by Clive Rutter, Silicon Engineering

Before 1975, substation tripping batteries were very simple to choose: either lead acid or pocket plate nickel cadmium. The lead acid batteries were either Plante, designed during Michael Faraday’s time 170 years ago, or high antimony (Sb) traction tubular plate to give 1200 cycles. Both technologies provided theoretically long life (15 to 20 years) and pulse current ability. But both required an unbelievably high amount of maintenance. Then in 1975, Bell Telephone Labs gave the battery industry its growth projection for telecom batteries, indicating that the company did not have sufficient resources to undertake the maintenance.

The firm warned that if the battery industry did not reduce the amount of maintenance needed, it would have to find an alternative energy source. This resulted in the biggest battery development in history and suddenly, new low maintenance technologies appeared. Plante is a pure lead battery with limited cycles (only 50 to 100 cycles) and nothing could be done to reduce maintenance. The high Sb tubular was revolutionised by reducing Sb from 12% to only 1,6% and replacing with superior alloys such as Selenium (Se) in tiny quantities. Gates registered a patent in 1975 for a glass fibre so thin that sulphuric acid could adhere to it by surface tension only. This was the birth of the absorbent glass mat (AGM) valve, regulated with calcium (“sealed”) as the alloy to increase cycles.

There were further developments to overcome new operational problems such as turning the H2SO4 into a jelly by adding Silicon Dioxide SiO2. Nickel Cadmium (NiCd) faced a challenge since they did not use alloys to change as the cell was basically an intercalation type as opposed to a chemical reaction. Lithium is also an intercalation cell. The NiCd required six monthly maintenance and frequent boost charging. The new recombination technology NiCd has addressed this successfully, reducing maintenance intervals to three to five years. This means in the 20-year life of the battery maintenance is reduced from 40 times to only seven times. A reduction of 33 services over the battery life. That has saved maintenance costs in excess of the battery cost. 

One should only use recombination NiCd cells for this reason alone. By 1985, there was a plethora of new battery technologies on the market with each requiring their own charging and handling requirements. A high Sb LA cell requires frequent boost charging to prevent antimony poisoning and loss of cell capacity. Similar boost charging of AGM sealed cells results in high pressure and water loss through the vent valve or drying out with reduction of life. The users had a problem to ensure the correct charging protocol was used on their new technologies. Silicon Engineering embarked on a solution to this dilemma by defining all the protocols and then reviewing the current specifications in use.

We partnered with mines, railways, universities and even Eskom DC committee to make a universal specification to address the new low maintenance technologies. The conclusion of this partnership was that the old analogue, wall-to-wall PCB chargers were incapable of solving the issue. We decided to develop a microprocessor with intelligent capability and memory to ensure the chargers always charged and monitored the correct charge, no matter which technology was used. Remote monitoring and SCADA were an immediate free spinoff of this decision. Silicon Engineering contracted Siemens to develop the microprocessor and 35 systems were installed. The first was installed in Bisho in Eastern Cape in 1989. We soon found that a detailed knowledge of batteries was essential. We redesigned the system with new software and hardware all designed in-house. This was done in the days of the XT computer with DOS 3.1.

The advent of Windows 95 spurred an upgrade path, and the BMS-Plus was released. In 2020 we partnered with BHP Billiton to include SCADA in their requirements and our team added the BMS-Studio application to run on Windows, for really inexperienced users to monitor remotely. The BMS-Elite has an Event Recorder with up to 2000 events stored. Every alarm is included, and the same hardware can be used for a single charger, dual chargers, dual batteries, single or three phase and even dual BMS systems. BMS Elite has various internal alarms to self-diagnose nternal faults and report on the screen in English or other languages.

The 1989 models can be upgraded, virtually pin-for-pin with BMS Elite. Silicon BMS chargers have built in redundancy so even if the BMS fails, the charger continues to fully charge the battery. Many BMS features have now appeared in mainstream specifications such as periodic battery test. The event recorder makes complying with insurance requirements, to prove battery health, simple, by downloading the load test results monthly and sending to the insurance company. The remote capability has allowed large collective substation BTUs to be centralised and monitored from the control room. This is in operation in large shopping malls and large plants. A German engineering company uses the BMS Studio for remote monitoring of mine winder BTUs. Silicon BMS are also being used in nuclear power stations. The reach is over 60% of the African continent from Cape Town to West Africa. Substations used to use the CDG protection relay which was rotating disk mechanical mechanism. They replaced the CDG with the new electronic relay types (Micon, SEL, Solkor, Vamp, Ingeteam, etc.). Silicon BMS did the same to the tripping battery unit. Silicon BMS is far more cost-effective when compared with wall-to-wall PCB BTUs and delivery can be made in less than a week in many cases. The future is in technology. Good engineering saves you money every time.

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