
Conclusions
SERVATO – CONFIDENTIAL/PROPRIETARY
Outline

IoT applications will require investment in
network reliability
► As more devices connect to the Internet –
not just cellphones and PCs but cars,
residential and industrial appliances, other
personal devices – downtime is more
impactful
The foundation of network reliability are
VRLA batteries that today are almost
exclusively continuously float charged
► Worse, they are subject to inadequate
maintenance cycles. Millions of essential
batteries right now, constantly charging
The Internet of Things (IoT)
An example of VRLA Batteries for a
standby system in a telecommunications
deployment

VRLAs have been successful in reducing
maintenance costs by elimination of watering,
they have shorter life than the flooded type
► They incorporate a gas recombination mechanism
that is exothermic (generating heat inside them)
Heat trapped inside the battery and can only be
removed by transmission through the container
walls
► Batteries are usually closely packed in telecom
installations exacerbating heat removal issues
Higher temperatures accelerate failure
► A cabinet like the one on the right could routinely see
temperatures in excess of 45C during the summer
Problems of Float Charging VRLA
Batteries in a small
Outside Plant Cabinet

Accumulation of heat from oxygen recombination drives the primary
drawbacks of continuous float charging
Increased battery temperature from gas recombination accelerates:
► Grid corrosion
► Dehydration
► Dry-out
Active material degradation and capacity loss take place as a result
of:
► Plate softening
► Loss of cohesion
Problems of Float Charging

Telcos rely on manual, cyclical maintenance that may
involve checks as frequently as every few months, but
usually happen once a year or less
Inadequate maintenance exacerbates battery decline
► Long periods of time without a site check mean that
battery health readings provide limited insight into true
State of Health
► Without data it’s impossible to take proactive actions to
protect reliability
► Equipment failures of other kinds such as fans or heat
exchangers can end up damaging batteries in other ways
not directly related to charging
Maintenance protocols and performance are
linked, and we need to treat them that way
Reliability Impacted by Maintenance

Battery companies are reluctant to require frequent in-situ equalizing
► VRLA batteries are starved of electrolyte and equalizing would cause even more
overcharge and the associated gassing and corrosion
► Repeated equalizing of continuously floated batteries will accelerate dry-out
The status quo is inefficient:
► Battery companies do not require in-situ equalizing
► Ineffective manual maintenance inhibits proactive battery improvement
► Continuous float charging reduces battery life
If these destructive processes can be eliminated, battery life can be greatly
increased
► Intermittent, or periodic, charging has been proposed as a solution to these problems
Status Quo vs. Effective Charging

“Intermittent” or “periodic” charging describe a strategy for
float charging for a specific period of time, and then placing
the batteries on open circuit for some period of time after
► Importantly, in “intermittent” or “periodic” charging, the ratio of float
time to open circuit time is fixed
► No matter what the battery or environmental conditions are, the
cycle proceeds at fixed intervals
Reduces time on float and thus overcharging, but still has
shortcomings:
► Correct ratio of float to open circuit time is a moving target
dependent on temperature and battery condition
► An incorrect ratio can result in overcharging or undercharging
Intermittent or Periodic Charging

A float to open circuit ratio that might be adequate at 40°C will not be
satisfactory at higher or lower temperatures because of different rates of
corrosion and dry out
► The rate of self-discharge is temperature dependent and the amount of charge
required to maintain 100% state of charge at 40°C will be considerably greater than at
25°C
► These magnitudes of temperature fluctuations are common, especially in outdoor
cabinets, and with a fixed charge to rest ratio it is impossible to continually adjust float
voltages and currents to maintain an optimum charge
A further weakness is that a fixed ratio may not be capable of compensating for
power outages
► In cases where numerous short power outages occur, the charge period must also be long
enough to restore the battery to full charge
A fixed ratio does not meaningfully improve upon standard float charging
► To compensate for varying rates of self-discharge at different temperatures and ensure
maximum battery charge for use, the ratio of open circuit to float needs to adapt
Temperature Dependency

A methodology that uses battery data to determine
and administer battery charging needs on an ever-
changing basis
► Batteries are only ever charged exactly as much as is
necessary and otherwise remain in an isolated state
► Using a unique hardware appliance capable of automated
testing and charge control, data is automatically collected
on pertinent battery parameters many times per day to
ensure that batteries end each day fully charged
The practice also allows the identification of other
potentially negative events
Adaptive Charging

Servato’s adaptive charging regimen uses a dv/dt charge
termination to ensure that charging stops immediately when
the battery is fully charged, thereby preventing continuous
overcharge and overheating
► It adapts to the depth of discharge of the preceding discharge
and compensates for the effect of temperature
► That is, dv/dt=0 indicates that the battery is charged whether it is
at 25°C or 40°C, and whether it has experienced a recent
discharge or simply been isolated at rest
This eliminates/reduces the need for temperature
compensation of the rectifier
Adaptive Charging

