Development of a Float Cycling Telecommunication Battery for Emerging Markets in Regions with Unstable Electricity Grids

1. Development of a Float Cycling Telecommunication Battery for Emerging Markets in Regions with Unstable Electricity Grids Benjamin J. Craftand Frank A. Fleming Northstar Battery USA

2. Background • The following development program is the result of a request from Ericsson to NSB to investigate, and engineer a solution for premature reduction in battery back up time in Radio Base Stations located in regions with unstable AC grids • Several suitable sites were identified in Bangladesh and were made available for investigation

3. Electric AC Grids Stable AC Grids Float Battery No AC Grid High Cycling Battery Very Unstable Grids PSOC Cycling Battery Source: NASA GSFC 40% of the worlds population lives with no electricity or with unstable electric grids

4. Example of an Unstable AC Grid in Bangladesh Not enough time to fully recharge Uncontrolled PSOC cycling Moderate Cycling Deep Cycling Moderate cycling followed by deep cycling with insufficient power to be fully recharge

5. AGM Cycle Performance Traditional Cycling STD AGM Undercharge (PSOC)Cycling STD AGM Traditional AGM’s require proper charging to obtain 100% designed cycle life. . PSOC’ cycling will severely reduce the life

6. Findings in Bangladesh • AGM batteries failing prematurely after approximately 2-months • Temperature is stable in cabinets • 17C to 35C • Severe Sulfation on electrodes • Soft Positive Active Material Uncontrolled PSOC Cycling with insufficient recharge power

7. How To Solve • Increase recharge power or use boost voltages • Not always practical • Change Battery Chemistry • Increased Charge Acceptance • Able to support PSOC cycling • Ability to operate in a low SOC for extended periods

8. Blue Battery Positive grid alloy; High Cyclic Alloy New positive grid design; High Cyclic Design Negative Electrode • Reduced lignosulfate concentration • Optimizes charge acceptance Blend of Carbon • Minimizes negative plate sulfation • Increases high rate performance • Acts as a ‘expander’

9. AGM Cycle Life PSOC Cycling NSB Blue Technology PSOC Cycling STD AGM The Blue Battery can be PSOC cycled and will achieve 2-4 times the designed cycle life

10. Simulation of Field Data SE Asia Test Cycle Cycle #1 Charge 8-hours at constant voltage, CV, with 1160W/24V Discharge 2-hours at 280W/24V Cycle # 2 Charge 2-hours at CV with 1160W/24V Discharge 3-hours at 280W/24V Cycle #3 Charge 4-hours at CV with 1160W/24V Discharge 5-hours at 280W/24V, record EODV

11. SE Asia Test Cycle Standard AGM

12. SE Asia Test Cycle NSB 100 Blue

13. Cyclic Recharge Performance Recharge Time at 2.27VPC Sufficient Overcharge Undercharged

14. Cyclic Recharge Performance Recharge Time at 2.35VPC Sufficient Overcharge PSOC cycling or Undercharged

15. Bangladesh • 4 Demonstration Sites • Installed GSM data loggers • Replaced NSB170FT with NSB100 Blue • Back-up time reduced by 50%

16. Bangladesh 3 Month Period Over 500 outages in 3 month period. Outages vary from 30 minutes to 6 hours Data logger only recorded outages longer than 5 minutes.

17. Bangladesh Into the Summer Instances where the site went down, but the batteries still work once they are recharged! June May Batteries are still strong at 12 months even though they are undersized by 50%

18. Bangladesh Daily Outages Average daily outage is 3-6, but can be as high as 13 per day

19. Bangladesh Summary Undercharge Batteries should be sized based upon PSOC cycling capability and not total back up time in unstable grid areas

20. NSB Battery Summary • The Blue Battery has been developed which can be cycled in an uncontrolled PSOC regime • The Blue battery can be cycled using a low power recharge using only the standard float settings • The Blue Battery has completed over 1800 cycles in Bangladesh which is the equivalent 330 *100% DOD • The standard AGM can be employed, but needs to have high power and the use of boost voltages