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Wednesday, June 8, 2011

Conclusion: Replacement of Battery Cells with Low Specific Gravity

We had adjusted before the float voltage charge of the 125 Vdc battery bank no. 1 of our substation (please see related posts: Low Specific gravity... and Update on Low....) inorder to improve the specific gravity of its four battery cells.  Upon monitoring the voltage and specific gravity of the affected cells, cell nos. 1 and 48 had improved their specific gravity results. While the voltage of each battery cells are all normal, this is not conclusive that the battery cells are in good condition.
Low specific gravity also affect the discharge rate of the battery cells, thus when load is connected, the affected cells will discharge faster compared to other cells. The adjacent cells of defective units will then be affected as they will initially take the extra burden of defective cells before the load is being distributed to all cells. So, after two months of monitoring, cell nos. 2 and 52 still have the same failing specific gravity value thus we are going to replace the said battery cells for replacement. Here is the procedure in the replacement of defective battery cells:

1. Shift the loads of 125Vdc Battery Bank No. 1 to Bank No. 2
2. Disconnect the Charger connected to Battery Bank No. 1
3. Carefully replace the defective station battery cells one at a time
4. Remove the connecting terminals of the defective battery cells
5. Connect the replacement battery cells
6. Measure the total voltage of 125 Vdc Battery Bank No. 1. It should be near the nominal voltage value (130VDC)
7. Connect back the Battery charger to 125 Vdc Battery Bank No. 1. Set the battery charger to float charge


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    Tampa electrical contractor


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