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Regeneration of sealed accumulator batteries

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Regeneration of sealed accumulator batteries

  1. 1. Regeneration cost: 20—30 % from price of a new battery Lifetime exhaustion RECYCLING RELEVANCE OF THE PROBLEM Mobile TeleSystems OJSC exploits a lot of sealed lead-acid accumulator batteries Necessary to renew: up to 10% per year Cost of replacement for one Accumulator (12 V, 90 A*h): 15—20 thous. rub. Presentation Page 1 Other defects • electrode corrosion (+); • damage of contact layer; • evaporation of water and/or acid; • short circuit up to 20% Sulphation: more than 80% of batteries should be replaced Reason of failure May be regenerated up to ratings 3240 rub.
  2. 2. LEAD-ACID ACCUMULATOR: HOW DOES IT WORK Presentation Page.2 PbO2 Positive electrode: lead dioxide FULLY CHARGED ACCUMULATOR DISCHARGED ACCUMULATOR Pb Negative electrode: spongy lead H2O + H2SO4 Electrolyte: sulfuric acid solution PbSO4 Positive electrode: lead sulfate PbSO4 Negative electrode: lead sulfate H2O + H2SO4 Electrolyte: less acid, more water
  3. 3. MAIN PHYSICO-CHEMICAL PROCESSES IN LEAD-ACID ACCUMULATOR Presentation Page 3 Accumulator discharge results in formation of a lead sulfate layer of fine-pored structure on both electrodes, and the strength of sulfuric acid in electrolyte solution diminishes. During accumulator charge the sulfate dissolves and then deoxidizes till metal lead on the negative and till lead oxide on positive electrode, and acid strength grows. per one cell
  4. 4. MAJOR DEGRADATION CAUSE FOR LEAD-ACID ACCUMULATOR CHARACTERISTICS: SULPHATION of negative and positive electrodes Presentation Page 4 Degradation of accumulator plates due to sulphation SWEL Energy Ltd. has worked out an innovative technology for desulphation and regeneration of battery performance during its electrical charge Partial sulphation Deep sulphation Very deep sulphation
  5. 5. REGENERATION TECHNOLOGY and PROCEDURE Internal resistance of lead-acid accumulator :  Active r. — depends upon accumulator structure and its charge condition — cannot be reduced  Polarization r. — is determined by electrochemical processes in the accumulator — can be reduced Presentation Page 5 Oscilloscope traces for charging voltage and current Voltage CurrentMinimal internal resistance SWEL Energy Ltd. has worked out an algorithm of accumulator charge by small energy ‘portions’, that provides separation in time of electrical and chemical processes. As a result the polarization component of accumulator internal resistance declines almost to zero. Regeneration algorithm provides optimal speed of sulfate dissolution and accumulator charge at minimal internal resistance
  6. 6. PRACTICAL APPLICATION EXPERIENCE Presentation Page 6 During the last two years SWEL Energy Ltd. has successfully executed a number of projects on performance regeneration of lead-acid accumulators of different manufacturers. 1. Under contract with Rostelecom OJSC we regenerated accumulator batteries for 3 exchange stations: • “Gorky-10» in Moscow region, Odintsovsky microdistrict, Gorky-10 settlement, 31 (Sonnenschein A412/50 A batteries); • Switching substation-597 “Maliye Vyazyomy” in Moscow region, Odintsovsky microdistrict, Maliye Vyazyomy settlement, Petrovskoye highway, 3а (Oerlikon COMPACT-POWER 12CP50 batteries); • Non-commercial partnership of gardeners “Droujba” in Moscow region, Odintsovsky microdistrict, Zhavoronky settlement (Oerlikon COMPACT-POWER I 2CP50 batteries). All accumulators have been functioning nominally during 20 months (since April 2013). 2. Under contract with Rostelecom OJSC branch in Novgorod we regenerated Delta accumulators (50 Ah). All batteries have been functioning nominally during 8 months (since 2014). 3. Under contract with MGTS OJSC we regenerated Sonnenschein accumulators (65 Ah) for one exchange station. All batteries have been functioning nominally during 1 year (since November 2013). 4. Under contract with Ecomotors Ltd. we regenerated Sonnenschein and Tudor UPS 12V360 batteries (88 Ah). All batteries have been functioning nominally in cyclic operation (30—50% discharge) during 2 years (since December 2012). Since May 2014 a part of batteries has been functioning in off-nominal traction mode (100% charge/discharge cycle) providing charge-discharge ratings. 5. Under contract with Cleanford Ltd. (Moscow region, Krasnogorsk) we regenerated Sonnenschein accumulators (2V/225 Ah). During 10 months (since February 2014) all batteries have been functioning daily as normal with 100% discharge, providing charge-discharge ratings.
  7. 7. Regeneration of accumulator batteries TUDOR UPS 12V360 under contract with Mobile TeleSystems OJSC Presentation Page 7 In October-November 2014 SWEL Energy Ltd. regenerated 198 batteries Tudor UPS12V360 under contract with Mobile TeleSystems OJSC, which Mobile TeleSystems OJSC had used for 8 years as part of uninterruptible power systems. Voltage ‘sag’ It was identified that during operation all batteries had been more or less subjected to sulphation (huge voltage ‘sag’ during discharge, decrease of discharge capacity in comparison with nameplate capacity). After processing and regeneration the accumulators demonstrated charge- discharge characteristics generally equivalent to nameplate values.
  8. 8. Regeneration of accumulator batteries TUDOR UPS 12V360 under contract with Mobile TeleSystems OJSC Presentation Page 8 After regeneration all regenerated batteries were tested in 15-minute discharge mode. Consequently, 18 batteries were considered defective that amounted to 9% of the total number of batteries, delivered for regeneration. Such defective ratio should be considered as very low.  After regeneration 91% of batteries were recognized usable for further operation;  The technology worked out by SWEL Energy Ltd., is very likely to provide complete regeneration of work capacity for accumulators suffered from deep sulphation.  Regenerated batteries display nameplate characteristics during discharge by small, medium and high current;
  9. 9. LIFE TESTS Presentation Page 9 In 2012—2013 SWEL Energy Ltd. carried out life tests of regenerated accumulators with its discharge by heavy current 3С (depth of discharge 30%). As shown on the figure, the lifetime of batteries regenerated with the help of SWEL Energy Ltd. technology, corresponds to ratings delivered by battery manufacturers. Test results Average values Initial capacity Measured capacity (% to initial discharge capecity)

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