Adap%ve Charging: A Further Development of Intermi9ent Float for - PowerPoint PPT Presentation

Adap%ve Charging: A Further Development of Intermi9ent Float for Charge Maintenance of VRLA Ba9eries in Telecommunica%ons Standby Systems By Steven n A. Mula lawski ski, , Dor orion on Car Carr, , David d P. Bode oden and and Ale lex x Rawitz Prese sented d by Ale lex x Rawitz, , Busi sine ness ss Develop lopme ment Manag anager, , Servato o Cor orp August st 4 th th , , 2016 2016 | BaIe aIery Power 2016 2016 | Denver, , CO

Outline § Issues with Con0nuous Float Charging of VRLA Ba;eries § Shortcomings of Intermi;ent/Periodic Charging as Improvements to Con0nuous Float § Adap0ve Charging § Overview § Principles § Case Studies: Examples of Adap0ve Charging’s Ability to Enable Ba;ery Life Extension, the Iden0fica0on of Bad Ba;eries, and other Equipment Issues § Conclusions 1 Servato Corp.

The Internet of Things (IoT) IoT applica0ons will require investment in § network reliability As more devices connect to the Internet – not § just cellphones and PCs but cars, residen?al and industrial appliances, other personal devices – down?me is more impac@ul The founda0on of network reliability are § VRLA ba;eries that today are almost exclusively con0nuously float charged An example of VRLA BaFeries for a standby system in a telecommunica?ons Worse, they are subject to inadequate § maintenance cycles. Millions of essen?al deployment baFeries right now, constantly charging 2 Servato Corp.

Problems of Float Charging VRLA VRLAs have been successful in reducing § maintenance costs by elimina0on of watering, they have shorter life than the flooded type They incorporate a gas recombina?on mechanism that § is exothermic (genera?ng heat inside them) Heat trapped inside the ba;ery and can only be § removed by transmission through the container walls BaFeries are usually closely packed in telecom § installa?ons exacerba?ng heat removal issues Higher temperatures accelerate failure § A cabinet like the one on the right could rou?nely see § BaFeries in a small temperatures in excess of 45C during the summer Outside Plant Cabinet 3 Servato Corp.

Problems of Float Charging Accumula0on of heat from oxygen recombina0on drives the primary § drawbacks of con0nuous float charging Increased ba;ery temperature from gas recombina0on accelerates: § Grid corrosion § Dehydra?on § Dry-out § Ac0ve material degrada0on and capacity loss take place as a result of: § Plate soVening § Loss of cohesion § 4 Servato Corp.

Reliability Impacted by Maintenance 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 ba;ery decline § Long periods of ?me without a site check mean that baFery § health readings provide limited insight into true State of Health Without data it’s impossible to take proac?ve ac?ons to § protect reliability Equipment failures of other kinds such as fans or heat § exchangers can end up damaging baFeries in other ways A technician manually tes?ng not directly related to charging baFeries in the field Maintenance protocols and performance are linked, and § we need to treat them that way 5 Servato Corp.

Status Quo vs. Effec0ve Charging Ba;ery companies are reluctant to require frequent in-situ equalizing § VRLA baFeries are starved of electrolyte and equalizing would cause even more § overcharge and the associated gassing and corrosion Repeated equalizing of con?nuously floated baFeries will accelerate dry-out § The status quo is inefficient: § BaFery companies do not require in-situ equalizing § Ineffec?ve manual maintenance inhibits proac?ve baFery improvement § Con?nuous float charging reduces baFery life § If these destruc0ve processes can be eliminated, ba;ery life can be greatly § increased IntermiFent, or periodic, charging has been proposed as a solu?on to these problems § 6 Servato Corp.

Intermi;ent or Periodic Charging § “Intermi;ent” or “periodic” charging describe a strategy for float charging for a specific period of 0me, and then placing the ba;eries on open circuit for some period of 0me aber § Importantly, in “intermiFent” or “periodic” charging, the ra?o of float ?me to open circuit ?me is fixed § No maFer what the baFery or environmental condi?ons are, the cycle proceeds at fixed intervals § Reduces 0me on float and thus overcharging, but s0ll has shortcomings: § Correct ra?o of float to open circuit ?me is a moving target dependent on temperature and baFery condi?on § An incorrect ra?o can result in overcharging or undercharging 7 Servato Corp.

Temperature Dependency A float to open circuit ra0o that might be adequate at 40°C will not be sa0sfactory 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 fluctua?ons are common, especially in outdoor cabinets, and with a § fixed charge to rest ra?o it is impossible to con?nually adjust float voltages and currents to maintain an op?mum charge A further weakness is that a fixed ra0o may not be capable of compensa0ng for power § outages In cases where numerous short power outages occur, the charge period must also be long enough to § restore the baFery to full charge A fixed ra0o does not meaningfully improve upon standard float charging § To compensate for varying rates of self-discharge at different temperatures and ensure maximum § baFery charge for use, the ra?o of open circuit to float needs to adapt 8 Servato Corp.

Adap0ve Charging § A methodology that uses ba;ery data to determine and administer ba;ery charging needs on an ever-changing basis § BaFeries 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 tes?ng and charge control, data is automa?cally collected on per?nent baFery parameters many ?mes per day to ensure that baFeries end each day fully charged § The prac0ce also allows the iden0fica0on of other poten0ally nega0ve events 9 Servato Corp.

Adap0ve Charging § Servato’s adap0ve charging regimen uses a dv/dt charge termina0on to ensure that charging stops immediately when the ba;ery is fully charged, thereby preven0ng con0nuous overcharge and overhea0ng § 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 baFery 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 compensa0on of the rec0fier 10 Servato Corp.

Adap0ve Charging Certain measurements collected by the appliance, such as open circuit § voltage, internal resistance and voltage under load give a good indica0on of whether a ba;ery needs to be charged or replaced OCV is an indica?on of Electrolyte Specific Gravity, State of Charge, Short Circuits § Internal Resistance indicates Ac?ve Material Sulfa?on, Dry Out, and Grid Corrosion § Voltage Under Load can tell us about increased Internal Resistance and Ac?ve Material § Degrada?on Monitoring these signatures coupled with data trending gives us useful § informa0on regarding when the ba;ery needs to be charged or changed out 11 Servato Corp.

Achieving Adap0ve Charging Servato has developed a line of hardware appliances – the Smart Power System (SPS) § Appliances – that allow for automated adap0ve charging in situ These unique appliances u?lize proprietary technology that allows them to inhibit baFery § charging when it is unnecessary These are the only systems that can “virtually disconnect” the baFeries from the bus § SPS-148 (1 String) SPS-48 (4 Strings) Ac?View 12 Servato Corp.

Achieving Adap0ve Charging In addi0on to the SPS appliances, there is a user-focused enterprise class sobware component, § Ac0View, that is used for visualizing ba;ery data and advanced analysis of ba;ery 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 baFery in the network can be accessed § The link between maintenance and performance is strong, and a tool that provides monitoring and § management capabili0es is a major asset to ba;ery managers in telecommunica0ons and other industries SPS-148 (1 String) SPS-48 (4 Strings) Ac?View 13 Servato Corp.

Principles of Adap0ve Charging Adap0ve charging is a simple § cycle Batteries O ff Charge The principle is to minimize the § amount of 0me ba;eries spend on float while maintaining full charge for backup applica0ons Periodic Measurements Charge Batteries Data Analysis 14 Servato Corp.