What is Battery Monitoring?
Battery degradation is not always detected by a simple voltage test. The best test is a periodic discharge test. But what happens between quarterly tests? Can battery cells fail that quickly? Yes they can and yes they do.
A VRLA cell, on a large kVA UPS can become faulty within days following a routine discharge test. This is caused by chemical changes taking place in the cell from the UPS charge and discharge cycles themselves. Cycles that take place even though the UPS never comes on line. In addition, corrosion can occur in all of the connecting hardware of the battery string, internal to the cell or external.
National Power provides NDSL Cellwatch battery monitoring.
NDSL Cellwatch
Your batteries can go from good to bad in as little as two days. The Cellwatch system was a pioneer in its ability to monitor batteries daily, now regarded as an essential requirement for critical UPS and power-protection applications. The modular design is well suited for every application, from small systems to multi-building campuses, and can be reconfigured if your needs change. Cellwatch software is included in a system and is written as Microsoft Windows application to be intuitive and informative. It has a number of standard graphical reports that provide optimal battery data. The intuitive entry screen shows instantly if something is wrong.
Features and Benefits
- Measures voltage on each cell, either 6 or 24 times per day. The software records data for graphical presentation during that day as well as average data for historical analysis or trending. Also compares this data continuously with high and low alarm settings for alarm activation.
- Measures internal resistance on each cell, either 2 or 4 times per day. The software records data for graphical presentation during that day as well as average data for historical analysis or trending. Also compares this data continuously with high and low alarm settings for alarm activation.
- Measures the temperature of either the battery room ambient or a ‘pilot’ cell. Records this figure for graphing as well as comparison with high and low alarm setting for alarm activation.
- Measures discharge current from a battery string and compares the data with a discharge alarm limit set in software. In the event of a discharge, rapidly records all cell voltage data as the battery discharges for later identification of weak cells under load.
- Supplied with dedicated computer running the Microsoft Windows operating system and Cellwatch proprietary application for reporting, recording and data analysis.
- The system is modular, so if your needs change, Cellwatch can be reconfigured or expanded.
- Low voltage DC components. Measurement components never see greater than 48V nominal DC so battery connections are all low voltage. Electrical isolation is achieved by plastic fiber optic cable.
