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The NWNS Battery Management System (BMS) monitors and protects the battery, keeping track of the state of charge, charging parameters, faults and data logging.
Batteries play an essential role, usually as a source of standby power. To ensure those batteries deliver their full performance when called upon to do so, you must rely on a regular testing regime. This is why a regular broad-based maintenance schedule is required to ensure standby batteries (when required) operate as expected.
Over 85% of back-up power failure accidents (including UPS) are associated with battery problems (Source: EPRI – Electric Power Research Institute, USA).
If one battery in a bank is defective, the string of batteries in series will not work. A battery is defective when it has a higher than specified internal resistance.
It is believed that a small percentage of newly installed batteries are defective without users knowing this. Batteries that have been kept in storage for a long time may show an increased internal resistance.
As a battery ages, it may corrode, sulfate, dry out, or deteriorate in many other ways, depending on maintenance, chemistry, and usage.
There are, of course, other problems that can affect the performance of a battery bank. It has been stated, for example, that loose inter-cell connectors cause around 50% of the failures in battery banks. The connectors loosen because of the heating and cooling that takes place during charging and discharging.
NWNS Offers Its Customers an Affordable Battery Bank Test, Monitoring & Maintenance Program:
Upon physical installation of the battery (bank), one of our engineers installs our unique monitoring tool and thoroughly tests the individual batteries followed by the entire system. We keep extensive record of the results which are first compared to suppliers specifications.
The records are uploaded to our secured database and made available to the customer via customer’s individual web portal and via an app that can be downloaded and installed on a smartphone.
As of day one we start monitoring the health of the battery bank against its environmental conditions. The system generates an alarm when the internal resistance shows a 30% increase for a pre-defined period of time. NWNS will check with the customer if a follow-up maintenance visit is desired or required.
Note: IEEE 1188-2005 recommends quarterly maintenance of batteries. Until recently this was an expensive exercise because it had to be scheduled and an engineer had to visit the premises. Very often it was forgotten about or postponed until the next hard outage. Such an inconvenience.
Our unique monitoring tool can be installed anywhere and does NOT require Internet access hence it cannot be hacked. It is very low cost, reliable and perfectly designed for monitoring battery banks installed in harsh and/or remote locations.
A physical maintenance visit may very well provide useful information, but a series of tests carried out over a period of time will not only provide much more information, but will also make that information vastly easier to interpret.
A sudden change in a test result that has previously remained almost constant, for example, immediately suggests that further investigation is desirable, even if both the old and new values in isolation would be considered as falling within the acceptable range.
At first sight, monitoring the condition of batteries may appear to be a complicated undertaking. However, if the testing regime is properly planned and split into simple tasks that can readily be carried out with modern instruments such as our monitoring tool, the overall effort and inconvenience are small and the cost savings enormous.
How much can be saved depends on the individual situation. Please allow NWNS to understand your situation and calculate your potential savings. We are happy to do this in a transparent way without imposing any further obligations.
Please submit your request via our on-line webform: NWNS Battery Bank Services
Typical the NWNS Battery Bank Test, Monitor & Maintenance Program circles around:
And typically includes the following standard tests:
Visual inspection — A visual inspection locates cracks, leaks, and corrosion. You can find these problems before they become catastrophic failures; however, visual inspection says nothing about the string’s state of charge (SOC), capacity, or state of health (SOH). Visual inspection is executed by an individual during the time of installation and physical maintenance.
Voltage testing — A low float voltage shows a cell that is not fully charging and cannot supply full capacity. A high float voltage is an indication of overcharging. This can lead to premature grid corrosion and higher temperatures in the battery. Incorrect float voltage shows something is wrong. However, if the float voltage is correct, it says nothing about SOC, capacity, or SOH
Float current — A high float current could be a precursor to thermal runaway. It could also indicate a short circuit/ground fault or be a sign of a high float voltage. Incorrect float current, once again, shows that something is wrong. But if the float current is correct, it says nothing about capacity or SOH.
Ripple current — Excessive ripple will cause internal heating of batteries. Ideally, ripple current should be less than 5A for every 100Ah. However, ripple current says more about the state of the charger than the battery. Ripple current does not provide any information about SOC, capacity, or SOH.
Temperature testing — Temperature is critical for batteries, as high temperatures reduce battery life. Temperature testing provides no information about SOC, capacity, or SOH. Regular measurement of the battery’s operating temperature is invaluable, because high temperatures invariably lead to premature failure. As a rule of thumb, battery life is halved for every 10°C increase in temperature. This means that a battery with a rated life of 20 years, which is operated at 30°C rather than 20°C, will only have a life of 10 years.
Specific gravity measurement — A specific gravity measurement reads the ratio of the density of a liquid to the density of water. Specific gravity measurements in batteries indicate how much sulfate is in the electrolyte, providing information about the SOC, but not capacity or SOH. This test only applies to specific types of batteries.
Impedance testing — An impedance test does not measure the capacity of the battery, but it is an indicator of the SOH of the battery and therefore a critical test.
(Limited) discharge testing — Discharge testing is the only form of test that will determine the actual capacity of the string, but not necessarily the SOH. Note: IEEE standards recommend that discharge testing be performed at the time of a battery strings installation and then every two to five years after that, depending on the age and capacity of the string. For complete discharge testing, the battery must be taken out of service for the duration of the test. One way of addressing this problem is to carry out limited discharge testing, which involves discharging the batteries by up to 80% without taking them out of service. This yields results almost as accurate as those provided by carrying out a 100% discharge test.
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