Certain measurements collected by the appliance, such as
open circuit voltage, internal resistance and voltage under
load give a good indication of whether a battery needs to be
charged or replaced
► OCV is an indication of Electrolyte Specific Gravity, State of Charge, Short
Circuits
► Internal Resistance indicates Active Material Sulfation, Dry Out, and Grid
Corrosion
► Voltage Under Load can tell us about increased Internal Resistance and
Active Material Degradation
Monitoring these signatures coupled with data trending gives
us useful information regarding when the battery needs to be
charged or changed out
Adaptive Charging

Servato has developed a line of hardware appliances – the Smart Power
System (SPS) Appliances – that allow for automated adaptive charging
in situ
► These unique appliances utilize proprietary technology that allows them to inhibit
battery charging when it is unnecessary
► These are the only systems that can “virtually disconnect” the batteries from the
bus
Achieving Adaptive Charging
SPS-148 (1
String)
SPS-48 (4
Strings)
ActiView

In addition to the SPS appliances, there is a user-focused enterprise class software
component, ActiView, that is used for visualizing battery data and advanced analysis
of battery signatures to detect harmful trends
► The data can be accessed from anywhere in the world via an Internet connected device such as a
computer or smart phone
► Every individual battery in the network can be accessed
The link between maintenance and performance is strong, and a tool that provides
monitoring and management capabilities is a major asset to battery managers in
telecommunications and other industries
Achieving Adaptive Charging
SPS-148 (1
String)
SPS-48 (4
Strings)
ActiView

Principles of Adaptive Charging
Adaptive charging is
a simple cycle
The principle is to
minimize the
amount of time
batteries spend on
float while
maintaining full
charge for backup
applications

Batteries are maintained in a standby (off charge) mode by isolating them
from the rectifier bus via Servato’s proprietary technology
► Batteries end up charged about 20% of the time and at rest about 80% and are still
kept at full capacity
Life is significantly increased by reducing internal temperature and all the
associated adverse affects through a limited oxygen recombination
► Reduced grid corrosion
► Reduced dehydration
► Reduced need for cooling
Since temperature increase is greatly reduced, thermal runaway
is virtually eliminated and the need for cooling is reduced
In this standby mode, batteries are still available for
instantaneous discharge in case of a power outage
Principles of Adaptive Charging
Batteries Off
Charge

Periodic
Measurement
s
While the batteries are at rest they are monitored at
periodic intervals multiple times per day
► Servato uses OCV and Temperature to indicate state of
charge
► State of Health is determined by evaluating several
parameters including DC Resistance, charge efficiency,
and self-discharge rates, among others
► All battery data is parsed for any trends that may indicate
existing or developing battery issues
Adaptive Charging Protocol

Data Analysis
The measurements are collected and analyzed
automatically by the SPS appliance
► Servato owns a library of battery data accumulated
through more than 5 million battery operating hours
► If stable , the batteries are allowed to remain in the
standby mode for a period of time when they will be tested
again
► If the data show changes greater than embedded set
points a charge is initiated

Charge
Batteries
If and only if charging is necessary, the batteries are put on the rectifier bus
until they are fully charged
► dv/dt charge termination
This replaces energy lost through self-discharge and any short term
discharges that may have occurred
► As soon as the full charge criteria are satisfied the batteries are again isolated from
the rectifier
► If the batteries have been discharged for more than a preset time during the standby
period they are immediately connected to the rectifier for charging to eliminate any
possibility of standing in a partially discharged condition

In a multistring application, the strings are
charged sequentially to assure string-to-string
equalization
► Each string is brought to full charge independent
of the other strings in the system
► This significantly reduces the adverse affects
caused by random inter-string variation
Charge
Batteries

Batteries Off
Charge
Following any charge event the battery
strings are given a state-of-health test
► A short discharge is applied to the batteries
► Voltage/Time characteristics are recorded and
used to calculate the internal resistance
► Batteries isolated again at rest
Charge
Batteries

Adaptive Charging
• Standby, available for backup
• Battery life extension
• OCV
• Internal
Resistance
• Discharge
test
• Library of battery data
• Charging decision
• If charge is required,
SPS places batteries
on rectifier
• Strings charged
individually
• Batteries are again
isolated from the
rectifier
Batteries Off
Charge
Periodic
Measurements
Data Analysis
Charge
Batteries

This sequence assures that the batteries
are charged whenever the data trends
indicate that a charge is necessary and not
anymore
► Automatically compensates for normal
temperature-dependent phenomena such as
self-discharge
► The accumulation of data means Servato can
detect many other issues (see Case Studies)SERVATO – CONFIDENTIAL/PROPRIETARY
Adaptive Charging Overview

