This article discusses charging of lead-acid industrial standby batteries on float charge and “off mains” locations. It does not include charging of batteries on full cycling applications such as daily traction duties or similar.
Charging of parallel battery strings, inrush currents, ripple voltage and ripple current are also discussed in outline.
Continue Reading...
Battery back up is essential in todays world, particularly when utilised in applications such as UPS systems and emergency lighting, but how does a lead acid battery produce the power needed to keep critical building services online?
There is a lot of information available on the internet which gives detailed information of the electrochemical reactions of the lead-acid battery. It can be seen that three effective components are require; lead, lead dioxide and dilute sulphuric acid. Looking at some of the basic information shows that Faraday discovered the theoretical amounts required to produce 1 ampere-hour (Ah) of electricity are; 3.87g of spongy lead (Pb), 4.46g of lead dioxide (PbO2) and 3.66g of dilute sulphuric acid (H2SO4). However, in practice many more time the theoretical value is required to produce an effective battery.
Continue Reading...
This article considers ohmic measurements as a means of identifying rogue cells and monoblocs of VRLA AGM and GEL product installed on float standby systems. For batteries operated on cycling applications there are better ways of identifying rogue cells or the end of life for the complete battery. For vented product, the established method of visual inspection, float voltages, specific gravities and ultimately discharge testing are more reliable than predictions based on ohmic measurement.
Searching the internet will show that there are many articles discussing battery ohmic measurements. Some will be written by operators such as telecommunication or UPS companies whilst others will be from instrument manufacturers and papers written by battery manufacturers are also available. Rarely is an article written with the intent of giving an overview of the subject and guidance for the interpretation of the results obtained and actual case examples. This article will show that whilst ohmic measurements may be used to identify rogue cells or monoblocs, the results can also be very misleading and may give the operator a false sense of security, or condemn product that is still fit for purpose.
Continue Reading...
This article discusses the float voltage characteristics of VRLA AGM and VRLA GEL cells and batteries in standby power applications when charged using commercially available battery charging systems having a constant voltage characteristic with limited current output.
Batteries in standby applications require a charging voltage that is sufficiently high to recharge following a discharge, and maintain a fully charged condition without overcharging the battery. This voltage needs to be regulated for different operating temperatures but for simplicity, this document considers operating at 20oC. The principals and overall characteristics shown in this document can be considered to apply for operating temperatures of between 0oC.and 40oC.
Continue Reading...
This article discusses the gasses given off by Industrial Batteries and how to manage these gasses. The document primarily considers Standby Batteries but the overall principals apply equally to lead acid and nickel cadmium types both vented or VRLA.
Under normal operating conditions, the gasses evolved are hydrogen (H) and oxygen (O). However, under extreme conditions other gasses may be produced such as hydrogen sulphide (H2S). Some strange gasses are also given off in very small quantities such as carbon dioxide (CO2). This document only considers the evolution of hydrogen, oxygen and hydrogen sulphide.
Continue Reading...
This article discusses the use of parallel string batteries in high voltage applications but the contents may be considered for any battery voltage.
The subjects discussed in the paper are: -
Continue Reading...