Test & Measurement


Lead-acid battery capacity analysers

11 July 2007 Test & Measurement

Today, most UPS, aircraft, telecoms and other critical application batteries are of the lead-acid chemistry. The unfortunate truth about most of these batteries is that you will never know their true capacity until you actually perform a full capacity test.

In order to correctly determine the capacity of a given lead-acid battery, the battery must first be fully recharged before being allowed to 'cool down' for several hours. Once cool, the battery must be discharged at the manufacturer's determined rate, down to a set end voltage. For example, a 12 V 100 Ah battery could be discharged at 10 A for 10 hours down to 1,85 V per cell. If the battery is able to sustain the 10 A discharge for 10 hours then it has 100 A hours of capacity at the C/10 rate, where C is the capacity of the battery. However, if the same battery can only sustain the 10 A discharge for say 5 hours, then the battery only has approximately 50% capacity left.

One of the most advantageous features of lead-acid batteries with pure lead-tin alloy (from suppliers such as NorthStar and Hawker SBS) as opposed to the cheaper and lower performance lead-calcium is that their state of charge (SOC) can be estimated simply by measuring their open-circuit voltage, since the open-circuit voltage is a direct function of the concentration of electrolyte within the battery - even though the battery might be dry. As the concentration of electrolyte decreases so too does the % SOC. For NorthStar batteries, the relationship can be linearly approximated by the following equation: % SOC @ C/20 = OCV x 62,5-712,5 where C is the capacity of the battery in question.

Aztec Electronics stocks a wide range of lead-acid (and NiCad) battery analysers/dischargers. Aztec's Beta D-50 analyser is suitable for 12 V and 24 V batteries and can be adjusted for constant current discharges between 0 and 50 A. The end-point voltage and test time can be set prior to discharging. Once complete, the digital display will show elapsed time, voltage and current and a green lamp will illuminate when the battery capacity is above the preset requirement. Alternatively, a red lamp will illuminate if the battery fails to meet preset limits.



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

New range of Tektronix DSOs
30 June 2020, Comtest , Test & Measurement
Comtest has released Tektronix’s new TBS2000B series of digital storage oscilloscopes (DSOs) that was developed to meet the performance, usability and affordability needs of both engineers and educators. ...

Read more...
Contactless ESD testing and access control unit
30 June 2020, Actum Group , Test & Measurement
In the electronics manufacturing industry, an electrostatic discharge (ESD) can cause irreparable damage to electronic components. This micro-lightning bolt can burn holes through insulating layers and ...

Read more...
How are IR cameras calibrated and how does ambient temperature affect readings?
30 June 2020, Instrotech , Test & Measurement
Infrared thermometers are calibrated with the help of reference radiation sources, so-called ‘black bodies’. These radiant sources are able to produce different temperatures with a high stability.  ...

Read more...
Thermal monitor for fever screening
30 June 2020, Actum Group , Test & Measurement
The TCSF256 thermal monitor from Actum Group is a fully automated, plug-and-play fever screening unit. It adopts an infrared radiation measurement technique that can measure body temperature by non-contact ...

Read more...
Uncover EMI issues early with simple pre-compliance tests
30 June 2020, Concilium Technologies , Test & Measurement
An effective pre-compliance testing methodology will reduce test cycle times, which ultimately impacts a company’s bottom line.

Read more...
The promise of 5G wireless communications
30 June 2020, Lambda Test , Test & Measurement
The deployment of 5G services worldwide is driving a massive increase in fibre densification for the required fronthaul and backhaul links interconnecting radio base stations and web-scale core packet networks.

Read more...
Phase noise analyser for precision oscillator characterisation
29 April 2020, Altron Arrow , Test & Measurement
To help research and manufacturing engineers make precise and accurate measurement of frequency signals, including those generated by atomic clocks and other high-performance frequency reference modules ...

Read more...
Ethernet tap for IO Ninja
25 March 2020, RF Design , Test & Measurement
Monitoring network communications of your PC can be accomplished without any specialised hardware – just use the Pcap Sniffer plugin of IO Ninja. The task of tapping into the Ethernet traffic of a non-PC ...

Read more...
Bench-top vector signal generator
29 April 2020, RFiber Solutions , Test & Measurement
The T3267E series bench-top vector signal generator from Transcom Instruments has excellent radio frequency performance and rich signal generating function. It can provide arbitrary wave, continuous ...

Read more...
Tektronix and Coherent Solutions partner for fully integrated optical comms
25 March 2020, Comtest , Test & Measurement
Comtest has announced that technology companies Tektronix and Coherent Solutions have an exclusive partnership agreement to provide fully integrated optical communications platforms to new and existing ...

Read more...