Life Testing
An independent test laboratory was
used to compare the capacities of
VRLA batteries over time when they
were on continuous float and when
managed by the Adaptive Charge
Management (ACM) of the SPS
system
► Tests were carried out at 40ᵒC (104ᵒF) to
simulate hot weather conditions
► Four strings of batteries were tested,
battery capacities were measured at
approximately three-month intervals and
averaged and charted as shown
This predicts that the life of batteries
operated by the ACM regimen will be
twice as long as batteries on continuous
float
Expected failure for the continuously floated
string = 39 months
Expected failure for the adaptively charged
string = 79.5 months

Field applications of the adaptive charge management system have
been underway in locations throughout the USA for over four years
► The examples cited below are intended to show typical examples where
an adaptive charging regimen has increased battery performance,
detected deteriorated batteries, or found other equipment issues
► Only a system capable of adaptively charging and automated tests
enables such a wide range of benefits so cost-effectively
Evidence of battery life extension has been expanded
Proven ability to detect and predict battery issues as well as other
equipment problems
Field Testing Overview

75
80
85
90
95
100
1 2 3 4
Percentnominalcapacity
Battery Number
Float
ACM
Case Study A:
Battery Capacities from Outside Plant Installations After 18
Months
At an installation in Arizona after 18 months
of testing, a string of adaptively charged
batteries shows higher capacity than a
control string on float (data at right)
► The data reflects that found in the
independent trial
In another trial in Colorado, the SPS-48
device was placed on a battery string
approximately 5 years old next to a 2-year
old string being floated
► After 18 months (total battery life = 3.5 and
6.5 years) both strings showed 96% nominal
capacity
► It would be expected that the capacity of the
6.5-year-old batteries would be lower

Case Study B:
Detection of Aging Battery by DC Resistance
Trending
The importance of an adaptive
management system that will report on
battery issues rather than try to
compensate for them improperly cannot be
understated
The graph at the right shows an example of
increasing internal resistance of a
deteriorating battery in a telecom network
► This was from an aging battery in a string in
which the other batteries in the same string
were showing a constant resistance and
were operating properly
► This allowed timely changing of the battery
to prevent deterioration of other batteries

Case Study C:
Trend in Open Circuit Voltage
In this graph the OCV of a string of 12-Volt
VRLA batteries is shown
► ActiView was able to detect that Battery A3
had a declining OCV before the battery
ultimately failed and it was replaced
► The battery was shipped to the manufacturer
and an autopsy revealed a manufacturing
defect that caused a short circuit
► OCV cannot be used as an indicator of
battery condition if the batteries are on float
since they are always polarized
Periodic scheduled maintenance and spot-
checking would be unlike to reveal this
issue

Case Study D:
Detection of Faulty Rectifiers
With Servato appliances this company discovered
several sites experiencing what appeared to be
brief power outages, sometimes multiple times per
day (see graph at left)
It had been assumed that the rectifiers were
working normally despite the fact batteries were
dying very quickly at these sites
► ActiView showed healthy batteries ruling out
faults or issues the batteries
► As the batteries were charged with the Servato
appliance, the rectifier voltage would drop
► When the rectifiers were examined bad blades
were discovered and as the company replaced
the rectifiers the outages ceased
► Had they not been replaced the batteries would
have been damaged

Continuous charging as a method of maintaining standby batteries
at 100% state of charge has been standard for many years but has
serious negative consequences that can add significant cost to
battery management budgets
► Float accelerates battery failure due to increased temperature, grid
corrosion, plate degradation and dry-out resulting in high replacement
costs
► Battery life can be increased by removing these harmful failure
mechanisms and by charging only when necessary and only for as long
as necessary
Adaptive Charge Management combines an automated battery
management process and an enterprise class remote monitoring
solution to maximize visibility into backup batteries
Conclusions

Servato’s Adaptive Charge Management delivers
meaningful and measurable benefits in four
strategically important areas:
► Battery Life Extension: Adaptive Charging improves
battery life
► Site Insight: Using the remote monitoring software we
make it easier to detect battery and equipment issues by
looking at the data of rested batteries
► Optimized Maintenance: Better insight means better
maintenance, reducing costs and improving reliability
► Other Reduced Costs: Battery life extension and optimized
maintenance are key pieces, but the business case has
many other cost savings associated with Adaptive
Charging SERVATO – CONFIDENTIAL/PROPRIETARY
Conclusions

Thank you
Alex Rawitz
arawitz@servatocorp.com | 504-655-2733
1441 Canal Street, Suite 221
New Orleans, LA 70112

Servato - Battery Power 2016

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