Are the days of battery monitoring numbered?

Canara has been monitoring the health of critical batteries for major co-location and enterprise data center clients around the world for over 25 years.

 With some global companies having battery assets worth upwards of many tens of millions of dollars, Canara has always strived to allow its clients to get the absolute maximum from this major asset by leading with new technologies and constantly improving its monitoring and reporting service as well as its asset analytics.

With this continuing focus, Canara has now taken its established monitoring technology and moved to the next technological step of turning “battery monitoring” into “battery management”.

By developing its patent pending “Active Capacity Balancing” (ACB) Canara is using new technology to control, maintain and manage the environment of each individual unit within a string of batteries. For the first time since the development of the lead acid battery, each individual unit within a string of batteries can have its environment closely monitored and controlled, much closer to, if not precisely to, the battery manufacturer’s specification.

Shows the basic principle of Active Capacity Balancing

 Shows the basic principle of Active Capacity Balancing

Since batteries were first put together in a string, the established technique has been to add up the recommended charge voltage per cell by the number of cells and set the battery charger or rectifier accordingly.

In an ideal world each cell or jar is then charged at the correct voltage. In the real world however, what happens is some cells charge at a higher voltage, consequently others must charge at a lower voltage due to the constant voltage nature of the charger. In the past, nothing could be done about this discrepancy and it has been the accepted norm. Overcharging a unit by just 0.6 of a volt can shorten the life by up to 60%. ACB now holds that unit to the correct float voltage for its corresponding temperature.

“Overcharging a lead acid unit by just 0.6 of a volt can shorten the life by up to 60%”

Temperature is a major factor in determining battery longevity. It is well established that every 17° F over 77° F (10° C over 20° C) will halve the life of that very expensive asset. It therefore stands to reason that Canara is very conscious that clients keep their batteries as cool as possible while not over cooling and incurring extra cooling expenses.

“Every 10° C rise over 20° C halves the remaining life of a lead acid battery”

Using its already established technology, Canara battery monitoring technicians, having the benefit of being able to see individual unit temperatures, have noticed that the temperature of each unit within a battery string may vary by some 20° F or even more. This means that even with temperature compensated charging, hotter units within a string are getting overcharged while the relatively cooler batteries in the string are not being charged sufficiently.

With ACB, the ability to control the corresponding float voltage depending on temperature (taken from the negative terminal) mitigates both of these major threats to longevity of battery life.

Shows the typical correlation between temperature and recommended float voltage

A further accepted rule within battery circles is that in older battery strings a new replacement jar will age rapidly and quickly catch up to the age and performance of the other jars in the old string. With this limitation, it is normally recommended that a maximum of between 10% and 20% of jars be replaced before the entire sting is taken out and replaced with a complete new one. ACB now controls and prevents this overcharging allowing more replacement units to be installed and further extending the useful life of the entire battery asset.

Thermal runaway is an ever increasing problem for battery owners and operators. As space becomes tighter and cooling becomes more expensive, the environment which encourages the exothermic reaction known as thermal runaway becomes ever more prominent. It is now well known as a major cause of fires within data centers and since 2009 the International Fire Code has ordained that any VRLA battery containing more than 50 gallons of electrolyte must have a method of detecting and preventing thermal runaway.

IFC608.3 states that anyone with VRLA batteries with over 50 gallons of electrolyte must have a means of detecting and preventing thermal runaway.

ACB devices sense the temperature of every negative terminal so trends indicating this phenomenon are detected very early on and additionally the system manages the situation to bypass current which would normally continue to overheat the problem jar.

An added benefit of having each battery being held to its recommend float voltage according to its temperature is that the jars that would normally have to dissipate more heat no longer have to do so and tests in the field indicate that in some cases the average string temperature of a string with ACB can fall by 1°F to 2°F.

All the benefits of having individual temperature compensated float voltage control quickly come together. It is Canara’s belief that battery life will be extended and that users will be able to run their battery installations more safely, and over longer timeframes using Active Capacity Balancing.

Shows Active Capacity Balancing under lab conditions
Shows Active Capacity Balancing working in the field. Stratification of temperatures is typical within a cabinet of batteries. Note how ACB varies with those temperatures.

Coupled with Canara’s remote monitoring service, the added benefit of its’ automated ACB feature means that batteries are being tended to maximize their performance and lifespan as well as being monitored by experts.

Why just monitor batteries when for almost the same cost the batteries can be managed?

So, is simple battery monitoring a thing of the past?

If you want to learn more about Voltage Balancing, please download our latest White Paper – Extend Battery Life Through Float Voltage Control.