Latest from the Blog

A Guide To VRLA Battery Discharge Testing.

Thursday, 7th September 2017 Battery Advice

This article discusses test discharging of VRLA batteries. The principal is almost identical to the procedure that should be followed when testing vented Lead-Acid batteries but some important changes are necessary to obtain the correct results.

The article covers the broad spectrum of testing and some manufactures and users may prefer to test batteries in a slightly different way. Never the less, this article follows the UK accepted practice as given in BS 6290 Part 4 1997. It also discusses the International Standard IEC 60896 -

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Comparing VRLA Battery Specification Standards.

Tuesday, 25th July 2017 Technical

The document is intended to give the reader a better understanding of the difference between the major classifications of BS 6290 Part 4 (Lead-acid stationary cells and batteries – Part 4 Specification for classifying valve regulated types) and IEC 60896 – 22 (Stationary lead-acid batteries – Part 22: Valve regulated types – Requirements).

This document is not intended to comment on the specification classifications or make any judgement to the validity of tests or claims by manufacturers. The article is intended to draw attention to the different classifications and how the British Standard varies with the latest International Standard.

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Battery Open Circuit Voltage Characteristics.

Wednesday, 10th May 2017 Battery Advice

The open circuit voltage of lead acid cells can give us useful information providing it is used correctly.

This article shows the relationship between the open circuit voltage and state of charge of lead-acid cells and how to interpret the values. The values are always considered as that of a single cell and monobloc voltages must be averaged according to the number of cells. This method was developed primarily for VRLA cells where the specific gravity cannot be measured. Measurement of the specific gravity will give a good indication of the state of charge. For measurement of either specific gravity or open circuit voltage, the fully charged and fully discharged specific gravity must be known. Used correctly, the method described in this article will give reasonable results to the state of charge of cells on open circuit.

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Lead Acid Batteries For Cycling Applications.

Friday, 31st March 2017 Technical

There have been many myths about lead-acid battery cycling.

This article will give the reader a better understanding of the more important aspects of battery cycling and battery choice. Different applications are discussed along with charger requirements and how the number of cycles varies with the depth of discharge. This article looks at applications where the recharge is not regular such as solar and wind charging. Intermittent diesel charging is also discussed.

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Battery Internal Resistance & Short Circuit Current.

Friday, 16th December 2016 Technical

Battery internal resistance and short circuit current values are available from battery manufacturers. The method used to arrive at the published values varies but when a method recognised by International Standards is used a comparison between products can be considered.

Searching the internet will reveal many papers discussing actual case studies where a battery has been shorted and interesting results have been obtained. With no fuse or battery circuit breaker in the system short circuits may result in fires and catastrophic failure. Alternatively, the protection may work and isolate the battery from the point of failure and the load resulting in loss of power to the equipment which the battery was intended to protect. It therefore follows that the subject of battery short circuit current can have at least two points of view when looked at in practical terms.

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