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Remote Station Engineering - Effect of Long Term Cold Storage on SLA Batteries

EFFECT OF LONG TERM COLD STORAGE ON SLA BATTERIES

In late 2007, 44 brand new SLA batteries (Deka 8G31) were cached by the USAP South Pole Traverse near the Beardmore Glacier at 84S 169E, a staging area for installing POLENET remote GPS stations. However these particular stations were not deployed due to logistical constraints, and the South Pole Traverse retrieved these batteries in early 2009. Since each battery was fully charged and tested prior to caching, this was a unique opportunity to assess the effect of long-term storage in deep cold on battery health. After retrieval, each battery was fully charged then re-tested with the same Midtronics Midtron 3200 conductance tester used in 2007.

Figure 1 shows changes in absolute voltage and relative conductance of each fully charged battery, with all charging and testing performed at room temperature. The average change in fully-charged voltage was -0.13V. The average change in conductance was -1%, with no battery showing a decrease in conductance greater than than 10% relative to the average conductance of 1055 mhos for a new battery. No discharge test was performed with any battery, however in our experience, conductance has been a reliable indicator of true battery capacity when compared to a discharge test. Therefore this result indicates that the Deka 8G31 battery suffers minimal, if any, decrease in capacity due to extreme cold exposure if stored in a fully charged state. A similar result was also obtained with a smaller number of Concorde PVX-1080T AGM batteries stored at the same location.

Furthermore, since reduction in battery capacity due to self-discharge is dramatically reduced at low temperatures as shown in Figure 2, storing these batteries cold is not only harmless but preferable.

Figure 1: Change in voltage and conductance of fully charged Deka 8G31 batteries after 14 months cold storage.

Figure 2: Nominal decrease in SLA battery capacity from self-discharge at various temperatures (from East Penn-Deka).

 

Last modified: 2019-12-24  02:12:28  America/Denver