It is important to understand that no single test tells the whole story. The purpose of testing is to determine what condition the batteries are in and hopefully give some idea where this condition is headed and possibly how fast. You do not want to find out during a power outage that the batteries did not have sufficient capacity and your load was dropped sooner than designed or that the entire system failed due to a single component failure and that all of this could have been predicted and prevented. Because of this it is always best to have as much test data as possible and be sure to record all of the data.
It is important that the entire system is looked at. The battery surfaces should be clean and free of dust, dirt, tools, and electrolyte. Floors should be clean and the mechanical system supporting the batteries should not have any rust or look distressed in any way. Make sure ventilation systems are verified to be working and thermostat setting checked and recorded. Each battery jar should be checked for signs of leaks or cracks and inter-cell straps need to be checked for signs of corrosion. Each of these items whether correct or not should be recorded and corrected if needed and noted that the correction was made.
Charger Output Voltage and Current:
The charger’s output voltage and current is typically measured and displayed on the charger itself. It is important, however, to understand that the measurement and/or the display on the charger may not be accurate. Because of this and the fact that the charger plays such an important role in the life of the battery, the output voltage of the charger should be verified with a DC voltmeter and the charger output current be verified with a DC amp meter and adjusted accordingly. This should be done at float levels and if available at equalization charge levels.
Float voltage should be measured and recorded across each cell at the battery posts. The measurement is made on the battery post and not on the straps or hardware. This should be measured during float conditions and not during discharge or recharge. The value measured should be compared to the manufacturers recommended value of float voltage per cell. The sum of each individual cell’s float voltage must equal that of the charger output.
At Protec Equipment Resources we can guide you through recommendations on both basic and advanced battery maintenance programs. We also carry a complete line of battery maintenance equipment including ohmic trending equipment like the Megger BITE 2P and BITE3 series as well as the Alber Cellcorder. We will explore ohmic trending further in future bog posts.